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^^RICULTURE LIBRARY
:OOPERATIVE EXTENSION SERVICE
HOME, YARD ^ GARDF^^
f college of agricultural, consumer and environmental sciences, university ( '^-' ^
liege of agricultural, consumer and environmental sciences, university (
Illinois at urbana-champaign A Illinois natural history survey, champaign
I DrcT
NcvviLtriER
(,PR25B97
^G Ubrar^
No. 1» April 16, 1997
This is the first of 22 issues of the Home, Yard and Garden
Pest Newsletter. It will be prepared by Extension specialists
in plant pathology, agricultural entomology, horticulture,
and agricultural engineering. Timely, short paragraphs
about pests of the home and its surroundings will make up
the newsletter When control measures are given, both
chemical and nonchemical suggestions (when effective) will
be given.
Welcome
Welcome to the first issue of the 1997 Home, Yard
and Garden Pest Newsletter. The newsletter reports
on the appearance and management of diseases,
weeds, and insect pests of turfgrass and ornamental
plants in Illinois to the professional landscape
maintainer, arborist, lawn care specialist, golf course
superintendent, sod grower, nurseryman, and garden
center operator. Management methods and suggested
pesticides will primarily be those appropriate for the
professional rather than the homeowner. Many times,
however, the methods will be appropriate for
homeowner use.
We will publish 22 issues, most of which will be
four pages long, with an occasional longer issue.
Issues will be published biweekly during April,
weekly during May, June, and July, and then biweekly
again during August and September. There will also
be an issue near the end of October and another near
the end of November. All issues are published on a
schedule to coincide with pest management needs.
We welcome input concerning the newsletter. Let us
know what you like or dislike about our newsletter
and give suggestions on how it could be better. With
only a few authors for our articles, it is difficult for us
to see or hear about every pest problem that develops
throughout Illinois. If you see something unusual —
either in the fact or in the timing of its occurrence —
let one of the authors know or contact Phil Nixon, the
newsletter coordinator, at (217) 333-6650. If you wish
to discuss a specific article in the newsletter, contact
the author whose name appears in parentheses at the
end of the article. The author's telephone number will
usually be listed at the end of the newsletter. (Phil
Nixon)
PLANT DISEASES
Plant Clinic Opens May 1
The plant clinic serves as a clearinghouse for plant
problems sent to the University of Illinois. Diagnosis
is provided for trees, shrubs, turf, fruit, vegetables,
field crops, and almost any other type of plant you can
imagine. Specialists are called to help with diagnoses
as needed; in an average year, about 20 different
specialists may provide input on plant samples. Plant
clinic services include plant and insect identification;
diagnosis of disease, insect, weed, and chemical
injury (chemical residue testing is not available);
nematode assays; and help with nutrient-related
problems, as well as management recommendations
involving these diagnoses.
The University of Illinois Plant Clinic is open
May 1 through September 12, 1997. Much of the
operation of the clinic is supported by user fees. These
fees, which have not increased since last year, are
listed below. A check (payable to the University of
Illinois) should accompany each sample.
General diagnosis (including cuhures) $ 1 0
Specialty tests (SCN, PWN, ELIS A)* $ 1 5
Other nematodes (usUally com) $30
*SCN indicates the test for soybean cyst nematode. PWN
indicates pinewood nematode analysis. ELISA is a technique used
to test for various viral pathogens.
A specimen data form, or equivalent information,
should always accompany a plant sample. The ability
itate, County, Local Groups, and U.S. Department of Agriculture Cooperating
he Cooperative Extension Service-provides equal opportunities in programs and employment
(BS
to provide a thorough diagnosis is directly related to
the quality of the sample and the type of information
provided. (As the saying goes, "garbage in — garbage
out.") Each Cooperative Extension Service unit office
should have a copy of the specimen data form.
Photocopy these as needed. You can also find the
form in the Master Gardener Manual at the end of the
disease section (or the end of the IPM section, de-
pending on your version).
When submitting plant samples, prepare them to
survive a rough ride in a very hot mail truck. When
sending whole plants, wrap them as you would if you
intended them to be planted. Wrap soil and roots in
plastic to retain moisture and to keep soil off the
foliage. Do not wrap foliage in plastic. If only leaves
are sent, place them between cardboard and keep
them dry. We can always rehydrate dry material at the
clinic, but it is not possible to remove mold from
rotted tissue. Send as much of the plant as possible —
affected as well as healthy tissue — and carefully label
the sample. A photograph of the plant and surround-
ing area is always helpful.
When in doubt about how to package a sample or
what to send, call the clinic at (217) 333-0519. The
mailing address is Plant Clinic, 1401 West St. Mary's
Road, Urbana, IL 61802. Business hours are 8:00 a.m.
to noon and 1 :00 to 4:30 p.m., weekdays only. Ar-
rangements can be made to drop off samples at other
times. (Nancy Pataky)
Sphaeropsis Blight of Pine (formerly Diplodia
Blight)
This disease of pine has been quite devastating the
last several years. The fungal pathogen thrives in cool,
wet weather and often invades injured wood. We have
experienced lengthy, cool, and wet spring weather for
the past two years, and winter freeze-thaws have been
common. Ideal weather conditions, plenty of fungal
inoculum, and susceptible pines have set the stage for
Sphaeropsis blight. We see most problems on Austrian
and Scotch pines, but other pines are susceptible. The
disease may even occur on some fir and spruce
species.
The fungus {Sphaeropsis sapinea) infects young,
healthy, unwounded needles of new candles (new
growth), which is where we see the typical blighting
of branch tips. All needles in the terminal 6 inches or
so of growth turn brown and dry out. This phase of
the disease is unsightly but does not cause branch
death. Usually the tree develops new growth below
the dead area and results in crooked-looking branches
so typical of Austrian pine. The fungus may, however.
also infect the twigs of trees weakened by stress (such
as drought, compacted soil, root injury, hail, or winter
injury). Cankers develop on the twigs, usually causing
noticeable sap exudate at the canker. When the canker
girdles the twig, tissue beyond that point dies. In the
last two or three years, we have seen an increase of
Sphaeropsis twig blight at the clinic.
This disease is difficult to control. In fact, even the
best efforts do not always give 100 percent satisfac-
tory results. The first step is to recognize the disease.
Look for black pinhead-sized fruiting bodies of the
fungus in the brown needles at the tips of branches.
The combination of tip blighting and these fruiting
bodies is probably enough evidence to suspect
Sphaeropsis blight. If necessary, laboratory confirma-
tion is quick and easy.
Next, remove all dead wood (or as much as pos-
sible) from the tree. This is best done in the dormant
season but can be done at other times when the
foliage is dry. Cones are the next target for control.
You will find hundreds of the black fruiting bodies of
this fungus on cones, which serve as a major overwin-
tering site. Remove cones from the tree and the
surrounding ground.
We don't always advocate fungicide sprays for
disease control, but in this case chemicals are neces-
sary for near-complete control. Three sprays are
recommended: one at budbreak (very soon now), one
at half-candle elongation (about 10 to 14 days after
the first spray), and another at 10 to 14 days after the
second spray. Chemical options are listed in the 7997
Illinois Commercial Landscape and Turf Pest Man-
agement Handbook. University of Illinois Grounds
Department personnel have dealt with this disease and
have tried many chemicals. They have had the best
luck with Cleary 3336. This is not a scientific evalua-
tion but an observation of success. A product contain-
ing the same active ingredient and packaged for
homeowner use is called Ferti-lome Halt systemic.
For more details about this disease, consult Report on
Plant Diseases No. 625, a fact sheet available through
the Crop Sciences Department, Plant Pathology
Extension. (Nancy Pataky)
HORTICULTURE
Spring Cleanup and Preparation Tips
This has been a long, cold winter but spring is just
around the comer. Regardless of the amount of
cleanup you did last fall, some spring cleanup,
pruning, and preparation is needed.
i\o. I • /\prii 10, /yy/
Pruning Raspberries: Spring pruning of red and
yellow raspberries should be done before the buds
begin to swell. All short and weak canes should be
removed and the vigorous canes should be thinned so
they are 4 to 8 inches apart. Only the largest canes
should be saved. Cut the canes back to 3 or 4 feet. The
canes of everbearing varieties should be topped back
if they were not pruned after last fall's harvest.
Strawberries: On mulched strawberries, remove
part of the straw as the new growth starts. Remove the
excess and leave some of the straw between the rows.
Do not fertilize until after harvest is complete and the
patch is renewed.
Blueberries: Blueberry plants should be pruned
before the new growth begins. Remove dead or
injured branches as well as any short, stubby branches
near the ground. It is important to remove some of the
older branches to allow younger, vigorous branches to
develop. If the plants have an unusual load of fruit
buds, the tips of the branches can be cut back to 4 to 6
fruit buds. The fruit buds are large, round, and plump;
the leaf buds are smaller, thinner, and sharply pointed.
Cutting the fruiting branches reduces yields slightly,
but the berries will be larger.
Roses: Remove the covering (soil, leaves, cones)
on roses that were protected for the winter. Clean up
the rose beds by removing any leaves and debris that
could carry disease from one season to the next.
While the plants are dormant and the weather has
moderated, prune them to improve health, appearance,
and productivity. Begin by removing all dead, dam-
aged, and blackened wood. Cut down to healthy
wood, just above a leaf bud. Remove any crossing
branches, twiggy growth, or side growth. Take out old
wood at the bud union and leave 3 to 5 evenly distrib-
uted canes. Do not mulch at this time; a mulch will
^^aa^ tUa c-/-^;l nnn] unH clrju/ thp arnwth nf the bushes.
This volume Is bound without
which is/are unavailable.
buds. Do not prune back material until the buds start
to grow. Once new growth appears, prune dead
material back to the new growth, bud, or a branch.
(Jim Schmidt and Rhonda Ferree)
INSECTS
Phil and John Have Moved
John Lloyd and Phil Nixon, Extension entomologists
in the Department of Natural Resources and Environ-
mental Sciences, have moved to 103 A and 103B
Vegetable Crops Building, respectively. This move
puts them in better proximity to other Extension
colleagues in the department. If you have the opportu-
nity to stop by, feel free to do so. Their new mailing
address is Department of Natural Resources and
Environmental Sciences, University of Illinois at
Urbana-Champaign, 103 Vegetable Crops Building,
1 103 South Domer Drive, Urbana IL 61801 .
Tom Royer in Oklahoma
Tom Royer, former Extension entomologist at the
Edwardsville Extension Center, has moved south to a
position as assistant professor in the Department of
Entomology at Oklahoma State University. We will
certainly miss Tom's contributions to the Urban IPM
program and his numerous columns in this newsletter.
We already noticed a twinge of an Oklahoma accent
in his last e-mail. We wish him all the best in his new
position.
Multicolored Asian Ladybird Beetle
This home invader is once again becoming a nuisance
this spring as the weather warms. Adult multicolored
Asian ladybird beetles vary in color — as their name
sueeests — from pale yellow-orange to bright red.
illy have 17 spots on their elytra (shell), but
; as well. The multicolored Asian ladybird
s introduced into the United States to assist
ling soft-bodied insects such as aphids and
es. It was fairly successful and has adapted
nng and reproducing in the United States,
le unknown irripact this beetle is having on
lybird beetle populations, it tends to be a
for homeowners because of its overwinter-
).
;etles overwinter in cliff faces in their native
owever, the closest thing we have to cliffs in
id northern Illinois are buildings. If founda-
ing, and screens are in good repair, then most
to provide a thorough diagnosis is directly related to
the quality of the sample and the type of information
provided. (As the saying goes, "garbage in — garbage
out.") Each Cooperative Extension Service unit office
should have a copy of the specimen data form.
Photocopy these as needed. You can also find the
form in the Master Gardener Manual at the end of the
disease section (or the end of the IPM section, de-
pending on your version).
When submitting plant samples, prepare them to
survive a rough ride in a very hot mail truck. When
sending whole plants, wrap them as you would if you
intended them to be planted. Wrap soil and roots in
plastic to retain moisture and to keep soil off the
foliage. Do not wrap foliage in plastic. If only leaves
are sent, place them between cardboard and keep
them dr>'. We can always rehydrate dry material at the
clinic, but it is not possible to remove mold from
rotted tissue. Send as much of the plant as possible —
affected as well as healthy tissue — and carefully label
the sample. A photograph of the plant and surround-
ing area is always helpful.
When in doubt about how to package a sample or
what to send, call the clinic at (217) 333-0519. The
mailing address is Plant Clinic, 1401 West St. Mary's
Road, Urbana, IL 61802. Business hours are 8:00 a.m.
to noon and 1 :00 to 4:30 p.m., weekdays only. Ar-
rangements can be made to drop off samples at other
times. (Nancy Pataky)
Sphaeropsis Blight of Pine (formerly Diplodia
Blight)
This disease of pine has been quite devastating the
last several years. The fungal pathogen thrives in cool,
wet weather and often invades injured wood. We have
experienced lengthy, cool, and wet spring weather for
the past two years, and winter freeze-thaws have been
common. Ideal weather conditions, plenty of fu
inoculum, and susceptible pines have set the sta
Sphaeropsis blight. We see most problems on A
and Scotch pines, but other pines are susceptible
disease may even occur on some fir and spruce
species.
The fungus {Sphaeropsis sapinea) infects you
healthy, unwounded needles of new candles (ne\
growth), which is where we see the typical bligh
of branch tips. All needles in the terminal 6 inch(
so of growth turn brown and dry out. This phase
the disease is unsightly but does not cause brand
death. Usually the tree develops new growth bek
the dead area and results in crooked-looking brar
so typical of Austrian pine. The fungus may, how
also infect the twigs of trees weakened by stress (such
as drought, compacted soil, root injury, hail, or winter
injury). Cankers develop on the twigs, usually causing
noticeable sap exudate at the canker. When the canker
girdles the twig, tissue beyond that point dies. In the
last two or three years, we have seen an increase of
Sphaeropsis twig blight at the clinic.
This disease is difficult to control. In fact, even the
best efforts do not always give 100 percent satisfac-
tory results. The first step is to recognize the disease.
Look for black pinhead-sized fruiting bodies of the
fungus in the brown needles at the tips of branches.
The combination of tip blighting and these fruiting
bodies is probably enough evidence to suspect
Sphaeropsis blight. If necessary, laboratory confirma-
tion is quick and easy.
Next, remove all dead wood (or as much as pos-
sible) from the tree. This is best done in the dormant
season but can be done at other times when the
foliage is dry. Cones are the next target for control.
You will find hundreds of the black fruiting bodies of
this fungus on cones, which serve as a major overwin-
tering site. Remove cones from the tree and the
surrounding ground.
We don't always advocate fungicide sprays for
disease control, but in this case chemicals are neces-
sary for near-complete control. Three sprays are
recommended: one at budbreak (very soon now), one
at half-candle elongation (about 10 to 14 days after
the first spray), and another at 10 to 14 days after the
second spray. Chemical options are listed in the 1997
Illinois Commercial Landscape and Turf Pest Man-
agement Handbook. University of Illinois Grounds
Department personnel have dealt with this disease and
have tried many chemicals. They have had the best
luck with Cleary 3336. This is not a scientific evalua-
tion but an observation of success. A nrnHnz-t nr^ryfn,\r.
nfji II I o, I yy/
Pruning Raspberries: Spring pruning of red and
yellow raspberries should be done before the buds
begin to swell. All short and weak canes should be
removed and the vigorous canes should be thinned so
they are 4 to 8 inches apart. Only the largest canes
should be saved. Cut the canes back to 3 or 4 feet. The
canes of everbearing varieties should be topped back
if they were not pruned after last fall's harvest.
Strawberries: On mulched strawberries, remove
part of the straw as the new growth starts. Remove the
excess and leave some of the straw between the rows.
Do not fertilize until after harvest is complete and the
patch is renewed.
Blueberries: Blueberry plants should be pruned
before the new growth begins. Remove dead or
injured branches as well as any short, stubby branches
near the ground. It is important to remove some of the
older branches to allow younger, vigorous branches to
develop. If the plants have an unusual load of fruit
buds, the tips of the branches can be cut back to 4 to 6
fruit buds. The fruit buds are large, round, and plump;
the leaf buds are smaller, thinner, and sharply pointed.
Cutting the fruiting branches reduces yields slightly,
but the berries will be larger.
Roses: Remove the covering (soil, leaves, cones)
on roses that were protected for the winter. Clean up
the rose beds by removing any leaves and debris that
could carry disease from one season to the next.
While the plants are dormant and the weather has
moderated, prune them to improve health, appearance,
and productivity. Begin by removing all dead, dam-
aged, and blackened wood. Cut down to healthy
wood, just above a leaf bud. Remove any crossing
branches, twiggy growth, or side growth. Take out old
wood at the bud union and leave 3 to 5 evenly distrib-
uted canes. Do not mulch at this time; a mulch will
keep the soil cool and slow the growth of the bushes.
Perennial Flowers: This is also the time to care-
fully remove any mulch that was placed around
perennials to protect them. Don't be alarmed if no
new growth is evident; many plants are slow to
emerge in the spring. Unprotected plants or those
sensitive to temperature extremes may have damage
to the crowns or the plants may have "heaved" from
alternate freezing and thawing. Before removing any
plants, wait for temperatures to warm to see if any
growth appears.
Woody Ornamental Winter Injury: Some plants
are showing winter injury, particularly evergreens.
Use a wait-and-see approach. Regardless of the
amount of injury showing, most plants have viable
buds. Do not prune back material until the buds start
to grow. Once new growth appears, prune dead
material back to the new growth, bud, or a branch.
(Jim Schmidt and Rhonda Ferree)
INSECTS
Phil and John Have Moved
John Lloyd and Phil Nixon, Extension entomologists
in the Department of Natural Resources and Environ-
mental Sciences, have moved to 103 A and 103B
Vegetable Crops Building, respectively. This move
puts them in better proximity to other Extension
colleagues in the department. If you have the opportu-
nity to stop by, feel free to do so. Their new mailing
address is Department of Natural Resources and
Environmental Sciences, University of Illinois at
Urbana-Champaign, 103 Vegetable Crops Building,
1103 South Domer Drive, Urbana IL 61801.
Tom Royer in Oklahoma
Tom Royer, former Extension entomologist at the
Edwardsville Extension Center, has moved south to a
position as assistant professor in the Department of
Entomology at Oklahoma State University. We will
certainly miss Tom's contributions to the Urban IPM
program and his numerous columns in this newsletter.
We already noticed a twinge of an Oklahoma accent
in his last e-mail. We wish him all the best in his new
position.
Multicolored Asian Ladybird Beetle
This home invader is once again becoming a nuisance
this spring as the weather warms. Adult multicolored
Asian ladybird beetles vary in color — as their name
suggests — from pale yellow-orange to bright red.
They usually have 17 spots on their elytra (shell), but
this varies as well. The multicolored Asian ladybird
beetle was introduced into the United States to assist
in controlling soft-bodied insects such as aphids and
some scales. It was fairly successful and has adapted
well to living and reproducing in the United States.
Besides the unknown irripact this beetle is having on
native ladybird beetle populations, it tends to be a
nuisance for homeowners because of its overwinter-
ing habits.
The beetles overwinter in cliff faces in their native
habitat; however, the closest thing we have to cliffs in
central and northern Illinois are buildings. If founda-
tions, siding, and screens are in good repair, then most
beetles looking for hiding places in the fall will
remain outdoors. However, if gaps exist in the peri-
meter defense of a building, many homeowners will
have to deal with these unwanted guests.
As temperatures cool, the metabolism of the
ladybird beetles slows down and they become inac-
tive. When we have a period of continuous warm,
sunny days, their metabolism begins to increase, and
they once again become active. It is during this time
when most homeowners come in contact with lady-
bird beetles indoors, looking for a way to get out.
Ladybird beetles feed only on soft-bodied insects.
They will not damage anything indoors and can be
safely removed by vacuuming. Captured beetles can
be released outdoors, or can be drowned in a pail of
soapy water. We do not recommend the use of insecti-
cides to control overwintering ladybird beetles.
Buildings that had large populations of beetles
overwinter indoors should be examined during the
summer, and all screens, cracks in the foundation, and
gaps in the siding should be fixed to prevent the
influx again in the fall. (John Lloyd)
Scouting Report
Dormant oil spray can still be applied to most trees in
northern Illinois and to some trees in other parts of the
state. This pesticide, which works by covering and
suffocating exposed insects, is applied to control
overwintering aphid eggs and most scale insects. It is
not effective on scales that overwinter at least par-
tially as eggs, such as oystershell scale and pine
needle scale. The dormant oil spray is applied when
temperatures will be above 32°F (40°F for ever-
greens) for 24 hours after application. This allows the
oil to evaporate rather than soak into the plant and
cause damage. Do not apply to Japanese or sugar
maple. It will take the blue color off Colorado blue
spruce.
Eastern tent caterpillar and European pine sawfly
should be hatching in southern and central Illinois.
Acephate (Orthene), carbaryl (Sevin), and chlor-
pyrifos (Dursban) are among the many insecticides
effective against these insects. Bacillus thiiringiensis
kurstaki, sold as Dipel, Thuricide, and other trade
names, is an effective and highly recommended
control for Eastern tent caterpillar. It is ineffective
against sawflies because they are wasp larvae, not
caterpillars.
The blooming of Magnolia X soulangiana, saucer
magnolia, is associated with several occurrences in
insect activity, according to Don Orton in the book
Coincide. This excellent book is inexpensive (about
$20) and should be on the shelf of every professional
involved in the management of insect pests on orna-
mental trees and shrubs. Saucer magnolia was in full
bloom during the week of April 6 in central Illinois.
Refer to the 7997 Illinois Commercial Landscape and
Turf Pest Management Handbook for suggested
controls.
Cooley and eastern spruce gall adelgids are active
and controllable on warm days when saucer magnolia
is in pink bud. Once blooming occurs, control will not
be effective on spruce, although control on Douglas-
fir is possible throughout the growing season.
Zimmerman pine moth larvae are active at early
bloom of saucer magnolia and can be controlled with
applications of chlorpyrifos (Dursban) or dimethoate
(Cygon).
Cankerworms hatch during bloom of saucer
magnolia and may be common on elm, hackberry,
honey locust, maple, and other trees. Sprays of
Bacillus thuringiensis kurstaki (Dipel, Thuricide) are
very effective, as are other insecticides. This insect is
not as common in Illinois as it was before Dutch elm
disease eliminated most of the American elms. The
cankerworm has been numerous in some areas of
northeastern Illinois for the last several years.
Ash plant bug adults overwinter and become active
on ash during the late bloom of saucer magnolia. They
can be controlled with sprays of acephate (Orthene),
insecticidal soap, and pyrethroids such as bifenthrin
(Talstar) and cyfluthrin (Tempo). Treating now will
prevent the stippling and leaf distortion caused by this
insect on ash leaves. (Phil Nixon and John Lloyd)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon and John Lloyd,
(217) 333-6650. and Fredric Miller, (708) 352-0109.
entomologists; Nancy Pataky, plant pathologist,
(217) 333-0519; and Rhonda Ferree, Tom Voigt, and David
Williams, horticulturists, (217) 333-0350. Phil Nixon is the
executive editor of the Home, Yard and Garden Pest
Newsletter. This newsletter is written by faculty in the
Department of Natural Resources and Environmental
Sciences and the Department of Crop Sciences. The
newsletter is edited by Peggy Currid, typeset by Oneda
VanDyke, and proofread by Herbert Morgan, all of
Information Services.
COOPERATIVE EXTENSION SERVICE
HOME, YARD & GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
illinois at urbana-champaign A i II inois natural history survey, champaign
NEWSLETTER
No. 2 • April 30, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard,
and garden. Current control procedures, application
equipment and methods, safe storage and disposal of
pesticides, and other topics of interest are discussed.
INSECTS
1997 Illinois Woody Plant & Pest Diagnostic
Workshop
The Illinois Arborist Association, in cooperation with
the University of Illinois and the Morton Arboretum,
is sponsoring a diagnostic workshop for professionals
interested in learning how to diagnose plant problems.
The workshop is scheduled for May 30 and 31 at the
Morton Arboretum in Lisle, Illinois. Plant patholo-
gists, entomologists, and horticulturists will instruct
professionals in the diagnostic process and will
provide hands-on experience with common, and not
so common, Illinois plant and pest problems in the
laboratory and the field. Hand lenses, pruning shears,
and pocket knives are required. Rain gear is optional.
Participants in this workshop will receive preference
when registering for the 1997 Plant Health Care
Workshop in Indianapolis. Contact Julie Ruffolo (630)
960-5922 to register for the diagnostic workshop.
Space is limited, so register early. This workshop will
provide ISA Certified Arborist CEUs. (Phil Nixon)
1997 Midwest Plant Health Care Workshop
The 1997 Midwest Plant Health Care Workshop is
scheduled for July 11 and 12 in Indianapolis. This
hands-on workshop is being hosted by the Indiana
Arborist Association and Purdue University and is
designed to assist professionals in developing and
maintaining productive Plant Health Care (PHC)
programs for residential and commercial/municipal
properties. Dr. John Ball will lead discussions about
using PHC in landscape situations. Outdoor field
sessions with PHC and pest management experts from
Indiana, Illinois, and Ohio will take participants
through the process of mapping properties, diagnosing
plant problems, interacting with property owners, and
making management decisions using the Appropriate
Response Process (ARP). Space is limited. Partici-
pants in Illinois, Indiana, Missouri, or Ohio diagnostic
workshops will receive preference when registering.
Contact Rita McKenzie at Purdue University (765)
494-3625 for registration information. This workshop
will provide ISA Certified Arborist CEUs.
(Phil Nixon)
Plant Clinic to Handle Insect IDs
All "urban" ornamental and structural insect speci-
mens sent in to the University of Illinois will now be
processed by the University of Illinois Plant Clinic. A
$10 fee will be charged for this processing. This
arrangement will better facilitate the response time
and handling of specimens that were previously sent
directly to specialists on campus. Samples will still be
identified by the specialists, but records will be
retained by the Plant Clinic. We sincerely appreciate
the willingness of the Plant Clinic staff to assist us
with this effort. (John Lloyd and Phil Nixon)
Eastern Tent Caterpillar
Traveling with an entomologist this time of year may
be detrimental to your health. Extension entomologist
Phil Nixon, who is the unrivaled Illinois champion
window scouting surveyor, can spot eastern tent
caterpillar tents from a distance of over 1 00 yards
while driving 65 m.p.h (yeah, right!) with one hand
on the wheel, a foot on the gas, and his camera with
telephoto lens pointing out the open driver's side
window.
A C^p C College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urbana-Champaign
ces
Helping You Put Knowledge to Work — State • County • Local Groups
U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
opportunities in programs and employment.
While driving down 1-57 south of Effingham, Phil
counted approximately 15 tents per tree, which sug-
gests we are likely to see some sizeable populations of
this pest in the southern part of the state.
Tents of eastern tent caterpillar begin to form in
branch crotches of infested trees each spring. The
caterpillars leave the tents during the day to feed on
new foliage and return in the evening to the protection
of the tent. Small tents and caterpillars can be easily
removed by hand in the evening on accessible plants.
Severe infestations and hard-to-reach tents can be
treated with Bacillus thuringiensis kurstaki (Dipel,
Thuricide) to prevent further defoliation. Other
insecticides listed in the 1997 Illinois Commercial
Landscape and Turf Pest Management Handbook will
also effectively control this pest. Penetrating the tent
with the compounds and treating adjacent foliage in
the evening will help ensure control. Healthy plants
defoliated by this caterpillar will refoliate later in the
spring. (John Lloyd)
Pine Sawfly
Pine sawfly is present throughout the state, particu-
larly on Scotch and mugo pine. Young larvae are one-
eighth to one-quarter of an inch long and light gray to
pale green with large black heads. They feed in a
group on the needles. As they mature, the larvae get
larger and develop a series of light- and dark-green
stripes. Although these insects look like caterpillars,
they are really wasp larvae and thus are not controlled
by Bacillus thuringiensis kurstaki (Dipel, Thuricide).
They can be controlled with a broad-spectrum insecti-
cide such as carbaryl (Sevin) or chlorpyrifos
(Dursban). (Phil Nixon)
Leafminers: Artists in Their Own Way
Leafminers are immature larvae of beetles, flies,
wasps (sawflies), and moths. Once females lay eggs
on the surface of host plants (sometimes directly in
host plants), larvae will hatch and burrow into leaves
and feed between the upper and lower leaf surfaces.
Damage from leafminers is primarily aesthetic — only
very heavy infestations are likely to affect tree health.
Their feeding behavior will discolor leaves in one of
two patterns: serpentine leaf mines or blotch leaf
mines. Serpentine leaf mines are snakelike in appear-
ance. On the other hand, blotch leaf mines are simply
irregular blotches on the leaves. It is quite easy to
determine if a leafminer is present. Hold the leaf up to
a light source and look for the larva(e) and small
excrement pellets. Many different leafminers occur in
IHinois. Here are a few examples.
Birch leafminer (sawfly): Birch leafminer pupae
overwinter in soil at the base of infested birch trees.
Adult sawflies fly to leaves in early May, about one
week after leaves unfold. Eggs are laid within young
leaves. Larvae mine leaves for two to three weeks, until
they chew a hole in the leaf and drop to the ground to
pupate. There are three to four generations per year.
Controlling the first generation (mid-May) will, for the
most part, reduce not only this generation, but also
subsequent generations throughout the summer. This
leafminer is most damaging in northern lUinois.
Hawthorn leafminer (sawfly): Adults emerge in
early May. Eggs hatch a few days after being laid
within the leaves. At the end of May, larvae leave
their mines and pupate within the soil. Overwintering
also takes place in the soil. Hawthorn leafminers have
only one generation per year. Controls should be
applied around the first of May (caution: acephate
may bum some varieties of hawthorn). As with the
birch leafminers, monitor trees for adult activity as
well as egg-laying scars on the leaves.
Locust leafminer (beetle): As temperatures begin
to warm in the spring (May), overwintering adults
become active, when feeding, mating, and laying eggs
on new leaves takes place. Eggs will hatch in mid- to
late May, with extensive mining visible during the
first part of June. Unlike the other leafminers, locust
leafminers pupate within leaves. Adults emerge and
lay eggs. Locust leafminers have two generations per
year. Insecticidal control is most effective against the
adults. Make sure that the leafminers are not in the
late larval stage or in the pupal stage because they are
not readily susceptible to pesticides. This leafminer is
most noticeable in southern Illinois.
Holly leafminer (fly): Holly leafminer larvae
overwinter in leaf mines. Larvae then pupate in late
March or early April. Adults emerge and lay eggs over
a period of six weeks. A contact insecticide can be
applied every ten days from early April through May
to control the adults.
Oak leafminer (moth): Oak leafminer is primarily
a late-season pest with mines first appearing in early
summer. White and bur oaks are the most heavily
attacked species, with several generations of caterpil-
lars causing heavy aesthetic damage by the end of the
growing season. Because this leafminer overwinters
as pupae in fallen leaves, raking up and disposing of
these leaves will reduce the infestation as long as any
nearby forest areas are not infested. Sprays applied
when new mines first appear will help reduce later
damage.
No. 2 • April JU, I yy/
Control of leafminers involves more than one type
of management. First, keep trees properly watered and
fertilized. Second, consider natural enemies when
determining whether a pesticide should be imple-
mented. Natural enemies are normally present and can
easily fmd leafmining larvae. Round holes through
the leaf surface over a mine or dead larvae in the mine
are evidence of natural enemy attack. Third, systemic
insecticides, such as acephate (Orthene), avermectin
(Avid), and imidicloprid (Merit), are very effective
against young leafminers. Always read and follow
label directions when using pesticides. (Corey K.
Gerber, Purdue University, and Phil Nixon)
PLANT DISEASE
What's New at the Plant Clinic for 1997?
There is one small yet significant change for those of
you sending samples by mail. Urbana is now large
enough that the postal service has split it into several
zip codes. The Plant Clinic zip code is now 61802
rather than 61801.
A more exciting change is the connection of the
clinic to the University fiber optics system. Our
building is at the South Farms and had not been con-
nected to the computer cable system on the main
campus. Modems did not provide acceptable speed
and were subject to frequent transmission problems.
Now that the fiber optics line has been connected to
the building, the Plant Clinic will soon be connected
to computers for access to e-mail and the Internet. We
will provide information about how this can speed up
clinic responses to CES offices and others with e-mail
addresses. We look forward to many other improve-
ments through this new connection.
A final change is that all insect samples will now
be processed by the clinic. This is not a big change for
clinic staff because many insect samples were handled
this way in the past. However, all insect samples will
now be given a clinic number and all paperwork
associated with those samples will be handled by the
clinic. The entomology specialists who handled your
samples in the past will be the same specialists who
handle your samples now. The difference is that the
samples will be opened, logged, and prepared for
diagnosis even if your chosen entomologist is out of
town. This process should speed up responses and
will definitely save time for those specialists. As with
any clinic samples, the same fees will be applied.
(Nancy Pataky)
Turf Disease
We have received many inquiries about dead or
yellow areas in turf. The most common concern is
what can be sprayed on the lawn to stop the "disease."
This is not an infectious disease and does not warrant
any fungicide applications. Much of the yellowing of
blades of turf or patches of yellow turf has been
attributed to cold temperature injury. This is particu-
larly true with tall fescue. As temperatures remain
consistently warm, turf color should begin to improve.
The only infectious disease we have seen so far this
year, and only in a few cases, is leaf spotting. The
Helminthosporium types, or possibly Curvularia, are
caused by fungi and result in leaf-spotting lesions. We
tend to see these more readily in cool conditions on
poor, compacted soils or in areas under stress. Rather
than rush to apply a fungicide, follow these cultural
practices:
• Fertilize to encourage moderate growth of the turf,
but avoid high rates of nitrogen.
• If watering is necessary, apply in the morning to
encourage drying of the blades before evening.
• Mow at the recommended height for the species.
Closely mown lawns have more problems with leaf
spots.
• Open up the area to air flow by pruning surround-
ing plants and avoiding dense plantings.
• Consider resistant turf grasses, which are readily
available.
If fungicide control is determined to be necessary,
consult pages 11 and 15 of the 1997 Illinois Commer-
cial Landscape and Turf Pest Management Handbook
for recommended chemicals; see page 17 for turf
RPDs. Chemical applications provide only temporary
control of leaf spots. Cultural controls and use of
resistant varieties will provide long-term control.
Consult Report on Plant Diseases No. 405 for details
about these diseases. (Nancy Pataky)
Cedar-Apple Rust Sporulation
Cedar-apple and related rusts are rust diseases caused
by the Gymnosporangium spp. of fungi. They require
two hosts to survive. Part of the fungal life cycle
occurs on the cedar (actually a Juniperus species), and
the remainder of the life cycle occurs on apple, crab-
apple, hawthorn, or quince. Galls form on the infected
twigs of the cedar (actually red cedar or other juni-
pers). In wet periods of spring, these galls produce
spores that are blown to the broadleaf host, causing
further infection. In late summer, the spores on the
broadleaf host form and blow back to the juniper host.
This series of events, called the disease cycle, ex-
plains how the disease is perpetuated from season to
season.
Juniper galls can be seen in winter and spring.
They begin as dark brown galls and range from one-
quarter to more than one inch in diameter. In spring,
they develop orange to yellow horns or gelatinous
tendrils that release rust spores. The galls and spore
horns are conspicuous and often quickly gain the
attention and concern of homeowners. Plant patholo-
gists think they are pretty.
Juniper-quince rust forms more of a canker on the
stems than an actual gall. (It may also cause bark
cracking.) Still, these cankers will also become
gelatinous. Spore horns on juniper galls have begun to
show in central Illinois. The galls will dry down and
re-swell with the weather, releasing six to eight crops
of spores. If the juniper infection is fairly light,
removal of the galls may help control the disease,
especially if there are no other infected junipers
nearby. Remove galls in dry weather. The rust dis-
eases usually do not have much impact on the juni-
pers, but preventing juniper infection will prevent
further spread of the rust.
The best option for disease control is the use of
resistant varieties. There are many crabapples and
hawthoms with resistance. For established trees,
fungicides may be necessary. Usually the broadleaf
host is targeted. Many fungicide application instruc-
tions suggest initiating sprays when new growth
begins. If you are able to use one of the sterol-
inhibitor fungicides, sprays can be started when
nearby apples are in the pink bud stage. A second
spray with a sterol inhibitor should occur three weeks
later. Protectant (contact) sprays would have to be
applied more often, every seven to ten days being the
usual recommendation. Because fungicide resistance
may occur with the sterol inhibitors, a combination of
sterol inhibitor and contact fungicide is best. Be
certain to follow label directions carefully. Sprays
should be continued until galls dry up for the fmal
time — usually two to three weeks after petal fall. For
more information on rust diseases of apple, crabapple,
and hawthorn, consult Report on Plant Diseases No.
802. (Nancy Pataky)
Baking Soda as a Fungicide
Several years ago I reported in this newsletter that
work was in progress to register a formulation of
sodium bicarbonate as a fungicide. At that time, it was
anticipated that this would occur within months!
Recently there have been follow-up questions about
the use of baking soda to prevent disease, and I
promised to find out more about the topic.
First, any product we recommend to control a pest
must be a registered pesticide. We cannot recommend
a home remedy unless it bears a chemical registration
and label, regardless of how safe we think it is. This is
the law.
Research has shown that the use of sodium bicar-
bonate prevents some fungal diseases and that some
of its relatives, potassium bicarbonate and potassium
carbonate, also work when combined with sodium
bicarbonate. The chemical must be applied in such a
way that it can be spread over the plant. In other
words, it needs a carrier. The active ingredient and
carrier must be safe and must also pass the same tests
that any fungicide must pass to ensure that the entire
product is safe to apply to plants. Therein lies the rub.
My digging so far has found that the big chemical
companies have given up on this registration. I have
reason to believe that it may still be in the works with
a small company.
I will keep you posted. Meanwhile, we do not
recommend the use of baking soda or any other
product as a pesticide unless it is registered and the
label clearly states its use. (Nancy Pataky)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon and John Lloyd,
(217) 333-6650, and Fredric Miller (708) 352-0109,
entomologists; Nancy Pataky, plant pathologist,
(217) 333-0519; and Rhonda Ferree, Tom Voigt, and David
Williams, horticulturists, (217) 333-0350. Phil Nixon is the
executive editor of the Home, Yard and Garden Pest
Newsletter. This newsletter is written by faculty in the
Department of Natural Resources and Environmental
Sciences and the Department of Crop Sciences. The
newsletter is edited by Peggy Currid, typeset by Oneda
VanDyke, and proofread by Herbert Morgan, all of
Information Services.
^-^5 COOPERATIVE EXTENSION SERVICE
JUN 2 6 1997
HOME, YARD & GARDEN PES!
college of agricultural, consumer and environmental sciences, university of
illinois at urbana-champaign a i 11 i nois natural history survey, champaign
NEWSLETTER
No. 3 'May?, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
HORTICULTURE
Wildflowers: Friend or Foe?
Many wildflowers are blooming in yards across the
state. These include Star-of-Bethlehem, spring beauty,
violet, and trout-lily. Some people want these plants
in their yard, particularly in naturalized areas. How-
ever, others find them quite undesirable, particularly
in well-maintained lawns.
Star-of-Bethlehem results in a number of calls to
Extension. Like other small, spring bulbs, it sends up
dark green foliage at the first hint of spring. In a lawn,
most homeowners mistake it for wild onion or garlic.
However, Star-of-Bethlehem does not have a strong,
onionlike smell. Its leaves are flat and have a solid
core. If not mowed, Star-of-Bethlehem will produce a
flower stalk in mid-May that will have a set of small,
star-shaped white flowers.
To keep or increase any of these plants, allow them
to flower and set seed; most will self-sow. Delay
mowing for as long as possible to build up food
reserves in the perennial root structures. Avoid
applying postemergence herbicides directly to the
plants you wish to keep. Finally, be aware that all of
the plants mentioned, except violet, die back to the
ground as the weather warms up and within a few
weeks will no longer be noticeable.
For those who want to get rid of these wildflowers,
we also have a few suggestions. Combination prod-
ucts containing 2,4-D, triclopyr, or clopyralid are
preferred. A repeat application may be necessary to
eliminate this "weed." (Rhonda Ferree, adapted from
The Ohio State University Extension's The P.E.S.T.
Newsletter, 21 April 1997, Vol. 6, No. 3)
Cool Temperatures Stall Turf Growth
Cool temperatures have stalled turf growth and
development during spring 1997. Recently, one
central Illinois turf manager indicated that the soil
temperature at his golf course was 48°F on April 24
and, except for perennial ryegreiss, very little turf
growth was taking place. During a recent trip to the
southern part of the state, I saw zoysiagrass and
bermudagrass with partial green-up, but putting on
virtually no growth. After a warm spell in early
spring, turf growth has indeed been interrupted.
Stalled growth this spring makes sense, given the
temperatures and turfgrass physiology. Spotty, uneven
growth was a common response to the cold and was
seen in many parts of Illinois this spring. There are
certainly species-response differences to the cold. It
has been reported that bunchtype grasses may initiate
shoot grov^h before the spreading species do. Among
spreading types, spring green-up of creeping
bentgrass is typically slow, while Kentucky bluegrass
is usually much better. What's more, differences
within a given species can occur. Based on data
collected in 1996 and 1997 in Urbana, 'Shamrock'
and 'SR2000' were among the Kentucky bluegrasses
that showed early spring green-up and growth, while
others (for example 'Baron' and 'Unique') showed
slower green-up.
Chilling injury that caused a loss of chlorophyll
was also seen in parts of Illinois. It was most com-
monly manifested as yellow patches of mowed tall
fescues.
A (^^P C College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urbana-Champaign
ces
Helping You Put Knovirledge to Work— State • County • Local Groups
U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
opportunities in programs and employment.
Table 1. Temperature ranges and growth responses
Growth response
Temperature range
optimal cool-season turf root growth
optimal cool-season turf shoot growth
optimal warm-season turf root growth
optimal warm-season turf shoot growth
optimal rhizome development
optimal stolon development
50-65°F (soil temperature)
60-75°F (at soil surface)
7(>-90°F (soil temperature)
80-95°F (at soil surface)
temperatures similar to those for root development
appears to occur at temperatures similar to those for optimal
shoot growth
Table 2. Optimal temperatures for seed germination for cool-season turfgrasses
Turf grass species
sheep and red fescues
creeping bentgrass and Kentucky bluegrass
chewings fescue
perennial ryegrass and tall fescue
Source: Beard, 1977, Turfgrass Science and Culture.
Temperature range
Approximately
16
Approximately 8
hours per day
hours per day
59°F
77°F
59°F
86°F
68°F
77°F
68°F
86°F
Table 1 presents growth responses and the tempera-
ture ranges in which they most optimally occur. Be
aware that these are not absolutes. For example,
Kentucky bluegrass root growth is optimum at 60°F.
Management practices such as mowing and fertiliza-
tion can have some effect as well.
Dormant or spring-seeded turfgrasses may be slow
to germinate this season due to the cold soil tempera-
tures. While germination can occur at temperatures
below the optimum required, germination is usually
slow and sporadic. Optimal germination occurs when
soil temperatures alternate during a daily period; these
optimal temperatures for cool-season turfgrasses are
shown in Table 2.
Cool temperatures may alter other turf management
practices as well. For instance, such practices as core
cultivation may be delayed until the turf is actively
growing. Also, keep in mind that cool temperatures
may postpone the need for pest control applications
this spring and summer (Tom Voigt)
INSECTS
Internet Resources for Northern Illinois
Extension educators in horticulture and Integrated
Pest Management in the Chicago area have placed
pest management and horticulture fact sheets and
newsletters on the World Wide Web for homeowners
and professionals in northern Illinois. These fact
sheets and newsletters can be accessed via the
University of Illinois Cooperative Extension Service
home page (www.ag.uiuc.edu) through the Urban
Programs Resource Network.
Also available on the Web is Horticulture Inside
Lines, a newsletter for the commercial horticulture
industry in the Chicago area (www.aces.uiuc.edu/
-uplink/Resources/hil.html), lawn care fact sheets for
northern Illinois (www.aces.uiuc.edu/~uplink/
Resources/lawntalk.html), and The Bug Review, a
guide to common household and garden pests in
northeastem Illinois (www.aces.uiuc.edu/~uplink/
bugreview/bu greview.html). (John Lloyd)
Spruce Spider Mites
Overwintered eggs of spruce spider mites have now
hatched in central and southern Illinois, and popula-
tions of this cool-season mite are beginning to build.
Thorough coverage of green foliage is necessary to
achieve maximum efficacy with any of the miticides
recommended in the 1997 Illinois Commercial
Landscape and Turf Pest Management Handbook. As
a cool-season pest, spruce spider mites may be a
problem again this fall. Since it is unlikely that any
spring application will provide 100 percent control.
dy /, lyy/
the progeny of the "leftovers" can contribute to high
populations during the cool fall months.
Remember that spider mites also serve as food for
many predaceous mites. Using miticides may in some
cases aggravate problems by killing the predators that
are feeding on the spider mites. This may release the
spider mites from the natural control that keeps their
populations in check. A simple test can be used to
determine whether you have spider mites or preda-
ceous mites. Shake the branch in question over a white
paper tablet or other firm white surface. If you notice
little yellowish "dots" running all over the place, you
probably have predatory mites. Spider mites tend to be
less active. For those who really want to "get into" the
examination, squish the dots on the paper. If they make
a green streak they are plant-feeding mites — most
likely spider mites. A yellow-orange streak means that
you should feel extremely guilty for sacrificing one of
the predators.
Another word of caution: tiny "rust" mites of spruce
may also be active. These truly cool-season mites are
active in November and December and again from
March until mid-May. They can cause considerable
yellowing and bronzing of the foliage and premature
needle drop. Rust mites, combined with spruce spider
mites, are one of the leading causes of needle drop in
dwarf Alberta spruces, so look closely! Spruce may be
infested with the cigar-shaped rust mites as well as the
more rounded spruce spider mites. Rust mites can be
controlled with any registered miticide. Again, cover-
age must be thorough. (David Shetlar, The Ohio State
University, and John Lloyd)
Spring Grub Control
Annual white grubs will be coming up to feed through-
out Illinois as the soil in the root zone rises to 50°F.
These grubs feed for only a short time in the spring
before pupating and do not need to be controlled
unless you have new sod or newly seeded turf in areas
that were damaged last fall by grubs. In cases where
the turf is becoming established, the loss of even a few
roots can be a problem. Several insecticides are
suggested for control, including imidicloprid (Merit,
Grubex), trichlorfon (Dylox, Proxol), bendiocarb
(Turcam, Intercept), and diazinon.
Ever since imidicloprid came on the market as
Merit and Grubex, there have been questions about
early season applications. This insecticide will last
three to four months, so it is feasible to apply it in
April or May for grub control in late July and August.
Certainly on golf courses where black turf grass
ataenius is a problem, treating with Merit in May
when Vanhoutte spirea is in bloom makes sense to
control this insect. This Merit application will likely
last into late summer and control hatching grubs,
although superintendents are advised to look for grubs
in early August and treat if numbers warrant it.
Applying Grubex or Merit before July is not
recommended. By waiting until July, you can deter-
mine the likelihood of a treatable infestation, due to a
small adult grub flight or sufficient rainfall to keep
unirrigated soil moist and turf green. Such conditions
will usually result in a small, undamaging grub
population. Also, there is some evidence to suggest
that older residues of imidicloprid result in a higher
percentage of control failures.
Thus, we recommend that insecticide application
for annual white grubs should normally be done either
in early July or early August, depending on the
conditions and the insecticide used. (Phil Nixon)
PLANT DISEASES
Plant Disease Fact Sheets
Many of the disease articles in this newsletter end
with an RPD number that refers to an additional
source of information — for example, "Refer to RPD
No. 621 for more information on anthracnose of shade
trees." RPD stands for Report on Plant Diseases.
