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| Che Forest Insect
Disease “Situation
Lalee States, 1957
LIBRAR\
LrPAR
MAY 1 2 1¢58
- S. DEPARTMENT OF AGRICULTURE
On eeennn
ee
: 1958
TATION PAPER NO. 60 APRIL
FOREWORD
Forest insects and diseases are ever-present threats to Lake States tim-
ber resources. Past losses in tree growth and mortality are indicative
of how destructive such pests have been and may continue to be in the
years ahead. To appraise adequately the regionwide insect and disease
situation, the Lake States Forest Experiment Station summarizes each
year the information on the current status of insect infestations and
disease infections.
To prepare such a report it is essential that use be made of all avail-
able information. Many individuals, State organizations, and forest in-
dustries have been helpful. Their active and willing cooperation is
gratefully acknowledged. Special acknowledgment is made of the informa-
tion and help given by the following.
Michigans:
Division of Forestry, Conservation Department
Bureau of Plant Industry, Department of Agriculture
University of Michigan
Michigan State University
Minnesota:
Division of Forestry, Conservation Department
Office of State Entomologist, Department of Agriculture
University of Minnesota
Wisconsin:
Forest Management Division, Conservation Department
Office of State Entomologist, Department of Agriculture
University of Wisconsin
Copies of the report may be obtained from the Lake States Station, who
collected some of the original material, summarized all information,
and processed the report.
Cover: Drawing represents an adult Saratoga spittlebug; photograph
shows damage to red pine twigs with bark removed.
THE FOREST INSECT AND DISEASE
SITUATION
LAKE STATES, 1957 .
Donald C. \Schmiege
and
Ralph L. (Anderson
Station Paper No. 60
April 1958
eS Lake States Forest Experiment Station
~ U.S Forest Service, U.-S. Department-of-Agriculture
~ 5*St. Paul 4, Minnésota
— - ‘
M. B. Dickerman, Director
-
os
ny
-
1°
-
CONTENTS
Page
FOREWORD). 72 e005) os WS iC ERO GUO OCU DOD OREO OL siooeees LnSszde front cover
INTRODUCTION....... SIG Cie OI ORC OEE OUI GET OtIO Oe Doli Oo Le 1
HIGHGIGHES: FOR 1997. 3. 2. 23 se SOOO USD OUD OODO CO Dm OO ODOOUO OOo ac ane aL
TIS © CIE Sieites a osloce se! ol's.eheljereejie lool) etelslis/e ef'sl/aleia 6 401016 e101 s, 66 61s 616. © « ores ioe avereie aL
Review of major insects........ Sietekekelalsioleleletelele i eleiers Soo aaa Go 1
Two insects are potential threats... ccreceresvsevvesevee 2
DAUSCASCSieispcleevetolelsioicialels oletolelec)clslsis «el eie AOU OOS od oat SOUSA ase s
Several new disease problems were noted in 1957........... 2
Changes in prevalence and severity were noted
EOGESOME sOdisCASCS letters setei el cielateencicielevcls ioielleleie/sue sieiste islet els) sielsrs 4
The status of some other diseases merits mention..... SG Oe “E
THE MOST IMPORTANT FOREST INSECTS IN 1957.....cceceeecvee 4660 65% 5
Spruce budworm=--epidemic situation continues............ oe +3)
Jack=pine budworm=——population declineS.......ccecccccevvece 6
European pine shoot moth--extends range......cceeccecveoee 6
Saratoga spittlebug=-=-continues as major pest.......... ayaiote 8
White=pine weevil--causes degrade and volume loss...... plete 9
Pine sawflies-=-populations increase in some plantations... 9
Larch sawfly~-defoliation over wider area......ccecseeeeee- LO
Root collar weevil=--becoming more important..... Yosecaodoog ~All
Gypsy, moth=——control, program SUGCCESSTIUL . ccscciccessseccesces LS
Forest tent caterpillar--population increase predicted
LM SCAGtLCTeG ATCAS sss cre sets 0 «0 sie) sic lls iele! eels) ster sel oletels tomo. ls:
Hardwood defoliators=-—five species are active............. 13
THE, MOST IMPORTANT FOREST DISEASES. EN 1957.25.06 os ccc coe cess wes 14
Maple blight as causing much Concern. ...ssccceccsctee ooo ke!