These informational summaries on plant diseases in
Illinois are prepared by the Department of Crop
Sciences and contain a wealth of information about
the disease-causing organism(s), conditions needed
for infection, and prevention and control strategies. A
list of RPDs involving diseases of ornamental plants
is printed in the 7997 Illinois Commercial Landscape
and Turf Pest Management Handbook, and a list will
also be printed in the pest control circular for
homeowners.
RPDs may be obtained from your local Coopera-
tive Extension Service office or from the Department
of Crop Sciences. Each report costs $1. Make your
check payable to the University of Illinois, and send
the order to Department of Crop Sciences, Plant
Pathology Extension, N-533 Turner Hall, 1102 South
Goodwin Avenue, Urbana, IL 61801. (Nancy Pataky)
Bicarbonate Update
After more digging by Bruce Paulsrud and some help
from researchers at Cornell University, we have more
information about the use of sodium bicarbonate
(baking soda) as a preventive fungicide. (See Issue
No. 2, April 30, 1997, of this newsletter for the first
part of this story.)
Both sodium bicarbonate and potassium bicarbon-
ate have been registered with the Environmental
Protection Agency for use as fungicides. This means
the active ingredients are registered. An environmen-
tally friendly formulation containing potassium
bicarbonate as the active ingredient along with
surfactants has been submitted to the EPA and awaits
label approval. This formulation is called "Armicarb
Potassium Bicarbonate," and its use will include
prevention of some foliar fungal pathogens of orna-
mental plants. It is anticipated that Armicarb Potas-
sium Bicarbonate may be available in some states this
summer. (The registration of Armicarb Sodium
Bicarbonate is still in a holding pattern.) We couldn't
find any specific host information but expect both of
these products to provide some control of black spot
and powdery mildew on roses at the very least (based
on research abstracts found in the literature).
There was also some mention in the EPA search
that a product known as Kaligreen has been submitted
for registration. It contains potassium bicarbonate and
targets powdery mildew on grapes, cucumbers,
strawberries, tobacco, and roses. Again, the product
has not yet been approved; it is waiting for label
approval. We will try to report progress as it occurs.
(Nancy Pataky)
Rhizosphaera Needle Cast of Spruce
This fungal disease is a particular problem on Colo-
rado blue spruce, but it may also infect other spruce
species, as well as some pines. If you have had a
problem with this disease in the past, now is the time
to take action to help your tree.
How do you know you have had problems? The
disease will cause first-year needles to turn brown to
purple in the fall. Keep in mind, however, that many
environmental stress factors will cause these same
symptoms. On trees with Rhizosphaera needle cast,
the affected needles may stay attached until the next
summer or fall. This needle cast disease evenmally
causes needles to fall (thus the name) and may kill
twigs if infection recurs from year to year. Often the
newest needles appear as green, healthy tufts at the
end of defoliated branches. Infected trees appear to
have "holes" scattered throughout the canopy. When
infected needles are moist, the fungal pathogen will
form pinhead-sized fruiting structures (pycnidia) in
neat rows on the needles. Place affected needles in a
plastic bag with a wet paper towel and pycnidia
should develop within one to two days. These pyc-
nidia actually protrude from the needle surface, so
they are readily visible — especially with a hand lens.
The presence of symptoms and fruiting bodies as
described is all that is necessary to confirm this
disease.
As with most fungal diseases, infection occurs in
warm, wet weather. With Rhizosphaera needle cast,
spores are released from spring until fall. Good air
circulation will help prevent infection, so prune
surrounding plants to attain better air movement, or
consider removing crowded plants. Fungicides are
effective as a preventive control but must be applied
when needles are half elongated and again when fully
expanded. Chemical options are given on page 89 of
the 7997 Illinois Commercial Landscape and Turf
Pest Management Handbook. (Nancy Pataky)
New Publication on Resistant Plants
A publication was recently brought to my attention
that may be of interest to many of you: Pest Resistant
Ornamental Plants, compiled by Deborah C. Smith-
Fiola at Rutgers University. It is based on trials
around the country and lists resistance to insects and
diseases. The publication sells for $7.00 plus $1.70
shipping. Order from Ocean County Board of Agri-
culture, Rutgers Cooperative Extension, 1623
Whitesville Road, Toms River, NJ 08755-9720.
(Nancy Pataky)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd, (217) 333-6653, andfredric Miller, (708) 352-
0109, entomologists; Nancy Pataky, plant pathologist,
(217) 333-0519; and Rhonda Ferree, Tom Voigt, and David
Williams, horticulturists, (217) 333-0350. Phil Nixon is the
executive editor of the Home, Yard and Garden Pest
Newsletter.
t
OOPERATIVE EXTENSION SERVICE
^m 2 6 1997
AG ! )>>•-. n/
HOME, YARD & GARDEN PEST
college ot agricultural, consumer and environmental sciences, university of
Illinois at urbana-champaign a i 1 1 inois natural history survey, champaign
NEWSLETTER
No. 4 « May 14, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
Pest Management Handbooks
The Illinois Urban Pest Management Handbook has
been divided into separate publications to better meet
the needs of its users. Suggestions for the manage-
ment of weeds, diseases, and insect pests of profes-
sionally managed turfgrass and ornamental plants will
be found in the 7997 Illinois Commercial Landscape
and Turf Pest Management Handbook ($8). This book
will continue to be revised annually.
The Illinois Homeowners ' Pest Management Guide
will contain suggestions to homeowners for the
management of insect pests, diseases, and weeds of
turf, ornamentals, vegetables, and fruit. Information
on indoor insect pest management will also be in-
cluded. The book will be available later this spring
and will be revised every few years as necessary.
Aquatic weed management suggestions are now
available as a separate circular for $2. Greenhouse
and interiorscape insects and disease management
suggestions will be available as a separate circular
later this spring. A rights-of-way weed management
circular will be available next year. Until then, refer to
rights-of-way weed management suggestions in the
7996 Illinois Urban Pest Management Handbook,
which will be sold as a circular for the rest of this
year. The three new circulars will be revised bian-
nually.
The 7997 Illinois Agricultural Pest Management
Handbook ($17) contains suggestions for the manage-
ment of weeds, diseases, and insect pests for profes-
sionally managed vegetable and field crops. This
publication is revised annually.
All of these publications can be obtained through
your local Extension office or by calling (217) 333-
2007 during business hours. (Phil Nixon)
INSECTS
Honeylocust Plant Bug
Honeylocust plant bugs are active in central and
southern Illinois. At this time of year, they appear as
pinhead-sized green insects running actively over the
leaves and along the small branches when disturbed.
They overwinter as eggs laid in first-year twigs on
honey locust, hatching shortly after the leaves start to
emerge. They feed for several weeks in the spring on
the expanding leaves, causing the leaflets to be curled
and misshapen and to have brown areas. On very
heavily attacked trees, the leaflets will fall off and be
replaced with new leaves by late June. Less heavily
attacked trees will retain their misshapen leaflets
through the summer.
The insects mature throughout May, getting larger
with each nymphal molt. By late May or early June,
the insects turn into adults that are about one-eighth
inch long. They have wings and fly readily when
disturbed. In June, the plant bugs mate and lay eggs in
the still soft and green stems at the branch tips. They
remain as eggs through the rest of summer and fall
and emerge as nymphs the following spring.
Preventing damage involves scouting and treating
at this time of year. Even one bug per compound leaf
can cause obvious aesthetic damage. Because field
scouting is not likely to detect all of the bugs present,
finding three or four bugs per compound leaf cluster
probably justifies an insecticide application. Another
way to scout is to brush the foliage lightly. If you see
A (^^T7 Q College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urbana-Champaign
G^gj^2 Helping You Put Knowledge to Work— State • County • Local Groups
M^i^ U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
opportunities In programs and employment.
No. 4 • May 14, 1997
several bugs running on the foliage and along the
twig, then treatment is probably warranted.
Control the bugs with sprays of bifenthrin (Talstar),
cyfluthrin (Tempo), acephate (Orthene), or insecti-
cidal soap. There appears to be a relationship between
spraying for plant bugs and heavy infestations of
honeylocust mite later in the summer: these insecti-
cide sprays also kill mite predators, allowing honey-
locust mites to build up to high numbers. Thus, if you
have trees that tend to have honeylocust mite prob-
lems, you might wish to avoid spraying, or use
insecticidal soap instead. Insecticidal soap should
have less of an impact on mite predators than do the
other insecticides.
In Illinois, honeylocust mites tend to occur on trees
in hot, dry areas — such as close to buildings and in
small parking lot islands. Damaged leaves turn
yellowish in mid-to-late summer and drop early,
sometimes in late summer. (Phil Nixon)
Pollen Bees
Wild honeybees are greatly reduced in number,
primarily due to the tracheal mite and Varroa mite,
which make honeybee colonies more likely to die out
in severe winters. Beekeepers are able to keep their
hives healthy with the use of pesticides against the
mites, but there are concerns about possible resistance
in the mites to these pesticides. These concerns have
increased the interest in pollen bees.
"Pollen bees" is a recently coined term referring to
bees that do not produce honey or wax in sufficient
quantities that people can harvest. Recent research has
shown that at least some pollen bees are much more
effective pollinators than honeybees are, requiring
only hundreds of bees to pollinate the fruit and
vegetables that would take tens of thousands of
honeybees to accomplish.
Many carry the pollen on hairs on their undersides,
making them very efficient pollinators as they visit
and brush against flowers. Many pollen bees are
present only for a few weeks per year, making it
possible to have important crops pollinated without
having to worry about additional pollen sources to
keep the bees fed during the remainder of the growing
season. Following are some of the more common
pollen bees.
Mason bees, Osmia spp., nest in cavities in wood,
soil, and masonry and in the hollow stems of reeds
and other plants. They place a mixture of pollen and
nectar with an egg inside a cavity that is then lined
and capped by a cementlike mixture of clay, sand, and
the bee's own oral secretion. The blue orchard bee
{Osmia lignaria) and the homfaced bee {Osmia
comifrons) are kept and raised in four-by-four-inch
blocks of wood with 5/16-inch-diameter holes or
bundles of coated cardboard tubes of the same diam-
eter. The blue orchard bee is present as an adult from
early April through mid-May in southern and central
Illinois and is a dark blue metallic-colored bee just
under one-half inch long.
Leafcutter bees, Megachile spp., are closely
related to mason bees and use similar-sized or smaller
holes in similar locations for their nests. They differ in
that they cap their nests with circular and oval leaf
pieces cut from rose, redbud, maple, and other plants.
They are not hairy, are one-quarter to one-half inch
long, and are black, metallic blue, green, or purple.
The alfalfa leafcutter bee, Megachile rotundata, is
used commercially, particularly in alfalfa seed fields
in western states.
Digger bees, Andrenidae, are small, sparsely
haired bees that are commonly gray and black striped.
Many common species are about one-quarter inch
long, but some species approach one-half inch in
length. They nest underground and can be numerous
in garden soil, mulched areas, and clay banks. They
are present throughout most of the spring and
summer.
Sweat and mining bees, Halictidae, are similar to
andrenid bees in habits and appearance. They will
sting if swatted. They nest underground. Many
species are metallic green or black, while others are
gray. They are not as hairy as andrenid bees. The
alkali bee, Nomia melanderi, is used commercially as
a pollinator of alfalfa seed crops. Sweat bees are
attracted to perspiration, commonly landing and
walking around on human skin. In Illinois, the "sweat
bees" that most people refer to are actually flower
flies. These quarter-inch long, black-and-yellow-
banded insects hover around perspiring skin and land
to feed on perspiration. They do not bite or sting.
Yellowjackets (which are often mistaken for bees) are
about one-half inch long, black-and-yellow-banded
wasps that are attracted to perspiration and sting
readily when disturbed.
Plasterer and yellow-faced bees, Colletidae, are
small, dark-colored bees, about one-quarter inch long.
Some species are very hairy, others are not. Plasterer
bees line their underground burrows with a thin,
translucent material. Yellow-faced bees have yellow
faces and nest in underground burrows, plant stems,
and other crevices and cavities. They are very com-
mon in late summer.
No. 4 • May 14, 1997
Small carpenter bees, Ceratinidae, are about 3/8-
inch long, black to metallic blue-green, heavy bodied
like bumblebees, and almost hairless when viewed
from above. They tunnel out the pith of reeds and
brambles for their nests and are quite common later in
the summer.
Large carpenter bees, Xylocopidae, are about one
inch long. They are yellow and black, with heavy
bodies like bumblebees. Unlike bumblebees, their
abdomens are totally black with little hair. They nest
in one-half-inch-diameter tunnels in wood; they prefer
dead branches, logs, and unfinished lumber. Large
carpenter bees are active in the spring, and their
young emerge during the summer.
Bumblebees, Bombidae, are about one inch long,
yellow and black, heavy bodied, and very hairy. They
make softball-sized nests underground in old rodent
burrows and other cavities. They are active from
spring through summer. These bees can be raised
commercially and are used in the pollination of
greenhouse-grown tomatoes.
Many pollen bees, most of them native, were here
pollinating plants before some of the first European
settlers brought the honeybee to this continent. With
the advent of the two mites parasitic to honeybees,
these mite-resistant bees are once again becoming
more important in pollination. (Phil Nixon)
PLANT DISEASES
Anthracnose of Shade Trees
The anthracnose group of diseases has been addressed
repeatedly in the past. Briefly, there are several fungal
pathogens that cause spotting or blighting of the
leaves and sometimes cankers on stems of plants.
These symptoms, along with the development of a
fungal spore-bearing structure (known as an acer-
vulus), usually categorize the disease as an anthrac-
nose. The term "anthracnose," then, is a rather general
term referring to spotting and blighting of leaves or
stems. Accurate identification and control recommen-
dations depend on recognizing the disease symptoms
and knowing the host species involved. In Illinois, the
major shade trees that often host anthrac- nose are
sycamore, ash, oak, maple, elm, and walnut. Wet
conditions are a must for all anthracnose diseases.
These fungi cause symptoms to develop on succu-
lent tissue in the spring. Some fungi infect and grow
better in cool, wet weather. Others, such as the ash
anthracnose fungus, actually grow more quickly in
warmer weather. Anthracnose is most prevalent in the
spring, probably because of the slow development of
the host in the cool, wet conditions prevalent that time
of year. Slow host development means a longer time
with the presence of tender, succulent, and susceptible
plant tissue.
We have not yet seen anthracnose on trees in
central Illinois. The weather, however, keeps jumping
from cool days to warm days to very cool nights, so
leaf development has been slow. Also, some areas
have received abundant rain. In those areas, I suspect
anthracnose will show in about one or two weeks. Dry
areas may be able to avoid problems with anthracnose
in 1997.
Unless a tree has been repeatedly hit by anthrac-
nose fungi in the past, we do not recommend the use
of fungicides. Anthracnose diseases do not kill trees;
some defoliation may occur, but refoliation with
healthy leaves follows in warmer weather. Concen-
trate on helping tree vitality, which will promote new
growth. Remove dead or dying branches, water in
periods of drought, and fertilize the tree when appro-
priate. If fungicides are chosen as a disease control for
anthracnose, keep in mind that fungicides are effec-
tive only as preventives and should have been initi-
ated when buds first began to open. Options are listed
in the 1997 Illinois Commercial Landscape and Turf
Pest Management Handbook under the specific host
in question. For more information on anthracnose of
shade trees, refer to Report on Plant Diseases No.
621. (Nancy Pataky)
Fire Blight This Year?
Fire blight is a potentially serious disease that appears
in years when warm, wet conditions occur during
blossoming. Fire blight is a disease of about 75
different plant species in the Rosaceae family. Those
affected in Illinois generally include apple, pear,
susceptible crabapples, mountainash, and quince. The
causal agent is a bacterium, Erwinia amylovora,
which thrives in temperatures of 65°F or higher in wet
conditions (even a dew will suffice).
Fire blight may appear as a blossom blight, shoot
blight, or branch and trunk canker. Infected blossoms
wilt and turn brown to black. Initial infection occurs
in the blossoms, and then the bacteria may move
down the pedicel, into the fruit spur, initiating shoot
blight. Often the result is a bending of the tip of the
shoot, giving it a shepherd's crook appearance. This is
the phase recognized by most growers. Some species,
such as mountainash, may not show the crooking but
No. 4 • May 14, 1997
will have a blackened or brown blight of the shoot
terminals as though the branch had been burned by a
fire (thus the name "fire blight"). Dark-brown to black
cankers of the wood often follow.
This disease has been severe in the past few years,
and we have received several questions this year at
the clinic from people concerned about this year's
plants.
Dr. Steve Ries is a fruit pathologist on campus. He
supervises the U of I fruit pathology farm at which a
computer-based program is used to predict occur-
rences of fire blight. The computer program uses
temperature and moisture data from a weather station
in the orchard and estimates surface bacterial growth
to predict low, medium, and high threats of fire blight.
Fruit growers initiate chemical sprays based on these
predictions.
According to Ries, data gathered by the computer
program this year do not suggest that fire blight will
be a threat in central Illinois in 1997. Of course, he is
quick to point out that conditions can change in as
few as two or three days.
The initial bacterial infection occurs in blossoms
during warm, wet weather. Central Illinois apples are
already at full bloom, and temperatures are cool and
predicted to remain so. Therefore, the threat of fire
blight is currently low to nonexistent. If blossom
infection does not occur, then shoot blight in June will
also be reduced. Computer data analyses have not
predicted any need for sprays in the northern two-
thirds of the state. Southern Illinois growers, however,
may be seeing fire blight now. (Fire blight has been
reported in the St. Louis area.)
What does this mean for ornamental hosts of fire
blight? Basically, the information discussed still
applies. Many ornamental rosaceous hosts flower later
than edible apples, so blossom infection could still
occur on susceptible hosts, but we do not advocate
spraying for fire blight on ornamentals. If infection
occurs, try pruning out the first blighted tips, but
disinfect pruners with household bleach or rubbing
alcohol between cuts to avoid spreading the bacterial
pathogen. If the disease still spreads, prune during
hot, dry weather. Forcing abundant succulent growth
by heavy spring pruning will provide more suscep-
tible tissue and more opportunities for infection.
Avoid high nitrogen levels for the same reason. To
allow better air flow, try to maintain an open habit for
plants. Also, there are many resistant varieties now
available in the ornamental trade. For more informa-
tion on fire blight, consult Report on Plant Diseases
No. 801. (Nancy Pataky)
HORTICULTURE
Ground Ivy Control
Recently, I have heard discussion about using borax
as a control for creeping Charlie (ground ivy). Ac-
cording to the U.S. Environmental Protection Agency,
it is legal for a homeowner to apply borax as a weed
control on his or her own home lawn. However, it is
not legal to sell or commercially apply borax as a
control for ground ivy because it is not labeled for
that use. Furthermore, the University of Illinois
Cooperative Extension Service does not recommend
borax for creeping Charlie control because no sub-
stantive research has been conducted on application
rates, timing, and techniques. Although borax may
cause some damage to creeping Charlie, it may also
damage the turf or other plants in the area.
Creeping Charlie is one of the most troublesome
broadleaf weeds in turf. It commonly starts in poorly
drained, shaded areas and often creeps into sunnier
areas. Unfortunately, once ground ivy gains a foot-
hold, it is difficult to control using cultural practices.
Hand-pulling is a laborious process and, even when
repeated, rarely reduces the weed population. Improv-
ing light penetration and soil drainage may help the
turf compete with this weed but is not a long-term
solution.
The 1997 Illinois Commercial Landscape and Turf
Pest Management Handbook lists several possible
controls for creeping Charlie. Combination products
(e.g., 2,4-D + MCPP 4- dicamba, or 2,4-D -i- triclopyr)
will usually provide better control than products
containing a single herbicide. Be aware that control-
ling creeping Charlie may require more than one
herbicide application. Finally, always read, under-
stand, and follow the label directions when using any
pest control product. This will result in the safest use,
as well as the most effective results. (Tom Voigt)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd, (217) 333-6653, and Fredric Miller, (708) 352-0109,
entomologists; Nancy Pataky, plant pathologist, (217) 333-
0519; and Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350. Phil Nixon is the executive
editor of the Home, Yard and Garden Pest Newsletter.
4^ ^-^ ■
■p^
JUN 2 6 1997
HOMErYARD & GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
Illinois at urbana-champaign a i 1 1 inois natural history survey, champaign
NEWSLETTER
No. 5 • May 21, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
is time to divide plants, remove all rotted plants, or
the rotted portions, and allow rhizomes to dry in the
sun. Replant in a new location, if possible, choosing a
site with good drainage. When replanting, allow the
upper half of the rhizome to remain out of the soil to
help avoid future problems. (Nancy Pataky)
PLANT DISEASES
Bacterial Soft Rot of Iris
Bacterial soft rot causes the lower leaf tissue and the
rhizomes of iris to rot, destroying hope for flower
production and eventually killing the plant. Because
the pathogen is a bacterium and because the tissue is
very succulent, a soft, mushy, smelly rot results. Early
stages of infection may show leaf tip browning and
leaf wilt, but that often goes unnoticed or is blamed
on water imbalances. Water-soaked streaks may
extend down the leaves. The bacterium causes the
entire rhizome interior to rot, leaving only the tough
outer skin intact. This is a particularly tragic disease
because iris plants take so long to form established
beds. However, because the pathogen can enter only
through wounds, it can be avoided.
The major cause of wounding is the iris borer; the
bacterium enters the young leaves in wounds made by
the borer. If you have had problems with borers in the
past, consider using insecticides. Entomologists
recommend the use of dimethoate (Cygon 2E) in
April or when leaves are five to six inches tall. Only
one treatment is recommended. Follow the label
directions carefully. The chemical is to be used as a
dilute spray, not a concentrate.
If you discover that your irises have soft rot and
borers, you could remove rotted plants now. When it
Gray Mold of Strawberry
Gray mold is caused by the fungus Botrytis cinerea
and thrives in cloudy, rainy weather on dense, lush
foliage, especially in areas with poor air movement.
Strawberry fruit infection can greatly reduce yields
and may cause storage problems after harvest. The
gray, moldy growth produced by this fungus is
familiar to most gardeners. The mold appears on
flowers, vegetables, and fruit — indeed, on almost any
plant material. The growth is a mass of spores and
mycelia of the fungus. Wind can easily move these
spores from plant to plant.
Early detection is necessary. Fruit pathologist Dr.
Steve Ries says the disease begins as a blossom
blight. He emphasizes that control of the early phase
of the disease will greatly reduce, if not eliminate,
later fruit infection. Many strawberries in the central
part of the state are in bloom now, so watch for
symptoms of blossom infection. One or several
blossoms may turn brown and die. Once blossom
infection sets in, the dead material will be covered
with a gray, moldy growth.
Read about cultural controls for this disease in
Report on Plant Diseases No. 704. Obviously, a
sunny planting site with sufficient air movement and
good soil drainage is preferred. Proper plant spacing
will improve air flow, and proper fertilization will
help prevent an overabundance of lush, susceptible
foliage. Because rotted or injured plant material is
more likely to become infected with this fungus, use
A (^^Xh Q College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urbana-Champaign
ces
Helping You Put Know^ledge to Work — State • County • Local Groups
U.S. Department of Agriculture Cooperating
Tfie Cooperative Extension Service provides equal
opportunities in programs and employment.
straw mulch to cut down on fruit rot and to keep fruit
off the ground.
Fungicides are very effective in controlling gray
mold on strawberry. However, as Ries pointed out, the
goal is to control blossom infection so that the fruit
will not have to be sprayed later. Sprays are ideally
initiated when the plants are at 10 percent bloom, and
sprays must be continued every seven to ten days
throughout the bloom period. Many fungicides are
labeled for this use, but be certain to check the label
for proper registration, rates, and timing before
spraying. Captan, Thiram, and Benlate will work and
are fairly easy to obtain for commercial operators and
homeowners alike. (Nancy Pataky)
Leaf Curl and Blister
The clinic has received several calls concerning leaf
curl and leaf blister. Reports from Ohio indicate the
diseases have been seen there, as well.
Peach leaf curl occurs on peach, nectarine, and
some ornamental Prunus species. "Leaf curl" and
"leaf blister" refer to a similar group of diseases on
oak and occasionally on poplar. Several Taphrina
species (fungi) cause all of these diseases. Leaf
distortion and blisterlike growths or puckering of the
leaves is common. The leaves are often thickened and
almost crisp. Leaves turn downward and inward and
may become red or purple.
The causal fungi overwinter in buds and twigs.
They infect leaves and flowers in the cool, moist
weather of early spring, from bud swell to bud open-
ing. Ideal temperatures for infection are 50°F to 70°F.
Infected trees may show early leaf drop, but generally
the life of the tree is not threatened. Repeated yearly
infections may weaken a tree and predispose it to
other problems.
The reduced quality of fruit is a concern. For fruit
growers, we recommend a single dormant fungicide
spray before budbreak; most commercial growers
incorporate this treatment into their spray programs.
Landscape managers should focus on promoting tree
health by pruning, watering, and fertilizing, rather
than relying on fungicides. (At this point in the
season, fungicides would be useless against this
disease anyway.) For more information on leaf curl
and blisters, consult Report on Plant Diseases No.
805, Peach Leaf Curl and Plum Pockets, or No. 663,
Oak Leaf Blister. (Nancy Pataky)
Juniper Tip Blight
Another fungal disease initiated in warm, wet weather
is Phomopsis tip blight. We see this blight on arborvi-
tae, Douglasfir, and true firs, but the typical host in
Illinois is juniper. The usual symptom is twig tip
blight. Infection appears first on the youngest needles
(older needles are resistant), starting as yellowish
spots. The tips of shoots soon fade to light green and
eventually turn reddish brown. A grayish band is often
visible at the base of the dead shoot. In this band are
pinhead-sized black fruiting bodies (pycnidia). The
fungus survives over the winter in the pycnidia on the
previous year's infection.
Infection is not initiated until temperatures are
warm (60°F to 80°F) and moisture is present. New,
succulent tissue is susceptible to infection by this
fungus, but there is a great deal of difference between
juniper cultivars in terms of resistance to this tip
blight. Once infection occurs, it will be another seven
to ten days before any symptoms might begin to show.
Pycnidia develop on current-year growth three to four
weeks after infection. This means you will soon be
seeing current-year symptoms of Phomopsis blight on
your susceptible junipers.
Planting resistant varieties is the easiest way to
control this disease. Still, Phomopsis may be con-
trolled by pruning out infected foliage when the plant
is dry and by using preventive fungicides. Pruning is
important because the most common source of spores
is the infected tissue from the previous year. Prune dry
foliage to avoid spreading spores.
Fungicides can protect new, healthy foliage from
Phomopsis blight. Although sprays should have been
initiated in early spring, they may still have some
benefit if wet weather is expected and plant growth is
active. Consult the 1997 Illinois Commercial Land-
scape and Turf Pest Management Handbook for
chemical options. Homeowners can try mancozeb
products or products containing thiophanate-methyl
(such as Ferti-Lome Halt) or copper sulfate (such as
Hi- Yield Bordeaux mix). Always read the label for
crop or host clearance. Report on Plant Diseases No.
622 contains more information on Phomopsis tip
blight of juniper, including resistance ratings. (Nancy
Pataky)
No. 5 • May 21, /yy/
HORTICULTURE
Postemergence Chemical Controls of
Broadleaf Weeds in Turf
In areas where cool-season annual and perennial
broadleaf weeds are actively growing, it is time to
initiate postemergence herbicide controls.
Studies conducted over several years at the Univer-
sity of Illinois Landscape Horticulture Research Center
show that several herbicides provide effective
postemergence control of common broadleaf weeds
such as white clover, dandelions, and plantains. These
herbicides are 2,4-D + MCPP + dicamba; triclopyr +
clopyralid; and 2,4-D + triclopyr. For additional
information regarding other chemical weed controls or
other weeds, see Chapter One of the 1997 Illinois
Commercial Landscape and Turf Pest Management
Handbook.
When using any chemical pest control, be sure to
read, understand, and follow the label directions for
proper use of these chemicals. If mishandled or misap-
plied, postemergence broadleaf herbicides may damage
or kill many desirable omamental or edible plants in
the landscape. Follow these general recommendations
when using postemergence broadleaf products.
1 . Apply postemergence broadleaf herbicides when
weeds are young and actively growing.
• Avoid applications when weeds are heat- or
drought-stressed; such conditions might interfere
with herbicide uptake or translocation.
• Do not mow for a few days before and after
application. This allows maximum leaf surface
for interception and absorption of herbicides.
• Apply these herbicides to newly seeded turfgrass
only after the grass has been mowed three or four
times. Wait at least 30 days following application
before seeding into areas treated with post-
emergence broadleaf herbicides. Bromoxynil can
be applied to newly seeded, nonresidential turf to
control some broadleaf weeds.
2. Apply postemergence broadleaf herbicides when
environmental conditions are appropriate for control.
• To avoid drift, be aware of wind speed. Often,
wind is less of a problem in early mornings.
• Do not apply these herbicides when air tempera-
tures are expected to exceed 85°F.
• Maintain adequate soil moisture; this will
encourage translocation of herbicide throughout
the entire weed.
• Do not apply these herbicides when precipitation
is expected within 24 hours. Do not irrigate turf
for several days following application.
• Be especially cautious when using ester formu-
lations as air temperatures rise. Ester-formulated
broadleaf herbicides are more prone to volatil-
ization than amine-formulated herbicides.
3. Limit the use of pesticides by making spot
applications where possible, rather than treating
large areas.
4. Because many cool-season annual and perennial
broadleaf weeds are best controlled in aummn, apply
postemergence herbicides during the fall when
broadleaf weeds are actively growing. Use herbicide
applications in the spring to control broadleaf weeds
that escape autumn control. (Tom Voigt and Bruce
Branham)
INSECTS
Oystershell Scale
Oystershell scale brown race eggs have hatched into
crawlers in southem Illinois. They will hatch soon in
central and northern Illinois, as will the gray race
crawlers in southem Illinois.
Oystershell scales overwinter on the host as eggs
under the scale covers of the females. These scale
covers are about one-eighth inch long and shaped
like an oyster shell — wider at one end and curving
slightly toward the other, narrower end. There are
two races of scale. The brown race is almost uni-
formly brown; the gray (or banded) race has bands
of brown and gray. Older scale covers of the gray
race tend to become whitish.
The eggs hatch into tiny gray nymphs called
"crawlers," which is the dispersal stage of this insect.
The crawlers move actively over the foliage and
branches. Scale crawlers travel to new hosts by raising
their back end into the wind, which makes them easily
blown off the plant. They also crawl onto the feet of
birds, who carry them to new host plants.
After a crawler period of ten days to two weeks, the
scales settle onto the stems of the plant, where they
feed, molt to the next nymphal stage, and secrete a
waxy covering over the body. This waxy covering
protects the insect from insecticides, making it
difficult to control after the very vulnerable crawler
stage. Throughout their lives, the scales suck the sap
out of the plant and, through successive nymphal and
adult molts, lose their eyes, antennae, and legs as they
grow larger and increase the size of their waxy covers.
Oystershell scale is known to feed on over 120
hosts. Heavy infestations will cause dieback or death
of the host. The insect is frequently present for several
years on only one or two branches before spreading.
The brown race is most common on apple, dogwood,
and poplar.
Crawlers appear when bridal wreath spirea (Spi-
raea X vanhouttei) is in full to late bloom, according
to Don Orton in the book. Coincide. The gray race is
most common on lilac, ash, willow, poplar, and
maple. Its crawlers appear when Spiraea x vanhouttei
finishes blooming.
Both the brown and gray races are found on most
host plant species. The brown race has a second
generation of crawlers through much of Illinois, when
hills-of-snow hydrangea {Hydrangea arborescens
'grandiflora') blooms are turning from white to green
and when wild carrot (Daucus carota), also known as
Queen Anne's lace, is blooming.
When bridal wreath spirea is in early bloom, scout
infested plants every two or three days by looking for
crawlers on the branches and leaves. If you have a
microscope or powerful hand lens, flip over a few scale
covers with a knife tip or pin and check for hatched
crawlers under the covers. The hatched crawlers will
stay under the scale covers for several days before they
emerge onto the plant, where they can be controlled
with insecticides. With this technique, it was deter-
mined that brown race scale on lilac in east central
Illinois was still in the egg stage on May 16.
Control of the crawlers can be achieved with many
contact insecticides, such as insecticidal soap, sum-
mer spray oil, malathion, diazinon, acephate
(Orthene), cyfluthrin (Tempo), lambda-cyhalothrin
(Scimitar), and permethrin (Astro). Control of older
nymphs and adults that are protected by their waxy
covers is difficult. (Phil Nixon)]
Lilac/ Ash Borer
Landscapers and nursery personnel should be on the
lookout for the lilac borer (Podosesia syringae), also
called the ash borer. The lilac borer is a clearwing
moth that resembles a wasp. The moths overwinter as
late instar larvae and emerge as adults from pupal
cases in spring to mate and lay eggs. Eggs are laid and
hatch in late May or early June, depending on their
location in Illinois. Larvae burrow into affected plant
materials and feed on the phloem tissue. Unlike beetle
borers (such as bronze birch borer), clearwing moth
larvae leave an entrance hole to the outside where sap
and sawdust collect.
Like most boring insects, the lilac borer takes
advantage of plants that are low in vitality due to
environmental stress. Newly transplanted materials
are extremely susceptible to this moth. The lilac borer
will injure lilac, ash, privet, and other members of the
olive family. In addition to cultural methods such as
watering and mulching to increase the vitality of the
plants, well-timed insecticidal treatments can be used
to control lilac borer.
Traps that contain an attractant pheromone are
available. The pheromone in the traps is an analogue
of the sex pheromone produced by the female moth.
Moths caught in the traps are males looking for
unmated females. The traps themselves will not cure
the problem, because only males are caught and, even
so, some will undoubtedly avoid the trap and insemi-
nate females. The pheromone traps are most useful in
providing a more accurate estimate of when to treat.
Current recommendations suggest treating the
branches and trunk of plant materials with
chlorpyrifos (Dursban) one week after peak trap
catch. This treatment also coincides with the time
when Vanhoutte spirea is in mid- to late bloom. These
plants are already in mid-bloom in southern Illinois
and early bloom in central Illinois. (John Lloyd)
Other Vanhoutte Spirea Phenology
Indications
Besides lilac borer and oystershell scale, which are
discussed in detail above, several other insect events
correlate with the blooming of Vanhoutte spirea. The
following information, from the book Coincide,
should help practitioners plan scouting activities.
Birch leaf miner: Look for small mines when
blooming starts.
Pine needle scale: Red crawlers are active when
blooming starts.
Taxus mealybug: Nymphs are active during
blooming.
Lilac/ash borer: Egg hatch begins in full to late
bloom.
No. 5 • May 21, IW/
Oystershell scale (brown race): Crawlers hatch
and are active in full to late bloom.
Black vine weevil: Look for feeding notches as
blooming finishes.
Bronze birch borer: Egg hatch begins when
blooming finishes.
Elm leaf beetle: Feeding damage will begin to
occur as blooming finishes.
Oystershell scale (gray race): Crawlers hatch
when blooming finishes. (John Lloyd)
European Pine Sawfly
Cool weather has certainly slowed insect development
in northern Illinois. Scouts at the Morton Arboretum
in Lisle noticed European pine sawfly hatching from
eggs during the week of May 11 to 16. Feeding by
sawfly larvae in central and southem Illinois is
continuing two to three weeks ahead of their northern
counterparts. Damage is becoming obvious south of
Interstate 80, with infested trees exhibiting the tufts of
new growth without needles behind them. Remember
that sawflies are not caterpillars and will not be killed
by any of the Bt (Bacillus) products used for caterpil-
lar control. Carbaryl (Sevin) is extremely effective
against sawflies. Other effective controls are listed in
the 7997 Illinois Commercial Landscape and Turf
Pest Management Handbook. (John Lloyd)
Other Pine Problems
As pines continue to turn brown across the Midwest,
more and more homeowners, as well as nursery
managers and Christmas tree growers, are "discover-
ing" insect problems. Generally, Zimmerman pine
moth has been the main problem, but some others are
showing up. A little discussion on how to identify
these various critters is in order.
First, the Zimmerman pine moth produces fairly
large pitch masses that contain bits and pieces of
sawdustlike material, which is actually frass (bug
feces). At this time, most of these masses should be
fairly hard because they are from last year's activity.
The new crop of Zimmerman caterpillars is very tiny
now and is just beginning to make new pitch masses.
However, their previous feeding at the bases of
branches may now be causing branches to die (or at
least turn brown) and break off in wind storms.
If a pine shoot (generally about the diameter of a
pencil) suddenly wilts or turns brown from now until
mid-June, suspect the pine shoot moth. This insect is
most common in white pine, although Scotch pine is
occasionally attacked. The caterpillar, which will be
inside the stem, is usually cream-colored with a
greenish cast. If you find a pinkish or burgundy
caterpillar, it may be an errant Zimmerman.
Any small black or brown beetles in shoots now are
most likely pine cone beetles, not pine shoot beetles.
Pine cone beetles are nothing to worry about. (Dave
Shetlar, The Ohio State University)
Periodical Cicadas
Periodical cicadas will emerge this year near the end
of May in a few Illinois counties. Next year will bring
a large emergence throughout most of the southem
two-thirds of the state. Very small trees may be
subject to heavy damage by this insect's egg-laying
activities.
Periodical cicadas occur in most areas of the
eastern half of the United States. In the northern half
of the country, these insects have a 17-year life cycle;
those in the southem half have a 1 3-year life cycle.
Nymphs that hatch from eggs inserted into stems drop
to the ground, burrow into the soil, and find a root to
feed upon. The nymphs suck sap from the roots until
the last year of their life cycle, when they emerge
from the soil in the late spring, climb a tree, and
emerge as adults.
The adults are black, about one-and-one-quarter
inch long, and have red eyes. They have clear wings
with orange veins. The adults do little feeding,
spending most of the daylight hours involved in
reproductive activities. Male cicadas sing during the
day to attract females. Mated females select twigs and
branches up to one inch or more in diameter and
insert their eggs into slits that they make with their
ovipositors.
In 1997, we anticipate emergence of the 17-year
brood in Henderson, Warren, Knox, Fulton, Schuyler,
northeastern Brown, and southeastern McDonough
counties in western Illinois. Periodical cicada emer-
gence will also occur in DeWitt, northern Piatt, and
north westem Champaign counties.
In 1998,we anticipate emergence of the 13-year
cicadas from Hancock and eastern McDonough
counties south to Morgan, Sangamon, and Macon
counties and also from Ford, southern Livingston, and
western Iroquois counties south. The rest of southern
Illinois is included in this 13-year brood emergence
except Iroquois, Vermilion, Edgar, Clark, Crawford,
Lawrence, and Wabash counties on the east and
Alexander, Pulaski, Massac, Union, Jackson, Perry,
and southern Randolph counties in southern lUinois.
Periodical cicadas are a threat to small trees with
trunk diameters of two inches and smaller. Their egg
laying may cause trunks and branches to snap off in
windy conditions. Avoid planting very small trees
before an emergence in areas where cicadas are likely
to appear. Realize, though, that even in the regions
listed above, some areas will have few cicadas or none
at all. If an area has been cleared of trees and shrubs
within the last few hundred years or was originally
prairie, periodical cicadas are unlikely to be present.
These insects do not fly very far from where they
emerge. That fact, combined with their long genera-
tion times, means that the spread of periodical
cicadas is very slow.
Insecticides are only marginally effective against
cicada, with carbaryl (Sevin), bifenthrin (Talstar),
permethrin (Astro), lambda-cyhalothrin (Scimitar),
and cyfluthrin (Tempo) providing only a small
amount of control. Young trees with small trunks
should be protected with hardware cloth, screening,
or tree wrap during the few weeks that the adult
periodical cicadas are present. (Phil Nixon)
Home, Yard and Garden Pest Newsletter is prepared by Extension specialists from the University of Illinois at Urbana-
Champaign and the Illinois Natural History Survey. Information for this newsletter is gathered with the help of staff
members. Extension field staff, and others in cooperation with the USDA Animal and Health Inspection Service.
Major authors are Phil Nixon, (217) 333-6650, John Lloyd (217) 333-6653, and Fredric Miller, (708) 352-0109,
entomologists; Nancy Pataky, plant pathologist, (217) 333-0519; and Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350. Phil Nixon is the executive editor of the Home, Yard and Garden Pest Newsletter. This
newsletter is written by faculty in the Department of Natural Resources and Environmental Sciences and the Department
of Crop Sciences. The newsletter is edited and typeset by Peggy Currid and proofread by Herbert Morgan, both of
Information Services.
Reference and
Teaching Materials
from the
University of Illinois
ACES
Quality You Expect
Expertise You Want
College of Agricultural, Consumer and Environmental Sciences
University of Illinois at Urbana-Champaign
-The Illinois Commercial Landscape and Turf Pest — ,
Management Handbook is a must for any
horticulture professional or educator. Topics include
management of weeds, insect pests, and diseases for
• turfgrass • woody ornamentals
• landscaping • flowers, trees, and shrubs
• nursery crops
using both chemical and nonchemical controls.
Revised Annually
ICLT-97 $8.00
In pest and weed identification, pictures are
worth a thousand words. The combination of
high-quality information and superb
photography makes these slide sets great
teaching tools in classrooms or staff trainings.
Lawn Weeds-Identification and Control
76 frames with script
S650a $39.85
Takes the learner through a step-by-step
approach to controlling weeds in turf.
Shade Tree and Woody Shrub Insects:
Identification and Control
78 frames with script
S654.4 $40.85
Tuff Insects: Identification and Control
39 frames with script
S654.2 $41.85
Two sets that help the learner identify pests,
understand their life cycles and then select
appropriate chemical and nonchemical
controls to manage them.
^^ Looking for more resources?
Here are two World Wide Web sites packed with
possibilities from the University of Illinois!
www.ag.uiuc.edu/~vista/catalog/catintro.html
www.aces.uiuc.edu/~vo-ag/
-Photo sheets make great identification tools.
Photos on one side with descriptions and
explanations on the back. Certainly an
effective study aid for any student. High
quahty at a very reasonable price. Here's a
sampling of what you can order:
Ornamental Insects X698.16
Tree and Shrub Pests I X698.17
Turf Pests I X698.31
Tree Diseases I X699.16
Tree Diseases II X699.17
Tree Diseases III X699.18
Woody Ornamental Diseases I X699.30
Turfgrass Diseases I X699.31
Turfgr asses for the Midwest X699.35
Turfgrass Establishment
in the Midwest X699.36
$ .40 each
To order the Illinois Commercial
Landscape and Turf Pest Management
Handbook, slide sets and photo sheets
call (217) 333-3871. MasterCard and Visa
accepted. Bulk discounts available.
Shipping is extra and may vary by order.
Orders over $10.00 may be billed.
'COOPERATIVE EXTE N^(udf^sTRV I C E
HOME, YARD & GARDEN PEST
NEWSLETTER
college ot agricultural, consumer and environmental sciences, university ol
Illinois at urbana-champaign ▲ i I linois natural history survey, champaign
No. 6 ' May 28, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, arui
other topics of interest are discussed.
HORTICULTURE
Managing Aquatic Vegetation
Aquatic vegetation is useful in many ways, but an
excess of such plants can cause problems. Because
aquatic areas are special ecosystems, control measures
must be chosen carefully. For more information, refer
to the new circular on aquatic weed management. [To
order, call (217) 333-2007.]
The most important step in controlling aquatic
vegetation is proper identification. Control measures
vary widely, depending on weed type. If you are not
familiar with aquatic vegetation (including algae
types), call your Extension office for help.
Another important factor to consider is site use.
Most aquatic herbicides have use restrictions (listed as
the number of days that must pass before the site
should be used as intended). Before selecting a
herbicide, you should know whether the water will be
used for human consumption, animal consumption,
swimming, fish, or irrigation.
Control options include chemical and nonchemical
measures. Several nonchemical control options are
available: Preventive control is achieved through
nutrient control or habitat manipulation; mechanical
control physically removes the vegetation; cultural
control includes the use of drawdowns, dyes, plastics,
or aeration; and biological control relies on geese,
swans, or triploid grass carp, all of which feed upon
aquatic vegetation.
Only a handful of herbicides are labeled for use in
aquatic areas. Commercial applications require an
aquatic applicator license from the Illinois Depart-
ment of Agriculmre. In general, chemical recommen-
dations are as follows:
Vegetation Type
Algae
Flowering plants
submersed (pondweeds,
naiads, watermilfoil)
free-floating
rooted-floating (lilies)
emergents (cattails)
Recommended
Herbicide(s)
copper products
Aquathol, Sonar, or
Reward
Rodeo
Rodeo or 2,4-D
2,4-D Amine or
Rodeo
Always follow label directions closely.
(Rhonda Ferree)
INSECTS
Turf Insects
True white grub adults are flying in central and
southern Illinois. They lay eggs in turf, which can
cause turf root damage later in the summer. Adults
feed at night on the leaves of many trees, but they
prefer ash, crabapple, and oak. Checking damaged
trees after 10:30 p.m. will reveal large numbers of
these inch-long, reddish brown to dark brown, stocky
May beetles feeding on leaf margins. Leaf foliage
may be eaten all the way to the midvein. An applica-
tion of carbaryl (Sevin) should be effective in prevent-
ing further injury.
Sod webworm may become an important turf pest
if this spring continues to stay drier than normal.
These slender, gray-to-tan colored caterpillars with
dark brown spots live in siUc-lined tunnels in thatch
A C^P C College of Agricultural, Cortsumer and Environmental Sciences.
University of Illinois at Urbana-Champaign
ces
Helping You Put Knowledge to Work— State • County • Local Groups
U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
opporturuties In programs and employment.
during the day, emerging at night to feed on grass
blades. Damage is seen as brownish turf areas as a
result of thatch showing through thinned-out feeding
areas. There may also be green, pinhead-sized fecal
pellets present. Damage is more likely to occur first
on berms, slopes, and other well-drained areas. Sprays
of chlorpyrifos (Dursban), carbaryl (Sevin), diazinon,
bifenthrin (Talstar), or trichlorfon (Dylox, Proxol)
should be effective controls. (Remember that diazinon
cannot be applied at golf courses and sod farms.) The
nematode Steinemema carpocapsae, sold as Biosafe
and Vector, should also be effective.
Black turfgrass ataenius first-generation larvae
hatch — and are treatable — when bridal wreath spirea
{Spiraea x vanhouttei) is in full bloom. The 1/4-inch,
black beetles have been seen on golf greens for
several weeks, but the insects are controlled most
effectively during the early larval or grub stage. The
second generation is controlled along with annual
white grub in late summer. Black turfgrass ataenius is
likely to be a pest only in highly managed turf areas
such as golf course greens and fairways. Damage is
most common along the aprons of greens and in
fairway swales where water accumulates from irriga-
tion. Any of the recommended white grub insecticides
are effective for control. (Phil Nixon)
Caterpillars
Cankerworms, pine sawfly larvae, and eastern tent
caterpillars continue to be active throughout the
state. This year, eastern tent caterpillar is as uncom-
mon in northern Illinois as it is common in southern
Illinois — only one colony has been found at the
Morton Arboretum in Lisle. The Morton Arboretum
also reports that pine sawfly larvae have just recently
hatched and are still quite small, so it will take careful
scouting in northern Illinois to detect this pest.
White-marked tussock moth larvae are hatching
from eggs in east-central Illinois. The best way to
identify these caterpillars when they are young larvae
is to examine the egg mass, which is white and fuzzy
with little white eggs. As with moth caterpillars,
young larvae feed on the lower epidermis of the leaf
but not the upper epidermis, which results in a win-
dowed appearance.
Achieve control of all these caterpillars when they
are young by pruning out or removing the egg mass
and any associated young larvae. (Phil Nixon, John
Lloyd, and Fredric Miller; Karol Jacobs of the
Morton Arboretum)
Sap-Feeding Arthropods
Honeylocust plant bug is present throughout Illinois
and feeding on the leaflets of honey locust. Leaflets in
central Illinois are already starting to show the
distortion and curling associated with feeding dam-
age. Control these insects with synthetic pyrethroid
sprays such as bifenthrin (Talstar), cyfluthrin
(Tempo), lambda-cyhalothrin (Scimitar), or perme-
thrin (Astro). Imidicloprid (Merit) will also be effec-
tive. Insecticidal soap and summer spray oil are
effective on small nymphs. If the treated trees tend to
have problems with honeylocust mite later in the
summer, use one of these latter two materials to
reduce the impact on mite predators.
Ash plant bug continues to be present throughout
the state. Where populations are large, the insecticides
suggested for honeylocust plant bug are effective in
preventing heavy damage.
Oystershell scale brown race has hatched in
central Illinois. Crawlers should be present and
treatable through the end of the month. Crawlers of
the gray or banded race should be hatching in about a
week in central Illinois and should already be present
in southem Illinois. This scale should start hatching in
northern Illinois near the end of May.
Potato leafhopper is present in southem and
central Illinois. In central Illinois, only the slender,
1/8-inch-long, green adults are present. Look for them
on leaf undersides, particularly on red maple, sugar
maple, redbud, and winged euonymous (burning
bush). Sprays of the insecticides listed above for
honeylocust plant bug are effective on this insect.
Also, imidicloprid, sold as Merit, is effective if
applied as a soil injection or soil drench. The soil
drench is most effective on bare soil. This insecticide
will move systemically to branch tips and provide
control. One soil application should provide season-
long control.
Spruce spider mite continues to feed throughout
the state. This mite and its close relatives will be
feeding on spruce, juniper, pine, and other needled
evergreens into late June before laying over-
summering eggs. Before initiating treatment, be sure
that these mites are correctly identified. Knock some
of them off the foliage onto a piece of white paper.
Plant-feeding mites will make green streaks when
squashed. Dicofol (Kelthane), insecticidal soap,
summer spray oil, and several pyrethroids are effec-
tive against these pests.
No. 6 • May 28, 1997
Hemlock eriophyid mite (hemlock rust mite) is
active at the Morton Arboretum. Although eriophyid
mites are usually associated with gall formation
(maple bladder mite) or the stunting of new growth
(cyclamen mite), the hemlock rust mite feeds on the
needles. Heavily attacked needles turn blue and then
brown before falling off. Feeding occurs primarily
during the spring, with populations dropping and
remaining low throughout the summer. This mite also
attacks fir, spruce, yew, and golden-larch
(Pseudolarix). Dicofol (Kelthane), insecticidal soap,
and summer spray oil should provide control. (Phil
Nixon, John Lloyd, and Fredric Miller; Karol Jacobs
of the Morton Arboretum)
"Phantom" Insects
The cold snaps that dropped the temperatures below
freezing a couple of weeks ago damaged many
immature leaves and buds. This damage became
apparent as the leaves unfolded, revealing dead leaf
tissue or holes where tissues dropped out. When new
leaves are damaged by cold and high wind, they can
appear to be suffering from insect damage. An inspec-
tion of the damage pattern will distinguish leaves
damaged by weather conditions from those damaged
by insects. With weather-damaged leaves, there is no
pattern to the damage and the holes in the leaf are
jagged. Leaves with wind damage may also have
straight-line rips in the tissue. If leaves are damaged
while still in the bud, a uniform pattern may appear as
they unfurl. Although in some cases, this damage may
be initiated by insects feeding on the bud, we should
avoid always placing blame for the damage on
insects. In many cases it's actually the fault of Mother
Nature. (John Lloyd)
PLANT DISEASES
Anthracnose Update
Sycamores in central Illinois have not disappointed
pathologists this year — these trees are heavily in-
fected with anthracnose. What many of us mistook for
late leafmg out was actually anthracnose killing the
first set of leaves. The later leaves are now beginning
to unfurl, and shoot blight is very evident. Don't
worry, though — the infected leaves will fall, and new
growth will soon provide shade below the sycamores
(not to mention many leaves to rake in the fall).
Although sycamores are infected each year, the
species still manages to thrive. Concerned growers
may want to provide supplemental water in periods of
drought, then leave the trees alone.
We have also found a fairly severe case of ash
anthracnose in the Champaign-Urbana area. Ash trees
tend to react to leaf loss much harder than sycamores
do, but again, they will fill in with warmer weather.
Deep root watering will be particularly helpful for ash
trees.
For more information about anthracnose, see the
article on anthracnose of shade trees in Issue No. 4 of
this newsletter. (Nancy Pataky)
Cytospora Canker of Spruce
Spruce trees in the Midwest seem to have taken a
beating over the past year. We've received complaints
about stressed or poorly growing spruce trees from
most areas in Illinois; newsletters from both Ohio and
Indiana report similar problems. The causes are many,
but tend to be environmental: compacted soil and
extremes in water availability and temperature.
Another common cause of spruce stress is the spruce
spider mite.
Stressed spruce trees are quite susceptible to
Cytospora canker, which is probably the most com-
mon and damaging infectious disease of spruce in
Illinois. Colorado blue and Norway spruce are very
susceptible, especially 10- to 20-year-old trees. This
disease appears on the spruce as dead or dying
branches, usually starting at the base of the tree and
moving upward. Occasionally the affected branches
will be scattered throughout the tree. The needles may
drop early from affected branches or could hang on
for several months, leaving dry, brittle twigs. The
disease can continue to spread until all the branches or
the entire tree is dead. Conspicuous patches of white
resin commonly form on the bark in the cankered
areas. The diseased tissue is brown under the thin
layer of outer bark. Black pinhead-sized fruiting
bodies of the fungus (pycnidia) form in the inner bark,
often embedded in the resin.
Don't be fooled when diagnosing Cytospora
canker. The mere presence of dead branches does not
confirm Cytospora. Look for resin areas at the base of
the dead branches. Then look even further for black
pycnidia. We have seen so much damage to spruce
from environmental stress this past year that it is
possible the injury has nothing to do with an infec-
tious agent. On the other hand, stressed spruce trees
are more susceptible to Cytospora canker, and it is
highly likely that the disease will eventually invade
the stressed tree as a secondary pathogen.
There are no chemical controls to prevent or
eradicate this disease. Remove dead branches as they
occur, but be certain to wait for dry weather for this
pruning. Try to improve tree vitality by watering in
drought stress periods. It may be helpful to apply an
organic mulch under the full spread of the branches
but not up against the trunk. The mulch will help
retain moisture and maintain a more even temperature
and moisture environment for the roots. For more
information on Cytospora canker of spruce, consult
Report on Plant Diseases No. 604. (Nancy Pataky)
Red Thread of Turf
This fungal disease is commonly associated with cool,
damp weather in spring and fall. This year is no
exception. Weather conditions have been ideal for red
thread development in many areas of Illinois.
Laetisaria, the fungus that causes this disease,
forms conspicuous, pale-to-bright coral-pink, orange,
or red threadlike masses on the grass blades and leaf
sheaths. In the morning dew, the color is even more
evident. As the disease progresses, blades die from the
tip downward. The diseased turf is eventually
bleached tan, yellowed, or scorched in circular to
irregular patches. These patches may be anywhere
from one to two inches in diameter. Because the dead
leaves are generally interspersed with apparently
healthy leaves, the turf will appear scorched and
ragged. If that is the case, examine the turf in the early
morning to confirm or rule out this disease.
Red thread rarely kills turfgrass plants, but it may
weaken them and contribute to decline or infection by
other diseases. The disease is particularly prevalent on
slow-growing, nitrogen-deficient turf. Other condi-
tions favorable for red thread are excess thatch, low
soil calcium levels, water stress, a sudden drop in
temperature, and misused herbicides. Correcting these
stress factors will help control this disease. Often a
fertilization treatment will correct the problem, but
red thread may occur even in well-fertilized lawns.
If you have a problem with this disease, put the
mower bag back on the mower and collect the clip-
pings. Because the fungus remains viable on the
clippings, you should remove the inoculum from the
lawn. Some bluegrass varieties with resistance to the
red thread fungus are listed in Report on Plant
Diseases No. 413. Check with your local seed source
for availability of other resistant varieties.
Chemical options are not the usual course for red
thread control, but some are available for that use and
are listed in the 7997 Illinois Commercial Landscape
and Turf Pest Management Handbook. Fungicides
must be initiated when the disease is first evident and
must be repeated at 7- to 21 -day intervals during
moist weather when daytime temperatures average
65°F to 75°F (Nancy Pataky)
Vinca Stem Blight
In areas of the state where rain has been heavy or
where regular watering is practiced, a common
problem that will soon appear is stem blight of Vmca
minor (periwinkle or ground myrtle). This stem blight
is a fungal disease caused by Phoma exigua var.
exigua.
Vinca stem blight causes rapidly expanding, dcirk
brown to black girdling lesions on the stems. New
shoots grow over the infected canes, so look under
new growth to detect Phoma. Lesions appear at the
stem base on new shoots and at nodes along runner
stems, especially where the stems contact the soil. The
stems then wilt, turn brown to black, and die, becom-
ing obvious to the homeowner.
The fungal pathogen commonly colonizes dead or
dying plant material. It is beUeved to overwinter as
dormant mycelia and as pinhead-sized, brown to
black fruiting bodies (pycnidia) on the dead stems and
leaves. When establishing a bed of vinca, carefully
inspect new plants for the lesions and pycnidia
described. Use only clean plants from a reputable
nursery.
Because this disease thrives in wet locations, water
only enough to maintain plant vigor. Incidence of the
disease will taper off during the hot, dry conditions of
summer, but new infections may occur any time from
June through August following prolonged periods of
cool, wet weather. Mancozeb and many copper
fungicides are registered for use against this stem
blight. Carefully read the label for crop clearance
before purchasing such a product. For more informa-
tion on this disease, refer to Report on Plant Diseases
No. 640. (Nancy Pataky)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members. Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd, (217) 333-6653, and Fredric Miller, (708) 352-0109,
entomologists; Nancy Pataky, plant pathologist, (217) 333-
0519; and Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350. Phil Nixon is the executive
editor of the Home, Yard and Garden Pest Newsletter.
This newsletter is written by faculty in the Department of
Natural Resources and Environmental Sciences and the
Department of Crop Sciences. The newsletter is edited by
Peggy Currid, typeset by Oneda VanDyke, and proofread
by Herbert Morgan, all of Information Services.
JUN 2 6 1997
C^P ^ AG Ubra/v
COOPERATIVE EXTENSION SERVICE
HOME, YARD & GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
Illinois at urbana-champaign a i 1 1 i nois natural history survey, champaign
NEWSLETTER
No. 7 • June 4, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
INSECTS
Scouting Report
Cool temperatures during the past week have re-
stricted the development of insects throughout the
state. The scouting report in the previous issue of this
newsletter should still suffice for this week's pest
problems, although most of the pests discussed in that
issue will be present slightly farther north in the state.
Key pests to be treated are lilac/ash borer in northern
Illinois, bronze birch borer in southern and central
Illinois, European pine sawfly in central and northern
Illinois, euonymous scale in southern and central
Illinois, and spruce spider mite, oystershell scale, and
pine needle scale throughout the state. (Phil Nixon
and John Lloyd)
A Galling Situation!
Every year about this time, people start noticing
bumps or other abnormal growths on their trees and
shrubs. These abnormal growths, called galls, can be
very disturbing to the people whose plants are af-
fected. Fortunately, most galls affect only the appear-
ance of the trees and are not detrimental to plant
health.
Galls are a plant's response to insects, mites,
bacteria, fungi, or nematodes. Galls are actually
created by the plants themselves in response to some
stimulus from the invading organism. In the case of
insect and mite galls, they are the plant's natural
response to these pests' feeding. Feeding damage and
insect secretions initiate the production of normal
plant growth hormones within the plants. These
hormones produce abnormal cell growth, which
results in the development of galls. For gall formation
to occur, the stimulus (in this case, feeding) must be
initiated when leaves or other plant parts are growing
rapidly. Hence, the development of galls in the spring.
Once the galls have been initiated, nothing can be
done to prevent their development. Even if the insect
or mite is removed, the plant will continue to produce
the gall tissue.
Many species of mites, wasps, midges, aphids, and
psyllids can initiate plant galls. These creatures
benefit from galls, which form barriers around the
immature stages of the pests and protect them from
predators, pesticides, and adverse environmental
conditions. The gall makers feed on gall tissue
produced in response to their feeding. So, in a way,
the gall makers cause the plant to create a smorgas-
bord for feeding.
Despite the protection of a gall, some natural
enemies of gall makers manage to circumvent these
plant-made defenses and attack the gall makers inside.
When dissecting insect-initiated galls, it is not uncom-
mon to discover the larvae or pupae of parasitic wasps
dining on the gall makers.
Gall-inducing insects and mites have species-
distinct galls. Identification of the gall maker is based
on the gall it produces. Over 2,000 types of galls on
trees are produced by insects. The majority of these
insect galls are produced by wasps, and over 700 of
these wasp-produced galls occur on oak trees.
Of the galls found on trees, leaf galls on the petiole
and upper or lower leaf surface are the most common.
These galls appear as leaf curls, blisters, nipples, or
hairy growths. Although leaf galls may be unsightly,
the majority do little or no damage to the host plant.
For most leaf galls, management is unnecessary and
A ^^^P C College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urbana-Champaign
ces
Helping You Put Knowledge to Work — State • County • Local Groups
U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
opportunities in programs and employment.
I^U. / ' Jul ic ■
impractical. Chemical control of leaf galls is difficult,
if not impossible. Control to prevent galls must be
initiated before gall formation begins. Treatment after
gall formation is initiated may kill the gall maker, but
the gall will continue to grow. Treatments to control
leaf galls may aggravate the problem by killing the
natural enemies that regulate the gall maker popula-
tions, which will increase gall problems in the future.
Galls that occur on woody portions of plant materi-
als can cause more of a problem for tree health and
appearance than leaf galls do. Unlike leaf galls,
woody galls are not removed with leaf fall. Old galls
that no longer contain the gall makers remain on
branches and twigs and can reduce growth beyond the
gall in future years. In some cases, these galls will
even girdle the branch. Pruning out these galls when
they are still green and destroying them is the primary
form of management. In addition, pruning out the
newly forming galls might help reduce the probability
for infestations in subsequent years.
Only in severe situations is chemical management
with an insecticide a viable option for controlling gall
makers. Insecticidal management must be initiated
prior to budbreak, during leaf expansion, or at other
times when the pests are active. This timeline for
treatment is extremely short and, in many cases,
impractical.
It has yet to be determined whether new injection
technologies and systemic insecticides will provide
any reduction in gall production on infested trees. To
prevent gall formation, insecticides administered
through injection must remain active prior to the
insect feeding. The malformed tissues of the gall may
affect the ability of the insecticide to reach the tissues
upon which the insects or mites are feeding. As
information on the effectiveness of these types of
treatments becomes available, we will share it with
you.
The 7997 Illinois Commercial Landscape and Turf
Pest Management Handbook contains chemical and
nonchemical management recommendations for the
most common galls that attack trees in Illinois.
(John Lloyd)
PLANT DISEASES
Damping-Off or Seedling Blights
Seedling diseases are usually most severe under
conditions that slow the growth of young plants,
including cool soil temperatures, overly wet soils, and
poor seed quality. Although we may be able to control
the last factor, nothing can be done about the cool,
wet spring we've had. Many of us planted seeds in
gardens, assuming that temperatures would soon
warm up. Cool temperatures have persisted, wet
weather has prevailed and, as a result, seedling blights
have been common.
All species of plants grown from seed are suscep-
tible to one or more of the soil-borne fungi capable of
causing damping-off of seedlings. Both in the field on
direct-seeded crops and in the greenhouse during the
production of transplants, damping-off can be a
serious problem. Plants wilt and die suddenly, some-
times before emerging from the soil (preemergence
damping-off), and sometimes after emerging from the
soil (postemergence damping-off). Symptoms can
include root rot, stem lesions, and general seedling
wilt. At this time of year, the problems are seen in
vegetable plantings and flower beds.
It is well worth the money to use high-quality seed
that will germinate quickly and allow plants to rapidly
become established. Mature seedlings are more
resistant to seedling blights than young seedlings are.
If possible, buy seeds or transplants certified as
disease free. Many commercially produced seeds are
treated with broad-spectrum fungicides, such as
captan or thiram, to help protect the seeds and young
seedlings from fungi. This protection lasts for only a
week or two after planting. Because our weather has
remained cool and wet for over three weeks, even the
treated seed may have problems.
Choose a planting site that is well drained and
without a history of seedling disease problems. Plant
when soil temperatures and moisture conditions favor
quick germination and plant growth. Using raised
beds may help improve soil drainage and increase soil
temperatures to allow rapid growth.
Fungicides, applied at planting or transplanting, are
registered for controlling seedling diseases on some
vegetable crops, such as snap beans, peas, and pep-
pers. Many ornamental plants may be treated as listed
by host in the 7997 Illinois Commercial Landscape
and Turf Pest Management Handbook. As with most
disease control, the fungicide treatments of seeds are
intended to protect against the damping-off fungi. You
cannot wait for the problem to occur before you treat.
Further information on damping-off diseases is
available in Report on Plant Diseases No. 615,
Damping-off and Root Rots of House Plants and
Garden Flowers, as well as No. 916, Damping-off and
Seedling Blights of Vegetables. (Nancy Pataky)
No. 7 'June 4, 1997
Volutella Leaf and Stem Blight of
Pachysandra
The shade-loving ground cover pachysandra has
played host this year to a particularly devastating
fungal disease called Volutella blight. The disease
may begin as brown blotches on leaves, but pro-
gresses through stems and stolons, causing cankers
that girdle and kill stems. The disease often follows
some type of stress, such as winter injury, insect
infestation, sun scald, or recent shearing.
Look for wilted pachysandra plants with brown
blotches on the leaves. Push back the leaves to find
the blotches and cankers on stems. Infected stem
cankers will be damp and have pinhead-sized,
salmon-pink spore masses. Remove and destroy any
severely infected plants. (Do this when plants are dry,
if you can wait.) Chemicals may be used as pro-
tectants; repeat applications are necessary at 10- to
14-day intervals. Chlorothalonil, copper fungicides,
Duosan, Fore, mancozeb, and Zyban are registered for
this use on pachysandra.
It is also helpful to keep insects under control and
to mulch pachysandra with a material that does not
hold moisture. Pruning any surrounding plants for
better air movement in the area may also help manage
this fungus. Consult Report on Plant Diseases No.
649 for additional information. (Nancy Pataky)
Crabapple Scab
We have not placed much emphasis on this disease in
1997, partially because it was so devastating last year
and received so much press, and partially because the
scab has been slow in developing this year. Apple
scab is a fungal disease that causes serious injury to
apples and crabapples. Similar fungi cause scab on
cotoneaster, firethom, hawthorn, mountainash, pear,
quince, and a few other species. The economic loss to
ornamentals may not justify the expense of fungicidal
sprays every year, but fungicides can provide valuable
assistance to the fruit grower.
The first infections usually appear on the
undersurface of flower sepals or flower cluster leaves.
Infections appear as small, irregular spots that are
light brown to olive green. These spots enlarge to
become circular, velvety, and olive green. Spots
blacken and cause the leaves to become dwarfed,
curled, and often scorched. Leaves eventually turn
yellow and drop from the trees. Central Illinois
growers are seeing the velvety spots spreading across
susceptible leaves now, but defoliation has not begun.
Infection levels this year are not nearly as severe as
they have been in the past two yecu*s.
A grower cannot wait for symptoms to develop
before starting a spray program. As we have preached
in the past, sprays must begin at budbreak to protect
new leaves as they emerge. Many fungicides are
registered for this use. Recommendations for orna-
mental hosts are listed in the 7997 Illinois Commer-
cial Landscape and Turf Pest Management Hand-
book.
After two years of dealing with severe scab,
growers should consider replacing susceptible trees
with one of the many scab-resistant choices. (Refer to
Report on Plant Diseases No. 803 for resistant variety
suggestions.) Also, choose a variety that is resistant to
cedar apple rust and powdery mildew, two other
common diseases of apple and crabapple trees.
(Nancy Pataky)
Verticilllum Wilt
Maples, smoke tree, and magnolia have been the most
popular hosts for Verticillium wilt at the plant clinic in
recent years. However, more than 300 plants (includ-
ing weeds) are susceptible to this fungal disease. The
soil-borne Verticillium fungus is now active, and tends
to invade weakened or stressed plants more often than
it does healthy, vigorous plants. It invades plants
through wounds above or below ground. Once
introduced into the soil, the fungus can survive for
five years or longer, so identification of the problem is
important when considering replanting in the same
spot.
Symptoms include wilting and yellowing, as well
as the death of leaves, branches, or entire plants.
Chronic symptoms may follow: stunted, chlorotic,
and deformed foliage; leaf scorch; slow growth;
abnormally heavy seed crops; and dieback of shoots
and branches. The vascular tissue is discolored,
usually brown, black, or light to dark green. In terms
of diagnosis, this factor is most significant. Samples
taken for laboratory cultures must contain this discol-
oration for valid results. Tissue must be alive but
showing active wilting.
Resistant varieties are available for a few plants,
such as strawberry and tomato. Thorough watering
and proper fertilizing to promote vigorous growth
often aids affected trees and shrubs. Most species will
not readily recover from this disease, but maples have
been known to "wall off' the fungus within the wood
when growth is rapid. Do not grow susceptible crops
on land where crops that proved susceptible to
Venicillium wilt were grown previously. A rotation of
five years or more for vegetables and flowers may
help reduce the amount of inoculum in the soil. For
more information, including lists of susceptible and
nonhost crops, plus additional control measures, read
Report on Plant Diseases No. 1010. (Nancy Pataky)
HORTICULTURE
Command Herbicide — Off-Target Drift
Although I don't know of any specific incidences of
Command herbicide injury, it certainly may be
occurring in Illinois. The May 27, 1997, Indiana
Educator Update from Purdue's Plant and Pest
Diagnostic Clinic indicated that they have recently
received from commercial growers and homeowners
samples of ornamentals, flowers, and vegetables with
symptoms (such as bleached foliage) of Command
herbicide injun,'. In each case, Command had been
applied to a soybean field somewhere in the area, but
not necessarily adjacent to the affected plants.
Command is a herbicide that controls various
annual grasses and certain broadleaf weeds, such as
velveileaf, in soybeans. Last year, a new formulation
of Command was introduced. The new product is
used as a preemergence treatment and does not
require immediate incorporation into the soil. This
formulation, known as Command 3ME, is a
microencapsulation of the active ingredient,
clomazone.
Command 3ME does not require incorporation
because it is not as volatile as the old "EC" formula-
tion. However, off-target injur\- to susceptible plants
may still occur from 3ME, Even though the 3ME
product is less volatile than the old product, spray
pressure, particle size, nozzle type, boom height, and
high winds can all cause off-target drift of this (and
other) herbicides on the day it is applied.
Applicators must be cautious when applying this
product near sensitive plants, particularly on days
with gusty winds. In fact, the Command 3ME label
warns not to apply it on days with winds in excess of
10 mph. Also, the label prohibits the use of this
product within 1 ,200 feet of towns, housing develop-
ments, commercial fruit or vegetable production, and
commercial greenhouses or nurseries.
If Command injury symptoms are evident on plants
grown for food, such as garden vegetables and
strawberries, the fruit should not be consumed,
because this is considered an off-label application.
(Rhonda Ferree)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members. Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Senice.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd, {217) 333-6653, and Fredric Miller, (708) 352-0109,
entomologists; Nancy Pataky, plant pathologist, (217) 333-
0519; and Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350. Phil Nixon is the executive
editor of the Home. Yard and Garden Pest Newsletter.
This newsletter is written by faculty in the Department of
Natural Resources and Environmental Sciences and the
Department of Crop Sciences. The newsletter is edited by
Peggy Currid, typeset by Oneda VanDyke, and proofread
by Herbert Morgan, all of Information Services.
op
9-
JUN 2 6 199?
COOPERATIVE EXTENSION SERVICE
HOME, YARD & GARDEN PEST
:ural, consumer and environmental scJenct
Illinois at urbana-champaign A illinois natural history survey, cnampaign
NEWSLETTER
No. 8 'June 7 7, 7997
This neyvslener is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed
PLANT DISEASES
Scouting Update
Man\- of the diseases that we have discussed over the
last several weeks are now in full bloom. Cool
conditions have slowed plant gro\Uh and allowed
fungi to infect and pervade plant tissue. Wet condi-
tions in many parts of Illinois have also provided ideal
conditions for fungal growth.
Leaf spot diseases are prevalent over most of the
state. At the clinic, we have seen anthracnose on
sycamore, maple, ash, and elm. Strawberries have
their share of leaf spots again this year, with common
leaf spot the most prevalent so far.
Scab is beginning to cause problems on susceptible
crabapples, most recently as leaf yellowing.
Peach leaf curl has many peach growers con-
cerned, and the closeh' related leaf curl of oak has
been common, at least in central Illinois.
Rhizosphaera needle cast on spruce has caused
needle purpling and needle drop in all parts of Illinois.
Cedar quince rust has been identified on haw-
thorns throughout the state, causing stem swellings
and cankers.
Red thread is the predominant turf disease we
have been dealing with.
Watch for Guignardia leaf blotch on horse-
chestnut. Also watch for Verticillium >nlt on trees
that have had problems in the past. The clinic also
identified a case of pine wilt this past \\ eek. (Nancy
Pataky)
Pine Wilt
Pine wilt is caused by the pine wood nematode. It is
vectored (spread) b>' the sawyer beetle and a few
related long-homed beetles. Many readers of this
newsletter probably think of nematodes as soil or root
pathogens, but the pinewood nematode lives in the
wood of the tree. The nematode is microscopic and
blocks water-conducting tissues, causing a wilt
similar to the fungal wilt diseases. Although the
nematodes are too small to be seen, the symptoms of
infection can be observed.
Pine N'.ilt causes a sudden decline and death of the
entire tree within a few weeks or months after the first
sign of disease. Symptoms acmally occur in four
stages: needles first appear light grayish green, then
yellowish green, then turn yellowish brown, and
fmally tum completely brown. On affected trees, this
color change can occur branch by branch or over the
entire tree. However, on Austrian pine, we have seen
cases in which trees tested positive for pine wilt but
initially showed symptoms on branch tips only.
Pines with root problems, water-related stress, or
cold injun.- will decline from the top downward. The
decline could also start at the bottom of the tree and
move up, or possibly start in branch tips and move
inward. Needle color, however, does not progress
from grayish green to brown. Instead, necrosis is
fairl)- quick.
Samples to be tested for pine wilt should be sent to
the Plant Clinic or another lab where a nematologist is
available. Our fee is $15.00. Branch samples should
be one to two inches in diameter and long enough to
put into a vise so that wood discs can be cut from both
ends of the branch. Because the pinewood nematode
is not uniformly distributed within a tree, we fmd that
the most reliable samples are from branches that have
brown needles still attached.
No effective chemical controls exist for either pine
wilt or its vector. Affected trees should be burned or
buried to reduce reservoirs of infection. Recent
.-\CES
College of Agreultural, Cortsumer and Environment] Scia-tces.
University of IBirxxs at Urttana-Champaign
ces
Helping Vou Put Kno*Te(Sge to Work — Stale • County • Local Groups
U.S. Departrrveni of AgncuSure Cooperating
The Cooperattve Extension Servce proviOes equal
opportunities r programs anc erTvpoyment.
research shows that it is probably safe to chip the trees
for mulch. Still, you might want to compost the mulch
before use or spread it out to dry before placing it near
pines. Prune dead branches from live trees to mini-
mize attractiveness to beetle feeding. Beetles that
emerge from the dead wood may carry the nematode
and fly to healthy pines several miles away. When
beetles feed on a healthy pine, they may transmit the
nematode to the heahhy tree through feeding wounds.
The nematode enters the resin canal and eventually
clogs the water transport system of the tree.
Replace dead pines with Norway or blue spruce,
Douglas-fir, cedar, hemlock, or other nonsusceptible
species. Consult Report on Plant Diseases No. 1 104
for details about pine wilt disease. (Nancy Pataky)
Black Knot of Plum and Cherry
Some concern was expressed about this disease at a
recent disease training session in northern Illinois.
Black knot is a rather ugly disease, but it can be
controlled with fungicide applications and pruning.
The causal fungus, Dibotryon morobosum, can infect
at least two dozen species of cherries, plums, and
other members of the Prunus genus, including some
ornamental species.
Black knot causes elongated, rough, girdling, black
swellings on twigs, branches, and sometimes even the
trunk. The knots are a velvety olive green in the
spring; they gradually become hard, brittle, and coal
black. If stems become girdled, dieback is evident.
The trees weaken and may die unless effective control
measures are taken.
Purchase only disease-free nursery stock. Never
buy trees with visible knots or abnormal swellings on
the twigs and branches. Look for this disease in its
early stages, when it appears as light brown swellings
that later rupture the bark and tum darker. Prune and
bum (or bury) all infected wood in late winter or early
spring before growth starts and as soon as new knots
appear. Make cuts four to eight inches behind any
obvious black-knot swellings. Use a knife and chisel
to carefully cut away knots on the trunk and large
limbs — remove about an inch of healthy bark and
woody tissue beyond any visible gall tissue. If pos-
sible, destroy (bum) all wild, neglected, or worthless
plum and cherry trees.
Most infections of black knot occur between
budbreak and two weeks after bloom, when wet
conditions are accompanied by temperatures ranging
from 55°F to 77°F. For effective protection against
this fungus, apply fungicide sprays when buds open
and repeat the spray every two weeks until about three
weeks after petals fall. These early season fungicide
sprays are protectants: they will help prevent new
infections but will not stop infections already present
on the tree. Recommendations are listed in the 7997
Illinois Commercial Landscape and Turf Pest Man-
agement Handbook.
The only product that we can recommend for
homeowners is copper. There are many formulations
of copper, so read the label carefully to be certain that
the formulation you choose is registered for the host
tree that you have. Also be sure that the product is
specifically labeled for use against the black knot
fungus. In addition to chemical treatment, all visible
knots must be pruned from the trees to remove old
infections.
For more information concerning this disease,
consult Report on Plant Diseases No. 809, Black
Knot of Plums and Cherries. (Nancy Pataky)
Leaf Spots of English Ivy
English ivy is a hardy vine that works well in shady
locations; however, it is frequently attacked by
bacterial leaf spot and stem canker, as well as a few
fungal leaf spots.
Bacterial leaf spot and stem canker is more com-
mon than fungal leaf spots, although the fungal
diseases have been seen this season. Bacterial leaf
spot first appears as small, circular, dark-green, water-
soaked (oily) lesions on the leaves. As these lesions
enlarge, they have reddish brown to black centers
with a water- soaked margin and sometimes a yellow
halo. The spots also crack with age. In warm, wet
weather, the bacterium causes black cankers on the
stems and petioles; stems die, often with black tips.
The fungal leaf spots are caused by a variety of
fungal species. They cause round to irregular spots in
a variety of colors. Often a series of concentric rings
can be seen in the spots. Look closely on the spots for
small black specks, which are fruiting structures
containing spores of fungi. Bacterial spots do not have
fruiting structures because bacteria do not form
spores.
If you establish a bed of ivy this year, look closely
at new plants to be certain that you do not introduce
diseased plants. Remove any questionable leaves or
stems. It is also a good idea to remove old leaves and
debris from the beds each spring before new growth
starts. Because these diseases require water on the
No. 8 'June n, 1997
foliage to infect the blades, water the soil rather than
the foliage when possible. Water early in the day so
that wet foliage will dry quickly.
If fungal leaf spots have been severe in the past,
apply fungicides when new leaf growth begins in the
spring. Registered chemicals are listed in the 7997
Illinois Commercial Landscape and Turf Pest Man-
agement Handbook. Because the chemicals are
protectants, they usually require repeat applications
every seven to ten days as long as wet weather
persists in the spring and early summer.
Few chemicals protect plants from bacterial leaf
spot and stem canker. The copper compounds and
Chipco Aliette may help. Try to improve air move-
ment in the area by thinning the stand and pmning
surrounding plants. Never work with the plants when
they are wet. For more information about these
diseases, consult Report on Plant Diseases No. 652,
Leaf Spot Diseases of English Ivy. (Nancy Pataky)
INSECTS
Scouting Report
Bronze birch borer adults have emerged in the
Chicago area according to scouts at the Morton
Arboretum. Female beetles will soon begin laying
eggs in rough portions of the bark or branch crotches
of susceptible birch trees. (This egg-laying is already
occurring in southem sections of central Illinois.)
Trunk and limb treatments with chlorpyrifos
(Dursban) will provide a residual barrier that will kill
hatching larvae as they attempt to burrow into the
tree. To help prevent bronze birch borer problems,
avoid using birches in the landscape, or select less
susceptible varieties such as heritage, whitespire, or
river birch. In established landscapes, it is imperative
to provide susceptible trees with adequate amounts of
moisture through the use of frequent irrigation or
mulching. Regardless of maintenance practices,
realize that in urban landscapes, birch is a fast-
growing, short-lived species that will eventually
succumb to bronze birch borer and need to be re-
placed.
Bruce Spangenburg of the Grayslake Extension
Center has reported sod webworm activity in
McHenry County. Although webworm activity may
seem early given the unusually cool weather, we
might see a problem with that pest in areas (such as
the northern third of Illinois) that have not received as
much rain as we have in central Illinois.
Usually the first generation of sod webworm does
little or no damage because spring rains keep turf
healthy and provide a good environment for webworm
pathogens. Second- and third-generation webworm
feeding is the primary source of turf damage during
drier weather when the turf is not as lush. If damage is
noticed early in the season, management with a surface
insecticide should provide adequate control.
The little "splatters" across windshields on vehicles
throughout central Illinois are actually potato leafhop-
per guts. Potato leafhoppers are feeding on new
soybeans that are popping up in fields throughout the
area and should soon be causing damage on suscep-
tible ornamental plants. Although physical destruction
at 55 mph effectively kills some of the leafhoppers, the
spottiness of this method will not significantly reduce
their overall numbers. To prevent the symptomatic leaf
discoloration and shoot injury associated with leafhop-
per feeding, begin insecticidal management when
leafhoppers are noticed on red maple, euonymus, and
other susceptible plants. Synthetic pyrethroid insecti-
cides (such as Talstar, Tempo, and Scimitar) will
provide adequate control of this pest. (John Lloyd, Phil
Nixon, and Fred Miller; Karel Jacobs of the Morton
Arboretum)
Scales
The crawlers of pine needle scale, euonymus scale,
European elm scale, and the brown race of
oystershell scale are still active in northem regions of
Illinois. Scale crawlers are extremely sensitive to most
management measures. Most insecticides and less
toxic alternatives (insecticidal soaps and summer oils)
will provide good control of the crawlers before the
pests settle down. Treatments with insecticides should
be repeated twice at ten-day intervals for all scales. For
areas in southem Illinois, where the crawlers have
settled down, management techniques should focus on
the next period of crawler activity.
Pine needle scale crawlers will reappear in early to
mid- July in southem and central Illinois, usually when
the blooms on hills of snow hydrangea tum from white
to green. Shake branches over a white surface and look
for moving little red dots to determine if pine needle
scale crawlers are present. Second-generation crawlers
of euonymus scale also occur in early to mid-July.
Crawlers of the gray race of oystershell scale should be
present now that Spirea vanhouttei has finished bloom-
ing. A second generation of oystershell gray race
crawlers will appear in southern and central Illinois in
early August. (John Lloyd)
Caterpillars
Larvae of white-marked tussock moth are hatching
all over southern and central Blinois. When the
caterpillars are in their early stages of development,
they appear as nondescript, fuzzy little "moving
lines." It is difficult to distinguish these larvae from
those other caterpillars, even with a hand lens or
dissecting scope. The best way to identify them is to
look at the egg mass. Most defoliating caterpillars
have distinct egg masses. White-marked tussock moth
eggs are located in a fluffy white mass that is usually
attached to fine branches. Insects That Feed on Trees
and Shrubs (Johnson and Lyon) contains many good
pictures of common defoliating caterpillar egg
masses.
Cankerworms are still causing defoliation in
northern counties of Illinois. Populations do not
appear high enough to cause significant defoliation;
however, some leaf damage is evident on most elm
and honey locust trees in the Chicago area.
According to Joe Boggs at The Ohio State Univer-
sity, bagworms are starting to hatch in the Cincinnati,
Ohio, area. Scouts in southern Illinois should be on
the lookout for the young larvae. When they hatch,
young larvae feed on the upper epidermis of the leaf
and build a upward-pointing bag around the leaf. As
they mature, the larvae begin eating entire leaves and
enlarge the bag, which causes it to hang down.
Treatments for young larvae should be initiated after
the eggs have hatched and the larvae have finished
dispersing by ballooning. This usually occurs two
weeks after the first hatch.
Bacillus thuringiensis var. kurstaki (Dipel,
Thuricide, etc.) is a good control for all of these
caterpillars when they are young. (John Lloyd)
Aphids on Maples
Aphids are present in large numbers on maple trees in
several areas of the state. Specimens collected on
sugar maple in Aledo in northwestern Illinois were
identified as Neoprociphilus aceris by Dr. David
Voegtlin of the Illinois Natural History Survey. This
aphid hatches out in the spring on maple and then
migrates to cat briar {Smilax). These aphids will
probably be present for only two or three weeks
before leaving maples for the rest of the year.
Aphids similar in appearance to Neoprociphilus
aceris (probably the same species) occur in several
areas of the state in late spring in some years. These
aphids produce profuse amounts of honeydew, which
drips out of trees and onto cars, sidewalks, and
unsuspecting humans. Maple leaves that are attacked
may wilt and turn yellow. After a few weeks, the
aphids disappear.
Because these aphids occur on maple for only a
short time in huge numbers, they tend to overwhelm
natural enemies such as lady beetles, parasitic wasps,
lacewings, and syrphid flies. In any case, by the time
that the population of natural enemies is sufficient to
control aphids, the aphids are leaving the maples.
A variety of insecticides is available and will
provide control. Insecticidal soap may be one of the
most useful products because it kills aphids on
contact, is low in toxicity, and tends to wash some of
the honeydew off the trees. In many cases, rather than
apply insecticides, it may be best to wait a few weeks
for the aphids to migrate. (Phil Nixon)
Gypsy Moth Traps
The Illinois Department of Agriculture, in cooperation
with the U.S. Department of Agriculture Animal and
Plant Health Inspection Service, is setting traps for
gypsy moths in the northern half of Illinois. The
trapped area extends from the northem edge of
Sangamon County northward through the rest of the
state. The traps are being placed during June and will
be removed by the end of August.
Gypsy moth traps are triangular and approxi-
mately six inches long by three inches wide. Traps
are placed on one-mile grids and are made of lime
green, reddish orange, or tan cardboard. The inside
of the trap is coated with sticky glue, which catches
and holds moths. A synthetic pheromone is placed
inside each trap. This pheromone mimics the one
produced by the female moth to attract the male. No
insecticide is used.
Male gypsy moths are attracted to the traps from
more than half a mile away. Their presence in newly
placed traps alerts Department of Agriculture officials
to a possible problem. Trapping in subsequent years
allows an invading population to be located and
eradicated. Because many moths other than the gypsy
moth are attracted to the trap, the mere presence of
moths in the trap does not necessarily indicate a
problem.
No. 8 'June 11, 1997
If you notice traps in your area, leave them alone.
If one is on a tree, post, or other object that must be
removed, contact the Illinois Department of Agricul-
ture at (847) 294-4343 or (217) 785-2427. (Phil
Nixon)
Rose Pests
A variety of pests attack roses: aphid, rose midge,
roseslug, Japanese beetle, leafcutter bee, slug, and
two-spotted spider mite. Their relative importance
depends on the grower and the growing situation.
Several species of aphids attack rose buds, leaves,
and stems. In many situations, lady beetles and their
larvae, lacewing larvae, syrphid fly larvae, and other
predators, as well as parasitic wasps, will control
aphids without the use of insecticides. However, the
use of insecticides to control or prevent other pests
may kill beneficial insects and make aphid control a
necessity. Insecticidal soaps and other chemical
insecticides can provide effective control.
Rose midge larvae tunnel through the leaf and
flower buds, causing them to die and turn brown. The
tiny fly larvae are white, legless, and about 1/16 inch
long. They drop to the soil to pupate, emerging as
pinhead-sized yellowish to reddish flies. Rose midge is
very spotty in distribution — many growers have
fortunately never seen it. Some growers have been
successful in eliminating rose midge by aggressively
removing attacked buds and/or placing plastic sheeting
over the soil to catch larvae dropping from the plant to
pupate. Larvae that fall on the plastic will dry out and
die. Rose midge has a two-week life cycle that recurs
throughout the growing season. This short life cycle
allows it to develop insecticide resistance very rapidly.
Insecticidal control is directed at both the flies laying
eggs on the buds and the larvae dropping to the soil.
The use of several different insecticides in a rotation as
both foliar and soil treatments usually results in some
control. Try anything that is labeled, and do not rely on
just one or two insecticides.
Roseslug is a sawfly that occurs in the spring and
feeds on rose leaves as larvae. The larvae are covered
with a yellowish green slime and grow to about 1/2
inch long before dropping to the soil to pupate. When
young, they feed through one epidermis and the
mesophyll, leaving an epidermis intact, which turns
brown. Older larvae may eat holes in the leaves.
Roseslug is an uncommon insect in Illinois and can
usually be controlled by hand-picking. Various
insecticides are also effective.
Slugs can also attack rose leaves. These mollusks
are brown or black, about 1/2 to one inch long, and
slimy. Wherever they travel, they leave a slime trail.
Slugs feed at night or during damp, cloudy, or foggy
days. They leave irregularly shaped holes in the
middle of the leaves. Slugs are usually a problem on
low-growing roses that are heavily mulched. Remov-
ing the mulch normally reduces the slug problem.
There are also slug baits that can be used. Insecticides
are not effective, because these animals are not very
closely related to insects and their physiology is
different.
Japanese beetle adults cause heavy damage to rose
leaves and blooms through July into mid- August.
These 1/2-inch-long, stocky, metallic-green beetles
with coppery wing covers are difficult to control.
Carbaryl, sold as Sevin, will protect plants for about a
week, so repeat applications are necessary. Rosarians
growing show roses will usually put netting over buds
or entire plants to protect them from Japanese beetle
damage. Otherwise, some damage is inevitable.
Leafcutter bees cut 1/2-inch-diameter perfect
circles in the leaves to use in lining their nests and
dividing larval cells. Leafcutter bee populations are
usually small, and the bees are important pollinators.
For these two reasons, insecticidal or other controls
are usually not used. Leafcutter bees will also tunnel
into pruned rose canes to produce nests. This can be
prevented by using putty or thumbtacks to seal the end
of the stems at pruning time.
Two-spotted spider mites feed on the undersides of
rose leaves, giving the upper surface a speckled and/or
bronze appearance. This mite is most common during
the dry weather of mid- to late summer. These insects
are fed upon by predatory mites and insects. Heavy
use of insecticides against some of the other rose pests
mentioned in this article may kill beneficial predators,
allowing two-spotted mites to thrive and cause heavy
damage. Insecticidal soap is an effective control, but
this pest will rarely be a problem if you avoid insecti-
cide use. Damage that occurs in late summer or early
fall can usually be ignored.
Some rose varieties tend to be attacked more by
pests than others. Rugosa and other shrub roses and
miniature roses tend to have fewer insect problems
than some of the larger-flowered varieties. In my own
yard, Japanese beetles are much more damaging to
native American roses than they are to multiflora rose.
(Could it be possible that the multiflora rose, which is
Asian in origin, has some resistance to its evolution-
ary contempory, the Japanese beetle?)
Probably the most important factor in rose pest
control is the grower's preference. A grower who
allows some damage to foliage or blooms will use
insecticides less often and will conserve natural
enemies. The increased number of natural enemies
will control some pests such as aphids and mites,
reducing overall damage. When control is needed,
hand-picking of pests and the use of insecticidal soap
will have less of an impact on natural enemies than
the use of most insecticides. (Phil Nixon)
MACH 2 Registered for Turf
RohMid, a partnership between American Cyanamid
and Rohm & Haas, has announced that the U.S.
Environmental Protection Agency registered MACH 2
as a legal pesticide on May 20, 1997. The active
ingredient, halofenozide, is a molt-accelerating
compound that interferes with the normal molting
process.
Experimental tests have shown that MACH 2 is
effective against white grubs (including annual white
gmb), Japanese beetles, and black turf grass
ataenius — taking about three weeks to provide
control. It is also effective against such caterpillars as
black cutworm, sod webworm, and army worm —
providing control in about four days. MACH 2 has a
long-lasting residual and is a low-toxic pesticide (to
humans). (Phil Nixon)
HORTICULTURE
Pesticide Safety Education Program
Information
The 1996-1997 annual report on Illinois's Pesticide
Safety Education programs is now available. The 20-
page document highlights program goals and mission,
program structure, benefits of the program, and major
accomplishments, including educational material
development, pesticide-container recycling, commer-
cial PAT programs, private PAT programs. Worker
Protection Standard (WPS), homeowner programs,
drift-education activities. Operation Safe Fly-In
workshops, and many other programs.
The report demonstrates the depth and breadth of
Illinois's safety education programs. Although com-
mercial and private PAT is the first mission of the
pesticide safety program, it also provides pesticide
education to a diverse audience in other pesticide-
related areas.
If you would like a copy of the annual report,
please contact Patty Bingaman at (800) 244-2363. The
annual report is also available at The Pesticide Safety
Education home page at http://www.aces.uiuc.edu/
~pse/. This site contains the latest issues of the Illinois
Pesticide Review newsletter, fact sheets, links to other
resources, and pesticide applicator training schedules.
(Although the training schedules are currently out of
date, they remain on the home page because they
provide useful information about licensing require-
ments and specifications.) Schedules for 1997-1998
commercial and private pesticide applicator training
programs will be available this fall. (Rhonda Ferree)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana- Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd (217) 333-6653, and Fredric Miller, (708) 352-
0109, entomologists; Nancy Pataky, plant pathologist,
(217) 333-0519; and Rhonda Ferree, Tom Voigt, and David
Williams, horticulturists, (217) 333-0350. Phil Nixon is the
executive editor of the Home, Yard and Garden Pest
Newsletter. This newsletter is written by faculty in the
Department of Natural Resources and Environmental
Sciences and the Department of Crop Sciences. The
newsletter is edited by Peggy Currid, typeset by Jerry
Barrett, and proofread by Herbert Morgan, all of Informa-
tion Services.
Reference and
Teaching Materials
from the
University of Illinois
ACES
Quality You Expect
Expertise You Want
College of Agricultural, Consumer and Environmental Sciences
University of Illinois at Urbana-Champaign
-The Illinois Commercial Landscape and Turf Pest ,
Management Handbook is a must for any
horticulture professional or educator. Topics include
management of weeds, insect pests, and diseases for
• turfgrass • woody ornamentals
• landscaping • flowers, trees, and shrubs
• nursery crops
using both chemical and nonchemical controls.
Revised Annually
ICLT-97 $8.00
In pest and weed identification, pictures are
worth a thousand words. The combination of
high-quality information and superb
photography makes these slide sets great
teaching tools in classrooms or staff trainings.
Lawn Weeds-Identification and Control
76 frames with script
S650a $39.85
Takes the learner through a step-by-step
approach to controlling weeds in turf.
Shade Tree and Woody Shrub Insects:
Identification and Control
78 frames with script
S654.4 $40.85
Turf Insects: Identification and Control
39 frames with script
S654.2 $41.85
Two sets that help the learner identify pests,
understand their life cycles and then select
appropriate chemical and nonchemical
controls to manage them.
^^ Looking for more resources?
Here are two World Wide Web sites packed with
possibilities from the University of Illinois!
www.ag.uiuc.edu/~vista/catalog/catintro.html
www.aces.uiuc.edu/~vo-ag/
-Photo sheets make great identification tools-
Photos on one side with descriptions and
explanations on the back. Certainly an
effective study aid for any student. High
quality at a very reasonable price. Here's a
sampling of what you can order:
Ornamental Insects X698.16
Tree and Shrub Pests I X698.17
Turf Pests I X698.31
Tree Diseases I X699.16
Tree Diseases II X699.17
Tree Diseases III X699.18
Woody Ornamental Diseases I X699.30
Turfgrass Diseases I X699.31
Turfgr asses for the Midwest X699.35
Turfgrass Establishment
in the Midwest X699.36
$ .40 each
To order the Illinois Commercial
Landscape and Turf Pest Management
Handbook, slide sets and photo sheets
call (217) 333-3871. MasterCard and Visa
accepted. Bulk discounts available.