Black spruce root rot caused severe losses......... eccesse 14
Leaf blight of honeysuckle is common
IN ONOTEH Dakota MUrSCTiICS 4 sic oss 2106 01014. 6618 «<5 60/0 6s 0 big eee’ 15
A root rot of Russian olive was found in North Dakota..... 15
An unidentified canker of jack pine was found............. 15
The vigor of many elms was below normal 2...000.600s ste 6s 16
A sudden growth reduction was noted in some
red) pane plantatvOns.. «.0< css + Suohiafelisvereiievelel ofevoholoveneleneisieienctc ammnel ©
Birch decadence was less severe in 1957.6 icseccscccssecses L6
Needle droop of red pine was unusually severe....e.eseseee 17
A gradual deterioration and dying of white pine
WaSemOre mprevaie nity HAMM US Ua lcci ecenclcle oie (oes si etsle oie ceustse atevomeeled)
Jack pine - sweetfern rust is common in some
PLANET AGVONS crelccencterercteieteiete ol leuereners olloitol sls folairel o) clone! oleh een sions
Jack pine = comandra rust was found in one area........
A canker is very prevalent in poor red pine
plantations........ eretelshelsieieisiotele ole SapessoooonoGnne
Heart rot appears important in Russian Olive........
Hypoxylon canker continues to cause severe mortality
White pine blister rust prevalence is related
to MUCrOCTaAmMave 2.00. ois cc chels oo icle ve sie lelererelee7s see) e106
Oak wilt damage is intensifying... ..cecscrcrcccccces
Dutch elm disease has not been found in Minnesota......
Cause of oak mortality in northwestern Wisconsin
MUST MIN KMOWMsyerc 1 srersisicie a even sEshoichekoichonenorstchoqcnstclonenonshels oc
THE FOREST INSECT AND DISEASE SITUATION
LAKE STATES, 1957
by
Donald C. Schmiege and Ralph L. Andemson= 4
INTRODUCTION
Insects and diseases play an important part in the reduction of our vast
forest resource. Each year they cause large losses in timber growth and
result in tree mortality. But that is not all: These agents attack the
forest from seed to finished product. Stocking levels are lowered,
growth is retarded, and trees are deformed, thus reducing both quality
and quantity of forest products. The protection of our forests against
these destructive agents is the responsibility of everyone concerned witi
the national economy.
This report summarizes the information collected by many agencies and in-
dividuals on the forest insect and disease situation during 1957 in the
Lake States. The most important aspects are presented briefly in the
next few pages. For more detailed discussion see sections on The Most
Important Forest Insects (or Diseases).
HIGHLIGHTS FOR 1957
Insects
Review of Major Insects
Insect infestations in 1957 were characterized by fluctuations in popula-
tions and damage. Weather conditions and parasites play important roles
in declines in infestations.
Spruce budworm populations increased again in northern Minnesota, and de-
foliation was very noticeable over a wider area in the spruce-fir stands
along the Canadian border.
1/ Entomologist and pathologist respectively, Lake States Forest
Experiment Station. The Station is maintained at St. Paul 1, Minn., by
the Forest Service, U. S. Department of Agriculture, in cooperation with
the University of Minnesota.
Jack=-pine budworm infestations declined in many stands because of the in-
fluence of natural factors. The acreage sprayed in Wisconsin was reduced
very materially from that originally scheduled following appraisal sur-
veys in 1956.
Continued heavy larch sawfly defoliation caused an increase in tamarack
mortality in the tamarack bogs in Minnesota. Heavy defoliation was no-
ticeable wherever tamarack occurs in northern Wisconsin and Upper Michi-
gan.
The Saratoga spittlebug remained a serious pest of red pine plantations
in Michigan and Wisconsin. Although a hard freeze in mid-May reduced
nymphal populations in northern Wisconsin and the western part of Upper
Michigan, control operations were necessary on over 12,000 acres of plan-
tations south and east of the "freeze area."
The European pine shoot moth increased its range in Wisconsin and Upper
Michigan. Serious damage to plantations occurred throughout the range,
particularly in Lower Michigan.
The white-pine weevil caused losses in growth, and reduction in quality
in many plantations of white and jack pine and Norway spruce. Reports
of attacks on red pine are increasing annually.
The pine sawflies are a threat to all pine plantations. The red=-headed
pine sawfly is apparently increasing in abundance, and defoliation was
reported from numerous places in Michigan and Wisconsin.