Shipping is extra and may vary by order.
Orders over $10.00 may be billed.
.^
JUN 2 6 1997
i,p ! 'M'-'i^'
COOPERATIVE EXTENSION SERVICE
HOME, YARD 6l^ GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
Illinois at urbana-champaign a i 1 1 inois natural history survey, champaign
NEWSLETTER
No. 9 'June 18, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
INSECTS
Sucking Insects
Periodical cicadas have emerged in a small area of
northwestern Illinois centered in Knox and Henderson
counties. Cicadas are also expected to emerge in
DeWitt and neighboring counties. Next year, periodi-
cal cicadas should emerge through most of the
southern two-thirds of Illinois. Males will sing for
about two weeks, attracting the females to them for
mating. Egg laying by female cicadas will begin near
the end of that two- week period and last for another
week or two.
Use nylon netting, wire screening, or tree wrap to
protect tree trunks that are two inches or less in
diameter. Larger trees probably will not need protec-
tion. The degree of control offered by insecticides
ranges from totally ineffective to only mildly effective
against cicadas, so insecticide treatment is not recom-
mended in most cases.
Honeylocust plant bugs are in later nymphal and
adult stages throughout the northern half of Illinois
and in the adult stage in southern Illinois. Leaflet
distortion damage has already occurred and little will
be accomplished by spraying now. If you are experi-
encing heavy damage, be ready to scout and treat
soon after leaf emergence next year to avoid this
season-long damage.
Ash plant bugs are numerous throughout the state
and have been reported in Rockford and in northeast-
em and southern Illinois. Pyrethroid sprays may still
prevent some damage, particularly in northem Illinois.
The four-lined plant bug is a 1/4-inch-long,
greenish yellow, flat-topped sucking insect with four
black stripes as an adult. The nymphs are reddish and
tend to hide in growing tips and leaf bases. They suck
juices out of mint and a wide variety of flowers
including chrysanthemum, coreopsis, veronica,
artemisia, salvia, black-eyed susan, astilbe, and
cranesbill geranium. Their feeding causes blackish
areas on leaves; severe infestations lead to dieback.
The four-lined plant bug can be controlled with
insecticidal soap and other labeled insecticides,
particularly during its nymphal stage.
This year is developing into a major one for potato
leafhoppers, which are quite numerous throughout
the state on red maple, sugar maple, euonymous, and
other trees and shrubs. Damage has been minimal, so
treatment should prevent heavier damage from
occurring. Pyrethroid insecticides such as Astro,
Tempo, Talstar, and Scimitar should be very effective.
Monitor leafhopper numbers on trees. These insects
are such good fliers that re-treatments may be neces-
sary after a couple of weeks.
Aphids are present in large numbers on spirea at
the Morton Arboretum as well as in other areas of the
state. These aphids cover stems and leaf undersides
near branch tips. They produce large amounts of
honeydew, making affected bushes shine from the
light reflected from this substance on the leaves. By
now, infestations usually have been colonized by
lady beetles, syrphid fly larvae, and parasitic wasps.
For large infestations, look for these natural enemies
before treatment; their presence in even moderate
numbers will usually result in a major reduction in the
aphid population within the next two weeks. Aphid
infestations on spirea rarely need to be controlled
because plant distortion seldom occurs and the
honeydew isn't usually a nuisance. If treatment is
A /'"^"P Q College of Agricultural, Consumer and Environmental Sciences.
University of Illinois at Urbana-Champaign
ces
Helping You Put Knowledge to Work — State • County • Local Groups
U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
opportunities in programs and employment.
necessar>'. insecticidal soap or summer spray oil is
less harmful than other chemicals to the natural
enemies of aphids. (Phil Nixon and Karel Jacobs, the
Morton Arboretum)
Mimosa Webworm
Be watchful for mimosa Mebworm on honey locust
in southern Illinois. According to Don Orton's book.
Coincide, moth flight occurs as mock orange (Phila-
delphus) is in bloom, with young larvae present when
hills of snow hydrangea {Hydrangea arborescens
■grandiflora') is in full bloom. Mock orange has been
in full bloom in central Illinois for about a week.
Mimosa webv\orm has two generations per year.
The first generation is usually small in number and
easily overlooked. The greenish, brownish, or grayish
slender larvae feed on the leaflets of honey locust and
mimosa (silk tree). When disturbed, mimosa web-
worm larvae move quickly and violently, which helps
them escape. The first-generation larvae web two or
three leaflets together and feed on the leaflet under-
sides. This feeding causes the leaves to appear silvery
at first, particularly from a distance. As damaged
areas dr\'. they turn brown. Large numbers of first-
generation infestations scattered throughout a tree call
for an insecticide application to reduce the more
seriously damaging second generation.
The first-generation caterpillars pupate in the
uebbed leaves and emerge as small grayish moths.
These moths mate and tend to lay eggs back into first-
generation webbing. The second generation is usually
much larger in number than the first. These caterpil-
lars typically web together two to six compound
leaves, causing damage that is much more obvious.
Although treatment of the second generation is
usually successful, considerable damage may have
occurred before treatment.
Fully grown second-generation caterpillars migrate
out of the webbing to pupate in protected areas, such
as under loose bark on tree and shmb trunks and
under building siding. Research by Woody Hart (Iowa
State University). Fredric Miller (University of
Illinois), and Rex Bastian (Henderson the Care of
Trees) shows that fully grown larvae will commonly
migrate 50 to 80 feet from their host tree, thus, most
do not pupate on the host tree.
That research also showed that mimosa webworm
pupae can survive winter low temperatures of -1 1°F to
-24'F. Populations in Iowa survive at the colder end
of that temperature range, while those in Missouri and
Arkansas survive only at the warmer end of that
range. Many webworms pupate under siding and
around windows of heated buildings where tempera-
tures are a few degrees warmer — which explains why
higher populations of mimosa webworms are found in
trees near heated buildings and in years following
mild temperatures. With last winter's temperamres
relatively normal, look for populations to be moderate
to high, particularly on urban trees near heated
buildings.
Mimosa webworm is controlled with a variety of
insecticides, with BaciUus thiiringiensis var. kurstaki
(Dipel, Thuricide) the most environmentally friendly.
If an insecticide is used, high-pressure application
will move more of it through the webbing to the
caterpillars. {Phil Nixon)
Lilac Borers
Lilac borers are emerging throughout the northern
two-thirds of the state, with the Morton Arboretum
reporting significant numbers and large numbers also
being seen farther south. At this time, applications of
chlorpyrifos (Dursban) to the trunks and larger
branches of young, recently planted ash trees will
reduce attack. Once large numbers of moths emerge,
there is at least a two- week delay before egg hatching
occurs. One application of Dursban should provide
control throughout the egg-hatching period. (Phil
Nixon)
Caterpillars
Several caterpillar species appear at this time of year
on a wide varietv' of woody plants. Those on decidu-
ous plants cause aesthetic damage by leaf removal,
but usually no long-term effects. They are all easily
controlled with insecticide applications. Bacillus
thuringiensis var. kurstaki (Dipel, Thuricide) and
many other chemical insecticides are effective.
Bagworms are hatching in southern Illinois. Delay
treatment for a week in southern Illinois to allow
remaining eggs to hatch and for larval ballooning to
end. We have yet to see hatching farther north in
Illinois.
Be on the lookout for white-marked tussock moth
larvae in northern Illinois on oaks, crabapples, and
many other trees. Southern areas of the state should
be between generations of this insect.
First-generation yellow-necked and walnut
caterpillars should be present in southern and central
Illinois. These caterpillars are reddish when young but
No. 9 'June 18, 1997
turn black when older. Walnut caterpillars have a few
indistinct white stripes and are most common on
walnut, hickory, and pecan. Yellow-necked caterpil-
lars have many obvious white stripes and are common
on the same trees as walnut caterpillars, as well as on
oaks. (Phil Nixon)
PLANT DISEASES
More Anthracnose of Trees
This disease of trees has been discussed in Issue Nos.
4 and 6 and still causes concern. Leaf spotting has
been common on maple, elm, ash, and oak — although
many other species are susceptible. Bud blight, shoot
blight, and cankers have been common on sycamore.
Anthracnose also causes cankers on oak.
The most common concern is the leaf cupping and
distortion that sometimes occurs on oak and ash.
Owners usually fear that a chemical drift has been
involved. While that may be part of the problem,
anthracnose on these two species can, in fact, cause
leaves to curl and cup around the necrotic areas. (If
chemical drift is the problem, other species of plants
in the immediate area should show symptoms.) Cool
weather also causes newly emerged leaves to be
cupped or slightly twisted.
Anthracnose fungi seem to be present throughout
the state. Anthracnose has been a problem this year
because the weather conditions have stalled on "cool
and wet" for so long. Under these weather conditions,
when succulent new growth is present with the
pathogen, the disease will occur. We still maintain that
chemicals are not helpful at this stage of disease and
that improving tree vigor is all that can be done.
Annual infection may weaken a tree and contribute to
stressed growth, but we have not seen anthracnose kill
a tree. (Nancy Pataky)
Sphaeropsis Update
Sphaeropsis blight of pine also continues to be a
major problem and will continue throughout the
season (see Issue No. 1 for a complete description of
symptoms). Wisconsin plant pathologist Dr. Glen
Stanosz is involved in research on this fungus. He
said the current belief is that the tip blight of this
fungus and its canker phase are caused by different
strains of the same organism, usually referred to as
strains A and B. I had believed that the canker phase
invaded winter-injured wood, but the idea of different
strains provides food for thought. Stanosz's research
also explains the presence of the canker phase without
the tip blight in many cases.
According to Stanosz, preliminary studies suggest
that highly fertilized trees are actually more suscep-
tible to anthracnose. When tr>'ing to help a stressed
pine, don't push the fertilization levels. Instead,
concentrate on providing water to the trees whenever a
drought period lasts for two weeks or longer. (Nancy
Pataky)
Leaf Spots of Turf
The leaf disease known as Helminthosporium leaf spot
of turf has been reclassified into several leaf diseases.
We now refer to "Helminthosporium types" when
discussing leaf spots in the genera Bipolaris,
Drechslera, and Exserohilum.
These fungi are now active and may be found on all
turfgrasses in Illinois. The symptoms vary depending
on fungal species, grass species, weather conditions,
and cultural conditions. In general, look for small spots
or lesions varying in color from reddish brown to
purplish black. Lesion centers are often tan and
typically have a dark reddish brown border, giving an
"eyespot" appearance. In wet weather, the lesions may
merge, yellowing the turf or causing tip dieback.
These leaf spot diseases favor dry periods alternat-
ing with prolonged periods of cloudy, moist weather
and moderate temperatures. The diseases progress
quickly when grass is cut too short, turf is slow grow-
ing, or fertility is low. Excessive shade and excessive
use of nitrogen also encourage leaf spot diseases.
Other stresses contribute to disease severity.
Cultural control measures are usually effective. In
cases for which such measures are not adequate (such
as at some golf courses), chemical controls may be
used as protectants. Chemicals labeled for use in
Illinois are listed in the 1997 Illinois Commercial
Landscape and Turf Pest Management Handbook.
Correct mowing practices will help control leaf
spot. Mow all turfgrasses at the recommended maxi-
mum height for the species. Mow frequently enough so
that no more than one-quarter to one-third of the leaf
surface is removed at one time. If a lawn has been
fertilized, it may be necessary to mow every three or
four days during warm, wet periods.
These leaf spot diseases can be suppressed with
proper fertilization; however, it is important to avoid
high levels of nitrogen. Turf specialist Tom Voigt has
guidelines on iiow much fertilizer to apply to a home
lawn and when to make the applications.
Information is available on leaf spot disease
resistance by some bluegrass cultivars adapted to
Illinois. The resistance will vary somewhat by loca-
tion. Consult Report on Plant Diseases No. 405.
(Nancy Pataky)
"Wet Feet" of Trees, Shrubs, and Flowers
Many areas of the state have experienced an over-
abundance of rain in the last two months. This sets the
stage for root problems known as "wet feet" ("feet"
refers to roots). Symptoms are often the same as those
resulting from a lack of water and include withering
of leaves, little terminal growth, yellowing of foliage,
and dieback of shoots and roots. Some woody plant
species are particularly sensitive to such conditions —
yews, rose, white birch, Norway and sugar maples,
flowering dogwood, and forsythia, to name only a
few.
Water tolerance of many plants is discussed in
Diseases of Trees and Shrubs by Sinclair, Lyon, and
Johnson. Most tree identification books also list such
sensitivities as part of the species description.
It seems ironic that too much water causes plants to
die from a lack of water. Excess water causes a lack
of soil oxygen, and without oxygen, the roots cannot
respire properly and cannot take up water. Roots then
suffocate. For long-term control, you must improve
drainage, lighten the soil with a mixture of organic
matter and sand, and avoid too much additional water.
If you are not certain that excess water is the
problem, dig up some of the soil around the suspect
plant. In a typical situation with too much water, the
soil will be saturated and standing water may be
evident. Roots will be black or brown internally,
rather than white. In most cases, fungicides do not
help — they protect healthy plants from root-rot
pathogens, but do not revive dead roots. The water
problem must be alleviated for new roots to form.
In some cases, wet soils predispose plants to root
rots. For instance, Pythium and Phytophthora are
common mold fungi that invade stressed plants in wet
soils. If the water problem has been eliminated and
root rot is still present, then a root-rot fungus might be
involved as well. This is particularly true if not all
plants in a bed are affected. In such a case, consult a
lab or specialist trained to identify root-rot fungi. Soil
fungicide drenches are available to stop the progress
of root rots in herbaceous plants and small shrubs, but
there is nothing that can be used on mature trees.
Information on root rots is available in Report on
Plant Diseases No. 615 (Damping-Off and Root Rot
of House Plants and Garden Flowers), No. 602
(Armillaria Root Rot of Trees and Shrubs), and No.
664 (Phytophthora Root Rot and Dieback of Rhodo-
dendrons and Azaleas). (Nancy Pataky)
Home. Yard and Garden Pest Newsletter is prepared by Extension specialists from the University of Illinois at Urbana-
Champaign and the Illinois Natural History Survey. Information for this newsletter is gathered with the help of staff
members, Extension field staff, and others in cooperation with the USD A Animal and Health Inspection Service.
Major authors are Phil Nixon, (217) 333-6650, John Lloyd, (217) 333-6653, and Fredric Miller, (708) 352-0109,
entomologists; Nancy Pataky, plant pathologist, (217) 333-0519; and Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350. Phil Nixon is the executive editor of the Home, Yard and Garden Pest Newsletter. This
newsletter is written by faculty in the Department of Natural Resources and Environmental Sciences and the Department
of Crop Sciences. The newsletter is edited by Peggy Currid, typeset by Jerry Barrett, and proofread by Herbert Morgan,
all of Information Services.
1-n^ JUN2 6 1997
COOPERATIVE EXTENSION SERVIC?^ Libra''v
HOME, YARD ^ GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
illinois at urbana-champa ign a i 1 1 i nois natural history survey, champaign
NEWSLETTER
No. 10* fune25, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
PLANT DISEASES
Fire Blight After All!
In Issue No. 4 of this newsletter, we predicted that fire
blight would probably not be a problem in central and
northern Illinois. We should know better than to
predict based on normal weather conditions. The fire
blight bacterium will infect most readily during the
flowering period when wetting periods occur with
mild temperatures. Fruit pathologist Dr. Steve Ries
states that frequent rains in May with moderately cool
weather prolonged the bloom period, creating ideal
conditions for this disease. Ries now reports that fire
blight is being observed throughout Illinois. The
central and northern areas seem to be most noticeably
affected — the blossom blight phase is occurring in the
northern areas of the state, and the more typical shoot
blight phase is in the central section. Although Ries is
referring specifically to the disease on edible apples,
fire blight might also occur on crabapple, ornamental
pears, cotoneaster, firethom, hawthorn, mountainash,
quince, serviceberry, and spirea.
Streptomycin sprays are used by commercial fruit
growers to prevent fire blight. Although streptomycin
sprays are on the market for the homeowner applica-
tion as well, we do not usually recommend such use.
In any case, no amount of streptomycin will slow the
disease. Only hot, dry weather will accomplish that
feat. It is very tempting to immediately prune away
the shoot blight phase. However, the pruning process
will stimulate tree vigor, producing numerous new
succulent and highly susceptible shoots that will
become infected during the next rain. Wait until hot,
dry weather stops the disease before pruning out
infected wood. (Nancy Pataky)
Oak Wilt
Keep an eye out now for this oak disease. It is caused
by a fungus {Ceratocystis fagacearum) that enters and
plugs up the water-conducting vessels of sapwood.
Symptoms vary depending on the oak species in-
volved. Generally, oaks in the red and black group
develop discolored and wilted leaves at the top of the
tree or at the tips of lateral branches in late spring and
early summer. The leaves curl slightly and turn a duU
pale green, bronze, or tan, starting at the margins.
UsuaUy by late summer, an infected tree has dropped
all its leaves. We have seen red oaks move through the
phases of initial symptoms to total defoliation in as
little as three weeks.
The white and bur oak group generally shows
symptoms on branches scattered throughout the
crown. Leaves become light brown or straw-colored
from the leaf tip toward the base. The leaves curl and
remain attached to the branches. The tree may die in
one season but is much more likely to survive for
many years with a stagheaded appearance. Recent
appearances of anthracnose on white oak have caused
concern among many tree specialists who fear oak
wilt. Anthracnose causes brown spotting on leaves
and may cause slight leaf cupping as well.
Other problems can mimic oak wilt, including
construction damage, soil compaction, changes in the
soil grade or water table, lightning damage, nutritional
disorders, insect and animal injuries, chemical dam-
age, cankers, and root decay. None, however, have the
distinct vascular discoloration found with oak wilt. To
detect the discoloration, peel the baric back with a
knife. The sapwood of a healthy tree is white or tan. A
A (^~^P C College of Agricultural, Consumer and Environmental Sctences.
University of Illinois at Urbana-Champaign
ces
Helping You Put Knowledge to Work — Stale • County • Local Groups
U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equsil
opponunities in programs eind employnnent.
tree suspected to be infected b> oak v.ilt v.ill shos^-
brovk-n and white streaking of the wood. A sample
without the characteristic streaking does not rule out
the oak wilt fungus, which could be present elsewhere
in the tree. Therefore, pnoper sampling is important. A
slight brov^-n streak is nonnal on health) wood as air
comes into contaa v.ith the sapwood. The distinct
discoloration from oak v-ilt is evident as soon as the
bark is peeled back and does not intensify as the wood
dries.
The Plant Qinic can prepare cultures from wood
and detect the presence of oak wilt fungus. Branch
samples should be six to eight inches long, about as
thick as a thumb, alive but showing symptoms, and
must contain vascular discoloration It takes about
seven days for the fungus to develop in the lab to the
point that a corifirmauon can be made.
Oak wilt fungus infects through fresh wounds and
can spread by root grafts between trees. The disease is
particularly threatening because there is no complete
control or cure after infection. .Although it is not
possible to save an infected tree, surrounding trees
may be saved, so a correct diagnosis is important. For
more information, refer to Report on Plant Diseases
No. 618.
Hiis serious disease has been found in all pans of
Illinois over the last decade. However oak wilt does
not appear to be spreading any more quickly than it
has in the past, and we do not expect to see an epi-
demic. (Nancy Paiaky)
Slime Molds
These grov.Ths suddenly appear after heavy rains or
after watering plants in wanm. muggy weather Slime
molds are primitive organisms that flow (vers slowly*
over low -hing objects such as mulches, sidew alks.
and drivewa>s. and over vegetation such as
turfgrasses, strawberries, bedded flowers, ground
covers, weeds, and woody plants.
Slime mold organisms do not take nutrients from
the plant material (or from the sidewalk!). They feed
on deca>ing organic matter, fungi, and bacteria in the
soil and the turf grass thatch layer During warm,
moist weather the slim\. amoebalike stage flows over
low -hing objects and appears as waten. -white, gray,
cream-to-light-yeDow, violet blue, green, or purple-
brown greasy masses one to two feet in diameter This
stage soon develops into colorful crusty fruiting
bodies filled with masses of dusty spores.
Chemicals do not provide control against slime
molds. Instead, for abundant molds, break up the
unsightly spore masses by vigorous raking, brushing,
or hosing down with a stream of water Mowing the
lav.Ti usually removes spore masses. Slime molds
disappear with hot. dry weather For more information
about slime molds, read Report on Plant Diseases No.
401. which discusses slime molds in turf. (Nancy
Patakyi
Phomopsis Galls
We recently received a ver>' interesting case of galls
on forsNthia. The gall was caused by the fungus
Phomopsis. but looked ven.- much like a systemic
infection of crov^n gall or possibly a stem gall from an
insect. The galls were about 1 to 1-1/2 inches wide,
had a bumpy, roughened texture, and looked like a
cluster of nodules pressed tightly together They had
little points over their surface — similar to oak sower
galls. When we broke off the points of these forssthia
galls, however, we did not find insect chambers.
Instead, we saw a mass of undifferentiated plant tissue
and fruiting bodies (pycnidia) of Phomopsis.
Phomopsis galls can occur on many tree species,
including highbush bluebeny. American elm, hicko-
ries, maples, oaks, and privet On an oak in central
Illinois, v.e saw two masses of galls that were ap-
proximately two feet wide. The galls that we found on
fors\"thia were only about 1/2 inch wide. If these galls
girdle the twig, dieback will result. Otherv»ise, ver)'
little is knov.Ti about the disease cycle. (Nancy
Pataky)
INSECTS
Armv^vorms
.Armywonms have been causing damage to turfgrasses
southwest of Joliet. These caterpillars, when present
in large numbers, can defoliate large areas of turf.
Those in the Joliet area were small enough in nimiber
that the damage was relatively localized.
,'\rmywomi caterpillars feed primarily on smaU
grains such as wheat and rve. At this time of year,
they are likely to leave these field crops and attack
nearby turfgrass areas. They feed at night, moving
across the turf in large numbers like an army — hence,
their name. \Mien present in large nimibers, army-
wonns can eat all of the grass blades off half (or
more,) of a lawn in one evening, leaving only the
brown thatch behind. ArmN-worms hide in the thatch
the next day, emerging again at night to finish off the
other half of the lawn and possibly part of an adjacent
,\o. 10 » June 25, 1 997
one. Healthy mrf will recover by growing new leaves
off of rhizomes, but the lawn will not regain its
former appearance for at least a few weelcs. Smaller
numbers of armyworms may cause thin areas; light
damage may go unnoticed by many homeov-ners.
Armywonm caterpillars are 1 to 1-1/2 inches long
and are browTiish to black with two orange stripes on
each side and a pale orange suipe down the back.
WTien young and small, ihey are blackish with thin
stripes. Armv^'orm lanae are commonly attacked by
tachinid flies, which lay eggs on the back of the
caterpillars, usually just behind the head. The hatch-
ing fly larvae tunnel into caterpillar hosts, devour
their insides, and emerge as fully grown maggots. The
maggots then pupate and emerge as a fly that re-
sembles a large housefly.
Caterpillars that are not parasitized pupate in the
soil 10 emerge as orangish tan to grayish brown moths
with a tiny white dot in the center of each fore wing.
These moths, commonly referred to as "millers," have
a 1-1/2-inch wingspan and are strongly attracted to
lights at night. After mating, the female moth lays
eggs in rows or clusters on grass blades, rolling the
leaf blade around the eggs. TTiere are usually three
generations per year.
Armyworms can be controlled with a variety of
insecticides, including bifenthrin (Talstarj, carbaryl
(Sevin), chlorpyrifos (Dursban), diazinon, trichlorfon
(Dylox. Proxol), and the nematode Steinernema
carpocapsae (Biosafe-N, Biovector). The key to
successful control is recognizing the problem and
treating it before the lawn is devoured. Fortunately,
even high numbers of caterpillars may not cause
major turf damage if the parasitism rate is high.
(Phil Nixon)
Cicadas
Periodical cicadas are present in large numbers in the
Macomb and Galesburg areas. Protect young tree
trunks with tree wrap or netting to avoid serious
injun.- caused by egg laying. The protection can be
removed in mid-July. A year or two before a major
emergence in a particular area, a few cicadas will
appear. This explanation seems to be the case in the
southern two-thirds of Illinois, where very small
numbers of cicadas have been seen recentlv. These
numbers are too small to cause important damage, so
no protective measures need be taken, but the singing
by male cicadas is noticeable. (Phil Nixon)
Borers
Lilac borer moths are being attracted to pheromone
traps in significant numbers at the Morton Arboretum.
These moths resemble paper wasps. Their front wings
are brownish black, and the smaller rear wings are
clear Sometimes they have one or more yellow
stripes around their bodies. Lilac borer moths lay eggs
in the bark of trees and shrubs in the Oleaceae fam-
ily— especially lilac, ash, and privet. After hatching,
the larvae — which are creamy white with a brown
head — burrow under the bark and feed on phloem
tissue.
WTien scouting, look for dead canes and cracked
bark- The entrance holes are irregularly shaped and
contain frass. Exit holes are smaller, about 1/4 inch in
diameter and circular. Exit holes do not show signs of
frass. Branches can be severely damaged by this
borer
Peach tree borer moths are just starting to emerge
at the Monon Arboretum. These moths are dark blue
with orange bands around the abdomen. Primarily,
they aaack plants in the Prunus genus (flowering
cherr>-, purpleleaf plum, cherries, apricots, peaches,
and nectarines). WTien fully grown, the lan-ae are
about 1-1/4 inches long, are white with brown heads,
and have five pairs of prolegs (back legs). They feed
in burrows at the base of trees.
Borer activity frequently girdles small trees, so
they can be a serious problem in nurseries. They may
weaken older trees, making them more susceptible to
bark beetles. WTien monitoring, look at the root crown
for cracked bark, frass, and gummosis.
Chlorpyrifos (Dursban) is the standard treatment
for both lilac and peach tree borers on ornamental
trees. On fruit trees, growers should consult fruit-tree
management recommendations. In the northern half of
Illinois, lilac and ash borers should be treated now
with sprays on tree trunks and major branches. In
northern Illinois, treatment next week will not be too
late. Peach tree borers should be treated in southern
Illinois by spraying the base of the trunk. Treatment
should occur a week later in central Illinois and two to
i-nu. iw ' JUIIC ^J, 1^^/
three weeks later in northern Illinois. (KarelJacobs,
the Morton Arboretum; Fredric Miller and Phil
Nixon)
Caterpillars
First-generation fall webworm is hatching in south-
em and south-central Illinois. Fall webworm has two
generations throughout the southern half of Illinois,
but can have three generations in the far southern
reaches of the state. Fortunately in most of Illinois,
the major damage occurs from the second generation.
If, however, you are one of the unfortunate few with
early summer problems with this pest, take heart and
trim the tents out when they are small and easily
accessible. Otherwise, a treatment with Bacillus
thuringiensis var. kurstaki (Dipel, Thuricide, etc.) that
penetrates the tent should provide adequate control to
prevent major defoliation.
First-generation yellownecked caterpillar, walnut
caterpillar, and mimosa webworm are also hatching
throughout the southern and south central regions of
the state. (John Lloyd)
Leaf miners
Locust leafminer damage is becoming obvious on
black locust trees in southern Illinois. By this time of
the season, the mines are turning brown and the
damage is done. Throughout most of Illinois, there is
only one generation of locust leafminer per year, but
the extreme southern part of Illinois can have two
generations. Elm leafminer and holly leafminer also
have one generation per year. For these leafminers
with one generation, if the mines are brown, control
must be postponed until the following year.
Birch leafminer larvae are coming out of leaves
and dropping to the ground to pupate at the Morton
Arboretum in northeastern Illinois. Like other
leafminers, the larvae eat tissues between the upper
and lower leaf surfaces, creating brownish, blotchy
mines. One half or more of each leaf can turn brown.
The larvae are approximately 1/4 inch long and light
brown. Birch leafminer has three or four generations
per year.
Leafminers on oak, birch, and alder have several
generations per year. If the mines on birch and alder
are brown, begin scouting for new mines on new
leaves as the season progresses. Treatments with
systemic insecticides should help reduce damage by
new leafminers. If leafminer control is desired to
retain the appearance of affected trees, examine plants
with perennial leafminer problems earlier in the
spring for the first signs of leafminer injury. (Karel
Jacobs, the Morton Arboretum; Fredric Miller and
John Lloyd)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USD A Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd, (217) 333-6653. and Fredric Miller, (708) 352-0109.
entomologists; Nancy Pataky, plant pathologist, (217) 333-
0519; and Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350. Phil Nixon is the executive
editor of the Home, Yard and Garden Pest Newsletter.
This newsletter is written by faculty in the Department of
Natural Resources and Environmental Sciences and the
Department of Crop Sciences. The newsletter is edited by
Peggy Currid and Herbert Morgan, typeset by Oneda
VanDyke, and proofread by Herbert Morgan, all of Infor-
mation Services.
JUN 2 6 19^^
COOPERATIVE EXTENSION SERVICE
HOME, YARD &^ GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
Illinois at u rbana-champa ign A i 1 1 i nois natural history survey, champaign
NEWSLETTER
No. 11 'July 2, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
INSECTS
Birch Sawfly on Willow
Birch sawfly larvae feeding on willows have been
reported from the Rockford area and the Morton
Arboretum. This insect feeds on the leaves of gray,
paper, and other birches, as well as willow and alder.
Adult birch sawflies are present during June and
July, laying their eggs in slits they make in the leaf
margins. Larvae are present from June to September.
Fully grown larvae are yellowish, with 12 rows of
black spots. They are about one inch long and have
reddish yellow heads. Larvae spend the winter as
prepupae in silk cocoons spun in the leaf litter. There
is one generation per year.
The larvae can be controlled with carbaryl (Sevin),
diazinon, chlorpyrifos (Dursban), acephate (Orthene),
and a vziriety of other insecticides. Realize that this
insect is not a true caterpillar and is not controlled by
Bacillus thuringiensis van kurstaki (Dipel, Thuricide).
Because birch sawfly attacks fast-growing trees, one
or two years of heavy defoliation is unlikely to cause
much harm to the host tree. (Barb Larson, Winnebago
Extension Unit; Karel Jacobs, the Morton Arboretum;
Fredric Miller and Phil Nixon)
Bagworms
Bagworms have hatched in southern and central
Illinois, with reports from Morrisonville, Peoria, and
Champaign. Bagworms hatch over a period of about
two weeks. Newly hatched bagworms climb to the top
of the tree or shrub and hang on a strand of silk. These
strands break in the wind, and the bagworm blows
through the air. This ballooning is the main way that
bagworms find new hosts because the adult female
moth is wingless. She stays in her bag on the host tree
while filling her body with overwintering eggs.
This larval ballooning activity may cause sprayed
trees and shrubs to be reinfested from other areas. The
combination of the ballooning plus the extended egg-
hatching period is the basis of the suggestion that one
should wait for about two weeks after first hatch
before treating for bagworms. Otherwise, more than
one insecticide application will probably be needed.
Young bagworms feed on the leaf epidermis and
underlying mesophyll, causing whitish areas on the
leaves that later dry and turn brown. Older bagworms
eat through the leaves, causing skeletonization and
defoliation.
Many insecticides are effective against young,
small bagworms. It is time to control bagworms in
southern Illinois, with control recommended in about
a week in central Illinois and in about two weeks in
northern Illinois. Once the bagworms get at least 1/2
inch long, many insecticides provide little control.
Our research has shown that Bacillus thuringiensis
var. kurstaki (Dipel, Thuricide), trichlorfon (Dylox),
and cyfluthrin (Tempo) are effective against older as
well as younger bagworms. (Phil Nixon)
Potato Leafhopper
Potato leafhopper nymphs are feeding on American
elm, red maple, and Japanese pagoda tree. These
nymphs are 1/8 inch long or less, are green with white
eyes, and have wing buds. They also attack oaks,
other maples, red mulberry, cottonwood, birch,
apples, dogwood, hawthorn, euonymous, and cherries.
Leafhoppers feed on sap from the leaf's vascular
system. Frequently, severe stunting is seen, along with
extensive foliage damage. Damage can compromise a
tree's ability to cope with winter weather. (Karel
Jacobs, the Morton Arboretum; Fredric Miller, John
Lloyd, and Phil Nixon)
A ('^p C College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urbana-Champaign
ces
Helping You Put Knowledge to Work — Slate • County • Local Groups
U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
opportunities In programs and employment.
Scouting
It is amazing what a few weeks of average to above-
average temperatures bring about in the insect world.
Over the last several weeks, insect development has
caught up to what is normal for all areas of Illinois.
The cool spring of 1997 that delayed insect activity is
just another example why it is important to scout. For
ease of use, most insect events are correlated with the
calendar; however, insects can't tell time or read.
Insects and plants are cold-blooded and therefore rely
on warm temperatures to develop. In the 7997 Illinois
Commercial Landscape and Turf Pest Management
Handbook, we have added phenological plant indica-
tors from Coincide, by Don Orton, to assist practi-
tioners in identifying when pests may be active in
relation to plant development. Although active
scouting is necessary to identify if insect problems
exist, these predictive tools can help focus scouting
efforts. (John Lloyd)
Aphids
Aphids. or plant lice, feed on almost every living
plant. They feed on plant juices or sap. In most cases,
small populations do not cause much damage on
woody ornamentals.
Aphid populations can build up rapidly by means
of a reproductive process known as parthenogenesis.
Female aphids can reproduce without males. No
mating is necessary; each female aphid is essentially
bom pregnant. By virtue of this unusual reproduction,
one aphid can create an infestation with her offspring
in a short time. Each female aphid lives, on average,
about a month and produces from 80 to 100 offspring.
It usually takes less than a week for aphids to reach
adulthood from birth. Depending on the species and
area of the country in question, aphids can have from
1 0 to 50 generations per year. Extrapolate from here,
and you get a whole lot of aphids, all without the help
of males.
Some species of aphids produce males in response
to changes in day length and plant-sap content,
particularly toward the end of the growing season.
These same conditions also can initiate the production
of females incapable of parthenogenesis. The males
that are produced mate with the females, who produce
eggs that overwinter. The overwintering eggs hatch
the following spring and produce females that repro-
duce parthenogenetically.
Most parthenogenetic females are wingless and
thus never move from the plant on which they are
bom. If a young female aphid is touched repeatedly
while growing up, she remains wingless but bears
young that grow wings as they mature. In this way,
aphids can escape crowded host plants to attack other
suitable hosts.
With their high reproductive potential and their
ability to disperse when conditions warrant, it's
amazing that any plants survive onslaughts by aphids,
right? Wrong. Aphids, like many other insects, use
reproduction as a defense strategy. Rather than fight
or flee, they reproduce. It's like the story of the two
rabbits running away from a fox. As the fox catches
up to the rabbits, one rabbit turns to the other and
says, "Let's turn around and outnumber him." The
other rabbit replies, "We can't, stupid — I'm your
brother." As a result of their ability to create large
populations rapidly, aphids are a favored host for
many predators and parasites (also called natural
enemies). When aphids are found, there are usually
predators grazing on them. Ladybeetles are one of the
more commonly recognized predators of aphids, but
other common natural enemies include lacewing
larvae, flower and other fly larvae, and parasitic
wasps. The presence of these and other unusual-
looking insects in the midst of aphid populations is a
good indication that the aphids will probably be
reduced to very small numbers within one to two
weeks, so that insecticide applications will probably
not be needed.
Although there are aphids that can attack many
species of plants, most aphids are able to feed only on
a few closely related host plants. For this reason, high
numbers of aphids on weeds or other plants in the
vicinity are not usually a threat to cultivated plants
and do not need to be controlled. Indeed, their pres-
ence may attract and build up numbers of predators
and parasites that will be available to attack new
aphid populations that may occur on cultivated plants
in the vicinity. Unlike aphids, most of these natural
enemies are not very host-specific.
Most complaints about aphids in trees are based on
the honey dew, or leftover sap, that they excrete. It is
sticky and can be difficult to remove from vehicles
that are parked underneath trees with high aphid
populations. Honeydew is a good source of sugar for
ants. In some cases, ants herd and protect aphids from
predators and, in turn, feed on the honeydew they
produce. Sooty mold fungus can grow on honeydew
and may create a problem on plants located under-
neath other plants with high aphid populations.
At this time of the year, aphids can become numer-
ous on crabapples, yellow poplar, spirea, and other
plants throughout Illinois. Interestingly, most aphid
problems we are discovering are from areas that
haven't had rainfall during the last couple of weeks.
Aphids knocked off plants by rain usually don't make
it back to the plant. Also, high moisture is conducive
to development of fungal pathogens that kill aphids.
In fact, one form of control for aphids is to flush them
from the plant with heavy streams of water. This
method of control, as well as the use of insecticidal
soaps, usually allows predators, parasites, and patho-
gens to become better established within the aphid
population and continue their "natural" control of the
pests. When other "nonspecific" insecticidal com-
pounds with longer residuals are used for control, the
risk of killing off the natural enemy complex feeding
on the aphids and other pest insects can offset the gain
made by the insecticide application. Aphid popula-
tions will grow again but will not be held in check by
their namral enemies.
Aphids can be managed with a variety of com-
pounds that either act on contact or act systemically
through the plant. Contact insecticides, such as
insecticidal soap and horticultural oils, work well
when they come in direct contact with the aphids. In
situations in which the aphids are hidden, a systemic
compound such as acephate (Orthene) is more effec-
tive. All valid methods of aphid management are
listed in the 1997 Illinois Commercial Landscape and
Turf Pest Management Handbook. (John Lloyd and
Phil Nixon)
PLANT DISEASE
Dutch Elm Disease
It is time to be lookmg for symptoms of this elm
killer. Many people have the mistaken impression that
this disease is a thing of the past because there are
now so few elms around. Not so! We receive many
elms at the Plant Clinic each year with requests for
testing for the Dutch elm disease fungus. Unfortu-
nately, we are still able to make many positive isola-
tions.
Dutch elm disease (DED) is caused by a fungal
pathogen, Ceratocystis ulmi. The disease works much
like the other vascular diseases, causing plugging of
the vascular tissues and resultant wilting and death of
foliage. American elms are very susceptible to this
pathogen. Although Chinese elm and Siberian elm are
known to be more resistant, infection of these species
can occur as well. Work is still underway to develop
resistant elms, including the more resistant Sapporo
Autumn Gold, American Liberty, and Urban elms.
Watch for yellowing of leaves in the elm, followed
by wilting and browning. A single branch usually
shows symptoms first, with rather rapid spread to
adjacent branches and the entire tree. Look for vascu-
lar discoloration to help with diagnosis of this disease.
As with oak wilt and verticillium wilt (discussed in
earlier issues), DED causes a streaking of the sapwood.
Peel back the bark of a symptomatic branch to reveal
the brown streaks in the otherwise tan outer sapwood.
We generally select branches of about thumb thick-
ness, with wilted leaves. Verticillium wilt and
Dothiorella wilt can also cause this streaking in elm.
Positive identification requires laboratory culturing
of the fungus. Cut several six- to eight-inch long
sections from wilting, but living, branches that show
definite streaking in the sapwood. The fresh wood
sections should be a half to one inch in diameter and
sent in plastic or foil to the Plant Clinic for testing.
Expect about seven days of lab time for the fungus to
grow to the point at which it can be positively identi-
fied. There is a $10 fee for this service.
For more information on DED, including control
procedures, consult Report on Plant Diseases No. 647.
A similar disease caused by a phytoplasma is discussed
in Report on Plant Diseases No. 660, Elm Yellows or
Phloem Necrosis and Its Control. (Nancy Pataky)
Powdery Mildew
The powdery mildew diseases affect woody and
herbaceous ornamentals, as well as vegetable, cereal,
and fruit crops. These fungal diseases are easy to
identify due to the characteristic white to light grayish
powdery growth, primarily on leaves. In fact, I have
told gardeners that this is one disease that they must
know in order to become a master gardener.
After the initial "easy to identify" stages of this
disease, other lesser-known symptoms may occur.
Look for stunting, curling of the leaves, chlorosis,
premature leaf drop, and deformation of the flower
buds. Apples and crabapples are commonly infected,
but scab or some other accompanying disease often
gets blamed for the stunting, chlorosis, and curling of
leaves. Even the easy-to-diagnose white powdery
growth can be masked on plant species with heavy
pubescence.
The fungi that cause powdery mildews flourish on
warm to hot days followed by cool nights, and when
dews form on the leaves. Disease is most severe on
crowded plants, in shaded locations, or where air
circulation is poor. Unlike most fungal diseases,
powdery mildew is not as destructive when rains are
frequent. High relative humidity (but not rain) is
needed for spores to germinate, and mildew develops
rapidly in extended periods of warm, dry weather
when morning dews are heavy. Ideal disease condi-
tions are 90 to 99 percent relative humidity at 66°F to
72°F temperatures.
Look for cultivars resistant to mildew whenever
possible. Pruning out diseased wood (especially on
rose and crabapple) during the normal pruning period
greatly reduces overwintering inoculum. Try pruning
plants to allow better air circulation within the plant
as well as within the planting. Never handle the
infected plants when they are wet. As usual, plants
should be maintained in high vigor to withstand
disease attack.
Fungicides are available to control the mildews. In
fact, this is one of the few diseases that can be treated
after symptoms are observed. If sprays are begun at
the first sign of mildew, control can be attained.
Often, however, damage is only aesthetic, and the
actual vitality of the plant is not affected. If a fungi-
cide is chosen, use one of the products recommended
under the appropriate host in the 7997 Illinois Com-
mercial Landscape and Turf Pest Management
Handbook. Further information on the powdery
mildews is available in Report on Plant Diseases Nos.
61 1 and 617. (Nancy Pataky)
Frogeye Leafspot
Frogeye leafspot is a fungal disease that has been
prevalent in the Midwest the last several years on
apple and crabapple. It is the leafspot phase of the
disease known as black rot. Classic symptoms include
numerous small spots on older cluster leaves, with
marked zones of lighter and darker tissues within the
spots. The margins of the lesions remain purple, while
the centers become tan, giving the spots the typical
frogeye appearance. Leafspot causes early defoliation,
much like apple scab. In many cases, this disease is
overlooked or blamed on scab. Affected leaves are
always near dead or dying limbs on which a black rot
canker is present. This same canker (and, in some
cases, infected leaves) produces inoculum, which then
infects developing fruit in August and September. For
this reason, removal and destruction of all dead wood
during annual pruning is the recommended control
measure.
Secondary inoculum of a disease refers to spores or
bacteria that spread from the initial infection to
another site on the host. Most fruit diseases with a
secondary inoculum as part of their life cycle have
been in the secondary inoculum phase for weeks.
Scab, fire blight, powdery mildew on apple, brown rot
and scab of peach, cherry leafspot, and other diseases
require only rain to explode in numbers. Expect to see
these diseases on susceptible varieties. Most damage
to the tree occurs when the inoculum is present, leaf
tissues are young, and rain is present. As plant tissue
becomes older, less damage occurs.
Black rot and frogeye leafspot of apple is discussed
in Report on Plant Diseases No. 814. (Nancy Pataky)
Home. Yard and Garden Pest Newsletter is prepared by Extension specialists from the University of Illinois at Urbana-
Champaigu and the Illinois Natural History Surx'ey. Information for this newsletter is gathered with the help of staff
members. Extension field staff, and others in cooperation with the USD A Animal and Health Inspection Service.
Major authors are Phil Nixon. (217) 333-6650, John Lloyd. (217) 333-6653, and Fredric Miller, (708) 352-0109,
entomologists; Nancy Pataky. plant pathologist. (217) 333-0519; and Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350. Phil Nixon is the executive editor of the Home, Yard and Garden Pest Newsletter. This
newsletter is written by faculty in the Department of Natural Resources and Environmental Sciences and the Department
of Crop Sciences. The newsletter is edited by Mary Overmier and Peggy Currid. typeset by Jerry Barrett, and proofread
by Herbert Morgan, all of Information Ser\ices.
JUN 2 6 1997
^
AG
; ^^ f- ru
COOPERATIVE EXTENSION SERVICE
HOME, YARD 8^ GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
Illinois at urbana-champaign A illinois natural history survey, champaign
NEWSLETTER
No. 12 'July 9, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
PLANT DISEASES
Rose Rosette
Rose rosette symptoms are quite distinctive. The new
growth is deep red on leaves and stems. Leaves may
show crinkling and distortion, or a mosaic of green,
yellow, and red. An infected plant produces numerous
lateral shoots that grow in different directions, giving
the plant a witches '-broom appearance. These shoots
are typically deep red and much larger in diameter
than the canes from which they grow. Thorns on these
stems are more abundant than normal. Plants usually
die within about 22 months of infection.
The vector of this disease is an eriophyid mite,
which is so small that 20 of them could fit on a
pinhead. The disease can also be spread by grafting.
Rose rosette is believed to be caused by a double-
stranded RNA, which means that it is a viruslike
disease. It cannot be cultured in a lab, and confirma-
tion of the disease by the Plant Clinic is based purely
on symptomology. However, rosette can be diagnosed
without the help of a lab.
Multiflora rose is the most common host of this
disease, but it has been reported on cultivated flower-
ing varieties as well. Climbers, hybrid teas, floribun-
das, miniatures, and a number of "old-fashioned"
roses have been infected. Hybrid teas typically show a
color that is more yellow than red. So far, no other
host besides rose has been found.
Currendy, infected plants cannot be saved. Plants
with symptoms should be dug up and destroyed
(including roots) when first noticed. It is strongly
suggested that multiflora and garden roses be sepa-
rated as far as possible from each other. The efficacy
of mite control has been questioned in control of this
disease. If miticides are used, research suggests that
the critical mite transmission time is May and June, so
concentrate your efforts in these months. For details
of this disease, consult Report on Plant Diseases No.
666. (Nancy Pataky)
Crown Gall
Crown gall is a bacterial disease known to infect
hundreds of plant species. Common hosts in Illinois
include euonymus (ground cover), grape, raspberry,
and rose. Consult Report on Plant Diseases No. 1006
for a detailed list of hosts.
The crown gall bacterium, Agrobacterium
tumefaciens, enters the plant through a wound. The
plant then forms a gall in response to this infection.
Galls appear on the trunk, crown, roots, and some-
times on the stems of the host plant. Young galls are
white or tan, usually round, and are quite soft and
spongy. As the gall ages, it develops an irregular,
convoluted, rough, corky surface and a dark brown,
hard wood interior. These galls might be mistaken for
insect galls or other galls (such as Phomopsis galls,
described in Issue No. 10 of this newsletter). Cut the
gall open. Crown gall appears as a mass of undifferen-
tiated plant tissue. Insect galls have galleries or
pockets with or without insects present. Fungal galls
have small fruiting bodies containing spores.
Agrobacterium can survive for more than five years
in the soil on organic debris. It is easily spread in soil
water or rain splash but can penetrate plants only
through fresh wounds. Such wounds might be made
during pruning, cultivating, transplanting, budding or
College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urtiana-Champaign
ces
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No. 12 'July 9, 1997
grafting, or feeding by insects or other pests. Euony-
mus beds have been infected after animals have run
through the bed and wounded plants.
Control of crown gall is difficult. Begin by digging
up and destroying all severely infected plants. In some
cases, crown gall might be present but still have little
effect on plant appearance. Such plants can remain at
the site until growth declines. Eventually, when
replacement plants are needed, consult RPD No. 1006
or check the literature for plants that are resistant to
this disease. Before purchasing new plants, inspect
them closely for galls. Also, be aware that the bacte-
rium will infect susceptible plants put back into the
same area where crown gall was first discovered.
(Nancy Pataky)
White Pine Problems
Although the Plant Clinic has not received as many
white pine samples in 1997 as last year, continuing
complaints of problems with white pine prompts this
article. White pine problems seem to be present
throughout the state. Symptoms vary but generally
include some pattern of needle yellowing or brown-
ing, shriveled bark on branches or trunk, sap exudate
on branches, and in some cases, death of the tree.
Affected trees have ranged in size from 2 feet to more
than 20 feet.
The Plant Clinic has assayed samples for the
presence of pinewood nematodes; has cultured for
fungal pathogens of needles, stems, and roots; and
inspected for insect infestations or injuries. The only
common factor seems to be root decline. Few live
white roots have been found, but fungal pathogens
cannot be correlated with poor rooting. It appears that
roots are on the decline for other reasons. Some
possibilities include heat, drought, flooding, and
sudden extremes in temperature and moisture.
In 1995, we addressed this problem and explained
that white pines are understory trees that thrive in the
cool, moist, well-drained soils of Wisconsin, although
they grow with intermittent success in Illinois.
Many of the problem trees we have seen have been
situated on clay sites or exposed to the elements
(planted in new housing developments or used as
windbreaks). It is also likely that site stress has
contributed to the decline of these trees. The exces-
sive rains of the past two springs also may have
contributed to root injury and decline by saturating
the soil and causing a lack of soil oxygen.
Look for more white pine problems this year. If
roots were injured as we are suggesting, they will not
be able to pull up enough water to replace the loss
created by the extremely hot weather of the past two
weeks. Watering helps, as does the use of a natural
mulch over the root system, but without adequate root
mass, plants will not be able to use the available water
quickly enough to replace what is used by the foliage.
The result will be sudden browning or off-color
needles and death of branches.
Because these problems in white pine are not
usually the result of an infectious disease, immediate
removal of the tree is not necessary. Instead, try to
keep the tree watered and see how it responds. Also,
try digging into a bit of the root system for a better
picture of the situation. If roots are brown in cross-
section and the outer layer easily pulls off or is not
present, then root injury has occurred. If the roots are
white and healthy, then the problem is above ground
and our theory is wrong, at least in your case. (Nancy
Pataky)
Leaf Scorch of Trees
There are two types of leaf scorch on trees: the
environmental leaf scorch with which most arborists
are familiar, and the pathogenic bacterial leaf scorch
which is less well known.
Noninfectious leaf scorch occurs each year when-
ever water cannot be translocated to the foliage as
rapidly as it is lost. The causes vary and include root
injury, root rot, poor soil conditions, high winds,
transplant shock, flooding, and drought. A complete
listing of possibilities is discussed in Report on Plant
Diseases No. 520. Noninfectious scorch appears as a
browning of leaf margins as well as between the
veins. Symptoms appear first on newest, succulent
leaves and progress toward the trunk. Severely
affected leaves often drop from the tree. Generally,
the symptoms show on the more exposed parts of the
tree initially but may occur uniformly over the entire
tree.
The infectious leaf scorch (called bacterial leaf
scorch) is caused by the bacterium Xylella fastidiosa.
It has been reported in Illinois near St. Louis. Al-
though it is predominantly a disease found in eastern
and southern states, it is frequently found in western
Kentucky and could be present in more areas of
Illinois than we are aware of.
Bacterial scorch occurs on elm, oak, sycamore,
mulberry, and red maple. Look for scorch symptoms
that occur in early summer to midsummer and then
intensify in late summer. The symptoms occur first on
one branch or section of branches; each year the
No. 12 'Julys, 1997
number of branches affected may increase. Unlike
noninfectious scorch, bacterial leaf scorch develops
first on the oldest leaves and progresses toward the
tip. Also, infected leaves often remain attached until
autumn.
If you have a sample with a history of progressive
scorching and leaf retention, you may want to seek
lab help for bacterial scorch testing. The Plant Clinic
cannot perform the required enzyme-linked assay, but
staff can help with sample preparation and can
forward materials to the appropriate lab. The fee is
$15.00 for such samples. (Nancy Pataky)
INSECTS
Annual White Grub Adults
Check for the presence of annual white grub adults.
These 1/2-inch-long, tan June beetles emerge in
southern Illinois at the end of June. They emerge in
central Illinois just before July 4 and in northern
Illinois shortly thereafter. The cool weather we had
this spring may delay their emergence, but the hot
temperatures in the second half of June may have
made up for lost time.
These insects hide in thatch during the day, emerg-
ing at about 9 p.m. to mate and lay eggs. An ideal
time to observe peak flight is around 10:30 p.m.
Flight occurs into the early morning hours. The
beetles fly low over the turf and and are illuminated
by car headlights. They are also strongly attracted to
bright outdoor lighting and can be seen flying around
streetlights. Because these beetles do not feed, they
usually die about two weeks after emergence.
Mated females burrow into the soil to lay eggs,
choosing damp, soft soil over dry, hard soil. The
recent dry, hot weather means that much of the soil is
now dry and hard, which prompts the females to
select irrigated turf in which to lay their eggs.
The presence at this time of large numbers of adult
beetles in areas where unirrigated turf is dry and
brownish should trigger the application of
imidicloprid (Merit, Grubex) or halofenozide (Mach
2) over the next three to four weeks. If managed turf
is not (or only slightly) irrigated, it is probably best to
wait until early August to check for grubs and then
use a quicker-acting insecticide such as diazinon,
trichlorfon, or bendiocarb. Areas that have received
sufficient rainfall for nonirrigated turf to remain green
probably do not need an insecticide application, but
those areas should be checked in early August to be
sure. (Phil Nixon)
Japanese Beetles
Japanese beetles should be emerging throughout the
state. These stocky beetles are metallic green with
coppery wing covers and are 1/2 inch long. They feed
on the leaves of a wide range of plants, but prefer
crabapple, linden, birch, grape, and rose. Japanese
beetles are present through mid- August. Their feeding
can be reduced with weekly applications of carbaryl
(Sevin) or biweekly applications of synthetic pyre-
throids such as bifenthrin (Talstar), cyfluthrin
(Tempo), lambda-cyhalothrin (Scimitar), or
permethrin (Astro).
Select for treatment those plants that are most
important aesthetically in the landscape. Untreated
plants may lose much of their foliage, but their health
will not be seriously threatened — provided they were
healthy to start with.
These insects will also be attracted to irrigated turf
to lay their eggs. The resulting white grub larvae feed
on the turf and cause damage. Control measures for
annual white grubs also apply for Japanese beetle
grubs (see previous article). Because Japanese beetle
grub populations are usually mixed with those of
annual white grub in Illinois, Bacillus papillae, which
does not control annual white grub, is not recom-
mended. (Phil Nixon)
Black Vine Weevil
Black vine weevil damage is being found on new
growth of rhododendron. These beetles also feed on
azalea, yew, strawberry, euonymus, clematis, and
many other plants. These adult beetles, which are
nocturnal, chew notches on leaf margins. They are
hard-shelled, about 3/8 inch long, and grayish with
yellowish markings. The head is drawn out into a
broad muzzle. Feeding damage occurs at night; the
adults hide in debris beneath plants during the day.
Most of the damage is done by the larvae, which
feed on the roots but are difficult to control, except in
containerized nursery stock. All of these weevils are
females and must feed for two to three weeks before
laying eggs. Spraying the foliage heavily with
acephate (Orthene), bendiocarb (Turcam), or
cyfluthrin (Tempo) will control the feeding adults and
prevent subsequent egg laying. (Karel Jacobs, the
Morton Arboretum; Fredric Miller and Phil Nixon)
Sawflies and Casebearer
Casebearer and sawfly have been found on larch.
These sawfly larvae are pale gray-green on top and
even lighter underneath. They have black heads and
No. 12 'Julys, 1997
legs. Sawfly larvae feed on leaves of larch, usually
starting near the bottom of the tree. Casebearers mine
larch leaves, emerging in September. They are named
for the case they build for themselves, which is really
a mined-out larch leaf lined with silk. The case is
brown and cigar-shaped. (Thanks to Mike Fee for
pointing out these and many other insects this week.)
Sawfly larvae are also present on black locust.
These larvae are light green with pale pinkish green
heads. When young, they create holes in the leaflet's
interior. When more mature, they chew on the edges
of the leaflets. Birch sawfly continues to be present on
willow. It can also feed on birch and alder.
These sawflies and the casebearer can be controlled
with sprays of carbaryl (Sevin), diazinon, and many
other insecticides. Casebearer can also be controlled
with Bacillus thuringiensis var. kurstaki (Dipel,
Thuricide). (KarelJacobs, the Morton Arboretum;
Fredric Miller and Phil Nixon)
Woolly Aphids
Woolly aphids, which sometimes cause leaf curling,
have been found on the bark and leaves of white alder
(Alnus incana) and Kansu hawthorn {Crataegus
kansuensis). These insects are covered with a white,
waxy substance and are easily mistaken for mealy-
bugs. Woolly aphids can be distinguished from
mealybugs by their shape — aphids are more pear-
shaped and have cornicles (two pipelike structures
coming out of their abdomens), although it may be
hard to see the cornicles through all the wool. Mealy-
bugs are round to oval in shape and don't have
cornicles. Like other aphids, woolly aphids create
honeydew. They are controlled with forceful sprays to
penetrate the waxy protective coating and honeydew.
Many contact insecticides, such as synthetic pyre-
throids, provide effective control. (Karel Jacobs, the
Morton Arboretum; Fredric Miller and Phil Nixon)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana- Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd (217) 333-6653, and Fredric Miller, (708) 352-0109,
entomologists; Nancy Pataky, plant pathologist, (217) 333-
0519; and Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350. Phil Nixon is the executive
editor of the Home, Yard and Garden Pest Newsletter.
This newsletter is written by faculty in the Department of
Natural Resources and Environmental Sciences and the
Department of Crop Sciences. The newsletter is edited by
Peggy Currid, typeset by Oneda VanDyke, arui proofread
by Herbert Morgan, all of Information Services.
JUN 2 6 1997
a,n 1 ib''?''v
COOPERATIVE EXTENSION SERVICE
HOME, YARD & GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
llinois at urbana-c hampa ign a i 1 1 i nois natural history survey, champaign
NEWSLETTER
No. 13» fuly 16, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
INSECTS
Japanese Beetle and Annual White Grub
Adult Japanese beetles and southern masked chafers
(annual white grubs) are flying in the Chicago area,
according to Donna Danielson of the Morton Arbore-
tum Scouting Program. Reports of beetle emergence
from central Illinois have been relatively sporadic. As
was indicated in last week's newsletter, the cooler-
than-normal temperatures this spring slowed grub
development and delayed adult emergence.
Although time of emergence has been sporadic,
recent warm, dry weather and conscientious lawn
care practices have created ideal habitats for egg
laying. Lawns that go dormant in the summer or that
receive limited amounts of water are less attractive
for egg laying than lush areas of turf that have been
irrigated. Refer to last week's newsletter for turf grub
management options.
As Japanese beetles continue to emerge, more
damage will occur from the adults feeding on decidu-
ous plant materials in infested areas of the state.
Perhaps we should adjust our mindset and think of
Japanese beetles as one of the "joys" of living in
Illinois. When purchasing new plant materials, keep
Japanese beetle defoliation in mind and select plant
varieties that are less attractive to the beetle. If you
select plants that are favored by this insect, you
should get used to beetle-damaged plants or expect to
treat the plants weekly with an insecticide when the
beetles are present. University of Kentucky and
Purdue University scientists have been conducting
research to identify woody plant species that are less
favored by the Japanese beetle. We will include a list
of such species in next week's newsletter. (John
Lloyd, Fredric Miller, and Karel Jacobs)
Summer Defoliators
Yellow-necked caterpillars, walnut caterpillars,
and late first-generation mimosa webworm are still
causing damage in southern Illinois and in select
locations in central Illinois. Where defoliation is
extremely severe or where plant appearance is the
most important aspect of the landscape, treatments
with any of the compounds listed for caterpillar
control in the 7997 Illinois Commercial Landscape
and Turf Pest Management Handbook should elimi-
nate current infestations. Both yellow-necked and
walnut caterpillars feed as a group, so spot treat-
ments or removal of the caterpillars by pruning or
physical destruction are the most effective forms of
management.
In addition to these common summer defoliators,
we have been seeing some damage on willows by
spiny elm caterpillars in the Chicago area. The
larvae of this caterpillar are black, about two inches
long when fully grown, and have white and burgundy
spots along their backs. They also have long spines
around each segment. An interesting fact about this
defoliating caterpillar it becomes the mourning cloak
butterfly. For some people, this poses a dilemma:
What is more important — the appearance of the plant
or the beauty of the insect? (John Lloyd, Karel Jacobs,
and Fredric Miller)
£^C~^Y^ ^ College of Agricultural. Consumer and Environmental Sciences.
University of Illinois at Urbana-Champaign
ces
Helping You Put Knowledge to Work — State • County • Local Groups
U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
opportunities in programs and employment.
No. 13 'July 16, 1997
Carpenter Ants in Trees
We have taken numerous calls about carpenter ant
nests in trees. Carpenter ants normally do not need to
be controlled in trees because they usually cause little
or no damage to the tree.
Carpenter ants vary in size and color. The black
carpenter ant is probably the most common species in
landscapes. Worker ants are nonreproducing females
that are wingless and black. Workers come in two size
ranges. Minor workers are approximately 1/4 inch
long and do much of the food foraging, nest construc-
tion, and larval feeding; they also attend the queen.
Major workers are also wingless and black, but are
about 1/2 inch long and play a major role in defending
the nest and minor workers.
The black carpenter ant is the only carpenter ant in
Illinois that commonly locates its nests in buildings.
They tunnel out wood that is damp or decaying from
roof or water-pipe leaks. (The red carpenter ant is
another common species, with red, wingless workers
that are about 1/4 inch long. Other, smaller species of
carpenter ants are also found in Illinois.)
Carpenter ants build their nests by hollowing out
rotting wood; they do not eat the wood. Workers take
mouthful-sized chips of wood to the nest entrance,
where they deposit the chips. This results in a pile of
coarse sawdust at the base of a tree. The nest itself
consists of meandering, 1/4-inch-diameter tunnels that
are free of sawdust. Egg laying, larval rearing, and
pupation take place within these tunnels. Nests may
be present in rotting wood in trunks, limbs, or roots.
Nests that are at least five years old will contain
winged reproductives. Black carpenter ant males are
1/4 inch long and have two pairs of clear wings. The
queens are approximately 3/4 inch long and also
have two pairs of clear wings. Both sexes emerge
from the colony in early morning and fly towards the
light to escape the colony. Mating occurs, and the
reproductives break their wings off at weakened
spots. Then they tunnel into damp, rotting wood to
start a new colony.
Carpenter ant nests in trees are an indication of
rotting wood. Such trees should be checked to deter-
mine whether the rot has weakened the tree enough
that it becomes a hazard. Nests in trees close to a
house may result in ants entering the house to forage.
This nuisance can ht eliminated by spraying diazinon
into the nest or by pruning overhanging limbs at least
three feet back from the roof. Otherwise, carpenter ant
nests do not directly weaken the tree and do not
usually require control. (Phil Nixon)
PLANT DISEASES
Aster Yellows of Annuals and Perennials
Aster yellows is most commonly found on chrysan-
themum, aster, daisy, marigold, and petunia, but it
occurs on many other species as well. Affected plants
are easy to identify: they appear yellowish, stunted,
stiff, erect, and bushy. The flowers may be deformed,
with partially or totally green, leafy petals. The plants
look like they have been infected by a virus.
Aster yellows is a disease caused by a phytoplasma
(formerly known as mycoplasma). Phytoplasmas are
pathogens similar to fungi, bacteria, and viruses —
specifically, an organism between a bacterium and a
viral pathogen. The important things to remember
about phytoplasmas are that they are transmitted by
sucking insects (in the case of aster yellows, by leaf-
hoppers) and they cannot be cultured in a laboratory.
Because the pathogen can be transmitted by
leafhoppers, control measures include destroying all
affected plants when they are first seen, eliminating
broadleaf weeds, and, of course, buying symptom-free
plants. Spraying regularly to keep leafhoppers from
feeding may be beneficial in a commercial setting.
We do not see many aster yellows samples in the
lab. Part of the reason is that such plants are rogued
before they reach retail outlets. Symptoms are easy to
identify by comparing the suspect plant to disease-
identification photos. The pathogen cannot be cul-
tured in the lab, so sending a sample to the Plant
Clinic is not necessary. For a detailed description of
aster yellows, consult Report on Plant Diseases No.
903. (Nancy Pataky)
Bacterial Leafspot of Stone Fruits
This disease is caused by a bacterium (Xanthomonas)
that thrives in the rainy June and July weather we have
experienced throughout most of the state (apologies to
No. 13 'July 16, 1997
those of you who still have dry weather). Look for the
disease on peach, nectarine, almond, apricot, plum,
prune, and cherry, as well their ornamental equivalents.
Numerous spots (from as small as a pinprick up to
1/5 inch in diameter) form in the leaves. At first
these spots are circular and watersoaked, but soon
enlarge to become angular and deep purple to rusty
brown or black. The centers of the spots often dry
out and tear away, so you may notice only a shot-
hole appearance or even a wind-tattered effect.
Infected leaves turn yellow and drop early. Al-
though symptoms resemble those of nitrogen defi-
ciency, that deficiency usually results in holes
concentrated near the midvein on the leaf. This
bacterium also attacks twigs and fruit, reducing fruit
quality and yield or reducing aesthetic appeal in the
case ornamental species.
Some peach cultivars have resistance to bacterial
leafspot. Most apricot varieties are susceptible, as are
many nectarine varieties. Some resistant cultivars of
peach are listed in Report on Plant Diseases No. 810,
Bacterial Spot of Stone Fruits.
If you have a mature tree and do not wish to
consider replacement with a resistant variety, use
balanced fertility practices and open the trees through
pruning so that air circulation is improved. These
steps will make conditions less conducive to disease
development. (Nancy Pataky)
Russian Olive Cankers
Cankers occur on a great deal of the woody plant
material we see at the Plant Clinic. Cankers are
generally caused by secondary, or stress, pathogens
and are only a part of the problem. They are merely a
clue that something more is wrong.
A canker is a dead area, usually on a woody plant,
that often results in an open wound. Starting as a
small, sharply delimited, usually round-to-oval or
elongate lesion, a canker might enlarge and girdle the
cane, twig, limb, trunk, or root. The canker indicates
the area of the cambium that has been killed; the
sapwood underneath is generally brown or black. The
canker itself may be thickened and rough or it may
appear sunken. On very tightly barked trees, a color
difference in the bark may be all that delineates the
canker. Cutting into the affected area with a knife will
reveal that the cankered area has brown inner wood,
while the healthy area is white or green.
Russian olive trees suffer from many cankers. The
principal ones are caused by such fungi as Phomopsis,
Lasiodiplodia (Botryodiplodia), Nectria (Tubercu-
laria), and Phytophthora.
In Illinois, the most important canker by far is
Phomopsis. Unlike other canker fungi, Phomopsis is
an aggressive pathogen that can attack and kill
vigorous trees. Trees seriously injured by drought,
hail, or ice are subject to decline and more rapid
spread of the disease. Phomopsis-'mitcitd trees often
appear ragged, with several dying or dead twigs and
branches. Current-season twigs and small branches
often wilt and die, with the dead, withered leaves
hanging on for some time. Oval-to-elongate, sunken
cankers are most evident on the large branches and
trunks.
Diseased bark on Phomopsis cankers varies from
orange-brown to dark reddish brown. Ridges often
form around the canker margins. Branches girdled by
the enlarging and encircling cankers wilt and die. The
white sapwood beneath the cankers turns dark brown
to black and extends beyond the margins. Minute,
slightly raised, rounded pustules of the Phomopsis
fungus are embedded in the dead, cankered bark.
Avoid all unnecessary bark wounds because they
are the pathogen's main avenue of entry. All seriously
infected trees showing dieback should be cut off near
the ground and destroyed, preferably by burning.
More details on this disease can be found in Report on
Plant Diseases No. 606. (Nancy Pataky)
Sclerotinia White Mold
This is a fungal disease that we see only in very wet
years. Many ornamental crops could be affected,
including begonia, daisy, delphinium, hydrangea,
marigold, pansy, and zinnia. Vegetable crops com-
monly affected are tomato, green bean, and pepper.
White mold is caused by Sclerotinia, a fungus that
thrives in cool, wet weather. Due to near ideal
conditions in many parts of Illinois, this disease
should be expected. The fungus remains in a resting
state (sclerotia) in the soil for many years. With ideal
conditions, fruiting bodies (apothecia) form and
spores are released into the air. A period of wet
No. 13 » July 16, 1997
weather is then required for infection to follow the
spore release. It is easy to understand why the
alternating wet and dry periods experienced in some
parts of the state have been ideal for Sclerotinia
white mold.
Symptoms of white mold are bleached areas on the
stems and at the leaf axils. These areas appear almost
like animal bones dried in the sun. In cool, wet
weather, a white fluffy mold develops on the bleached
areas. Within seven to ten days, sclerotia form: large,
black structures, almost like rabbit droppings, found
inside the stem (and occasionally on the outside as
well).
Control options for this disease are limited. The
home grower can try to keep plant density low so that
air movement helps dry out plants sooner. There are
no rescue treatments available for commercial use.
Fungicide applications may help on a preventive basis
in areas where this is a problem every year. For
chemical options, consult the 7997 Illinois Commer-
cial Turf and Ornamental Pest Management Hand-
book. (Nancy Pataky)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd, (217) 333-6653, and Fredric Miller, (708) 352-0109,
entomologists; Nancy Pataky, plant pathologist, (217) 333-
0519; Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350, and KarelJacobs, plant
pathologist, the Morton Arboretum, (630) 719-5646. Phil
Nixon is the executive editor of the Home, Yard and Garden
Pest Newsletter. This newsletter is written by faculty in the
Department of Natural Resources and Environmental
Sciences and the Department of Crop Sciences.
;. c^
P-]
(A^^^
*-»rr!v^t \jr ncoCAMUH
JUL 2 4 1997
COOPERATIVE EXTENSION SERVICE
HOME, YARD ^ GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
Illinois at urbana-champaign A Illinois natural history survey, champaign
NEWSLETTER
No. 14 • July 23, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
PLANT DISEASES
Oops!
Issue number 12 of this newsletter contained an
article on leaf scorch of trees. In that article, we
referred to Report on Plant Diseases No. 520. The
correct number for the leaf scorch RPD is No. 620.
Our apologies. (Nancy Pataky)
Tomato Wilts
Wilt diseases of tomato are caused by three different
pathogens, as well as a toxin produced by walnut
roots. Walnut wilt of tomato, which is noninfectious,
produces symptoms similar to the wilts caused by
pathogens, including a brown discoloration of
internal woody tissue. Other noninfectious causes of
tomato wilt include flooding or rotting of roots,
some herbicide injuries, and mechanical injury to the
roots or stem.
The infectious vascular wilt pathogens of tomato
include bacteria and two fungi. Fusarium and Verticil-
lium are fungi that cause the very similar Fusarium
wilt and Verticillium wilt diseases. Infected plants
might be somewhat stunted, and leaves will turn
yellow and die, often starting at the base of the plant
and progressing upward. Leaves on one side of the
plant could show symptoms, while leaves on the other
side appear normal. Wilting might occur at or during
the hottest part of the day or when the plants are
stressed from dryness or a heavy fruit load. Infected
leaves might dry up before the wilting is detected, so
initial symptoms may appear as stems with dead
leaves. Both fungal diseases cause discoloration of the
vascular (woody) tissues.
With Fusarium wilt, the vascular tissue of stems
and petioles throughout the plant becomes brown to
reddish brown. With Verticillium wilt, only the lower
stem becomes discolored — grayish, in this case. This
distinction is not always clear cut, however, and
laboratory isolation is required to distinguish these
two pathogens. Both fungi are soilbome and infect
plants through root systems; both are able to survive
in soils in the absence of a susceptible tomato plant
for many years. Fusarium can also be seedbome.
Bacterial wilt is caused by a Pseudomonas species
and affects potatoes, eggplants, and peppers, as well
as tomatoes. This pathogen causes a sudden wih of
the plant without leaves first discoloring. The center
of the stem will be water-soaked at first, then brown,
and eventually may become hollow. If the plant wilts
as described but does not show any stem discolora-
tion, carefully dig up and inspect roots for root rot.
Roots injured by excess water and/or root rot will also
cause these symptoms.
Disease resistance is the most common and eco-
nomically practical means of controlling the fungal
diseases. Tomato varieties labeled "VFN" have
resistance to Verticillium, one or more races of
Fusarium, and nematodes. Occasionally the question
arises: Why do my VFN tomatoes have symptoms of
Verticillium or Fusarium wilt? The first possibility is
that the symptoms are the result of something other
than these two diseases. Or, it may be that the plants
were not actually the variety labeled. Another possible
explanation is that the particular variety of tomato has
been infected by a race of the fungus to which the
plant is not resistant.
Rotation out of an affected area for five to seven
years can help reduce the incidence of Verticillium
A (^^X7 C College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urt>ana-Cfiampaign
Gm^2 Helping You Put Knowledge to Work — State • County • Local Groups
t^'t^r U.S. Department of Agriculture Cooperating
Tfie Cooperative Extension Service provides equal
opportunities In programs and employment.
No. 14 » July 23, 1997
wilt; shorter rotations will be of little benefit. Remov-
ing infected plant parts, including roots, might reduce
the buildup of inoculum. Research shows that using
nitrate forms of nitrogen can help reduce the severity
of Fusarium wilt, while ammonium forms promote
disease development. Because Fusarium fungi favor
low soil pH, increasing the pH to a range of 6 to 7 can
help control the Fusarium wilt. A pH higher than 7.5
increases problems with Verticillium wilt. Details on
the wilts of tomato can be found in Report on Plant
Diseases No. 929. Details on Verticillium wilt on
many crops can be found in Report on Plant Diseases
No. 1010. (Nancy Pataky)
Witches' Brooms
Many plants develop a symptom known as witches'
brooms. On woody plants, this appears as a prolifera-
tion of shoots from one point, like a broom. The cause
of these symptoms varies with the host. Cherry and
blackberry witches' brooms are caused by fungi.
Other witches' brooms are the result of phytoplasmas.
Witches' broom of common hackberry is thought
to be caused by a powdery mildew fungus in associa-
tion with an eriophyid mite. This is such a common
condition on Illinois common hackberry trees that one
would think that witches' brooms were a characteris-
tic of the species. Many of the twigs in a broom will
die back in the winter. Buds on the surviving twigs are
numerous, larger than normal, usually grayish, and
have looser scales than normal buds do. The overall
effect on the tree is many clumps of thick growth
throughout the canopy. The brooms may be unpleas-
ant in appearance but will not kill a hackberry tree.
As far as we know, there are no practical control
measures for witches' brooms on hackberry. If you
want a tree without the brooms, do not plant a com-
mon hackberry. Sugarberry is less frequently affected,
and both Chinese hackberry and Jesso hackberry are
considered resistant. A Report on Plant Diseases (No.
662) on this condition is available. (Nancy Pataky)
Viruses of Brambles
Viral diseases of brambles cause a range of symp-
toms. Generally, the infected plant has low vigor. The
leaves may be yellowish, with a light to dark green
mottling. Leaves may also be blistered or puckered,
dwarfed, curled, wrinkled, and cupped downward
(with the mosaic types).
The leaf curl viruses generally cause slight stunting
and bushy growth with small, dark green, bunchy,
stiff, tightly curled leaves. These symptoms are also
very similar to those caused by some growth regulator
herbicides. Look closely at the pattern in the bramble
patch. Herbicide injury will be more intense near the
source of the herbicide and progressively less intense
moving away from the source. Other broadleaf plants
will likely show symptoms as well, and all at about
the same time. Viruses are more likely to occur on
scattered plants and to spread slowly during the
season. Viruses tend to be fairly specific to one type
of plant species.
Viral diseases reduce the yield and fruit quality of
bramble fruits more than they do for most other fruit
crops. Once infected, plants remain so for life. The
virus particle needs a live plant cell in which to
multiply and spread. It cannot be cultured, extracted,
or induced to sporulate in a lab. The viruses are
spread by the feeding of aphids, but not by pruning or
other mechanical injuries.
You cannot kill or inhibit virus particles with
sprays. Control involves destroying all infected
cultivated and wild brambles within 1,000 feet, if
possible. Start new plantings with certified virus-free
plants. If growing both black and red raspberries,
separate them by at least 150 feet to reduce virus
cross-infection. Maintain strict aphid control at all
times. For more information, refer to Report on Plant
Diseases No. 710. (Nancy Pataky)
INSECTS
Japanese Beetles
Although adult Japanese beetles have emerged
throughout much of Illinois, the numbers appear to be
low. In Ohio, beetles were few in number for a week
or two, but then started emerging more heavily. Many
pupae are still in the soil. Most of these pupae are still
in the mid stages of development; the adults will
probably not emerge for another couple of weeks —
probably creating an extended emergence pattern in
Ohio with an associated extended feeding period by
the adults. In Illinois, it remains to be seen whether
this pattern will be followed. Japanese beetles do
better in damp soils; because the past fall and spring
were average to dry in much of Illinois, we may not
experience a very large emergence of beetles this year.
If we do have an extended period of emergence,
susceptible trees and shrubs may need to be re-treated
more often than usual. Be sure to monitor regularly
and re-treat when necessary. There is nothing new in
No. 14 • July 23, 1997
the way of pesticide controls. The standard treatments
are Sevin (carbaryl), Dursban (chlorpyrifos), and
Orthene (acephate). However, the pyrethroids — Astro
(permethrin). Scimitar (lambda-cyhalothrin), Talstar
(bifenthrin), and Tempo (cyfluthrin) — are favored by
professional landscape managers. Wetable powders
and flowable formulations seem to have the longest
residual activity. In Illinois, we performed limited
tests of a Japanese beetle repellent containing
azadirachtin and found Sevin to be most effective in
keeping the beetles off susceptible plants.
Fellow entomologist Dan Potter (University of
Kentucky) has been conducting research on Japanese
beetle adult feeding and has some interesting findings.
Dan and his students were interested in why Japanese
beetles seem to cluster on some plants in the land-
scape and not others, even if the plants are the same
species. Potter has gathered some intriguing data
indicating that the adult beetles' attraction to phero-
mones may be one component of the clustering behav-
ior. (Pheromones are chemicals produced by the bee-
tles to attract other beetles for feeding and mating.)
The other major factor that caused groups of
beetles to amass on one plant was the feeding damage
itself. Plants that were skeletonized seem to release
odors that attract even more beetles. Removing leaves
and flowers that have been damaged by Japanese
beetles may reduce further feeding. Removed plant
material should be disposed of, not just dropped on
the ground beneath the plant.
We do not recommend using the Japanese beetle
traps that are sold in garden stores and seed catalogs.
All evidence suggests that the traps attract more
beetles into a landscape than would be there in the
first place. The traps are also only marginally effec-
tive in trapping the population that may be present.
However, it's difficult to convince the homeowner
who is proudly holding a bag of several hundred
beetles that the traps are not effective. You might try a
numbers game to illustrate how ineffective the traps
are at controlling the Japanese beetle population. One
Japanese beetle grub per square foot of turf translates
to 43,500 beetles in an acre of turf. If you capture
1 ,000 beetles in a trap, what percentage of the popula-
tion have you eliminated? Do the math! (Dave
Shetlar, The Ohio State University; Phil Nixon)
Japanese Beetle Host Plants
As we explained in last week's newsletter, because
Japanese beetle is relatively new in many areas of the
state, landscape designers and homeowners may be
unaware of the beetle's feeding preferences. The
Japanese beetle's most- and least-favored woody
plants in Illinois are listed below. We hope this
information will be useful to people designing new
landscapes in areas infested by this beetle. The
information was provided by Dr. Cliff Sadof from
Purdue University. (John Lloyd)
Least Favored by Japanese Beetle
Box elder
Dogwood
Euonymus
Green ash
Holly
Lilac
Mulberry
Persimmon
Red maple
Silver maple
Sweet gum
White ash
Yellow poplar (tuliptree)
Most Favored by Japanese Beetle
Birch
Black walnut
Elm
Grape
Hollyhock
Japanese maple
Linden
London planetree
Malus spp. (crabapple, etc.)
Norway maple
Prunus spp. (flowering cherry, etc.)
Rose
Sassafras
lyu. It ' juiy ^j, I yy/
Annual White Grub
Annual white grub adults have been numerous in
central Illinois since July 13 — about ten days later
than usual. These beetles were also reported at the
Morton Arboretum in northeastern Illinois the previ-
ous week. The number of beetles that we have seen
indicates this is a normal emergence. With the turf
being dry and brownish in nonirrigated areas, egg
laying is likely to be concentrated in watered lawns
and other turf.
Heavily irrigated turf areas should be treated over
the next couple of weeks with imidicloprid (Merit,
Grubex) or halofenozide (Mach 2). Be sure to water
the turf (at least 1/2 inch) after the application to
move the insecticide into the root zone where the
grubs live. Do not allow liquid applications to dry on
the grass blades before they are watered in.
Less-heavily watered turf should be scouted for
grubs in the second week of August. Areas with high
grub populations can be treated with a quicker-acting
insecticide such as trichlorfon (Dylox, Proxol),
bendiocarb (Turcam, Intercept), or diazinon to avoid
later turf damage. (Phil Nixon)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd (217) 333-6653, and Fredric Miller, (708) 352-
0109, entomologists; Nancy Pataky, plant pathologist,
(217) 333-0519; Rhonda Ferree, Tom Voigt, and David
Williams, horticulturists, (217)333-0350, and Karel
Jacobs, plant pathologist, the Morton Arboretum, (630)
719-5646. Phil Nixon is the executive editor of the Home,
Yard and Garden Pest Newsletter. This newsletter is written
by faculty in the Department of Natural Resources and
Environmental Sciences and the Department of Crop
Sciences. The newsletter is edited by Peggy Currid, typeset
by Oneda VanDyke, and proofread by Herbert Morgan, all
of Information Services.
COOPERATIVE EXTENSION SERVICE
HOME, YARD & GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
Illinois at urbana-champaign a il I inois natural history survey, champaign
NEWSLETTER
No. 14 • July 23, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
PLANT DISEASES
Oops!
Issue number 12 of this newsletter contained an
article on leaf scorch of trees. In that article, we
referred to Report on Plant Diseases No. 520. The
correct number for the leaf scorch RPD is No. 620.
Our apologies. (Nancy Pataky)
Tomato Wilts
Wilt diseases of tomato are caused by three different
pathogens, as well as a toxin produced by walnut
roots. Walnut wilt of tomato, which is noninfectious,
produces symptoms similar to the wilts caused by
pathogens, including a brown discoloration of
internal woody tissue. Other noninfectious causes of
tomato wilt include flooding or rotting of roots,
some herbicide injuries, and mechanical injury to the
roots or stem.
The infectious vascular wilt pathogens of tomato
include bacteria and two fungi. Fusarium and Verticil-
Hum are fungi that cause the very similar Fusarium
wilt and Verticillium wilt diseases. Infected plants
might be somewhat stunted, and leaves will turn
yellow and die, often starting at the base of the plant
and progressing upward. Leaves on one side of the
plant could show symptoms, while leaves on the other
side appear normal. Wilting might occur at or during
the hottest part of the day or when the plants are
stressed from dryness or a heavy fruit load. Infected
leaves might dry up before the wilting is detected, so
initial symptoms may appear as stems with dead
leaves. Both fungal diseases cause discoloration of the
vascular (woody) tissues.
With Fusarium wilt, the vascular tissue of stems
and petioles throughout the plant becomes brown to
reddish brown. With Verticillium wilt, only the lower
stem becomes discolored — grayish, in this case. This
distinction is not always clear cut, however, and
laboratory isolation is required to distinguish these
two pathogens. Both fungi are soilbome and infect
plants through root systems; both are able to survive
in soils in the absence of a susceptible tomato plant
for many years. Fusarium can also be seedbome.
Bacterial wilt is caused by a Pseudomonas species
and affects potatoes, eggplants, and peppers, as well
as tomatoes. This pathogen causes a sudden wilt of
the plant without leaves first discoloring. The center
of the stem will be water- soaked at first, then brown,
and eventually may become hollow. If the plant wilts
as described but does not show any stem discolora-
tion, carefully dig up and inspect roots for root rot.
Roots injured by excess water and/or root rot will also
cause these symptoms.
Disease resistance is the most common and eco-
nomically practical means of controlling the fungal
diseases. Tomato varieties labeled "VFN" have
resistance to Verticillium, one or more races of
Fusarium, and nematodes. Occasionally the question
arises: Why do my VFN tomatoes have symptoms of
Verticillium or Fusarium wilt? The first possibility is
that the symptoms are the result of something other
than these two diseases. Or, it may be that the plants
were not actually the variety labeled. Another possible
explanation is that the particular variety of tomato has
been infected by a race of the fungus to which the
plant is not resistant.
Rotation out of an affected area for five to seven
years can help reduce the incidence of Verticillium
A ('^"P C College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urbana-Champaign
(BB
Helping You Put Knowledge to Work — State • County • Local Groups
U.S. Department of Agriculture Cooperating
Ttie Cooperative Extension Service provides equal
opportunities in programs and employment.
/
No. 14 'July 23, 1997
wilt; shorter rotations will be of little benefit. Remov-
ing infected plant parts, including roots, might reduce
the buildup of inoculum. Research shows that using
nitrate forms of nitrogen can help reduce the severity
of Fusarium wilt, while ammonium forms promote
disease development. Because Fusarium fungi favor
low soil pH, increasing the pH to a range of 6 to 7 can
help control the Fusarium wilt. A pH higher than 7.5
increases problems with Verticillium wilt. Details on
the wilts of tomato can be found in Report on Plant
Diseases No. 929. Details on Verticillium wilt on
many crops can be found in Report on Plant Diseases
No. 1010. (Nancy Pataky)
Witches' Brooms
Many plants develop a symptom known as witches'
brooms. On woody plants, this appears as a prolifera-
tion of shoots from one point, like a broom. The cause
of these symptoms varies with the host. Cherry and
blackberry witches' brooms are caused by fungi.
Other witches' brooms are the result of phytoplasmas.
Witches' broom of common hackberry is thought
to be caused by a powdery mildew fungus in associa-
tion with an eriophyid mite. This is such a common
condition on Illinois common hackberry trees that one
would think that witches' brooms were a characteris-
tic of the species. Many of the twigs in a broom will
die back in the winter. Buds on the surviving twigs are
numerous, larger than normal, usually grayish, and
have looser scales than normal buds do. The overall
effect on the tree is many clumps of thick growth
throughout the canopy. The brooms may be unpleas-
ant in appearance but will not kill a hackberry tree.
As far as we know, there are no practical control
measures for witches' brooms on hackberry. If you
want a tree without the brooms, do not plant a com-
mon hackberry. Sugarberry is less frequently affected,
and both Chinese hackberry and Jesso hackberry are
considered resistant. A Report on Plant Diseases (No.
662) on this condition is available. (Nancy Pataky)
Viruses of Brambles
Viral diseases of brambles cause a range of symp-
toms. Generally, the infected plant has low vigor. The
leaves may be yellowish, with a light to dark green
mottling. Leaves may also be blistered or puckered,
dwarfed, curled, wrinkled, and cupped downward
(with the mosaic types).
The leaf curl viruses generally cause slight stunting
and bushy growth with small, dark green, bunchy,
stiff, tightly curled leaves. These symptoms are also
very similar to those caused by some growth regulator
herbicides. Look closely at the pattern in the bramble
patch. Herbicide injury will be more intense near the
source of the herbicide and progressively less intense
moving away from the source. Other broadleaf plants
will likely show symptoms as well, and all at about
the same time. Viruses are more likely to occur on
scattered plants and to spread slowly during the
season. Viruses tend to be fairly specific to one type
of plant species.
Viral diseases reduce the yield and fruit quality of
bramble fruits more than they do for most other fruit
crops. Once infected, plants remain so for life. The
virus particle needs a live plant cell in which to
multiply and spread. It cannot be cultured, extracted,
or induced to sporulate in a lab. The viruses are
spread by the feeding of aphids, but not by pruning or
other mechanical injuries.
You cannot kill or inhibit virus particles with
sprays. Control involves destroying all infected
cultivated and wild brambles within 1 ,000 feet, if
possible. Start new plantings with certified virus-free
plants. If growing both black and red raspberries,
separate them by at least 150 feet to reduce virus
cross-infection. Maintain strict aphid control at all
times. For more information, refer to Report on Plant
Diseases No. 710. (Nancy Pataky)
INSECTS
Japanese Beetles
Although adult Japanese beetles have emerged
throughout much of Illinois, the numbers appear to be
low. In Ohio, beetles were few in number for a week
or two, but then started emerging more heavily. Many
pupae are still in the soil. Most of these pupae are still
in the mid stages of development; the adults will
probably not emerge for another couple of weeks —
probably creating an extended emergence pattern in
Ohio with an associated extended feeding period by
the adults. In Illinois, it remains to be seen whether
this pattern will be followed. Japanese beetles do
better in damp soils; because the past fall and spring
were average to dry in much of Illinois, we may not
experience a very large emergence of beetles this year.
If we do have an extended period of emergence,
susceptible trees and shrubs may need to be re-treated
more often than usual. Be sure to monitor regularly
and re-treat when necessary. There is nothing new in
No. 14 • July 23, 1997
the way of pesticide controls. The standard treatments
are Sevin (carbaryl), Dursban (chlorpyrifos), and
Orthene (acephate). However, the pyrethroids — Astro
(permethrin), Scimitar (lambda-cyhalothrin), Talstar
(bifenthrin), and Tempo (cyfluthrin) — are favored by
professional landscape managers. Wetable powders
and flowable formulations seem to have the longest
residual activity. In Illinois, we performed limited
tests of a Japanese beetle repellent containing
azadirachtin and found Sevin to be most effective in
keeping the beetles off susceptible plants.
Fellow entomologist Dan Potter (University of
Kentucky) has been conducting research on Japanese
beetle adult feeding and has some interesting findings.
Dan and his students were interested in why Japanese
beetles seem to cluster on some plants in the land-
scape and not others, even if the plants are the same
species. Potter has gathered some intriguing data
indicating that the adult beetles' attraction to phero-
mones may be one component of the clustering behav-
ior. (Pheromones are chemicals produced by the bee-
tles to attract other beetles for feeding and mating.)
The other major factor that caused groups of
beetles to amass on one plant was the feeding damage
itself. Plants that were skeletonized seem to release
odors that attract even more beetles. Removing leaves
and flowers that have been damaged by Japanese
beetles may reduce further feeding. Removed plant
material should be disposed of, not just dropped on
the ground beneath the plant.
We do not recommend using the Japanese beetle
traps that are sold in garden stores and seed catalogs.
All evidence suggests that the traps attract more
beetles into a landscape than would be there in the
first place. The traps are also only marginally effec-
tive in trapping the population that may be present.
However, it's difficult to convince the homeowner
who is proudly holding a bag of several hundred
beetles that the traps are not effective. You might try a
numbers game to illustrate how ineffective the traps
are at controlling the Japanese beetle population. One
Japanese beetle grub per square foot of turf translates
to 43,500 beetles in an acre of turf. If you capture
1 ,000 beetles in a trap, what percentage of the popula-
tion have you eliminated? Do the math! (Dave
Shetlar, The Ohio State University; Phil Nixon)
Japanese Beetle Host Plants
As we explained in last week's newsletter, because
Japanese beetle is relatively new in many areas of the
state, landscape designers and homeowners may be
unaware of the beetle's feeding preferences. The
Japanese beetle's most- and least-favored woody
plants in Illinois are listed below. We hope this
information will be useful to people designing new
landscapes in areas infested by this beetle. The
information was provided by Dr. Cliff Sadof from
Purdue University. (John Lloyd)
Least Favored by Japanese Beetle
Box elder
Dogwood
Euonymus
Green ash
Holly
Lilac
Mulberry
Persimmon
Red maple
Silver maple
Sweet gum
White ash
Yellow poplar (tuliptree)
Most Favored by Japanese Beetle
Birch
Black walnut
Elm
Grape
Hollyhock
Japanese maple
Linden
London planetree
Malus spp. (crabapple, etc.)
Norway maple
Prunus spp. (flowering cherry, etc.)
Rose
Sassafras
lyu. I'* ' )uiy zj, \vr)/
Annual White Grub
Annual white grub adults have been numerous in
central Illinois since July 13 — about ten days later
than usual. These beetles were also reported at the
Morton Arboretum in northeastern Illinois the previ-
ous week. The number of beetles that we have seen
indicates this is a normal emergence. With the turf
being dry and brownish in nonirrigated areas, egg
laying is likely to be concentrated in watered lawns
and other turf.
Heavily irrigated turf areas should be treated over
the next couple of weeks with imidicloprid (Merit,
Grubex) or halofenozide (Mach 2). Be sure to water
the turf (at least 1/2 inch) after the application to
move the insecticide into the root zone where the
grubs live. Do not allow liquid applications to dry on
the grass blades before they are watered in.
Less-heavily watered turf should be scouted for
grubs in the second week of August. Areas with high
grub populations can be treated with a quicker-acting
insecticide such as trichlorfon (Dylox, Proxol),
bendiocarb (Turcam, Intercept), or diazinon to avoid
later turf damage. {Phil Nixon)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd, (217) 333-6653, and Fredric Miller, (708) 352-
0109, entomologists; Nancy Pataky, plant pathologist,
(217) 333-0519; Rhonda Ferree, Tom Voigt, and David
Williams, horticulturists, (217) 333-0350, and Karel
Jacobs, plant pathologist, the Morton Arboretum, (630)
719-5646. Phil Nixon is the executive editor of the Home,
Yard and Garden Pest Newsletter. This newsletter is written
by faculty in the Department of Natural Resources and
Environmental Sciences and the Department of Crop
Sciences. The newsletter is edited by Peggy Currid, typeset
by Oneda VanDyke, and proofread by Herbert Morgan, all
of Information Services.
JUN 2 6 1997
I 75
-"r COOPERATIVE E XTE N SIO N S E'RV I C E
HOME, YARD ^ GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
Illinois at urbana-champaign a i 1 1 inois natural history survey, champaign
NEWSLETTER
No. 15 • lulySO, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
INSECTS
Annual White Grubs
Adult annual white grubs are still flying in east central
Illinois, which means that egg laying is still occurring.
As we move into August, keep a lookout for damaged
turf in irrigated areas where preventive treatments
with imidacloprid (Merit, Grubex) or halofenozide
(Mach 2) have not been applied.
As damage starts to occur, lawns in which more
than 10 or 12 annual white grub larvae are present per
square foot may require rescue treatments with
trichlorfon (Dylox, Proxol), bendiocarb (Turcam,
Intercept), or diazinon to reduce turf damage. Drench
treated areas with at least 1/2 an inch of water within
30 minutes of the insecticide application to move the
insecticide into the root zone where the larvae are
feeding. To avoid turf damage by native wildlife that
feed on grubs (raccoons and skunks, for example),
treatments may be necessary at grub populations
lower than 10 or 12 per square foot. (John Lloyd)
Dog-Day Cicadas and Cicada Killers
I'm always comforted by the first drone of dog-day
cicadas in the trees, knowing that full summer has
arrived when I hear this sound. While most people
call these buzzing critters "locusts," cicadas are not
related to grasshoppers in any way. Apparently, tree-
dwelling grasshoppers are present in Europe, and
early settlers called our chirping cicadas "locusts,"
assuming that they were the same as the locusts in
Europe.
The dog-day cicadas take only a year or two to
complete their development. Unlike the periodical
cicadas that take 13 to 17 years to complete develop-
ment, dog-day cicadas appear each summer. The
common Illinois species is almost a solid light green,
although there is another species that is tan with
darker markings on the thorax. The periodical cicadas
are black with red-orange wings and red eyes.
Occasionally, you'll hear the dog-day cicada's song
interrupted by a distinct screech. This indicates an
attack by predatory birds or the cicada killer wasp.
Not surprisingly, we have been receiving many phone
calls about cicada killers as well as several other
"ground" or "sand" wasps. The cicada killer is the
largest and most impressive of this group. Adult
females can be as long as 1-1/2 inches, with a wing
span of three inches. People describe these wasps as
"incredibly large and mean looking." The bodies are
black and marked with white or yellow; the wings are
red-orange.
Cicada killer females dig holes in the ground,
usually in sandy areas, that may extend several feet
down. At the base of these burrows, they construct
cells in which they place a paralyzed cicada. An egg is
attached to each cicada and the wasp grub dines on
the cicada for the rest of the summer.
Female cicada killers usually go about their busi-
ness digging burrows, capturing cicadas, and laying
eggs. They may buzz about if you approach their
burrow, but they are relatively tame. The males are
another story. Male cicada killers are quite territorial
and they will "buzz-strafe" and "dive bomb" any
other wasp, animal, or person that enters their terri-
tory. Fortunately, the males do not have a stinger, so
they can only intimidate intruders.
A (^^Th Q College of Agricultural. Consumer and Environmental Sciences,
University of Illinois at Urbana-Champaign
G^I^S Helping You Put Knowledge to Work— State • County • Local Groups
t^4^ U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
opportunities in programs and employment.
No. 15 'July 30, 1997
The other common sand wasps, especially those in
the genus Bimbex, make smaller burrows in sandy
areas (golf course bunkers and playground sand
boxes). The common Bimbex is black with greenish
white markings and is less than one inch long. This
wasp is beneficial because it feeds its larvae with
adult horse and deer flies. As you can imagine, control
is not recommended for these wasps unless there is a
real risk of being stung. Most of these wasps are
extremely docile and require major provocation to
sting. They will not attack even if their nests are
disturbed, although they may make intimidating
buzzing noises.
For people who insist upon or require wasp control,
dusting the individual openings with carbaryl (Sevin)
will provide excellent control. (Areawide sprays seem
to have little effect on these ground-nesting wasps.)
Just a little of the dust over the hole is all that is
needed. You don't have to turn the ground white!
(Dave Shetlar, The Ohio State University; John Lloyd)
New Publications
The Good Guys! Natural Enemies of Insects is a set of
31 laminated cards that provide full-color photos and
life history information on beneficial natural enemies
of insects. The cards were developed and produced by
Mike Jeffords, Sue Post, and Rob Wiedenmann from
the Illinois Natural History Survey and Cliff Sadof
from Purdue University. The cards are available for
$8 from the Distribution Office, Illinois Natural
History Survey, 607 East Peabody Drive, Cham-
paign, IL 61820, (217) 333-6880.
Plant Health Care practitioners and other profes-
sionals will be interested in a new publication: Plant
Health Care for Woody Ornamentals: A Professional's
Guide to Preventing and Managing Environmental
Stresses and Pests ($45). This comprehensive manual
contains information on such topics as understanding
stress and pest complexes, diagnosis and management
of disorders and diseases, management of insect and
vertebrate pests, and weed management. To order, call
(217) 333-2007. (John Lloyd)
PLANT DISEASES
Rust of Turfgrasses
All turfgrasses can be infected with rust fungi, but
Kentucky bluegrass, perennial ryegrass, tall fescue,
and zoysiagrass tend to be most susceptible. Early
symptoms of rust diseases include light yellow flecks
on leaves and stems. The early stage is barely discern-
ible— you might notice a slight yellow cast to the
lawn. The flecks enlarge until spores of the fungus are
produced, causing the leaf tissue to rupture and
expose powdery, spore-filled spots known as rust
pustules. The pustules may be yellow, orange, brown,
or red. The spores rub off very easily on hands, shoes,
clothing, and animals. These diseases are called
"rusts" because the pustules resemble metal rust. One
of our colleagues said that he had been working in his
yard recently and discovered that his white shoes had
become orange from the new crop of rust in his lawn.
Severely infected turf appears thin and tinted
yellow, red, or brown, depending on the fungus. The
turf becomes weakened, unsightly, and more suscep-
tible to injury from environmental stresses and attack
by other pathogens.
Most rusts of turfgrasses thrive during a period of
four to eight hours of low light intensity, with tem-
peratures between 70°F and 80°F, high humidity, and
heavy dews or light rains, followed by eight to sixteen
hours of high light, high temperatures, and slow
drying of leaf surfaces. There are also a few cool-
season rust diseases. This may seem a bit complex,
but to put it simply, the rusts favor warm, cloudy,
humid conditions followed by hot, sunny conditions.
Much of Illinois has experienced these conditions in
the last two weeks.
Grasses growing slowly under stressful environ-
mental conditions are most susceptible to rust, par-
ticularly when water, fertility, and soil compaction are
inadequate for good growth. Of course, some cultivars
are susceptible to rust even when not under stress.
Regardless, control measures should target stress
areas. Leaf wetness is required for infection, so it is
important to water early in the day so the turf can dry
before night. Water turf infrequently but to a depth of
six inches or more at each watering. Avoid frequent,
light sprinklings. Fertilize to keep the grass growing
about one inch per week in summer and early fall
droughts. Use a balanced fertilizer. Do not apply
excessive nitrogen. As the grass grows, it pushes rust-
infected leaves outward, making it easy to mow and
remove infected blades. Mow regularly to remove
infected leaf tips, but avoid mowing below the
recommended height for the particular turf species/
cultivar. Prune surrounding trees and shrubs to
improve light penetration and air circulation around
densely shaded areas.
Badly infected areas of turf may have to be reno-
vated and reseeded, ideally in mid- to late August. Be
No. 15 * July 30, 1997
certain to use a blend of turf cultivars with resistance
to nist, as listed in Report on Plant Diseases No. 412.
Preventive fungicides are available but offer only a
temporary solution. Products registered for rust
control on turf are listed in the 1997 Illinois Commer-
cial Turf and Landscape Pest Management Hand-
book. (Nancy Pataky and Lindsey duToit)
Powdery Mildew Update
Powdery mildew was discussed in issue number 1 1 of
this newsletter, when the disease was just beginning
to appear. It is now present in many gardens, espe-
cially those with dense plantings and tree cover.
Powdery mildew develops best on warm to hot days,
cool nights, and under conditions that cause dew to
form on leaves. The disease has been found on lilacs,
zinnias, crabapples, dogwoods, sycamores, turf, and
many other hosts. (Nancy Pataky)
Brown Rot of Stone Fruits
This fungal disease causes an easily distinguishable
fluffy, brown rot of the fruit of peach, nectarine, plum,
prune, sweet and sour cherry, apricot, almond, and
Japanese quince trees, as well as on the ornamental
varieties. Already this summer we have seen brown
rot on a few cherry samples because conditions have
been ideal for the development of the fungal patho-
gen. The disease is most severe in areas with frequent
spring and summer rains.
Brown rot is caused by the fungi Monilinia
fruticola and M. laxa. They infect blossoms, fruits,
twigs, and small branches. Some type of wound or
insect injury is necessary for the infection to set in. In
warm, damp conditions, the fruit quickly turns light
brown, then develops tan to gray spore tufts, which
give the fruit a fuzzy appearance. The rotted fruit
eventually shrinks and blackens, taking on a mummi-
fied appearance. These mummies may stay attached to
the tree. Brown rot is not known to cause leaf infec-
tion. However, it may infect flowers, resulting in
wilting and the production of the same spore tufts as
seen on the fruit. If the fungus invades stems, cankers
result. Often the cankers ooze gum or sap. Injuries
and insect activity may also cause prodution of this
gum or sap on many stone fruit trees.
The most significant control measure is reduction
of inoculum. Remove mummified fruit and prune out
infected twigs or cankers. The fungus will continue to
develop on unpicked fruit throughout the season, so
remove mummified fruit as it appears. Also remove
all fallen ripe fruit during the season — don't wait until
autumn. Insect control is also essential because
insects make the wounds that are necessary for
infection. Commercial fruit growers generally use
fungicides during bloom and three weeks before
harvest to help control brown rot. For next year's
reference, bloom sprays should be applied when the
blossoms first appear and again four or five days later
at full bloom. Some control can still be attained this
year by spraying two to three weeks before harvest
and repeating at seven-to-ten-day intervals. Many
fungicides will work, but Captan is probably the
easiest for homeowners to obtain and is the least
expensive. Read the label carefully and honor
preharvest intervals (the number of days before
harvest that you can spray a particular chemical).
Brown rot is discussed in detail in Report on Plant
Diseases No. 804. (Nancy Pataky)
Black Root Rot of Strawberry
The black root rot complex of strawberry is caused by
a number of fungal pathogens that invade when plants
are grown in tight clay or poorly drained soils. These
sites become particularly easy to detect in a rainy
year. The disease also can be initiated by other
environmental stress, such as freezing. The winter of
1996-97 provided a couple of freeze/thaw cycles.
Spring 1997 has been rainy in many parts of Illinois,
and the wet weather has been spotty over the summer.
These conditions have been conducive to black root
rot development.
Strawberry plants with black root rot exhibit a lack
of vigor and productivity. When roots are washed of
soil, they show many black, rotted roots with only a
few white feeder roots. This disease cannot be identi-
fied any more certainly in the lab than in the field.
Isolations from the roots would provide several fungal
pathogens, none of which could be identified as the
sole cause of this decline. Many fungi have been
implicated in this disease complex, but treating the
fungi does not alleviate the problem. As long as the
site stress is present, the problem will continue.
If you have strawberries that have declined each
year, including dead plants with roots as described
above, consider establishing a strawberry bed in a
new site. Make certain that the soil is loose in the new
site and that drainage is away from the root zone.
Plantings on clay sites or in low spots in the field or
garden will cause chronic problems with strawberries,
(Nancy Pataky)
/vu. ID ' juiy ju, /yy/
Blossom-End Rot and Sunscald
Maturing tomato fruit sometimes develop large dead
areas on the surface. The two most common causes of
these lesions are blossom-end rot and sunscald.
Pepper, summer squash, and other cucurbit crops may
also show this problem.
Blossom-end rot develops as necrotic areas at the
blossom end of the fruit. Tomato fruit tips turn brown
to black, while the ends on peppers usually become
light brown or tan. Blossom-end rot results from a
calcium deficiency in the plant caused by large
fluctuations in soil moisture. When soil moisture is
limited, plant growth slows and nutrient uptake by the
roots is reduced. If water becomes available again,
from rain or irrigation, the plant begins to grow
rapidly, but the uptake of calcium lags behind. Thus,
the rapidly expanding fruit tip does not have enough
calcium available to develop properly, even though
there is plenty of calcium in the soil.
Foliar applications of a calcium-rich fertilizer to
control blossom-end rot have varying rates of success.
Certain studies indicate that some control is achieved
with the fertilizer, while other studies report little or
no reduction in the disease. The best method for
controlling blossom-end rot is to maintain even and
adequate levels of soil moisture. With soil that
becomes neither too dry nor too wet, the plants grow
at an even rate and the nutrients stay in balance. Of
course, this goal is not easy to accomplish.
Sunscald also causes large necrotic areas on tomato
and pepper fruit. Sunscald develops when an area on
the fruit surface becomes too hot from sun exposure.
On tomatoes and some peppers, therefore, sunscald
often develops on the sides or "shoulders" of the fruit,
near the stem end. Sunscald often develops on fruit
that forms in the shade of the plant canopy but which
is suddenly exposed to direct sunlight. Sunscald often
occurs when plants lose leaves from foliar diseases.
On tomatoes, early blight and Septoria leaf blight can
cause premature defoliation, which leads to sunscald.
On peppers, the defoliation occurs when plants
infected with bacterial spot drop their leaves. Vascular
wilt diseases and bacterial canker can also cause
defoliation and, thus, lead to sunscald.
Avoid sunscald by controlling diseases that cause
premature defoliation. Grow tomato varieties that are
resistant to Verticillium and Fusarium wilts. Plant
pepper varieties producing fruit that hang down and
are covered by foliage. Minimize plant breakage
during harvesting to avoid suddenly exposing the fruit
to sunlight. (Nancy Pataky)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd, (217) 333-6653, and Fredric Miller, (708) 352-0109.
entomologists; Nancy Pataky, plant pathologist, (217) 333-
0519; Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350, and KarelJacobs, plant
pathologist, the Morton Arboretum, (630) 719-5646. Phil
Nixon is the executive editor of the Home, Yard and Garden
Pest Newsletter. This newsletter is written by faculty in the
Department of Natural Resources and Environmental
Sciences and the Department of Crop Sciences. The
newsletter is edited by Peggy Currid, typeset by Oneda
VanDyke, and proofread by Herbert Morgan, all of Infor-
mation Services.
^.^
A fj ^^^ JUN 2 6 199/
COOPERATIVE EXTENSION SERVICE
AUG = 7 1997
HOME, YARD &^ GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
illinois at urbana-champa ign a i 1 1 i nois natural history survey, champaign
NEWSLETTER
No. 16 • August 6, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
PLANT DISEASES
Diagnosing Tree Root Problems
Tree decline may be caused by any number of below-
ground stresses — drought, floods, compaction of the
root zone, poor soil, planting too deeply, or inad-
equate space for roots, to name just a few. Often the
process of diagnosing such a problem is one of
eliminating possibilities that might cause similar
symptoms. One of the most difficult possibilities to
eliminate is root rot; many gardeners believe that they
cannot possibly know about the health of a mature
tree's roots.
The first sign of any root problem is top decline.
Look for a few clues to determine whether a tree is
growing well. You can see a tree's annual growth by
looking at the trunk cross-section. (Most of us have
done this as children. We counted the number of rings
to tell us how old a tree was when it died and looked
at the thickness of these rings to compare relative
growth between years.) A less destructive way to
determine amount of growth is to look at the stems.
Follow the stem tip back to the first set of closely
aligned rings (about 1/8 inch apart) around the stem —
that is one year's growth. Continue down the stem to
the next set of rings for the next year's growth. Most
twigs grow from six to eighteen inches in one year. Of
course, this amount varies by species and how much
sun is received by the part of the tree you are examin-
ing. If the twig has grown only one inch for the last
two years but grew eight inches three years ago, it is
safe to assume the tree is under stress and that the
stress began two years ago. Cankers on the stems,
stem tip dieback, off-color foliage, early fall color,
and early defoliation are also clues that a tree may be
stressed by underground causes.
To detect the pathogenic wood rots and root rots,
look for mushroomlike fungi growing at the base of
the tree or shrub. With wood-rot fungi, the conks (also
called "shelf fiingi" or "fruiting bodies") may be
found growing on the trunk or main branches. These
are signs of the pathogen. The actual mycelia of the
fungus is probably growing in or on the roots or
internally in the wood. One of the most common
types of rot is Ganoderma root rot, which produces a
shelf type of fungal structure at the base of trees,
especially honey locust. The structure is reddish
brown and appears varnished. Its presence indicates
that a root rot has invaded. Other fungi may indicate
wood rots. Wet weather often triggers the formation of
these conks, which are easily confused with fungi
growing on dead organic debris near a tree. If, how-
ever, they are growing from the tree itself, suspect
wood rot or root rot.
You can also carefully dig in the root zone of a tree
to try to determine the health of the roots. Do this near
the dripline in two or three spots. Healthy roots will
be brown on the outside but will be white internally or
at the very tips of the roots. If the roots have a soft,
brown outer layer that easily pulls off the center of the
root, then a root rot may be involved.
Some experts say that the presence of conks on a
tree or rot in the root system means that a tree will
soon die. That may be the case, but trees and shrubs
may survive for many years with wood or root rots.
Do not remove a tree simply because it has a conk.
Instead, consider the presence of conks as a diagnostic
tool in determining the true problem with the tree. If,
however, the tree appears to be a threat to life or
property because of potential to fall or blow over,
remove it as soon as possible.
ACES
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University of Illinois at Urbana-Champaign
ces
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A tree in decline cannot be helped with chemicals,
but wood and root rot do not necessarily doom a tree.
Use approved cultural practices to improve tree
vitality, including weekly waterings of one to two
inches of water in periods of extended drought. Also,
cut out dead branches in the dormant season, fertilize
in late fall or early spring, and keep traffic off the root
system. These measures may help the tree continue to
live for many years. For very old or very large trees,
though, fertilization and watering may have no
benefit. (Nancy Pataky)
Rhizoctonia Root Rot of Flowers
This fungal disease can cause damping-off of seed-
lings, a firm basal rot of cuttings, or root rot of more
mature plants. Infection is favored by an intermediate
moisture range and warm-to-hot temperatures, so we
see this disease every year. Because Rhizoctonia fungi
are found in most soils and can survive for many
years on debris or as sclerotia (resting structures), the
disease has the potential to infect many plantings.
Look for plants that are stunted, are low in vigor, or
wilt easily on a warm day. The foliage may turn
yellow to brown and may fall from the plant. In many
cases, the lower leaves fall first and leaf drop
progresses up the stem. There will not be any streak-
ing of the vascular tissue. Carefully dig the plant and
wash the roots and stems, looking for the signs of
rotting or decay. Rhizoctonia usually causes a dry rot
of roots and stems with a reddish brown color. The
stem may have distinct dead, sunken areas (still dry)
that partially or totally girdle the stem. You can
distinguish this root rot from either Pythium or
Phytophthora because those diseases cause a soft,
black rot.
Many cultural practices will help prevent the root
rot problems. Start with only top-quality seed or
transplants. Plant in fertile, light, well-drained soil. If
you are using containers, be certain that they are clean
and that initial plantings occur in sterile soil mixes.
When possible, avoid overwatering. Rotate annual
planting beds with unrelated plants for several years
to help reduce fungal buildup in the soil. Rhizoctonia
root rot is a particular problem on impatiens. Because
this is such a popular shade plant, growers rarely
rotate out of impatiens until forced to do so by this
disease. Some researchers suggest adding composted
hardwood bark as a growing medium or mulch to help
suppress root rotting fungi. Other control measures
and discussions of the major root rot fungi, disease
cycles, and related topics may be found in Report on
Plant Diseases No. 615, Damping-off and Root Rot of
House Plants and Garden Flowers.
Chemicals are used as preventive controls and must
be applied before symptoms are evident. Chemicals
may also be used to protect healthy plants once the
disease is spotted in a planting. Current recommenda-
tions are listed by host in the 7997 Illinois Commer-
cial Landscape and Turfgrass Pest Management
Handbook. (Nancy Pataky).
Peony Leaf Disease
Red spot, leaf blotch, and measles are names for the
same fungal disease that affects all above-ground
parts of peony. The disease occurs to some extent
every year and is caused by Cladosporium paeoniae.
It is most serious in large plantings in which plants are
dense and grown closely together and when the old
tops are not destroyed in late autumn or early spring.
Small, circular, red or purple spots appear on the
upper surface of young leaves just before the peony
blooms. Later, the spots appear on the underleaf
surface. The lower sides on infected leaves soon turn
dull chestnut brown, while the upper surfaces are
glossy, dark purple. As the host tissues mature, the
lesions enlarge rapidly and may form large, irregular,
unsightly blotches. Stem and petiole lesions are short,
reddish brown streaks at first. Later, the lesions on
stems near the soil line become somewhat sunken or
pitted and tend to merge and darken. Spots on all
plant parts remain purplish or brownish red through-
out the season.
Nothing can be done to help this year's plants. To
control the problem next year, remove all old tops to
ground level and destroy, bury, or remove them from
the garden. Do this in the fall or next spring before
new growth starts. Mark your calendar now so you
won't forget about this task.
Just before the shoots break through the soil surface
in the spring, spray the soil around the plants with
mancozeb or maneb. Be sure to soak the soil surface
area, stem stubs, and any remaining peony debris.
Spray the plants weekly during cool, damp, overcast
weather, starting when the new shoots are two to four
inches tall and continuing until the flowers begin to
open. The addition of a spreader-sticker will help
coverage. For more information on this disease, consult
Report on Plant Diseases No. 631 . (Nancy Pataky)
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INSECTS
Fall Webworm
Fall webworms are numerous throughout Illinois.
Their numbers are also high in other areas of the
Midwest, with large populations noticed by the
authors while on vacations in central Missouri and
southwestern Michigan. In the southern half of
Illinois, this infestation represents the second genera-
tion, while in the northern half of Illinois, the first and
only generation is present.
Fall webworm larvae appear as two races. The red-
headed race has a red head and yellow, hairy body
with few or no black spots. The black-headed race has
a black head and many black spots on a yellow, hairy
body, with a blackish stripe running down the back.
Both races feed as colonies of 50 to more than 100
caterpillars on leaves enclosed in a silk tent con-
structed by the caterpillars.
Young caterpillars cause damage by feeding on the
leaf undersides, eating away the lower epidermis and
mesophyll, leaving the upper epidermis intact. This
"window-feeding" damage causes the leaf to turn
brown. Older caterpillars eat the entire leaf blade
except for the major veins, a type of damage called
"skeletonizing." As the caterpillars eat all of the
leaves within the silk tent, they enlarge it to include
more leaves. Many tree species are attacked but
crabapple, maple, hickory, and walnut are the most
common.
Leaf loss at this time of year causes little damage
physiologically to the tree. Leaves are most produc-
tive early in their lives when they are still somewhat
soft and pliable. Much of this summer's production
for the tree has already been achieved, and leaves that
are eaten now will usually not be replaced by the tree.
Aesthetic damage due to leaf loss and large webs
is as great at this time of year as any other. Small,
young colonies can be pruned out or the caterpillars
can be physically stripped from the leaves. Many
insecticides are effective against fall webworm
caterpillars, including Bacillus thuringiensis var.
kurstaki (Dipel, Thuricide). Because fine spray will
not penetrate the silk tents, use high-pressure appli-
cators or stick the spray nozzle inside the tent. (Phil
Nixon and John Lloyd)
Beetles
Japanese beetles continue to be present and feeding
on rose, crabapple, linden, birch, and many other trees
and shrubs. Numbers appear to be lower this year
throughout the state, reducing the need for frequent
insecticide applications. These beetles will be present
until the third week of August.
Strawberry root weevil adults are present
throughout the state. These 1/4-inch-long, hard-
shelled brownish to blackish beetles have a head that
extends into a broad muzzle. Their larvae feed on the
roots of a wide range of ornamental shrubs, both
deciduous and evergreen. The adults eat out notches
on the leaf margins of rose, sunflower, daisy, and
many other flowers. They also migrate indoors to feed
on houseplants. Various pyrethroid insecticides are
labeled for indoor use to protect houseplants. Any
weevils seen rambling around the house should be
removed by hand or vacuum. If houseplants are not
present, the insects will not feed and will leave the
house next spring. Attacked outdoor plants can be
protected with carbaryl (Sevin), diazinon, methoxy-
chlor, acephate (Orthene), bifenthrin (Talstar),
cyfluthrin (Tempo), and other insecticides.
Annual white grub larvae should be scouted in
untreated, irrigated turf in the first week of August in
southern Illinois and during the second week of August
in the rest of the state. Cutting through the sod and
pulling it back will reveal the feeding larvae. Ten or
more larvae per square foot will cause damage, but five
or more per square foot will attract raccoons, skunks,
and birds to feed on them. These animals can cause
more damage by tearing up turf than the grubs do by
their feeding. Many insecticides will provide control,
including trichlorfon (Dylox, Proxol), bendiocarb
(Turcam, Intercept), and diazinon. (Phil Nixon)
Borers, Borers, Borers
"My tree died and it has all sorts of holes in it. What
killed my tree?" Performing a "phone autopsy" on a
tree (diagnosing the cause of death over the phone) is
a difficult task for any entomologist or plant patholo-
gist. Inevitably the answer is "Send in a sample and
we'll try to figure it out." When we receive a sample,
we try to look for specific indicators to provide some
insight.
When diagnosing borer-induced plant decline, we
look for such signs as the pitch mass between the
branch whorls that is associated with pitch mass borer
on pines, or the sap, sawdust, and frass pushed out of
the holes at the base of the trunk by many of the
clearwinged moth borers on deciduous plants. In
some cases, diagnosis is elementary. If holes are in
rows, are about the diameter of a pencil, and appear to
go through only the bark of the tree, it's most likely
yellow-bellied sapsucker damage (birds can make
rows but insects can't.) Unfortunately, most borer
problems are not that easy to diagnose.
For Zimmerman pine moth, the damage usually
does not become too obvious until wind rips off the
leader of the infested conifer. Trees attacked by
Zimmerman pine moth will survive but will lose their
central leader. Consequently, they will no longer look
like Christmas trees, but will have what we in pest
management call "character."
For most of the flatheaded borers, such as bronze
birch borer and flatheaded appletree borer, we don't
start looking for signs until the symptoms of decline
set in. Once the decline starts, it is usually possible to
detect the winding callus tissue created by the tree to
cover the damage created by the larvae burrowing
through the cambial layers of the tree. Also easy to
spot are D-shaped exit holes created by emerging
adult beetles. When shotgun holes are apparent in any
tree with decline, the list of potential suspects narrows
to bark beetles.
If we fmd insect damage, does that mean that the
insects are responsible for the decline and death of the
tree? Yes and no. Trees that have died and have holes in
them may actually be infested with insects that are
feeding on the dead wood. Not all borers prefer live
trees. Many of the borers, especially bark beetles, are
simply the final straw in a series of problems for a tree.
The majority of trees attacked by borers are
susceptible to attack because of other problems in
their environment. Several years of drought or flood-
ing will stress trees to the point of becoming borer
fodder. Improper tree selection, planting, and main-
tenance can also stress trees and make them more
susceptible to borers. Wounds from string-trimmers or
lawn mowers provide avenues for the borers to enter
the trees.
So we get back to the original question: Who or
what killed the tree? Ruling out borers and environ-
mental stresses often reveals the real cause: uninten-
tional damage or neglect from humans. (John Lloyd)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with
the help of staff members, Extension field staff, and others
in cooperation with the USDA Animal and Health
Inspection Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd, (217) 333-6653, and Fredric Miller, (708) 352-0109,
entomologists; Nancy Pataky, plant pathologist, (217) 333-
0519; Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350, and KarelJacobs, plant
pathologist, the Morton Arboretum, (630) 719-5646. Phil
Nixon is the executive editor of the Home, Yard and Garden
Pest Newsletter. This newsletter is written by faculty in the
Department of Natural Resources and Environmental
Sciences and the Department of Crop Sciences. The
newsletter is edited by Peggy Currid, typeset by Oneda
VanDyke, and proofread by Herbert Morgan, all of Infor-
mation Services.
COOPERATIVE EXTENSION SERVICE
HOME, YARD & GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
Illinois at urbana-champaign A il I Inois natural history survey, champaign
NEWSLETTER
No. 17 'August 20, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
Biweekly Issues
This is the first of the late-season biweekly issues of
Home, Yard and Garden Pest Newsletter. Three more
biweekly issues will take us through the end of
September. We will publish an issue in late October
and a final issue with an index for the entire year in
late November. (Phil Nixon)
HORTICULTURE
Water Your Landscape Plants
The rapid onset of unhealthy-looking landscape plants
is cause for concern. Many landscape plants in Illinois
are suffering from extremely dry weather. Symptoms
include severe leaf wilt, yellow leaves, early fall
coloring, and leaf scorch (browning along the mar-
gins) on broadleaf plants, and brown, dying turfgrass.
The symptoms are a result of the roots failing to
supply sufficient water to the leaves. This inability is
influenced by the moisture content of the soil and by
the location and condition of the root system. The
drought conditions have significantly reduced some
plant root systems, making them unable to supply
enough water to compensate for the tremendous
amount lost through the leaves.
As would be expected, some plants are affected
more by drought conditions than others. Especially
affected are potentilla, hydrangea, viburnum, euony-
mus, and holly shrubs; redbud trees; spruce and
hemlock conifers; and bog plants such as iris and
APR 0 7 1999
AG Library
astilbe. Fortunately, our native prairie species adapt
well to these conditions and, although the top growth
is dying back, this dieback helps build reserves into
the crown for growth next season.
Knowledge of plants' normal growth habits is
important. For example, although many white pines
continue to show signs of stress (see "White Pine
Problem" in issue No. 12 of this newsletter), these
pines naturally drop last year's needles in late August
through mid-October. By contrast, most other pines
and spruces keep several years of needles. If they
begin to drop last year's needles, severe stress or
disease could be present.
To save the landscape plants, water any stressed
plants now to encourage recovery growth and root
revival. Apply enough water to penetrate deeply
within the dripline. Newly installed plants, especially
those in containers, should be watched carefully and
watered properly. Never overwater. To prevent plants
from sending out succulent, frost-susceptible growth,
avoid fertilizing or pruning until plants are dropping
their fall leaves. (Rhonda Ferree and Floyd Giles)
INSECTS
Annual White Grubs
Although all indications are that larval annual white
grubs should be present now in large numbers, we
have yet to find any in central Illinois or in any other
part of the state.
The adult beetles emerged later than usual, prob-
ably because of the cool spring. We normally first see
adults in east central Illinois on the evenings of July 2
or 3, but we did not see them until July 7, almost one
week later. July 18 was the last time that we saw
beetles in central Illinois.
Because the beetles do not feed, they normally live
for only about two weeks. At the Morton Arboretum
in northeastern Illinois, annual white grub adult flight
A (^^P C College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urt>ana-Champaign
ces
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No. T7 'August 20, 1997
peaked on July 22, and a few were still present in the
first week of August. In most years, annual white grub
flight is over in northern Illinois near July 25. Beetle
flights ranged from normal in some areas of the state
to above average in many areas, including central
Illinois.
When turf is dry and dormant, the adults migrate to
irrigated turf to lay their eggs. Unirrigated turf
throughout most of Illinois was dry and dormant in
July. This should have resulted in large numbers of
eggs being laid in watered turf.
The eggs that the masked chafers or annual white
grub adults lay usually hatch in two to three weeks.
High soil temperatures — around 90°F and above —
will reduce hatching. However, soil temperatures have
been in the 70s during this time. The resulting white,
C-shaped grubs are easily noticed against dark soil,
even the newly hatched ones, which are approxi-
mately 3/16 inch long. They are present in the root
zone of turf if the soil is damp. Dry soil will cause the
grubs to move downward in the soil column.
With the late flight of the beetles, we do not
anticipate damage to occur until late August in
southern Illinois and until almost mid-September in
northern Illinois. Grub numbers often or more per
square foot are likely to cause turf damage.
If raccoons, skunks, or birds feed in the area, turf
damage will occur at much lower numbers — three to
five grubs per square foot. Raccoons peel back four-
to twelve-inch-wide sections of turf to feed on the
grubs. Skunks tear out divots of turf that are three to
six inches in diameter. While a raccoon usually tears
out six or fewer sections of turf in an area, a skunk
usually makes 30 or more holes. Birds pick at the turf,
tearing out the sod in one-inch pieces. Such feeding
causes the affected areas to turn brown from the
removed thatch and sod.
If treatment for grubs is needed at this time, use
faster-acting insecticides such as trichlorfon (Dylox,
Proxol), bendiocarb (Turcam, Intercept), or isozofos.
Triumph is labeled for use only on home lawns, sod
farms, and golf course tees, greens, and aprons.
Diazinon is not labeled for use on golf courses or sod
farms. Grubs treated with diazinon will stop feeding
but will take about three weeks to die. {Phil Nixon,
Fredric Miller, and Karel Jacobs)
Bagworms
Bagworms were late hatching this year, which re-
sulted in a later feeding season than normal. Usually
bagworms pupate in mid- to late August, but we are
still hearing reports of feeding bagworms around the
state and recently saw some in central Illinois that
were only 3/4 inch long. Bagworms usually pupate
when they are about 1-1/2 inches long.
Bagworms are whitish caterpillars that construct
individual silk cases around themselves. They cover
these silk cases with bits of leaves from the tree or
shrub they are feeding on. These bits of foliage turn
brown within a couple of days, resulting in brown
bags moving across the trees and eating leaves.
Throughout its entire life as a caterpillar, this insect
places new foliage at the top of the bag. Thus, an
actively feeding caterpillar has green foliage at the top
of its bag. If the caterpillar pupates, it ties off the top
of the bag to a branch, and any green foliage quickly
turns brown. If the caterpillar dies, the foliage on the
bag will be completely brown. Bagworms that are
alive and actively feeding can be controlled with
trichlorfon (Proxol, Dylox), cyfluthrin (Tempo), and
other synthetic pyrethroids. Bacillus thuringiensis var.
kurstaki (Dipel, Thuricide) is more spotty in its
control of large larvae but is the only option for do-it-
yourself homeowners.
Bagworms start to feed at the top of the tree and
work their way down. A pair of binoculars is useful
for detecting feeding bagworms on large trees.
Bagworms most commonly attack eastern red cedar
and other junipers, as well as spruces, arborvitae,
Douglas-fir, honey locust, pin oak, red oak, and
tallhedge. Stripped branches of coniferous evergreens
will probably die.
Bagworms will pupate later this summer. Male
bagworms emerge as black, one-inch-long moths with
clear wings. They mate in early fall with the adult
females that stay in the bag. Adult female bagworms
are brownish and larval in appearance. Mated females
fill their bodies with up to 1 ,000 eggs in the fall
before they die. These eggs hatch in June of the
following year.
Old bags that housed males will have dark brown
pupal cases (about 1/2 inch long) sticking out of the
end. The other bags are likely female bags that can be
picked off trees from late fall through spring to reduce
the number of caterpillars that are present next year. Do
not just toss the picked bags to the ground under the
tree because young bagworm larvae crawl long dis-
tances and will probably crawl up onto the tree. Picking
off all of the old bags will not totally eliminate bag-
worms from the tree because young bagworm larvae
are blown on strands of silk from tree to tree for a
couple weeks after they hatch in June. {Phil Nixon)
No. 17 • August 20, 1997
PLANT DISEASES
Bacterial Wilt of Cucurbits
This disease is caused by a pathogen so small that
hundreds can be found in bacterial exudate the size of
a drop of water. The pathogen can quickly multiply
and plug the vascular tissues so that water transport
does not occur. This tiny bacterium is transported
from plant to plant by both striped and spotted
cucumber beetles.
Bacterial wilt is most devastating on cucumbers
and muskmelons (cantaloupes). The disease can also
occur on pumpkins and squash, although not often as
severely. It rarely infects watermelon. In all cases,
wilt symptoms appear first on individual leaves and
quickly spread to lateral shoots, causing the entire
plant to wilt. Symptoms develop more quickly on
younger, smaller plants.
To confirm the presence of bacterial wilt, cut a live,
wilted runner off the plant. (Take the five or six
inches of stem nearest the crown.) Cut the stem
section in two, then hold the cut ends back together
and squeeze them until the plant sap flows out and
intermingles from each cut edge. Slowly pull the cut
ends apart. If there is a strand of sticky sap between
the cut ends, then a bacterium is likely present and
bacterial wilt is a strong possibility. Unfortunately,
once you confirm this disease, nothing can stop it in
the infected plant. However, steps can be taken to
prevent the wilt in next year's plants.
The primary method for controlling bacterial wilt is
to control the beetle vector. The beetles overwinter as
adults that are present when the vine crops emerge.
The application of both preplant systemic and
postemergence protectant insecticides might be
necessary to prevent a problem with bacterial wilt in
commercial plantings. Because the beetles are most
attracted to plants in the cotyledon stage, insecticides
should be initiated immediately after planting. Ento-
mologists warn that when blossoming begins, insecti-
cides should be applied late in the day so as not to
interfere with pollination by bees. Consult Report on
Plant Diseases No. 905 for details about bacterial
wilt. (Nancy Pataky)
Watch for Pine Wilt
Pine wilt, caused by the pinewood nematode, was
discussed in issue No. 8 of Home, Yard and Garden
Pest Newsletter We have confirmed several cases of
pine wilt at the Plant Clinic in the last two weeks, so it
is appropriate to review the symptoms of this disease.
Trees dying now were likely infected in spring or
summer.
Watch for the appearance of entire dead branches
or sudden decline and death of an entire pine within a
few weeks or months of initial symptoms. Be particu-
larly suspicious of 15- to 20-year-old Scotch pines
with these symptoms. Austrian pine is the only
species that may show tip dieback as the first symp-
tom. For symptoms on white pine, see issue No. 12 of
this newsletter. (Although we have assayed many
white pines for pinewood nematodes, we have never
confirmed the pinewood nematode in that species.)
Sawyer beetles vector the nematode from pine to
pine. Because there is no easy way to stop the beetle
and because no treatments exist for infected trees,
early detection is critical to disease control. To break
the disease cycle, quick removal of an infected tree is
important. Consult Report on Plant Diseases No.
1 104 for details about pine wilt. (Nancy Pataky)
Guignardia Leaf Blotch
Horsechestnut and buckeye trees that appear from a
distance to be severely scorched may actually be
infected with this fungal disease. On closer inspec-
tion, reddish brown leaf spots with bright yellow
margins are obvious. The spots will enlarge and
cover most of the leaf surface. Leaves then become
dry and brittle and drop early. You can distinguish
this disease from environmental scorch by the
presence of fruiting bodies formed by the fungus
(Guignardia aesculi) in the leaf lesions in moist
weather. These black, pinhead-sized structures are
called pycnidia. With Guignardia leaf blotch, all
leaves will be affected, unlike with scorch, which
first affects newest leaves on the sun or wind side of
the tree.
This disease is serious yet treatable in nursery
stock. Mature trees usually retain live buds and lose
leaves late in the season, so they are not significantly
harmed. Removing fallen leaves may be helpful in
reducing the amount of fungal inoculum living
through the winter on these leaves. Also try to prune
surrounding vegetation to allow better airflow
through the area for more rapid drying of foliage.
(Nancy Pataky)
No. 17 • August 20, 1997
Rhizoctonia Brown Patch
Brown patch is a fungal disease caused by Rhizocto-
nia species. It commonly occurs in hot, muggy
weather when night temperatures are at least 70°F and
daytime temperatures are in the 80s and 90s. It is
favored by heavy rains or watering and by grass that
is dense and at least adequately fertilized.
The disease appears as patches up to two or three
feet wide. The patches may be dark blue initially, as
though under drought stress. The color quickly
changes to purple-brown and then light brown. The
patches may develop green centers and resemble
summer patch or necrotic ring spot. In light infec-
tions, the turf generally recovers in two or three
weeks. When the attack is severe, the crowns, rhi-
zomes, stolons, and roots may turn brown and rot,
causing turf to be thinned or killed in large areas.
A few cases of brown patch have been confirmed
at the Plant Clinic. Many similar cases have been
caused by drought, not a pathogen.
Brown patch can be prevented with the cultural
practices listed in Report on Plant Diseases No. 411.
Once the disease occurs, chemicals may keep it from
spreading, but long-term control requires following
cultural recommendations. Chemical options are listed
in the 1997 Illinois Commercial Turf and Landscape
Pest Management Handbook. Be sure to read the label
on the selected product for recommended formulation,
rates, and timing for your particular turf conditions.
Because such applications usually require sprays at
five- to fourteen-day intervals throughout the summer,
fungicide control of brown patch is usually reserved for
golf courses. Products are not always available in
quantities suitable for homeowner use. The recommen-
dation for a severe infection in a home lawn is to rake
and remove the dead areas, follow cultural recommen-
dations, and re-seed with a blend of resistant turf
grasses suitable for the light requirements of the lawn.
(Nancy Pataky)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd, (217) 333-6653, and Fredric Miller, (708) 352-0109,
entomologists; Nancy Pataky, plant pathologist, (217) 333-
0519; Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350, and KarelJacobs, plant
pathologist, the Morton Arboretum, (630) 719-5646. Phil
Nixon is the executive editor of the Home, Yard and Garden
Pest Newsletter. This newsletter is written by faculty in the
Department of Natural Resources and Environmental
Sciences and the Department of Crop Sciences. The
newsletter is edited by Peggy Currid and typeset by Oneda
VanDyke of Information Technology and Communication
Services.
.-OFFIce OF RESEARCH
'a SEP -5 1997
JUN 2 6 1997
COOPERATIVE EXTENSION SERVICE
HOME, YARD & GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
Illinois at urbana-champaignAillinois natural history survey, champaign
NEWSLETTER
No. 18 * Septembers, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
PLANT DISEASES
Plant Clinic Closing
The Plant Clinic will close for the season at 5:00 p.m.,
Friday, September 12, 1997. It will reopen May 1,
1998.
Any samples received at the clinic by September 12
will be processed. Anything received after that date will
not be processed. There is no funding to staff the clinic
in the winter months, so diagnosis will be handled
through local Cooperative Extension offices without
the aid of a lab. In most cases, the lab is not needed in
the winter months.
Diagnostic staff becomes a skeleton crew after
September 12, and it takes until the end of the month
to finish all samples still in culture or requiring extra
attention. In the past we have tried to continue to
handle samples later in the season as time allows, but
this coming October is already booked with meetings,
prep time, and publication deadlines. The lack of time
available often causes feelings of ill will in clients
who do not understand that we are trying to fit them
in as time allows. This also causes much anxiety for
staff as we try to please everyone. To eliminate these
uncomfortable situations, the staff at the Plant Clinic
will not be handling any new samples after this
season's closing date.
After the closing date, if you have a plant prob-
lem, your first step should be to contact your local
Cooperative Extension office. If it is then deter-
mined that you need help from a specialist, the
following contacts may be helpful. Do not send
samples to a specialist unless you have first spoken
to him or her and established that a sample is re-
quired. (Nancy Pataky)
Insect problems
Disease problems
Tree and shrub care
Ttirf care
Herbaceous plant
problems
Vegetable questions
Phil Nixon: 333-6650
Nancy Pataky: 333-2478
Dave Williams: 333-2126
Floyd Giles: 333-2125
Tom Voigt: 333-7847
Jim Schmidt: 244-5153
Chuck Voigt: 333-1969
Cankers of Trees and Shrubs
A canker is a dead area of the vascular tissue and
surrounding wood of a tree or shrub. You might also
find cankers on herbaceous plant material, usually as
sunken, dead areas on the stems. The term "canker" is
a general term that refers to a symptom on the plant.
Cankers may be caused by injuries (such as from hail
or mowers), environmental stress (cold, heat, scald,
etc.), chemicals, or pathogens. Cankers are common
on a wide range of trees and shrubs, which is the topic
of concern here. Typically, cankers occur on trunks,
older branches, and injured areas on smaller twigs.
The newest tissue is usually the first to show
decline. Leaves begin to wilt, then turn yellow, and
finally brown. Some young twigs may curl down-
ward. Bark on younger twigs may lose color or
blacken, depending on the canker or plant involved.
(For example, fire blight cankers are often black on
pear but brown on apple.) If a canker girdles the stem,
the twig will die back to the canker. If the stem is not
girdled, it may show one-sided death, or some leaves
will be affected while others are green. Cankers
usually take months, or sometimes years, to enlarge
enough to girdle twigs, branches, and trunks. Cankers
can appear swollen, sunken, cracked, or discolored.
They may also bleed sap or moisture.
A (""^p Q College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urbana-Cfiampaign
CBS
Helping You Put Knowledge to Wor1<— State • County • Local Groups
U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
opportunities in programs and employment.
-^cri_'tt7/( ii^ti _//
Fungi are usually the cause of cankers on stressed
plants, but occasionally we find a bacterial canker.
The fungal cankers often contain fruiting bodies of
the fungus. The fruiting bodies are pinhead-sized
black specks embedded in the bark. Often these
fruiting bodies will appear as small bumps all over the
cankered area. In wet weather, they may exude
colorful spore tendrils.
Most canker pathogens enter through an injury
from sunscald (summer or winter) or through an
injury caused by insects, animals, diseases, pruning,
or mechanical and chemical sources. Weakened tissue
caused by poor growing conditions, transplant shock,
excess or deficient soil moisture, rapid temperature
changes, nutritional imbalance, or extensive defolia-
tion also provides entry points for the pathogen.
The likelihood of a tree having cankers can be
reduced by choosing plants adaptable to local growing
conditions. Buy vigorous, healthy-looking plants. Be
sure to plant them at the proper depth, and space the
plants based on mature size. Grow plants in well-
drained, fertile soils with the optimum soil pH for
growth. Simply put, avoid cankers by following the
good horticultural practices that we have learned over
the years.
When you notice a canker, try to determine why it is
present. If you can address the cause, you stand the
best chance of helping the tree. Next, determine
whether you need to remove the cankered area. If it is
on the trunk, you may opt to leave the area alone or
remove as much of the decayed wood as possible so
that the tree can more readily form a callus over the
injured area. Prune out stem cankers if they are aes-
thetically unappealing or when it is obvious that they
will soon girdle the stem. Some cankers, such as
anthracnose on sycamore, cannot be removed without
removing most branches. Leave these on the tree and
take measures to promote tree health.
When pruning out cankers, keep in mind that the
wood is infected with a pathogen. Remove the
affected wood from the site. Disinfect pruners be-
tween cuts when possible. Always try to prune in dry
weather to prevent pathogen spread. A report on
cankers and dieback diseases of trees is available in
Report on Plant Diseases No. 636. (Nancy Pataky)
Rose Cane Cankers
Three canker diseases (brown canker, stem or com-
mon canker, and brand canker) are common in Illinois
and are generally confused with winter injury or other
problems. Cane infections levels may approach 100
percent when control measures are not practiced.
You don't need to be able to distinguish among
canker species, but it is important to know when a
canker problem exists. The first symptoms are small,
roundish lesions in the canes; the spots are pale
yellow, reddish, or bluish purple. They gradually
enlarge, turn brown or grayish white (often with a
darker margin), and may partially or completely girdle
the cane. Complete girdling results in dieback or poor
growth of the plant parts above the affected areas.
Cankered areas are sprinkled with black, speck
sized, fruiting bodies. When left unchecked, infec-
tions may spread downward into the crown, causing
entire rose plants to wilt, wither, and die. Infection
occurs chiefly through wounds, including thorn
abrasions. Infections may also occur on the leaves and
flowers.
Good sanitation is critical to control these diseases.
Prune the canes in fall and early spring, according to
the type and cultivar grown. Remove and bum or haul
away all infected, dead, and weak parts of canes, as
well as infected leaves, flowers, buds, and hips. When
pruning cankerous stems, cut back to a strongly
growing shoot or branch at least two or three inches
below any sign of infection. Before each cut, dip the
shears in a disinfectant such as 10 percent chlorine
bleach or 70 percent rubbing alcohol. Use sharp tools
to make clean, slanting cuts no more than 1/4 inch
above a node.
Plant only top-quality, disease-free plants from a
reputable nursery. The plants should be free of cane
bruises or colored spots. Bargain roses are often
infected. Maintain plants in high vigor by proper
planting, spacing, fertilizing, watering, winter
protection, and thorough spraying with fungicides.
Start when the buds break open in the spring and
continue at seven- to ten-day intervals into Septem-
ber or early October. The fungicides that control
black spot usually control cankers as well, so no
additional spraying is required. Adding a spreader-
sticker material to the spray, however, helps wet the
canes for better protection. Consult Report on Plant
Diseases No. 626 for details concerning rose can-
kers. (Nancy Pataky)
INSECTS
The Invasion of the Gypsy Moth
It appears that we'll be hearing more and more about
gypsy moth in Illinois over the next several years.
According to Stan Smith at the Des Plaines office of
No. 18 • Septembers, 1997
the Illinois Department of Agriculture (IDA), moth
captures are much higher in 1997 in northern Illinois
than they have been in the past.
Gypsy moth pheromone traps are used to catch
male moths and identify areas for intensive searches
for egg masses (Figure 1). The presence of egg
masses indicates that a reproducing infestation of
gypsy moth is in the area. Egg mass surveys help
determine the areas that will be treated to control
gypsy moth the following spring.
In addition to the male moths caught in the phero-
mone traps, IDA personnel noticed gypsy moth
caterpillars near some trap locations, which suggests
that a reproducing population now exists in the Chi-
cago area. The areas of highest moth capture tend to be
in Cook, McHenry, and DuPage counties, although
moths have been trapped in counties on the border with
Wisconsin across the state to the Mississippi River.
Grundy, La Salle, and Kankakee counties are as far
south as the moth has been found, so far.
Starting in November, the IDA will begin egg mass
searches throughout the infested counties. IDA
personnel will enter yards and inspect trees for the
presence of any egg masses. Homeowners and
landscapers can help in the investigation by reporting
any suspected gypsy moth egg masses. (Egg masses
are light tan to yellow and about one inch long.)
Additionally, people who vacationed this fall in
Wisconsin, Michigan, or other gypsy-moth-infested
areas should examine their vehicles and other outdoor
equipment for egg masses that may have been laid
during their visit. If you suspect that you have found a
gypsy moth egg mass, please call the Des Plaines
office of the Illinois Department of Agriculture at
(847) 294-4343.
Figure 1. Gypsy moth egg masses
According to Smith, because of the large numbers
of moths captured this year in the northern tier of
counties, trapping efforts in southern Illinois will be
curtailed from the levels of past years. The IDA
usually traps northern and southern Illinois during
alternate years.
The IDA will continue with eradication efforts next
year to try to contain this most recent invasion. Hopes
are that with legislative support and potential support
from programs (such as the U.S. Forest Service's
"Slow the Spread" program), this severely defoliating
pest will be restricted to northern Illinois for the next
several years. {John Lloyd)
White Grubs
Annual white grubs continue to be difficult to find.
We do have a report of numerous white grubs in turf
in McHenry County in northern Illinois. They were
found after raccoons had heavily damaged the turf
while feeding on them. Elsewhere in the state, we
have yet to see or hear of any white grub infestations,
but it would be wise to remain vigilant.
Adult Japanese beetles are almost completely gone
by now, but they had been present in fairly high
numbers as recently as August 21 in central Illinois.
Eggs laid by these old beetles may hatch as late as
early September. In areas infested by Japanese
beetles, late-hatching eggs combined with dry spells
in September or October could result in turf damage
where annual white grub numbers are near the damag-
ing level (10 to 12 grubs per square foot).
Irrigation during dry spells in late summer through
fall will allow turf with smaller numbers of white
grubs to avoid dieback. With the help of watering, turf
with limited root systems due to grub feeding will be
able to stay green and healthy. Thus, a couple of well-
timed irrigations can prevent the need for an insecti-
cide treatment. (Phil Nixon and Bruce Spangenberg,
Extension Educator)
Sod Webworm
Although much of the state has received ample
rainfall in the last few weeks, some areas have not
been as fortunate. In those drier areas, sod webworm
may be a problem. Small sod webworm larvae in
sufficient numbers to damage turf were found on
August 25 in Lake County in extreme northeastern
Illinois.
Sod webworm larvae are attacked and killed by
microsporidia. These microorganisms are most
effective during damp conditions. They are so effec-
;vo. / o ' :3epiemoer j, i ^://
live in Illinois that we normally see sod webworm
problems only during dry weather or in well-drained
areas such as slopes and berms.
With a new generation of sod webworm larvae
present, look for early damage, particularly in dry
locations. Damage will first appear as indistinct
areas of brownish turf. Close examination will show
that many of the grass blades have been eaten off at
the base. You may also see tiny balls of green
caterpillar feces — about twice the size of a pinhead.
Large numbers of starlings, cowbirds, red-winged
blackbirds, or other blackbirds on the turf may also
indicate the presence of sod webworms.
You can flush the caterpillars to the surface with a
tablespoon of two percent pyrethrin insecticide or
with a mixture of dishwashing detergent and water
(one tablespoon detergent per gallon of water). Apply
the treatment over a square foot of turf and look for
brown-spotted, slender greenish or tannish caterpillars
coming to the surface. Two to three larvae per square
foot are enough to cause turf damage. (Phil Nixon and
Bruce Spangenberg, Extension Educator)
Locust Borer
Black locust is attacked by several insects that can
cause damage. The locust borer probably causes the
most severe damage. Adult locust borers are present
throughout Illinois. These one-inch-long beetles with
long antennae are black with very obvious bright
yellow straight and W-shaped bands on the back.
They are commonly found on goldenrod and other
late summer blossoms, feeding on pollen.
After emerging, adult locust borers mature, feed on
pollen, mate, and then lay eggs in bark crevices and
holes of black locust. The eggs hatch into larvae that
tunnel through the bark into the phloem, where they
feed and spend the winter. In June of the following
year, they tunnel deeper into the heartwood of the
tree. After about five inches of burrowing, they pupate
in the burrow and emerge in late summer.
Locust borer infestation is identified by the coarse
frass (feces) and wood shavings that are pushed out of
the holes made by borers. Damaged areas will be
swollen and appear as an enlarged area of the trunk.
Emergence holes are round and about 1/3 inch in
diameter. Heavily attacked trees will have branch
dieback.
In many Illinois landscapes, the best way to
manage the locust borer (and other pests) is to not
plant black locust trees. Sprays of chlorpyrifos
(Dursban) on the trunk will be effective now to
prevent further larval attack. (Phil Nixon and Bruce
Spangenberg, Extension Educator)
Ugly Nest Caterpillar
Ugly nest caterpillar makes a silk tent similar to fall
webworm, but smaller. This caterpillar is common on
cherry, hawthorn, rose, pyracantha, cotoneaster, and
other rose family plants. The larvae are numerous
within the webbed area, feeding on the leaves. They
are rose green, light green, yellowish green, or lime
green, depending on their age and host. Fully grown
larvae are almost one inch long and have black heads.
As the larvae become older, the silk tent fills with
frass (feces) and bits of leaves; hence, the name "ugly
nest caterpillar."
Adults emerge to lay masses of eggs on the host
plant; these eggs overwinter and hatch the following
spring. Because the season is so far along, treatment
at this time is probably not necessary, but be watchful
for the webbing next spring. This insect can be a
particular problem in sheared hedges, causing sparse
foliage and unattractive hedges. Ugly nest caterpillars
commonly feed just under the sheared surface where
branches are very twiggy, which makes identification
of the problem more difficult. (Phil Nixon)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members, Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650, John
Lloyd (217) 333-6653, and Fredric Miller, (708) 352-0109,
entomologists; Nancy Pataky, plant pathologist, (217) 333-
0519; Rhonda Ferree, Tom Voigt, and David Williams,
horticulturists, (217) 333-0350, and KarelJacobs, plant
pathologist, the Morton Arboretum, (630) 719-5646. Phil
Nixon is the executive editor of the Home, Yard and Garden
Pest Newsletter. This newsletter is written by faculty in the
Department of Natural Resources and Environmental
Sciences and the Department of Crop Sciences.
COOPERATIVE EXTENSION SERVICE
HOME, YARD & GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
Illinois at urba na-champa ign A i Hi nois natural history survey, champaign
NEWSLETTER
APR 0 7 1999
No.19-September17,1997 AG Library
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
INSECTS
auf Wiedersehen, Arr'ivederci, au Revoir ...
I'd like to take this opportunity to say farewell to the
colleagues, clientele, and friends with whom I had the
good fortune to work during the past five years at the
University of Illinois. I truly enjoyed my time here
and the opportunities to work with a variety of people
involved with pest management in the urban environ-
ment.
By the time this sees print, I will be embarking on a
new adventure in research and extension at the Ohio
Agricultural and Development Center of The Ohio
State University in Wooster, Ohio. Because I will
remain involved in tree and landscape pest manage-
ment activities, I will surely see many of you at
regional Plant Health Care workshops and other
educational programs.
I appreciate the opportunity I've had to work with
you and wish everyone the best for the future. I leave
you with the immortal words of Louis L' Amour: "We
must never forget that the land and the waters are ours
for the moment only, that generations will follow who
must themselves live from that land and drink that
water. It would not be enough to leave something for
them; we must leave it all a little better than we found
it." (John Lloyd, The Ohio State University)
White Grubs Are Here
We have been receiving reports of white grub activity
in various parts of the state. In the last newsletter, we
reported that grubs were present in McHenry County
in the northern part of Illinois. We have also received
reports of white grubs in the Collinsville area, with
three to five grubs per square foot found in
Casey ville. We have a report from Fairview Heights
of large numbers of Japanese beetle grubs in turf.
Decatur has areas with 25 white grubs per square foot;
Urbana has similar numbers. As of September 12,
annual white grubs in Urbana were a combination of
second and small third instar grubs. These are
younger than would be expected this late in the year,
indicating that egg hatch was late, grub growth was
slow due to cooler soils, or both.
In terms of turf management, even the higher levels
of grub infestations do not seem to be causing much
damage. This is likely due to frequent rains over the
last few weeks. Currently, the turf is able to grow
roots as least as fast as the grubs can eat them. As the
grubs grow, they will begin to feed more heavily on
the roots, making it difficult for the turf to survive. If
we have a dry spell in late September or October, the
grass will slow its growth rate and damage (brownish
areas) will become evident. Irrigation during times of
insufficient rainfall may reduce the need for an
insecticide application. The combination of winter
mortality on the grubs and spring rains will result in
fewer actively feeding grubs next spring, which
should mean little or no turf damage during the spring
in most areas.
If insecticide applications are necessary, use a
quick-acting material such as trichlorfon (Dylox,
Proxol), bendiocarb (Turcam, Intercept), diazinon, or
isozofos (Triumph). Diazinon usually takes three
weeks to kill the grubs, but they greatly reduce their
feeding during that time. If diazinon is used, make
sure that the maximum labeled rate is applied and that
the calibration is accurate to achieve a good level of
control. (Remember that diazinon is not labeled for
use on golf courses and sod farms.) Triumph is
labeled for use only on home lawns and sod farms, as
A C^U C College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urbana-Champaign
ces
Helping You Put Knowledge to Work — Slate • County • Local Groups
U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
opportunities in programs and employment.
well as on golf course tees, greens, and aprons. Be
sure to water-in any insecticide applications with at
least 1/2 inch of water to flush the insecticide into the
root zone. In areas that are watered infrequently,
irrigating the turf a day or two before application will
bring the grubs up to the surface roots and improve
control. (Phil Nixon)
Magnolia Scale
Magnolia scales are large, with mature females
growing as wide as 1/2 inch. These scales are yellow-
ish and tend to have an uneven surface, often leading
to the assumption that they are some type of fungus
fruiting body. Magnolia scale feeds only on magnolia,
most commonly Magnolia stellata, M. acuminata, M.
quinquepeta, and M. soulangeana. It produces large
amounts of honeydew. The limbs and branches of the
host tree become covered with a blackish sooty mold
that grows on the honeydew.
The grayish crawlers are produced this time of year
and can be controlled with sprays of malathion,
diazinon, or insecticidal soap. The crawlers overwin-
ter and can be controlled with the same sprays in the
spring. Molting occurs in mid-spring; the resulting
nymphs are purplish. The nymphs secrete a whitish,
powdery wax over their bodies, which makes them
more easily seen. Later in the summer, larger, yellow-
ish adults emerge. (Phil Nixon)
PLANT DISEASES
Fungicides: Clarifying the Terminology
Throughout the year we receive many questions about
fungicides: Is a systemic fungicide my best bet?
Which ones are systemic? How often do I need to
apply this product? and so on. These are all good
questions and, for the most part, the answers are on
the product label. (Of course, everyone enjoys hunting
through the label for these tidbits of information,
right?) Nevertheless, product labels tell us to do
things a certain way. For some people, that is enough;
others, however, want to know more. This short
article provides a more detailed description of fungi-
cide terminology and use.
Every category of pesticide has its own terminol-
ogy. Some terms are used interchangeably. For
example, the term "contact pesticide" can describe an
insecticide, herbicide, or fungicide. In the first case,
an insect that comes into contact with the insecticide
is killed. In the second case, the herbicide enters and
kills only the parts of the plant that are exposed to the
herbicide. In the third case, the fungus that attempts to
infect the plant sprayed with fungicide will die. These
pest-control processes are quite different; although we
can (and do) get by with the simpler term "pesticide,"
the correct terminology is, for example, "contact
fungicide as a protectant" or a "protectant-contact
fungicide."
Unlike a contact herbicide, a protectant-contact
fungicide does not enter the plant at all, but acts as an
exterior shield to protect the plant or seed from certain
fungi for some period of time. Uniform spray cover-
age is vital: How well does a shield work if it is filled
with holes? The length of protection provided by the
protective fungicide depends on many environmental
factors. As with any pesticide, rainfall soon after
application will wash away much of the pesticide
residue, greatly reducing its protective value. Even
after drying on the plant surface, residues of a protec-
tive fungicide will continue to be lost via rain, dew,
vaporization, sunlight, and other means. That's why
protective fungicides have shorter application inter-
vals than do systemic fungicides. The addition of a
spreader-sticker (one type of adjuvant) to the spray
mix may help alleviate both the problems of poor
coverage and premature loss of residues. This doesn't
necessarily mean that a spreader- sticker should be
added to a spray mix in all situations. Adjuvants may
increase penetration of systemic fungicides and cause
phytotoxicity. Before adding to a spray mix, consider
these questions:
1 . Does the fungicide formulation already have
certain adjuvants included by the formulator?
Always read the label directions (especially the
fine print) for the fungicide, and for the adjuvant
as well. The inclusion other adjuvants may
increase runoff and decrease pesticide deposits
or cause other problems. The addition of agents
to the fungicide during the formulation process
is becoming increasingly popular. Unfortunately,
the label does not always make this addition
apparent to the user (in such cases, adjuvants are
considered "secret inert ingredients" — at least
to the public and to the competition). Some trade
names, such as Daconil Weather Stik, obviously
indicate that an agent has been added to the
formulation. Even so, always read the label to
find out what you can and cannot add to a
particular spray mix.
2. Is the plant you want to treat difficult to "wet"
(the tissues are quite waxy or hairy)? Have you
experienced poor coverage (from poor wetting)
in the past?
If you cannot find the answers to your questions,
test the mix on a few plants and observe them for
signs of injury before implementing full treatment.
While reading fungicide labels and other literature,
you might notice the many terms to describe systemic
fungicides. Examples include "systemic," "translo-
cated," "eradicant," and "curative." At first glance,
these descriptions may seem irrelevant. However, let's
take a closer look at these terms, as they apply to
protective fungicides.
Translocation is the movement of any compound
within the plant body to tissues remote from the site
of application. Protective fungicides are not absorbed
and not translocated in the plant. They provide an
exterior shield of protection against infection only at
the site of application.
Local penetrant (also known as "local systemic" or
"eradicant") fungicides are absorbed into the immedi-
ate area of application and are not translocated in the
plant. They cure established infections only at the site
of application. The term "local systemic" is a poor
choice of words for such fungicides.
Systemic fungicides are absorbed and translocated
in the plant. They prevent the development of disease
at the site of application, as well as in other parts of
the plant.
Curative fungicides are absorbed and translocated
in the plant. They eliminate a pathogen after it is
already established within plant tissues. Use this term
cautiously because people not familiar with plant
diseases might be led to believe that their half-dead
plant will recuperate after treatment with a curative
fungicide.These products must be applied before the
pathogen has caused a substantial amount of plant
tissue and before obvious symptoms develop.
As you can see, the choice of terminology depends
on whether the fungicide is absorbed into the plant or
translocated in the plant. People tend to group sys-
temic and curative fungicides together and refer to
them simply as "systemics." If a fungicide is consid-
ered a systemic, does that mean it travels throughout
the entire plant? Not necessarily. In fact, among the
fungicides on the market today, relatively few will
translocate throughout the entire plant. Most
systemics are translocated only upward within the
plant's xylem (water-conducting) vessels. This type of
translocation is known as "apoplastic" (or "acro-
petal") translocation. On the other hand, adequate
distribution of a fungicide in the phloem (food-
conducting) tissues is referred to as "symplastic" (or
"basipetal") translocation, which includes transloca-
tion down into the roots.
Are there advantages to using systemic rather than
protectant fungicides? Systemics provide longer
residual activity because they are absorbed by the
plant and protected from washoff and weathering.
Systemics can protect plant tissues not effectively
reached by sprays (crowns, roots, and newly formed
tissues). They can also control fungi that have already
entered the plant.
The downside to systemic fungicides is these
products are relatively new on the market and, not
surprisingly, more expensive. Systemics tend to be
much more specific — targeting only a few types of
fungi — than the older protectant fungicides, which
can be good or bad. (Some of the most recent
systemics on the market, however, target a greater
variety of fungi.) Perhaps the biggest disadvantage of
systemics has been development of resistance or
tolerance by fungal pathogens. Generally speaking,
protectant fungicides tend to affect fungi in more
complex ways than do systemics.
What does all of this mean to the fungicide user?
When the products are used according to label direc-
tions, probably not much. The main point of this
article is that fungicides, even those within the
systemic group, do not act the same way after applica-
tion. Thus, application procedures and product
expectations should take these differences into
consideration. Further information about fungicide
use and terminology will be provided in Chapters 1, 4,
and 5 of the 1998 Illinois Commercial Landscape and
Turf Pest Management Handbook, available in
January 1998. (Bruce Paulsrud)
Selected References
Marsh, R.W., ed. Systemic Fungicides. 2nd ed. New
York: Longman, 1977.
Fermanian, T.W., Shurtleff, M.C., Randall, R.,
Wilkinson, H.T., and Nixon, PL. Controlling
Turfgrass Pests. 2nd ed. Englewood Cliffs, NJ:
Prentice-Hall, 1997.
Late Season Leaf Problems
Many tree samples received at the Plant Clinic this
time of year have leaf spots from fungal pathogens,
leaf injury from insect feeding, or symptoms of
scorch. Because most trees have completed the
process of bud formation for next year or have
obtained maximum carbohydrate transfer from
foliage, loss of leaves now probably will not threaten
the health of the tree.
The presence of scorch will not usually pose an
immediate threat to the tree either, but it may have
long-term health implications. Dozens of factors are
responsible for scorch symptoms, as discussed in
issue No. 12 of this newsletter. If symptoms recur
each year, the health of the tree will be compromised
and dieback and decline will occur. Annual appear-
ance of scorch symptoms should trigger an investiga-
tion into the cause of the scorch so that the problem
can be corrected. No one can simply look at leaves to
determine why they are scorched. It is necessary to
examine all of the possible causes and assess their
likelihood, given the site conditions. For now, keep
stressed trees well watered until a hard frost. Also,
consider fertilizing the tree this fall, as recommended
by horticulture specialists. (Nancy Pataky)
Plant Problems with Unknown Cause
The Plant Clinic is a clearinghouse for plant prob-
lems. "Clearinghouse" means different things to
different people. To many, it means that plant samples
can be sent to one place and input is available from
many specialists. This is true, with some limitations.
Not all specialists are available all the time. They
have full-time jobs on campus but usually try to help
out when called.
Others believe the clearinghouse concept means
that an exact cause can be determined for any plant
problem. People with some experience in the plant
business know that this is not always possible. At the
Plant Clinic, specialists examine the information and
sample provided and apply their experience to help
determine possible causes for the problem. In many
cases a specific insect, pathogen, or chemical may be
blamed. More often, however, a number of possible
causes are proposed.
When a plant problem is the result of several factors
producing a set of symptoms, the term "decline" is
often used. Ash decline and pine decline are two
common examples. This is not a "cop out" term, but a
way to indicate that several pathogens, site stress,
weather stress, or other factors are involved. In some
cases (for example, pine decline), specialists cannot
agree on the stress factors causing decline.
Several plant problems fitting this decline pattern
have become evident at the clinic over the last 10
years: white pine decline, ash decline, barberry
dieback, euonymus dieback, spruce decline,
sweetgum dieback, and oak scorch and dieback.
While it would be helpful if there were only one cause
of a plant problem, that is often not the case. The
Plant Clinic cannot always identify the exact cause of
the problem, but it does offer opinions and input from
professionals in many different specialties.
Reader input is important to us in tracking the
problems occurring throughout the state. Several
readers have reported plant problems observed over
wide geographical areas. This is helpful even when
the cause of the problem is not known. These reports
spur specialists to check with other states, check Web
sites for possibilities, and be alert when reading plant
journal articles. Your input is important to campus
specialists. Please keep in touch over the winter
months. (Nancy Pataky)
Home, Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana-Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members. Extension field staff , and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650
and Fredric Miller, (708) 352-0109, entomologists; Nancy
Pataky, plant pathologist, (217) 333-0519; Rhonda Ferree,
Tom Voigt, and David Williams, horticulturists, (217) 333-
0350, and Karel Jacobs, plant pathologist. The Morton
Arboretum, (630) 719-5646. Phil Nixon is the executive
editor of the Home, Yard and Garden Pest Newsletter. This
newsletter is written by faculty in the Department of
Natural Resources and Environmental Sciences and the
Department of Crop Sciences.
COOPERATIVE EXTENSION SERVICE
HOME, YARD & GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
iilinois at u rbana-champaign a i 1 1 inois natural history survey, champaign
NEWSLETTER
No. 20 • October 1, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
Two Issues Left
This is the 20th issue of Home, Yard and Garden Pest
Newsletter, only two issues remain in your 1997
subscription. You'll receive another issue in late
October and the final one at the end of November.
The last issue (no. 22) will contain an index of the
year's topics. As always, suggestions for the content
of the newsletter are welcome. Submit them to any
author listed at the end of the newsletter or to the
executive editor, Phil Nixon, at (217) 333-6650. (Phil
Nixon)
Subscription at $28 for 1998
Unfortunately, increased expenses are causing a
change in the subscription price for Home, Yard and
Garden Pest Newsletter for 1998. Rising personnel
and paper costs and an anticipated increase in postage
necessitate the $3 increase. The newsletter is run as a
break-even venture with no funds going to the au-
thors; however, costs are accrued for editing, design,
and subscription personnel. We work to keep these
expenses to a minimum. Subscription renewal forms
will be mailed to you this winter. (Phil Nixon)
Newsletter Goes on the Web
Home, Yard and Garden Pest Newsletter will be
available by subscription on the World Wide Web in
1998. This service will give Web subscribers immedi-
ate access to the information in the newsletter. An-
other feature of the Web version is electronic index-
ing, which will make pest information searches easier.
Paper editions of the newsletter will, of course,
continue to be available. (Phil Nixon)
HORTICULTURE
Tree and Shrub Fertilization
Fertilization helps maintain the healthy appearance
and vigor of trees and shrubs. Vigorously growing
plants not only look better but also withstand biologi-
cal and environmental pressures that can result in
plant decline.
Fertilizer applications should be timed so that
nutrients are available for periods of rapid growth.
Most professionals prefer fertilizing trees and shrubs
in early spring, early summer, or late fall. Spring
applications provide nutrients for the initial flush of
spring growth, when nutrients are often most needed.
Fall applications provide nutrients that are absorbed
by plants and stored until needed for growth. Addi-
tionally, although the top of the plant appears dor-
mant, root growth (and thus nutrient uptake) contin-
ues late into the fall. However, nutrients (such as
nitrogen) not absorbed by the roots can be lost by
leaching and thus not available for spring growth.
Fertilizers should not be applied to frozen soil.
Determine the need for fertilization by testing the
soil and/or looking for nutrient deficiency symptoms.
Nutrient deficiency symptoms include stunted leaves,
abnormal leaf color, subnormal growth, and early leaf
drop. Diagnosis should be made cautiously because
many other factors, such as drought stress, disease,
root injury, or herbicide damage, cause these same
symptoms. The frequency of application depends on
several factors and may vary from an annual treat-
ment to one made every three to four years.
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U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
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The preferred method of application is to place
fertilizers in holes in the root zone. Because most
feeder roots are in the top two feet of soil, this action
increases fertilizer contact with feeder roots. Fertiliz-
ers should be applied evenly within the plant's
dripline. The amount of fertilizer to use should be
based on the surface area of the space to be covered.
Some recommendations establish rates based on trunk
diameter, but these fail to consider the area of applica-
tion. For example, if you use a diameter-based rate for
a large tree growing in a restricted planter area, you
may add too many salts to the soil and injure the tree.
The University of Illinois recommends that fall
fertilization rates do not exceed 2 to 2-1/2 pounds of
actual nitrogen per 1 ,000 square feet. For trees
growing in turf areas, those numbers include nitrogen
applied to turf because that nutrient is mobile and will
leach to the tree roots.
Many landscapers are concerned that late fall
fertilizer applications will result in new succulent
growth that is susceptible to frost damage. At that
time of year, fertilization alone will not cause addi-
tional new growth. Plants will have already set their
terminal buds and started their hardening process.
However, pruning combined with fertilization will
result in new growth and frost damage is likely.
Therefore, fertilize in the fall but wait until the plants
are fully dormant before pruning.
For more information, refer to the horticulture fact
sheet Fertilizing Woody Plants, # NC-9-84 (cost: 25
cents), available from the University of Illinois at
Urbana-Champaign, Department of Horticulture,
1201 S. Domer Drive, Urbana, IL 61801. (Rhonda
Ferree)
PLANT DISEASES
Cane Blights of Brambles
Many readers are concerned about bramble appear-
ance this time of year. Diseases that may be involved
are anthracnose, cane blight, and spur blight. All are
easy to diagnose with the aid of Report on Plant
Diseases Nos. 700 and 709.
Although fungicides will control these diseases if
used as preventive sprays, we prefer to emphasize
other measures, namely removing and destroying all
fruiting canes as soon as they are done fruiting. The
young canes that will bear next year's fruit should be
left untouched. This cleanup process decreases the
amount of future fungal inoculum and opens the
planting to better air circulation and more rapid
drying. {Nancy Pataky)
Winter Preparation and Disease Prevention
Many gardeners wait until a problem occurs and then
scramble to correct the situation before it is too late,
often relying upon chemical treatments. An alternative
is to consider what can be done to help avoid future
disease problems in a lawn or garden. Many plant
diseases are best controlled with preventive measures.
Chemical rescue treatments may provide temporary
relief but are usually not the answer for long-term
disease control. These fall lawn and garden cleanup
procedures will help prepare plants for winter and
discourage development of disease problems.
1 . Keep grass mowed until it stops growing. This
helps prevent winter injury and damage from snow
mold.
2. Prune oak trees now to avoid an increased risk of
oak wilt. Pruning from September to early March is
recommended because doing so during the growing
season attracts bark beetles that transmit the oak
wilt fungus. Oak wilt is a potential threat through-
out Illinois, but more so in the northern areas.
3. Prune trees and shrubs to remove all dead and
seriously cankered wood, as well as any crossing
and interfering branches. Opening up the center of
woody plants helps promote faster drying, lets in
more light, and reduces foliar and stem diseases.
4. Provide recommended winter protection for roses,
evergreens, young thin-barked trees, and other
sensitive plants.
5. Prune tree and bush fruits according to recommen-
dations by Extension horticulturists.
6. Remove and bum (when possible), compost, or
bury plant debris to help control foliar and stem
diseases next year.
7. Review a variety of seed and nursery catalogs.
Select resistant varieties (if they are otherwise
horticulturally acceptable) and plant them where
you've had problems in the past but have no
rotation options. Choosing disease-resistant
hybrids, varieties, and species is usually the least
expensive and best long-term method of disease
control.
8. Make a map of your flower and vegetable gardens.
Next year, move related plants to another area of
the garden to keep down soil-borne pathogens.
Now is a great time to make soil amendments to
improve soil drainage.
9. Divide perennial flowers (when appropriate),
remove rotted or diseased parts, and replant them
in a new location. (Nancy Pataky)
No. 20 • October 1,1997
Apple Note
Many gardeners in Illinois grow apple trees. (We
know this from the number of questions we receive at
the Plant Clinic about apples.) Fruit pathology spe-
cialist Dr. Steve Ries recommends pruning apple trees
as soon as the crop is removed. It is probably a little
better for tree health to prune in March, but it is much
easier to do a good job now, when healthy plant
material is easy to distinguish from diseased tissue.
Ries points out that the primary reason for pruning is
to remove dead tissue. This practice will limit the
development of fire blight, black rot, sooty blotch, fly
speck, and apple scab. If the tree is known to be
infected with fire blight, be sure to disinfect the
pruners after every cut to prevent further spread of the
disease. Disinfecting may be done by dipping the
blades in rubbing alcohol or 10% chlorine bleach.
(Nancy Pataky)
INSECTS
White Grubs
White grubs continue to be reported in high numbers
throughout the state. Infestations of 15 to 25 grubs per
square foot are common. A dry spell will likely result
in widespread grub damage in untreated turf. On the
other hand, levels just slightly over the threshold of
10 to 12 per square foot can be tolerated if irrigation
is used during dry weather.
Adult Japanese beetles were still present in fairly
large numbers in central Illinois through at least
September 13. If these beetles were still laying eggs,
additional grubs may hatch in October — much later
than normal. Adult Japanese beetles usually die out by
mid- August. Be watchful for late-hatching grubs,
even in treated turf. Most grub insecticides are
effective for about one month; trichlorfon (Dylox,
Proxol) is effective for about one week. Isofenphos
(Oftanol) lasts about two weeks in many areas of the
state. Even long-lasting imidicloprid (Merit, Grubex)
may no longer be effective if it had been applied in
April or May. The point is that insecticide residues
may have broken down by the time grubs hatch from
recently laid eggs, making grub damage possible in
areas where large numbers of adult Japanese beetles
were recently present.
White grubs will continue to feed on turf roots as
long as the soil temperature in the root zone remains
at 50°F or above. As the soil temperature drops below
that level, the grubs will move downward where they
will overwinter. With root zone soil temperatures in
central Illinois at about 65 °F, it will take a consider-
able amount of cold weather to drop those tempera-
tures below 50°F.
In most years, grubs feed on turf roots through
mid-October in northern Illinois, early November in
central Illinois, and late November in southern
Illinois. Before treating in mid- to late fall, pull back
the sod and check for grubs in the root zone. If grubs
are present, treatment will be effective. {Phil Nixon)
Pine Needle Scale
A major pest of landscape pines and Christmas trees,
pine needle scale often goes unnoticed until infesta-
tions reach damaging levels. High-density infestations
can cause yellowing of needles and, in extreme cases,
tree death. Fortunately, pine needle scale problems
can be avoided with a little effort and a trained eye.
Like their relatives the aphids, scale insects feed on
plant juices sucked through needlelike mouthparts.
Scales are primarily sedentary insects concealed
beneath a protective wax cover, which for the adult
female pine needle scale is about 1/8 inch long, white,
and generally teardrop shaped. Male scale covers are
about half the size of the female's and more rectangu-
lar in shape. Beneath the wax cover, the adult female
is little more than a purplish blob with no legs or
antennae to speak of. These limbs have been all but
lost with adaptation to a stationary lifestyle.
Pine needle scale undergoes two generations per
year in the Midwest. Eggs remain all winter under
covers of females, hatching in about the middle of
May. Bright red, pinhead-sized nymphs (known as
crawlers) emerge from the eggs. These nymphs have
legs and wander the needles searching for a suitable
feeding site. Crawlers are the dispersal stage of scale
insects and are capable of walking short distances, but
they may also spread via wind. Upon finding a
suitable site, crawlers insert their mouthparts into the
needle and begin feeding; they will remain in that spot
for the rest of their lives.
Pine needle scales reach adulthood around the end
of June and beginning of July. Tiny winged adult
males (about 1/12 inch long) emerge from beneath
their covers and search for females. The second
generation begins when females lay their eggs in mid-
to late July, with crawlers emerging near the end of
July. This second generation reaches adulthood in
September or early October, when females lay the
eggs that will overwinter.
X^/LIU/L/C/ / , t y :7 /
Pine needle scale occurs on a wide variety of
coniferous trees but is most abundant and damaging
on Scotch and mugo pines. The scale rarely becomes
a problem in natural settings such as forests or woods,
where natural enemies tend to maintain scale infesta-
tions at very low densities. Areas of low plant diver-
sity, such as ornamental landscapes and tree farms,
tend to support low densities and diversities of
enemies. In these areas, scale infestations are free to
grow relatively unchecked.
Scouting for pine needle scale is an effective means
of minimizing damage to trees. The scale tends to be
most abundant on the lower and interior branches.
Clipping infested needles or branches is an easy way
to reduce light or medium infestations. Heavy infesta-
tions may require chemical controls. Because of the
protective wax cover of the older scales, insecticides
are most effective if applied when crawlers are active.
Good control can be obtained with traditional insecti-
cides such as Sevin, Orthene, and Malathion; how-
ever, horticulmral oils are also effective and easier on
natural enemies that contribute to pest control.
Natural enemies such as ladybeetles, tree crickets,
earwigs, and some parasitic wasps are thought to
suppress scale populations.
Methods of improving the efficacy of some natural
enemies in controlling pine needle scale, including
tiny stingless wasps that parasitize the scale, are
currently under investigation in the Department of
Entomology at the University of Illinois at Urbana-
Champaign. Presently, we are evaluating the influence
of habitat on parasite abundance and hope to develop
techniques for enhancing parasitism through land-
scape design. {John Tooker and Larry Hanks, Depart-
ment of Entomology)
Home. Yard and Garden Pest Newsletter is prepared by
Extension specialists from the University of Illinois at
Urbana- Champaign and the Illinois Natural History
Survey. Information for this newsletter is gathered with the
help of staff members. Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Service.
Major authors are Phil Nixon, (217) 333-6650 and
Fredric Miller, (708) 352-0109, entomologists; Nancy
Pataky, plant pathologist, (217) 333-0519; Rhonda Ferree,
Tom Voigt, and David Williams, horticulturists, (217) 333-
0350, and Karel Jacobs, plant pathologist. The Morton
Arboretum, (630) 719-5646. Phil Nixon is the executive
editor of the Home, Yard and Garden Pest Newsletter. This
newsletter is written by faculty- in the Department of
Natural Resources and Environmental Sciences and the
Department of Crop Sciences.
75
JUN 2 6 1997
AG U^rqr'
COOPERATIVE EXTENSION SERVICE
HOME, YARD 8^ GARDEN PEST
college of agricultural, consumer and environmental sciences, university of
Illinois at urbana-champaign A Illinois natural history survey, champaign
NEWSLETTER
No. 21* October 29, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
Turf-Related Events for Your Calendar
Two turf-related events cosponsored by the University
of Illinois Extension take place this fall.
The first is the 1997 University of Illinois-Central
Illinois Golf Course Superintendents Association
Educational Seminar scheduled for Wednesday,
November 12, 1997, at the Radisson Hotel in
Bloomington, Illinois. This event will provide up-to-
date information and education for golf course
personnel. Speakers at this one-day seminar include
university personnel from the Midwest, along with
local golf-turf professionals. There is a fee for this
seminar, and preregistration is requested.
The second event is the 1997 North Central
Turf grass Exposition (NCTE), December 1 through 4
at the Pheasant Run Resort in St. Charles, Illinois.
The NCTE provides educational opportunities from
Monday afternoon through Thursday morning for
individuals in golf course, sports turf, lawn care, sod
production, landscape, and other "green" industries.
The trade show features more than 80 vendors and
170 booths and is open on Tuesday and Wednesday of
the show. The North Central Turfgrass Exposition is
cosponsored by University of Illinois Extension and is
coordinated by the Illinois Turfgrass Foundation.
Registration fees can be paid in advance or at the door
during the Exposition.
For additional information about either of these
activities, call University of Illinois Extension
turfgrass specialist Tom Voigt at (217) 333-7847.
(Tom Voigt)
PLANT DISEASES
Pine Wilt
Pine wilt is caused by the pinewood nematode, which
is vectored from tree to tree via the Sawyer beetle.
Look for flagging (appearance of dead branches) or
sudden decline and death of an entire tree within a
few weeks or months of initial symptoms. We have
seen this disease on most pines in Illinois, especially
Scotch and Austrian, but it is rare on white pine. If
your white pines die suddenly, check their root
systems: white pines have been plagued by problems
related to root rot, and they are also susceptible to the
effects of site and environmental stress. Over the
years, the Plant Clinic has tested hundreds of white
pines for the presence of pinewood nematodes. In all
that time, the clinic has found only two cases of
pinewood nematode on white pine — and one of those
nematodes was dead when sampled.
As discussed in issue numbers 8 and 17 of this
newsletter, the only method of control that we can
suggest for pine wilt is to break the disease cycle by
removing dead trees as soon as possible. If your pines
are dead now, they are certainly not going to "green-
up" or come back to life in the spring. If you cannot
rule out pine wilt as the cause of death, play it safe by
removing the trees to prevent the possible spread of
the nematode to healthy pines in the area. The wood
must be burned, buried, or removed from the site to
prevent insect ovipositing and overwintering in
infected wood.
The question often arises as to whether wood
infested by pinewood nematode can be chipped and
safely used for mulch. So far, research leads us to
believe that such a practice is fairly safe. The research
has shown that the insects do not survive the chipping
process, that the nematode does not infect through the
roots, and that the insect does not inhabit wood chips.
Logically, there is no way for the nematode to move
A ('"^C Q College of Agricultural, Consumer and Environmental Sciences,
University of Illinois at Urbana-Champaign
ces
Helping You Put Knowledge to Work— State • County • Local Groups
US Department of Agriculture Coofserating
The Cooperative Extension Service provides equal
opportunities In programs and employment.
No. 27 • October 29, 1997
out of the chips and into a tree. To be safe, though,
spread the mulch on a concrete or blacktop surface
and let it dry before use, or put it through a true
compost cycle. {Nancy Pataky)
INSECTS
Gypsy Moth Survey
The Illinois Department of Agriculture, in association
with the USDA, has completed its 1997 gypsy moth
survey and analyzed the data. A total of 34,841 moths
were collected in pheromone traps — a marked in-
crease from the 2,643 moths collected in 1996. The
areas of heaviest counts are in the five northeastern-
most counties of Illinois (Lake, McHenry, Kane,
Cook, and DuPage), accounting for 33,714 moths. In
1996, these counties trapped 2,608 moths. Within
those five counties, areas near the shore of Lake
Michigan from Evanston northward had the heaviest
moth catches.
Almost all of the counties in the northern one-
quarter of Illinois had positive moth catches in 1997:
Jo Daviess, Stephenson, Winnebago, Boone,
McHenry, Lake, Cook, DuPage, Kane, DeKalb,
Ogle, Carroll, Whiteside, Lee, Rock Island, Henry,
La Salle, Kendall, Will, Grundy, Kankakee, and
Livingston. All of the counties in the northern half of
the state (generally, counties north of Springfield)
were trapped in 1997. Of the counties trapped, 28
did not have any moths.
In 1996, all counties in the southern half of Illinois
were trapped (that is, every county that was not trapped
in 1997). The northern Illinois counties of Stephenson,
Winnebago, Boone, McHenry, Lake, Kane, Cook,
DuPage, Kendall, and Will were also included in the
1 996 trapping program. Of these northern counties, all
except Stephenson had moth catches. The entire
northern half of the state was also trapped in 1995, with
positive catches in Winnebago, Boone, McHenry, Lake,
Cook, DuPage, Kane, DeKalb, Kankakee, Peoria,
McLean, and Vermilion counties. Again, the northeast-
em counties of McHenry, Lake, Cook, DuPage, and
Kane accounted for most of the catches, with 2,068
moths trapped that year.
Large numbers of gypsy moths have been found in
Michigan for many years. In Wisconsin, Door County
and some other areas have had high moth counts for
the last few years. Accidental human movement of
caterpillars and eggs during vacations, business trips,
and household moves probably accounts for many of
the new sitings. In areas near Wisconsin, natural
spread is also likely.
Hatchling gypsy moth caterpillars climb to the tops
of trees, spin out strands of silk, suspend themselves
on the strands, and are blown to new feeding sites. In
wooded areas, caterpillars on their strands of silk may
be carried on the wind for several hundred yards. In
more open areas, they can be blown for several miles.
The Illinois Department of Agriculture, with the
cooperation of the USDA and the affected communi-
ties, will continue the eradication efforts that have
been so successful in eliminating isolated gypsy moth
infestations over the past 25 years in Illinois. Unfortu-
nately, the numbers of trapped moths have never
before been this large. With nearby states containing
large numbers of gypsy moths, continual reinfestation
is likely.
Successful eradication in Illinois and in nearby
states probably depends on some help from nature.
Gypsy moth eggs are killed at temperatures of -20°F
and lower; three consecutive days at those tempera-
ture will kill almost all of the overwintering eggs.
Eradication of the caterpillars hatching from the few
surviving eggs would then be likely.
Thanks to Stan Smith, Illinois Department of
Agriculture, for supplying the survey counts used in
this article. {Phil Nixon)
Spider Ballooning
Huge amounts of silk webbing are being reported,
particularly in the northern and northwestern areas of
the state. Silk webbing is noticeably coating turf areas
and hanging from trees and buildings.
This phenomenon is caused by ballooning spiders.
When spiders hatch from their eggs, they climb to a
high location and spin out long strands of silk. This
silk is caught on the wind and carries the spiderling
for long distances. These silk strands with their
spiderlings have been collected by airplanes thou-
sands of feet above the ground. Charles Darwin noted
ballooning spiders on the rigging of the ship HMS
Beagle several hundred miles from land. The presence
of spiders on volcanos and other locations where
spiders could not live has established scientifically
that spiders can balloon for at least 18 miles.
The eggs of different species of spiders hatch at
various times during the growing season, so balloon-
ing spiders can be found throughout the warmer
months. The eggs of many spider species hatch during
the fall, making ballooning spiders common this time
of year.
No. 21 • October 29, 1997
Once the spiderlings are carried to appropriate
locations, they find a crack or crevice in which to hide
through the winter. They emerge in the spring to begin
feeding on insects and other small animals.
The silk strands are not likely to cause any damage
to turf or other ornamental plants and control mea-
sures are not recommended. After all, the next puff of
wind will just bring more strands of silk and their
passenger spiderlings. (Phil Nixon)
HORTICULTURE
Pesticide Storage Requirements
Pesticides used in the landscape are manufactured,
formulated, and packaged to specific standards.
However, when stored improperly, pesticides can
break down, especially under conditions of high
temperature and humidity. Some pesticides can lose
their active ingredients through chemical decomposi-
tion or volatilization. Dry formulations such as
wettable powders can become caked and compacted;
emulsifiable concentrates can lose their ability to form
emulsions. Some pesticides become more toxic,
flammable, or even explosive as they break down.
Pesticide formulations that contain low concentra-
tions of active ingredients generally lose effectiveness
faster than more concentrated forms. Sometimes a
liquid pesticide develops gas as it deteriorates,
making opening and handling containers quite hazard-
ous. Over time, the gas pressure may cause the
container to rupture or explode.
Certain pesticides have characteristic odors. A
strong odor in the storage area may indicate a leak,
spill, or improperly sealed container. It may also be a
clue that the pesticide is deteriorating because the
smell of some chemicals intensifies as they break
down. If none of these problems are found, you can
reduce chemical odors by installing an exhaust fan or
lowering the temperature of the storage area.
Characteristics that affect shelf life include the
pesticide formulation (liquid concentrate, wettable
powder, granules), types of stabilizers and emulsifiers
used, chemical nature and stability of the pesticide,
and type of container and its closure. Pesticide
containers have an important impact on storage and
shelf life. If stored for long periods, these containers
may eventually corrode, crack, break, tear, or fail to
seal properly. Also, their labels may become illegible.
If you find a damaged container, transfer its contents
to a similar sturdy container that can be sealed. Be
sure to transfer the label to the new container. Never
put a pesticide in a food or drink container!
Pesticides can have an extended shelf life if the
storage area is cool, dry, and out of direct sunlight.
Protection from temperature extremes is important
because heat or cold can shorten pesticide shelf life.
At temperatures below freezing, some liquid formula-
tions separate into their various components and lose
their effectiveness. High temperatures cause many
pesticides to volatilize or break down more rapidly.
Extreme heat may also cause glass bottles to break or
explode.
Pesticides packaged in paper or cardboard contain-
ers should be stored on shelves to keep them away
from water or dampness on the floor. To prevent
cross-contamination, separate volatile herbicides and
other pesticides. Keep all corrosive chemicals in their
proper containers to prevent leaks. Even the simple
step of tightly closing lids and bungs on containers
can help extend pesticide shelf life.
One way to minimize loss, cost, and disposal
problems associated with pesticides is to avoid mixing
more pesticides than you will use in a reasonable
period of time. Be sure to date the containers and keep
a current inventory of supplies. Avoid stockpiling; buy
what you need, but not to excess. Even with careful
planning, it is sometimes necessary to carry pesticide
stocks over from one year to the next. Check dates of
purchase at the beginning of each season and use the
oldest material first. To keep the label on a container
intact and legible, cover it with transparent tape or
lacquer. Given proper storage, some pesticides may
remain active for a number of years.
The following list contains shelf-life information
and storage guidelines for many pesticides.
bensulide (Betasan, Bensumec): Granules are
stable. Emulsifiable liquids may crystallize below
42°F, but crystals redissolve if stored or warmed at
high temperatures.
captan: Stable for at least two years under normal
storage conditions. Protect from extreme heat.
carbaryl (Sevin): Repeated freezing/thawing
cycles may decrease effectiveness of flowable formu-
lation. Wettable powders are quite stable under
normal storage conditions.
DCPA (Dacthal): Store in a dry place. Wettable
powders are stable for at least two years under proper
storage conditions.
diazinon: Use 4E within six months of opening
container. Do not store near a heat source. Keep lids
tightly closed; keep granular materials and dusts dry.
No. 2 J • October 29, 199?
dichlobenil (Casoron. Barrier. Dyclomec):
Granules are stable for at least two \ears if stored in
tightl\- sealed containers and kept in a cool. dr. place,
dicofol (Kelthane): Wettable powders are stable
under normal storage conditions.
dimethoate (Cygon. De-Fend): Liquid formula-
tions should be stored abo\"e freezing temperatures.
Dimethoate is flammable, so keep it away from heat
and open flame. Its flash point range is "^3 to lOO^T.
glyphosate (Roundup): Store above lO^^F lo
prevent freezing, w hich results in cr>"stals that settle to
the bottom of the container. Do not store, mix. or
appl> in gahanized steel or unlined steel containers.
malathion iCythion): Wettable powders are stable
for at least two \ears when stored properly. Do not
store liquid formulation below O^F. Keep away from
heat sources.
metam-sodium (Vapam): Do not store below O'F.
This pesticide crystallizes at lower temperatures.
Warm or store at higher temperamres; mi.\ to dissolve
cn.'stals and ensure uniformity before use.
simazine (Princep): Wettable powders and gran-
ules are stable for at least two \ears under normal
conditions. Simazine is nonflammable.
trifluralin (Treflan. Preen): If stored for long
penods below 40"F. emulsifiable concentrate formula-
tions may proNide poor weed control. Trifluralin"s
flash point is 1 19~F. so do not store near a heat source.
It is stable for at least two years with cool. dr> stor-
age. (Fredric Miller and Phil \ixon i
Bi-State Horticulture Conference
Dunng the winter, many opportunities are a\ailable
throughout Illinois for continued education in horti-
culmre. One relatively new offenng that targets the
commercial horticulmre industries m northwestern
Illinois and northeastern Iowa is the Bi-State Horticul-
mre Conference. The conference includes general
sessions as well lectures. The lectures are divided into
tw o tracks: one focusing on the turf industr), the other
on landscape and arboriculture industries.
This year's conference will be Wednesday, Novem-
ber 5. 1997. from 8:30 a.m. to 4:00 p.m. at the Holi-
day Inn. Quad Cities Airport, in Moline. Illinois. The
deadline for advance registration is October 31. 1997.
At-the-door registrations are accepted, but lunch will
not be included. The registration fee is $25 per
person. Advance registration is being accepted by the
Rock Island E.xtension office. 1414 Tenth Street. Suite
1. Sihis. IL 61282 [phone: (309) 796-0512: fax (309)
796-0673]. Checks should be made payable to the
University of Illinois.
Continuing education units for this conference have
been approved by the Illinois Golf Course Superinten-
dents Association of America. The Illinois Nursery
Professional Association has also approved continuing
education units for recertification.
For more information about the Bi-State Horticul-
mre Conference or the continuing education units
offered, call Martha Smith. Extension educator in
honiculture. at (309) 836-3366. (Nancy Pataky)
Home. Yard and Garden Pest Newsletter is prepared by
Extension specialists from the Uni\ersir\- of Illinois at
Urbana- Champaign and the Illinois Natural History
Suney. Information for this newsletter is gathered with the
help of staff members. Extension field staff, and others in
cooperation with the USDA Animal and Health Inspection
Senice.
Major authors are Phil Nixon, (217) 333-6650 and
Fredric Miller (708) 352-0109, entomologists; Nancy
Paiak}. plant pathologist, (217) 333-0519: Rhonda Ferree,
Tom Voigt. and David Williams, horticulturists, (217) 333-
0350, and Karel Jacobs, plant pathologist. The Morton
Arboretum, (630) 719-5646. Phil Nixon is the executive
editor of the Home. Yard and Garden Pest Newsletter Tliis
newsletter is written by faculty in the Department of
Natural Resources and Environmental Sciences and the
Department of Crop Sciences.
Lt>p. <^
DEC 0 5 1997
COOPERATIVE EXTENSION SERVIQSG Lihra"
HOME, YARD & GARDEN PEST
college of agricultural, consumer and environmental sciences, university oi
Illinois at urbana-champaign ▲ i I linois natural history survey, champaign
NEWSLETTER
No. 22 • November 26, 1997
This newsletter is issued weekly (biweekly in the early
spring and late summer) to provide timely information on
insect, weed, and plant disease pests of the home, yard, and
garden. Current control procedures, application equipment
and methods, safe storage and disposal of pesticides, and
other topics of interest are discussed.
Last Issue for 1997
This is the 22nd and final issue of Home, Yard, and
Garden Pest Newsletter for this publication year, and
it contains the index for 1997. We will resume publi-
cation in mid- April 1998 (depending on how early
spring arrives). Order forms for subscribing to the
1998 edition of the newsletter will be mailed in
February. If you do not receive a subscription bro-
chure, please call 1-800-345-6087.
We are interested in making this newsletter as
useful as possible for professional ornamental horti-
culturists. As always, your comments are appreciated
by me (as newsletter coordinator) and the contributing
authors. (Phil Nixon)
HYG Online in 1998
Home, Yard and Garden Pest Newsletter will be
available by subscription on the World Wide Web
beginning with the first issue in 1998 (mid-April).
Temporary, free access to the Home, Yard and Garden
Pest Web site will be available soon at http://www.
ag.uiuc.edu/cespubs/hyg/. Three issues of the newslet-
ter will be on the sample site to give people a chance
to explore all the features that will be offered to Web
subscribers next year.
The benefits of a Web subscription include imme-
diate availability of the newsletter, a keyword search
function, and convenient access to previous newslet-
ters and articles. The Web version of the newsletter
will also include features not available to print
subscribers, such as links to other Web sites and a
listing of announcements and meetings.
The Web subscription rate is $25. Subscribers can
also choose a combination of regular mail delivery
and the Web for $40. The price for a mail subscription
is $28, by fax $60. An online subscription form will
be ready soon. (Peggy Currid)
HORTICULTURE
Winter Preparation for Ornamental Plants ...
It's Not Too Late
This winter seems to have crept up on us before we
realized what was happening. Many of us were not
able to prepare our plants the way we normally
would. Although we are past the ideal time for many
preparations, there are several items you might still
consider to prepare plants for the depths of winter.
Needled and broadleaf evergreens are susceptible
to winter bum caused by desiccation. This occurs
when frozen soil reduces water absorption while the
plants are exposed to drying winds and deicing salts.
Needles or leaves typically begin to turn brown at the
tip and brown further backward, depending on
severity. One way to help prevent rapid moisture loss
through the leaves or needles is with antitranspirants,
which help reduce transpiration. Antitranspirants
should be applied now — before severe winter sets in.
Other types of cold injury include sunscald and
frost cracks. Sunscald and frost cracks are caused by
extreme temperature fluctuations. Sunscald is actually
a freezing injury and is most likely to occur on young
trees. Sunscald spots may develop into a frost canker.
Use tree wraps on susceptible trees to help reduce the
risk of damage from temperature fluctuation.
Frost cracks occur when the outside cells of the
tree lose water, shrink, and pull apart — causing a
crack to open longitudinally with the grain of the
wood. Again, tree wraps may help, but some species
are simply more prone to cracking than others. Trees
A (^^T^ Q College of Agricultural. Consumer and Environmental Sciences.
University of Illinois at Urbana-Champaign
ces
Helping You Put Knowledge to Work — State • County • Local Groups
U.S. Department of Agriculture Cooperating
The Cooperative Extension Service provides equal
opportunities in programs and employment.
iiy*_f ^KJf t ^ J /
shaded on the south and west sides, where the tree
heats up the most, will sometimes crack less.
Roses typically need additional protection, and it is
not too late to cover them. Ideally, excessively long
canes of hybrid teas, floribundas, grandifloras, and
polyanthas should have been pruned back slightly by
now. Because the plants should be covered after they
go dormant, do that now. Bushel baskets or commer-
cial covers work well. You will need to trim the canes
back to fit underneath the cover. Other ways of
protecting the roses include covering with leaves (oak
work best), pine needles, straw, old sawdust, or bark
chips. The depth of the material should be 12 inches.
Soil is not recommended as a cover because it stays
too wet and packs too solidly. In the spring, remove
the cover or mulch, trim the canes back to healthy
wood (just above the strong bud), and thin the plants
to four or five canes.
Climbing and rambling rose canes may also need
winter protection. Lay the canes on a bed of straw and
cover them with more straw. Be sure to cover the
crowns. Keep the straw in place by tying it or cover-
ing it with a small amount of soil. In the spring,
remove the covering, remove all damaged wood, and
place the canes or shoots back on the trellis.
Because of our late fall, many trees did not drop
their leaves until recently. If possible, you should still
try to remove the fallen leaves — particularly because
leaves left on the ground could damage grass. Addition-
ally, many leaves house pathogens capable of causing
disease the following year. Dispose of leaves through
community programs or use them as mulch or in a
compost pile. Check with your local law enforcement
agency or fire department before burning leaves,
because many local governments prohibit leaf burning.
In summary, the more work done through the fall
and winter, the less spring cleanup will be required.
Be sure to properly discard all plant wastes. Do not
remove winter-protective devices too early in the
spring. In areas subject to many late heavy snow-
storms and temperature extremes, early mulch re-
moval might be a serious mistake.
For more information, obtain the horticulture fact
sheet Winter Protection for Woody Plants, # LH 179.
(Rhonda Ferree and Jim Schmidt)
Plants Not Favored for Browsing by Deer
Deer are becoming an increasing problem in the
Midwest, especially for homeowners living near
woodlands. As open land continues to be developed,
less open space is available for the deer to live. In the
open space that remains, the deer population develops
unchecked because there are no natural predators,
such as wolf, cougar, and coyote. In good habitats, the
deer population can more than double each year.
Deer damage plants in two ways: battering by
antlers and browsing. Battering occurs in late summer
and fall. Young trees, two to three inches in diameter,
are used for "sparring practice." During late fall and
winter, deer browse (feed) on young succulent twigs
when other foods are less available. New buds and
shoots are also browsed in spring and early summer.
Staff members at The Morton Arboretum are
frequently asked to suggest plants that are not eaten
by deer. It is important to realize that deer will eat
almost any plant if they are under enough pressure,
such as snow cover and overcrowding. The plants in
the following lists are not favored for browse by deer.
The list was compiled based on the observations of
Pete van der Linden, Curator of Plant Collections, The
Morton Arboretum, Lisle, Illinois, and Galen Gates,
Manager of Horticulture Collections, Chicago Botanic
Garden, Glencoe, Illinois. The book Gardening in
Deer County by Karen J. Bernard (Croton-on-
Hudson, New York. 54 pp.) was also used as a source.
(Written by Kris R. Bachtell, The Morton Arboretum;
submitted by Phil Nixon)
Trees Not Favored by Deer
Ash (Fraxinus)
Beech (Fagus)
Birch (Betula)
Catalpa {Catalpa)
Cedar (Juniperus)
Chestnut (Castanea)
Cypress (Taxodium)
Dawn redwood (Metasequoia)
Ginkgo (Ginkgo)
Hemlock (Tsuga)
Ironwood (Ostrya)
Larch (Larix)
Locust, black (Robinia)
Locust, honey (Gleditsia)
Mimosa/silktree (Albizia)
Redbud (Cercis)
Sassafras (Sassafras)
Smoketree (Cotinus)
(continued next page)
No. 22 • November 26, 1 997
Trees Not Favored by Deer (cont.)
Sourwood {Oxydendmin)
Sweet gum (Liquidambar)
Spruce (Picea)
Sycamore (Platanus)
Tree lilac (Syringa reticulata)
Tuliptree (Liriodendron)
Shrubs Not Favored by Deer
Barberry (Berberis)
Boxwood (Buxus)
Coralberry (Symphoricarpos)
Forsythia (Forsythia)
Juniper {Juniperus)
Kerria (Kerria)
Lilac (Syringa)
Oregon-grape (Mahonia)
Smoke bush (Cotinus)
Snowberry (Symphoricarpos)
Spicebush (Lindera)
Spirea (Spiraea)
Sweet shrub (Calycanthus)
Witch-hazel (Hamamelis)
Groundcovers Not Favored by Deer
Ajuga (Ajuga)
Barren strawberry (Waldsteinia)
Bergenia (Bergenia)
Bunchberry (Cornus)
Catmint (Nepeta)
Epimedium (Epimedium)
Ferns (various species)
Ginger (Asarum)
Indian strawberry (Diichesnea)
Juniper (Juniperus)
Lady's mantle (Alchemilla)
Lamium (Lamium)
Lily-of-the-valley (Convallaria)
Lily turf (Liriope spicata)
Lungwort (Pulmonaria)
Mosses
Pachysandra (Pachysandra)
Potentilla (Potentilla)
Sedum (Sedum)
Sempervivum (Sempervivum)
Snow-in-summer (Cerastium)
Sweet woodruff (Asperula)
Vince (Vinca)
Violet (Viola)
Wild strawberry (Fragaria)
Willow (Salix)
Perennial Vines Not Favored by Deer
Akebia (Akebia)
Bittersweet (Celastrus)
Clematis (Clematis)
Grape (Vitus)
Honeysuckle (Lonicera)
Ivy, Boston (Parthenocissus)
Silver lace vine (Polygonum)
Trumpet creeper (Camp sis)
Virginia creeper (Parthenocissus)
Wisteria (Wisteria)
Deer-Resistant Hardy Bulbs
Allium (Allium)
Chionodoxa (Chionodoxa)
Colchicum (Colchicum)
Crown imperial (Fritillaria)
Crocus (Crocus)
Daffodil (Narcissus)
Eranthis (Eranthis)
Fritillary (Fritillaria)
Grape hyacinth (Muscari)
Narcissus (Narcissus)
Puschkinia (Puschkinia)
Scilla (Scilla)
Snowdrop (Galanthus)
Snowflake (Leucojum)
Deer- Resistant Annuals and Biennials
African daisy
Ageratum (Ageratum)
Alyssum (Lobularia)
Campanula (Campanula)
Candytuft (Iberis)
Forget-me-not (Myosotis)
Four o'clock (Mirabilis)
Foxglove (Digitalis)
Heliotrope (Heliotropium)
Larkspur (Delphinium)
Lobelia (Lobelia)
Marigold (Tagetes)
Mimulus (Mimulus)
Morning glory (Ipomoea)
Moonflower (Ipomoea)
Nasturtium (Tropaeolum)
Petunia (Petunia)
Poppy (Papaver)
Salvia (Salvia)
Snapdragon (Antirrhinum)
Stocks (Matthiola)
Sunflower (Helianthus)
(continued next page)
iiy^i ^\J,
Deer-Resistant Annuals and Biennials (cont.)
Sweet William (Dianthus)
Thistle (Cirsium)
Tithonia (Tithonia)
Deer-Resistant Hardy Perennials
Aconite (Aconitum)
Alyssum (Lobularia)
Anemone (Anemone)
Artemisia {Artemisia lactiflora)
Astilbe {Astilbe)
Bee balm (Monarda)
Bergenia (Bergenia)
Black-eyed Susan {Rudbeckia)
Butterfly weed (Asclepias)
Columbine (Aquilegia)
Coreopsis (Coreopsis)
Crane's bill (Geranium)
Cyclamen (Cyclamen)
Daisy (Chrysanthemum)
Dame's rocket (Hesperis)
Fleabane daisy (Eirgeron)
Foam flower (Tiarella)
Gentian (Gentiana)
Geum (Geum)
Goldenrod (Solidago)
Hellebore (Helleborus)
Hibiscus (Hibiscus)
Iris (Iris)
Jacob's ladder (Polemonium)
Loosestrife (Lythrum)
Lychnis (Lychnis)
Lythrum (Lythrum)
Marsh marigold (Caltha)
Meadow rue (Thalictrum)
Meadow sweet (Filipendula hexapetala)
Peony (Paeonia)
Phlox (Phlox)
Pinks (Dianthus)
Purple Coneflower (Echinacea)
Rock cress (Arabis)
Russian sage (Perovskia)
Salvia (Salvia)
Sedum (Sedum)
Sempervivum (Sempervivum)
Deer-Resistant Hardy Perennials (cont.)
Snakeroot (Eupatorium)
Sneezeweed (Helenium)
Snow-in-summer (Cerastiun)
Soapwort (Saponaria)
Toadflax (Linaria)
Valerian (Valeriana)
Veronica (Veronica)
Violet (Viola)
Yarrow (Achillea)
Yucca (Yucca)
Deer-Resistant Herbs
Angelica (Angelica)
Artemisia (Artemisia)
Basil (Ocimum)
Borage (Borago)
Burnet (Sanguisorba)
Catmint (Nepeta)
Chamomile (Matricaria)
Chives (Allium)
Comfrey (Symphytum)
Dill (Anethum)
Fennel (Foeniculum)
Feverfew (Chrysanthemum)
Germander (Teucrium)
Horehound (Marrubium)
Hyssop (Hyssopus)
Lamb's ears (Stachys)
Lavender (Lavendula)
Lemon balm (Melissa)
Lovage (Levisticum)
Mint (Mentha)
Mullein (Verbascum)
Oregano (Origanum)
Parsley (Petroselinum)
Perilla (Perilla)
Rosemary (Rosmarinus)
Rue (Ruta)
Sage (Salvia)
Santolina (Santolina)
Savory (Satureja)
Tansy (Tanacetum)
Thyme (Thymus)
CBS
Cooperative Eitenston Service
The Illinois Pesticide Review
y New About Pesticides and Regulations ^~
1201 S Dorner Dr. Urbana, IL 61801 (2170 244-4397
Vol. 10, No. 3
November 1997
Editorial Comment
I am extremely excited about this
issue of the Illinois Pesticide Review
(IPR) newsletter. The IPR is growing
and changing to meet our goals and
our clientele's needs. Due to increas-
ing requests for this newsletter, we
are now offering it as a paid sub-
scription through ACES's Newsletter
Service. Starting January 1998, the
IPR will be available for $15 per
year. However, we will continue to
offer this newsletter free of charge to
those with Internet capabilities. It is
available at .
The IPR design is being updated,
and the newsletter will now be
produced on a regular bimonthly
schedule. Similar to this issue, each
IPR provides pertinent, up-to-date
pesticide and pesticide-related
information. Members of the Pesti-
cide Safety Education program at the
University of Illinois strive to
remain current on pesticide-related
issues and work hard to foster
partnerships with others who do the
same, such as the Illinois Depart-
ment of Agriculture (IDA), US-EPA,
grower organizations, environmental
groups, and more.
In addition, each issue will spotlight
a part of University of Illinois
Endocrine Disruptors
Concerns about pesticides and other
chemicals functioning as endocrine
disruptors in wildlife and people
have made the news several times in
the last couple of years. The most
common of these have been chemi-
cals that mimic the human hormone
estrogen.
The endocrine system in humans and
other animals is a series of glands,
including pituitary, thyroid, and
adrenal glands, as well as ovaries or
testes. These glands produce hor-
mones, such as adrenalin and
adrenalin and estrogen, that travel
through the bloodstream and guide
development, growth, reproduction,
and behavior.
Endocrine effects can take a couple of
different forms. An endocrine modula-
tor causes a temporary hormonal
response that results in a reversible
change in the endocrine system. An
example is the use of estrogen in birth
control pills. An endocrine disruptor
causes a permanent change in the
endocrine system.
Effects of dicofol on alligators and
turtles in Apopka, Florida, and of
research, teaching, or outreach that
pertains to pesticides. This issue, we
spotlight the ever popular and
important Plant Clinic. Future
articles may feature pesticide-related
research, other pesticide programs,
related classes and degree programs.
Extension programs, or other inter-
esting and important work done at
the University of Illinois that per-
tains to pesticides.
As always, I welcome comments and
suggestions. Let me know if the IPR
meets your needs!
{Rhonda J. Ferree)
In This Issue
National PAT Conference —
Additional Perspectives 3
Spotlight on U of I:
What's Ailing You
(or, Rather, Your Plants)? 4
FQPA Update 5
Pesticide Update 6
College of Agricultural, Consumer and Environmental Sciences
University of Illinois at Urbana-Champaign, Urbana, Illinois
State/County/Local/U.S. Department of Agriculture Cooperating
The illinois Cooperative Extension provides equal opportunities in programs and employment
Illinois Pesticide Review
No. 3, November 1997
dioxin and PCBs on fish-eating
birds and lake trout in the Great
Lakes are two of the more heavily
studied endocrine-disrupter situa-
tions in nature. Commonly, the
effects of these hormone "mimics"
are that one sex or the other devel-
ops almost exclusively, resulting in
major drops in the population for
the affected wildlife species. An
increase in a substance that mimics
a sex hormone can cause developing
animals of one sex to underdevelop
sexually and the other sex to
become sexually malformed. Both
sexes usually become less fertile or
even sterile, depending on the
animal species, the endocrine
disruptor, and the concentration of
the chemical.
Less obvious affects of endocrine
disrupters include dead embryos,
birth defects, and developmental
abnormalities. Although most
studies have been on wildlife, effects
on humans are documented. The
health advisories against high
consumption of fish from the Great
Lakes by pregnant and nursing
mothers are the results of these
studies on humans. In these studies,
affected children showed reduced
neuromuscular skills, poorer
memory, lower IQs, and poorer
reading abilities. The individuals that
are most affected are the developing
young because endocrine disruptors
cause permanent changes there. In
adults, endocrine disruptors cause
temporary changes, and removal of
the disruptor allows the endocrine
system to return to normal.
PCBs and styrenes have been found
to be the most common endocrine
disruptors in the environment.
However, a breakdown product of
DDT is estrogenic in mammals and
birds and causes the early ceasing of
i
mother's milk production in humans
Atrazine also has been shown to have'
some endocrine-disruptor effects on
alligators and some strains of mice.
The Illinois Environmental Protection
Agency has published the list of
pesticides in Table 1 that have been
found to be known, probable, and
suspect endocrine disruptors. This list
was based on a search of the scien-
tific literature and is highly disputed
by some scientists and industry. It
does, however, serve as a basis for
refinement through appropriate
additions and deletions.
As can be seen in Table 1 , there are
several pesticides that are no longer
registered in the United States, such
as 2,4,5-T and the organochlorine
insecticides aldrin, chlordane, DDT,
dieldrin, endrin, heptachlor, and
toxaphene.
Table 1. Preliminary List of Chemicals Associated with Endocrine System Effects in Animals and Humans, as
of October 16, 1996.
Known
Probable
Suspect
atrazine (Atrazine)
chlordane (Chlordane)
DDT (DDT)
dibromochloropropane (Nemafume)
dicofol (Kelthane)
dieldrin
endosulfan (Thiodan)
lindane
methoxychlor (Marlate)
toxaphene
tributyl tin
alachlor (Lasso)
aldrin (Aldrin)
amitrole (Amitrole)
benomyl (Benlate)
2,4-D
endrin
heptachlor
hexachlorobenzene
mancozeb (Manzate, Dithane)
maneb
methyl parathion
metiram (Polyram)
mirex
parathion (ethyl parathion)
pentachlorophenol (PCP)
2,4,5-T
trifluralin (Treflan)
vinclozolin (Ronilan)
zineb
aldicarb (Temik)
carbaryl (Sevin)
cypermethrin (Ammo,
Cymbush, Demon)
esfenvalerate (Asana)
fenvalerate (Tribute)
malathion
methomyl (Lannate)
metribuzin (Sencor)
nitrofen
permethrin (Ambush, Pounce)
ziram
I
Illinois Pesticide Review
No. 3, November 1997
The U.S. Environmental Protection
Agency (US-EPA) currently requires
tests for effects on reproduction,
fertility, fetal development, birth
defects, and offspring growth and
development before a pesticide is
registered. Some older pesticides,
including some listed in Table 1, are
being reevaluated by US-EPA. The
Endocrine Disruptor Screening and
Testing Advisory Committee is
revising US-EPA's testing guidelines
for evaluating effects on reproduc-
tion and fetal development, which
should increase ability to detect hor-
mone-disrupting effects. This com-
mittee, which includes independent
scientists and industry reps, has a
report deadline of June 1998.
There is current debate on whether
the higher-dose, short-term studies
that US-EPA currently requires for
pesticide registration are applicable
to low-dose, long-term exposures
that wildlife and humans are likely to
experience once a pesticide is
registered. This issue becomes
stronger when endocrine disruptors
are involved. With both dicofol in
Lake Apopka and dioxin and PCBs in
the Great Lakes, the levels of these
chemicals in the water is within
approved standards and near or below
normal detectable levels. Yet preda-
tors near the top of the food chain
(alligators, lake trout, herring gulls)
are affected through
biomagnification.
Biomagnification allows some
chemicals, particularly fat-soluble
ones, to be retained in the body rather
than excreted. This retention contin-
ues as many individuals are eaten by
predators who themselves are eaten
by predators. By working through
several levels of predators (trophic
levels), the chemical that was con-
sumed initially in exceedingly small
amounts becomes concentrated in a
top predator. Add to this scenario that
hormones, and endocrine disruptors,
cause major effects in exceedingly
small amounts, and there is the p
potential for major effects to wildlife
and humans caused by very small
amounts in the environment.
Although several industrial chemi-
cals and no-longer-registered pesti-
cides appear to be more important
as endocrine disruptors at this time,
several labeled pesticides also ap-
pear to be involved. As the research,
debate, and rule-making continue,
the picture should become clearer.
The summary offered here is based
primarily on the following: presen-
tations at the National Pesticide
Applicator Certification and Train-
ing Workshop in Columbus, Ohio,
on June 12, 1997, and the National
Endocrine Disruptors Conference in
Chicago, Illinois, on July 14, 1997;
the publications Our Stolen Future
by Theo Colbom, Dianne
Dumanoski, and John Peterson
Myers ( 1 997), Endocrine Disrup-
tors Strategy by Illinois EPA (1997),
Pesticide & Toxic Chemical News
(Oct. 22, 1997), and Questions &
Answers: Potential of Chemicals to
Affect the Endocrine System by
USEPA (1996) were also used.
(Phil Nixon)
National PAT Conference — Additional Perspectives
Last issue we covered the Sixth
National Pesticide Applicator
Certification and Training Workshop
held June 9 to 12 in Columbus, Ohio.
In that article, I provided my take-
home message. Here are two more
personal take-home messages
providing the Private Pesticide
Applicator Training-perspective.
Bruce Paulsrud coordinates the PPAT
program in Illinois, and Bill Brink
conducts numerous PPAT programs
each year.
Bruce Paulsrud, Extension plant
pathologist: I was impressed with
the wide variety of sessions avail-
able. High technology, or low, there
was something for everyone. To me,
the most memorable and valuable
session was entitled "Private Appli-
cator Training — Where Is It
Headed?" Seven county agents from
five different states discussed their
educational programs, shared the
challenges they face, and voiced
their opinions of what PAT programs
should be in the future. Although
programs vary considerably from
state-to-state, it was an excellent
opportunity to generate new ideas. I
also witnessed the formation of the
Journal of Pesticide Safety Educa-
tion (JPSE). This electronic, peer-
reviewed publication will be avail-
able on the internet. Now we're
cookin' with gas! What a great
opportunity to interact with other
pesticide safety educators by sharing
research, program ideas, techniques,
and training material tips! The first
issue is scheduled for January 1998.
Even if you are not yet a member of
the American Association of Pesti-
cide Safety Educators (AAPSE),
your are invited to publish in the
JPSE. For more information, point
your Internet browser to .
Illinois Pesticide Review
No. 3, November 1997
Bill Brink, crop systems educator,
Springfield Extension Center:
Private Pesticide Applicator Training
(PPAT) is occurring in most every
state, but the methods and proce-
dures vary greatly among states and
even among counties within the
states. Some states require producers
to take and pass the test only once
and then compel them to have a
minimum number of continuing
education units (CEUs) each year or
each cycle for recertification. Not
every county will offer CEUs in all
the required subject-matter areas.
Therefore, producers needing specific
CEUs in different subject-matter
areas may have to attend several
meetings at several locations to
satisfy their needs. In some cases,
those meetings are production-type
meetings with specific pesticide and
crop recommendations.
The Illinois philosophy regarding i
PPAT is more on compliance rather '
than education on specific pesticide
recommendations. Illinois produc-
ers have to show a knowledge of
pesticide safety and handling by
passing an examination only once
every 3 years. This method seems
very adequate to satisfy the training
needs of farmers and is much less
complicated and more convenient
for everyone involved.
(Bruce Paulsrud, Bill Brink, and
Rhonda Ferree)
Spotlight on University of Illinois:
What's Ailing You (or, Rather, Your Plants)?
You're a pro at your job; you can
identify nearly any plant, pest, or
plant problem you encounter. And
you've seen a lot. However, who do
you turn to when the inevitable
happens, you're stumped? The
University of Illinois Cooperative
Extension Service and Plant Clinic
are here to help you answer the
tough questions.
The University of Illinois Plant
Clinic has served as a clearinghouse
for plant problems since 1976.
Services include plant and insect
identification; diagnosis of disease,
insect, weed and chemical injury
(field crops only); nematode assays,
and help with nutrient-related
problems, as well as recommenda-
tions involving these diagnoses.
Microscopic examinations, labora-
tory culturing, virus assays (per-
formed outside the Plant Clinic), and
nematode assays are a few of the
techniques used in the clinic. This
multidisciplinary venture involves
input from specialists in the areas of
botany, entomology, forestry, horti-
culture, mycology, plant pathology,
soils, soil fertility, and weed science,
as well as others as needed.
It is always best to try first working
through plant problems with your
local Cooperative Extension Service
educators. These folks have a better
idea of the local environmental
influences such as soil type, weather
conditions, or other factors that
might influence plant health. Use the
Plant Clinic for specialized or unique
situations and consultations.
How do you use the Plant Clinic?
The first step is collecting the
sample. Although the process is
often times quite obvious, remember
that an unrepresentative or minimal
sample (for example, a single leaf)
reduces the prospect for an accurate
diagnosis. Once you have a represen-
tative sample, what is the best way to
get it to the clinic? Think about the
type of sample you are sending, how
long it will take to arrive, and the
environmental conditions during its
transport. The biggest problem
4
encountered with mailed samples is
that they rot during transport because
they are sent in a sealed plastic bag.
If you have questions regarding |
sampling or packaging, please call
the Plant Clinic for instructions.
One last, and critical step, complet-
ing the sample submission form. You
may obtain a sample form from your
local Extension office or from the
Plant Clinic directly. The
diagnostician(s) must have a thor-
ough understanding of your plant
problem. Describe the site in detail
and the environmental conditions
preceding the problem as best you
can. Photos showing the plant(s) in
their environment are greatly appre-
ciated!
The diagnostic fee is $10 for most
samples, $15 for specialty tests (for
example, soybean cyst nematode,
pinewood nematode, or virus test)
and $30 for all other nematode tests.
Starting in 1998, the diagnostic fee i
must accompany the sample. You '
will receive a letter, usually 7 to 10
I
Illinois Pesticide Review
No. 3, November 1997
working days after sample submis-
sion, that explains the sample
diagnosis and other appropriate
information. The Plant Clinic is open
from May I to September 1 5 and is
located on the South Farms of the
Champaign Urbana campus. The
address is
Plant Clinic
1401 W. St. Mary's RD
Urbana, IL 6 1802
(217)333-0519
(Bruce Paulsrud and Nancy Pataky)
FQPA Update
I recently attended the 2nd Pacific
Northwest Pesticide Issues confer-
ence held October 22 in Yakima,
Washington. The conference was
hosted by Washington State Univer-
sity, and the topic of the day was the
Food Quality Protection Act
(FQPA) — an EPA status update and a
discussion of some of the major
provisions such as the "Risk Cup"
and "Common Mechanisms of
Action."
Because a summary of the entire
FQPA was published in the August
1996 issue (Vol. 9, No. 3) of this
newsletter, I will only discuss some
of the FQPA issues here.
Before describing these new provi-
sions, let's consider how the EPA
assessed risk and set food residue
tolerances before passage of the
FQPA in August of 1996. Basically,
the EPA assessed pesticide exposures
separately by source and did not
combine risks from similar sources.
For example, although residues of
pesticide "A" may be found in a
particular food product you eat, the
risks from exposure to pesticide "B,"
a compound with similar impacts on
human health, was not considered as
part of the total risk. Any risks from
pesticide "B" would be considered
separately from those of pesticide
"A." In other words, the EPA was
including only some percentage of
your actual exposure to potential
health risks from similar sources.
Keep in mind that there are (and will
continue to be) large safety factors
included in the risk-assessment
process to offset this limitation. It is
relatively rare to find foods with
pesticide residues above their legal
tolerance level.
The "Risk Cup"
The new "risk cup" provision
requires the EPA to combine (aggre-
gate), where applicable, nondietary
exposures with dietary exposures
and to group compounds that are
expected to have similar impacts on
human health. A risk cup considers
all exposure to a particular pesticide
or group of pesticides that a person
may experience, not just those in
food. There are numerous potential
nondietary pesticide exposures, such
as drinking water, residential lawns,
golf courses, parks, garden plots,
ornamental plants, pools, paint and
wood preservatives, indoor applica-
tions, pet applications, pesticide
drift, dust from farm fields, etc.
Imagine the task of obtaining all
these nondietary exposure estimates.
In light of all these additional
potential exposures, how would you
logically assign a new residue-
tolerance level for a food commod-
ity?
Basically, EPA is approaching this
question based on the concept that
the total level of acceptable risk to a
pesticide is represented by the
pesticide's reference dose (RfD). The
RfD is the level of exposure to a
specific pesticide that a person could
receive daily for a period of 70 years
without significant risk of long-term
or chronic, non-cancer health effects.
The analogy of a "risk cup" is used
to describe aggregate (combined)
exposure estimates. Picture a coffee
cup: It can accept only a certain
amount of coffee, just as it has been
determined that a person can safely
tolerate a certain amount of risk due
to a certain pesticide (that is, the
RfD). Each pesticide use contributes
some amount of risk to the cup. Start
filling! If the cup becomes full
before all the risk is added, pesticide
uses must be deleted. If the cup has
room after all existing risk is added,
more pesticide uses may be safely
added. What happens when there are
no (or limited) estimates for
nondietary exposure to a certain
pesticide? In such cases, EPA will
decide that the cup can be filled to
only 80 to 95% of capacity (80 to
95% of the RfD) to conservatively
allow for the lack of data. As you can
see, collecting this data may increase
the "room" in this cup, possibly
allowing additional (or saving)
pesticide uses. However, collecting
nondietary exposure data is not easy;
for an example of this type of data
collection, consider reading "Lawn
Pesticides Tracked Indoors" (Illinois
Pesticide Review, April 1997, Vol.
10, No. 2).
Common Mechanism of Action
The basic idea of this provision, as
eluded to above, is that if two or
more active ingredients have the
same toxicological endpoint and are
structurally similar, the EPA will
assume they have a common mecha-
nism of toxicity. Thus, from a risk
standpoint, they would share the
same risk cup. As you can imagine,
certain risk cups will become
crowded and overflow very quickly
under this provision. During the
Illinois Pesticide Review
No. 3, November 1997
conference in Washington, there
were a couple of major questions
raised regarding this risk assessment
approach. First, what exactly, is a
"toxicological endpoint" and second,
how exactly, is structural similarity
evaluated and is it a reliable and
appropriate indicator for this pur-
pose?
The organophosphate and carbamate
insecticide families provide a good
example here, especially because
they are at the top of EPA's
reregistration decision list. We know
that exposure to products in either
family affects the nervous system. Is
that the toxicological endpoint? If it
is, then those products share com-
mon mechanisms of toxicity with the
pyrethroid insecticides, and all three
insecticide families may be placed in
the same risk cup. However, we also
know that the organophosphate and
carbamate insecticides act by bind-
ing with an enzyme called acetylcho-
linesterase, while the pyrethroids do
not. Now, from a molecular stand-
point, there appears to be justifica-
tion to combine the organophosphate
and carbamate insecticides in one
risk cup and the pyrethroids in
another. Of course, in all cases, the
final decision of whether or not to
group will be based on structural
similarity.
In many cases, we don't know
exactly how a pesticide works in
mammalian systems. The EPA is
using caution with this provision and
will revisit its interim decisions as
the scientific knowledge-base grows.
Take-Home Message
As the risk cups overflow, which
uses will be lost? Simply stated,
pesticides with an overflowing risk
cup will likely "shed" the least
profitable uses from the label until
they are in compliance with the
amended laws. What does that mean
for minor-crop and minor-use pest
management? Consensus at the
conference in Washington was that
minor crops will lose many impor-
tant pesticides (particularly insecti-
cides, and to a lesser extent, fungi-
cides). However, there are many
provisions in the FQPA amendments
that directly address this issue, and
there are many new, safer products in
the "pipeline." In the meantime, stay
tuned and keep yourself informed.
(Bruce E. Paulsrud; additional
source, EPA Pesticide Registration
Notice No. 97-1)
Pesticide Update
The following infonnation provides registration status of particular pesticides and should not be considered as
pesticide recommendations by Illinois Extension.
Agronomic
Dekalbt, DeKalb Genetics
New active ingredient, which is com
that contains the B.t. gene.
Dekalb Genetics
The company will be the first to
introduce Roundup Ready com into
the market for the 1998 growing
season.
Magnate (imazalil), Makhteshim
New trade name for this wheat and
barley seed treatment.
V-53482 (flumioxazin), Valent
New soybean broadleaf herbicide to
be registered in 1999.
Many
Daza (dihydroazadirachtin), Thermo
Trilogy
New active ingredient for indooor
and outdoor use on ornamentals, turf,
agronomic, and horticultural crops.
Kocide 2000 (copper hydroxide),
Grijfin
Changed signal word from "danger"
to "warning."
Mitac WP (amitraz), AgrEvo
Deleting registration, effective 2-23-
98.
Morestan 25% WP (oxythioquinox),
Bayer
Deleting registration, effective 2-23-
98.
Pentac (dienochlor), Novartis
Due to the high cost of re-registra-
tion, this product will be canceled,
effective 1-12-98.
Other
Dow Chemical Co.
The company will change the name
for its agricultural chemical group
from DowElanco to Dow Agro
Sciences, effective 1-1-98.
Illinois Pesticide Review
No. 3, November 1997
»
»
Zeneca
The company will sell its Devrinol
(napropamide) business to United
Phosphorus.
Structures
Nylor JOEC (pyriproxyfen), MGK
Inc.
New product to control cockroaches
indoors.
Tlirf/Ornamental
Central Garden & Pet
This company purchased the insecti-
cides Mavrik and Enstar from
Sandoz.
Conserve SC (spinosad), DowElanco
Received EPA registration for use on
turf and ornamentals, to control leaf-
eating insects.
Cyclocel (chlormequat chloride),
American Cyanamid
Added use on marigolds and garde-
nias.
Cygnus (kresoxim-methyl), BASF
New fungicide for use on ornamen-
tals.
Dimension (dithiopyr), Rohm &
Haas
Added over 150 ornamental plants.
Hormodin (IBA), The Geiger Co.
New product, for use on ornamental
plants to improve rooting.
Medallion (fliidioxinil), Novartis
New product, to control root and
stem diseases on ornamental plants.
Simspray Ultra Fine Oil (petroleum
oil), Sun
Added 1 6 new ornamentals.
Terraclor 75% WP (PCNB),
Uniroyal
Added use on vegetable bedding
plants and additional ornamentals.
Vegetable/Fruit
Champ Formula 2 (copper hydrox-
ide), Agtrol
Added use on parsley and watermel-
ons.
Comite (propargite), Uniroyal
Added dry lima beans.
Di Terra ES (Myrothecium spp.),
Abbott Labs
Biopesticide receiving EPA registra-
tion to control nematodes on cole
crops and grapes.
Lepinox (B.t. strain EG-7826,
Ecogen
New active ingredient (formerly
Crystar), to control lepidoptera
insects.
Monitor (methamidophos), Bayer/
Valent
This product will now be marketed
on only three crops: cotton, potatoes,
and tomatoes.
Omi-88, Mitsubishi
New insecticide for use on cole
crops; vegetable and fruit crops.
Ronilan (vinclozolin), BASF
Approved to control white and grey
mold on snap beans.
Sovran (kresoxim-methyl), BASF
New fungicide, for use on apples,
grapes, pears, and cucurbits.
Terraclor F (PCNB), Uniroyal
Added use on vegetable bedding
plants and hot peppers.
(Rhonda Ferree; unless other noted,
adapted from Agricultural Chemical
News, August 1997, September 1997,
and October 1997)
)
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industry & fruit and vegetable producers
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No. 22 • November 26, 1 997
PLANT DISEASES
1997's Most Common Plant Diseases
The Bi-State Horticulture Conference in Moline on
November 5 was the rebirth of an annual conference
to address the concerns of landscapers in the northern
areas of Illinois and Iowa. Among others, I was asked
to speak at the conference with my Iowa Plant Clinic
counterpart, Paula Flynn. Our topic was the ten most
common tree and shrub disease problems in 1997.
The diseases we chose to discuss (not in order of
importance) were cedar-apple and related rusts,
anthracnose, oak wilt, Verticillium wilt, ash decline,
Sphaeropsis blight of pine, Rhizosphaera of spruce,
Cytospora of spruce, black knot of plum, and environ-
mental or abiotic disease.
Of course, Paula and I had a time limit to consider
for our talk, but based on what I saw at the Illinois
clinic this year, I would probably add Phytophthora
root rot, Phomopsis of juniper, pine wilt, white pine
decline, and Dothistroma/brown spot on pine to this
list. If you are aware of other diseases that were
particularly bothersome, drop me a line and I will
make time this winter for literature searches and to
prepare material for next year's Home, Yard and
Garden Pest Newsletter. It is not always possible to
do a thorough job researching articles in the midst of
the busy clinic season. Send in your ideas now so that
we can better serve you. (Nancy Pataky)
Changes at the Clinic for 1998
The 1997 season was a good one at the Plant Clinic in
terms of sample volume — we handled just over 3,000
samples this year. In terms of turnaround time, it was
one of the worst years in the past twenty. Part of the
reason for our problems was the timing of the greatest
influx of samples. Because of the extended cool, wet
spring and early summer, plant problems were thriv-
ing for all of June and half of July. Generally the heat
of summer slows things down enough that clinic staff
can catch up. That never happened this year and we
were behind from mid- June to closing.
Action has been taken to try to increase staffing for
1998. Nothing has been promised, but hopes are high
for additional help in the areas of plant pathology,
entomology, and weed science.
Beginning in 1998 payment must accompany the
samples. We do not have a separate billing office at the
clinic and to institute one would double existing fees.
Far too much staff time is spent on billings and associ-
ated paperwork. Payment sent with the samples should
free up office staff to help decrease turnaround time.
As you know, insect samples were also processed
at the clinic this year and will continue for 1998.
These samples will be subject to the same $10 fee.
Insect samples are handled by entomologists, but the
paperwork and letters are processed by clinic staff.
We look forward to a more efficient season in 1998
and encourage any helpful suggests you can offer.
Send them to Nancy Pataky at N533 Turner Hall,
1102S. Goodwin, Urbana, IL 61801 or
npataky@uiuc.edu. (Nancy Pataky)
Home, Yard and Garden Pest Newsletter is prepared by Extension specialists from the University of Illinois at Vrbana-
Champaign and the Illinois Natural History Survey. Information for this newsletter is gathered with the help of staff
members, Extension field staff, and others in cooperation with the USDA Animal and Health Inspection Service.
Major authors are Phil Nixon, (217) 333-6650 and Fredric Miller, (708) 352-0109, entomologists; Nancy Pataky, plant
pathologist, (217) 333-0519; Rhonda Ferree, Tom Voigt, and David Williams, horticulturists, (217) 333-0350, and Karel
Jacobs, plant pathologist. The Morton Arboretum, (630) 719-5646. Phil Nixon is the executive editor of the Home, Yard
and Garden Pest Newsletter. This newsletter is written by faculty in the Department of Natural Resources and Environ-
mental Sciences and the Department of Crop Sciences.
/\o. zz • isovemoer zo, i yy/
Index
Horticulture
Aquatic vegetation 6:1
Broadleaf weeds in turf 5:3
Command drift 7:4
Deer, plants avoided by and resistant to 22:2
Drift, of Command herbicide 7:4
Fertilization, tree and shrub 20: 1
Ground ivy, control of 4:4
Internet resources for Northern Illinois 3:2
New publications, Illinois Agricultural Pest Manage-
ment Handbook 4:1; Illinois Commercial Land-
scape and Turf Pest Management Handbook 4: 1 ;
Illinois Homeowners ' Pest Management Guide 4: 1 ;
Pest Resistant Ornamental Plants 3:4; Plant Health
Care for Woody Ornamentals 15:2
Pesticide safety program 8:6
Pesticide storage 21:4
Spring cleanup, preparation tips 1:2
Turf broadleaf weeds 5:3
Turf growth in cool temperatures 3:1
Watering landscape plants 17:1
Wildflowers3:l
Winter preparation, ornamental plants 22:1
World Wide Web 22: 1,20:1
Workshop(s), Bi-State Horticulture Conference 22:5,
21 :4; Midwest Plant Health Care 2: 1 ; Woody
Plants and Pest Diagnosis 2:1
Insects
Ants, carpenter 13:2
Aphids 11:2, 9:1, 8:4; woolly 12:4
Army worms 10:2
Ataenius, black turfgrass 6:2
Bagworm(s) 17:2, 11:1,9:2,8:4
Bees 4:2
Beetle(s) elm leaf 5:5; Japanese 16:3, 14:2, 13:1,
12:3; locust leafminer 2:2; multicolored Asian
ladybird 1:3; pine cone 5:5; strawberry root weevil
16:3
Borer(s) 16:3, appletree 16:4; bronze birch 16:4, 8:3,
5:5; lilac/ash 10:3, 9:2, 5:4; locust 18:4; peach tree
10:3; Zimmerman pine moth 16:4, 5:5
Cankerworm 8:4, 6:2
Casebearer 12:3
Caterpillar(s), bagworm 17:2, 11:1, 9:2, 8:4; canker-
worm 8:4, 6:2; eastern tent 6:2, 2:1; fall webworm
16:3, 10:4; mimosa webworm 10:4, 9:2; pine
sawfly 6:2; spiny elm 13:1; ugly nest 18:4; walnut
13:1, 10:4, 9:2; white-marked tussock moth 9:2,
8:4, 6:2; yellow-necked 13:1, 10:4, 9:2;
Zimmerman pine 5:5
Cicada(s), dog day 15:1: periodical 10:3, 9:1, 5:5
Cicada killer(s) 15:1
Defoliators 13:1
Grub(s), annual white 17:1, 16:3, 15:1, 14:4, 13:1,
12:3; spring control of 3:3; true white 6:1; white
20:3, 19:1,18:3
Leafhopper(s), potato 11:1,9:1,8:3,6:2
Leafminer(s), birch 10:4, 5:4, 2:2; elm 10:4; hawthorn
2:2; holly 10:4, 2:2; locust 10:4, 2:2; oak 2:2
Lloyd, J., farewell 19:1
MACH 2, registered for turf 8:6
Mealybug, Taxus 5:4
Mite(s), hemlock eriophyid 6:3; spruce spider 6:2, 3:2
Moth(s), gypsy 21:2, 18:2, 8:4; oak leafminer 2:2;
white-marked tussock 9:2, 8:4, 6:2; Zimmerman
pine 5:5
Nixon, P., and J. Lloyd, new office 1:3
Plant bug(s), ash 9:1, 6:2; four-lined 9:1; honeylocust
9:1,6:2,4:1
Plant Clinic to handle insect IDs 2:1
Rose pests 8:5
Royer, T., moves to Oklahoma 1 :3
Sap-feeding arthropods 6:2
Sawfly(ies) 12:3; birch leafminer 11:1, 2:2; European
pine 5:5; hawthorn leafminer 2:2; pine 6:2, 2:2
Scale(s), euonymus 8:3; European elm 8.3; magnolia
19:2; oystershell 8:3, 6:2, 5:3, 5:5; pine needle
20:3,8:3,5:4
Scouting 11:2,8:3,7:1, 1:4
Spider(s), ballooning 21:2
Sucking insects 9:1
Tissue damage and "phantom" insects 6:3
Turf insects 6:1
Webworm(s), fall 16:3, 10:4; mimosa 13:1, 10:4, 9:2;
sod 18:3,8:3,6:1
Weevil(s), black vine 12:3, 5:5
No. 22 • November 26, 1 997
Plant Diseases
Anthracnose 9:3, 8: 1 , 6:3; of shade trees 4:3
Apple tree, pruning 20:3
Black knot, of plum and cherry 8:2
Blight, cane, of brambles 20:2; fire 10:1, 4:3; seedling
7:2; Sphaeropsis, of pine (formerly Diplodia) 9:3,
1 :2; tip, of juniper 5:2; Vinca stem 6:4; Volutella
leaf and stem, of pachysandra 7:3
Brown patch, Rhizoctonia, of turf 17:4
Cankers, cytospora, of spruce 6:3; rose cane 18:2;
Russian olive 13:3; trees and shrubs 18:1
Crown gall 12:1
Damping off, of seedlings 7:2
Disease, unknown causes of 19:4
Diseases, most common in 1997 22:5
Dutch elm disease 1 1 :3
Fungicides, sodium bicarbonate (baking soda) 3:4,
2:4; terminology 19:2
Gall(s) 7:1, crown 12:1; Phomopsis 10:2
Good Guys! Natural Enemies of Insects, The (new
publication) 15:2
Leaf blister 5:2
Leaf blotch, Guignardia 17:3, 8:1
Leaf curl 8:1, 5:2
Leaf disease, of peony 16:2
Leaf problems, late season 19:3
Leaf scorch, of trees 12:2
Leaf spot(s), bacterial, of stone fruits 13:2; common
8: i ; English ivy 8:2; frogeye 1 1 :4; turf 9:3
Mildew, powdery 15:3, 11:3
Mold(s), gray, of strawberry 5:1; Sclerotinia white
13:3; slime 10:2
Needle cast, Rhizosphaera, on spruce 8:1, 3:4
Plant Clinic closes 18:1, opens 1:1, what's new, 2:3
Plant disease fact sheets 3:3
Powdery mildew 15:3, 11:3
Red thread, of turf 8: 1 , 6:4
Roots, diagnosing problems in tree 16:1
Root rot, black, of strawberry 15:3; Rhizoctonia, of
flowers 16:2
Rose rosette 12:1
Rot, bacterial soft, of iris 5:1; blossom-end, and
sunscald 15:4; brown, of stone fruits 15:3
Rusts, cedar-apple sporulation 2:3; cedar quince 8: 1 ;
turfgrass 15:2
Scab 8:1; crabapple 7:3
Scouting 8:1
Turf disease 2:3
Turf, leaf spots 9:3
Turf, workshops and events 21:1
Viruses, of brambles 14:2
"Wet feet," of trees, shrubs, and flowers 9:4
White pine problems 12:2
Wilts(s), bacterial, of cucurbits 17:3; oak 10:1; pine
21:1, 17:3, 8:1; tomato 14:1; Verticillium 8:1, 7:3
Winter preparation, and disease prevention 20:2
Witches' brooms 14:2
yellows, aster, of annuals and perennials 13:2
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