Two Insects Are
Potential Threats
From time to time insects considered of minor economic importance become
noticeable in this region or may be collected for the first time.
The European spruce sawfly, an important defoliator of spruce in northern
New England and eastern Canada about 20 years ago, was collected in nor-
thern Wisconsin for the first time.
The pine root collar weevil is causing increased damage to pine planta-
tions throughout the Lake States. This insect is a primary pest of pines
on good sites on light well-drained soils as well as on the poorer sites.
As extensive areas of our pine stands reach susceptible size we can ex-
pect more damage by this insect.
Diseases
Most of the common tree diseases causing damage in this region are not
subject to as pronounced buildups and declines as are many of the insects.
For many diseases, the 1957 situation is essentially unchanged from that
for other years during the present decade. In last year's report the
overall disease situation in the region was presented .2: In this year's
report attention will be limited to new diseases, marked changes in preva-
lence, and other new information on disease situations.
Several New Disease Problems
Were Noted in 1957
Maple blight caused severe mortality of hard maple in a northeastern Wis-
consin area. The cause of this mortality and its future potential for
serious damage are unknown. Plans are being made to study the problen.
Black spruce root rot killed about 50 percent of the black spruce trans-
plant stock in three nurseries this summer. The symptoms are those of a
root rot, but the actual cause is not known.
Honeysuckle leaf blight was found to be quite severe in some North Dakota
nurseries. This disease is caused by Glomerularia lonicerae.
Russian olive root rot was found on much of the stock in a North Dakota
nursery. Some of the trees died, but most of them recovered.
Jack pine cankers were noted on the Chippewa National Forest. The cause,
distribution, and importance of the disease have not been determined.
Poor vigor of elms was quite prevalent in Minnesota. It is believed that
this was caused by abnormally deep freezing of the soil last winter.
A sharp decline in red pine growth was noted in some Upper Peninsula of
Michigan plantations. No cause for this decline was apparent.
Dying of oak was noted in northwestern Wisconsin. Although the symptoms
are similar to those of oak wilt, the cause is believed to be some other
factor.
2/ Beckwith, L. C., and Anderson, R. L. 1956. The forest insect
and disease situation, Lake States, 1956. U.S. Forest Serv., Lake States
Forest Expt. Sta., Sta. Paper 42, 26 pp., illus.
Changes in Prevalence and Severity
Were Noted for Some Diseases
Birch decadence was not as severe as last year in tne Upper Peninsula of
Michigan. Most of the affected trees seemed to be holding their own or
recovering.
Needle droop of red pine was unusually severe in northern Minnesota, Wis-
consin, and some parts of the Upper Peninsula of Michigan. Some planta-
tions suffered serious damage.
A gradual deterioration and dying of white pines appeared to be more
prevalent than usual. This is sometimes referred to as needle blight,
but the symptoms appear more like those of the chlorotic dwarf disease.
The Status of Some Other
Diseases Merits Mention
Jack pine - sweetfern rust was found to be prevalent in additional plan-
tations, and some evidence of nursery infection was noted.
Jack pine - comandra rust was found on some jack pine in a localized
area. This disease does not appear to be common in the region.
Red pine cankers were found to be prevalent in Upper Peninsula of Michi-
gan plantations that have low tree survival and a generally unsatisfac-
tory appearance. The cause and whether tne disease is primary or secon-=
dary are unknown.
Heart rot of Russian olive appears to be an important factor limiting
the effective life span of this species in shelterbelt plantings.
Hypoxylon canker of aspen continues to cause severe mortality, but very
few new infections appeared in 1957.
White pine blister rust damage is localized in the southern parts of the
region. Apparent long-distance spread is a problem on some areas in the
northern part of the region.
Oak wilt damage appears to be intensifying at a relatively constant rate.
Dutch elm disease has not been found in Minnesota, but there is consider-
able apprehension about its invading tne State.
ny
THE MOST IMPORTANT FOREST INSECTS IN 1957
The status of the major forest insect pests in the Lake States is out-
lined in the following pages. Only those of primary importance are dis-
cussed in detail. Brief mention is made of some of the less important
species.
Spruce Budworm=--
Epidemic Situation Continues
During 1957 populations of the spruce budworm (Choristoneura fumiferana)
increased considerably in Minnesota. Approximately 660,000 acres of bud-
worm susceptible types were moderately to heavily defoliated, an increase
of 36 percent over 1956 (fig. 1). Within the northeastern section of the
State extensive stands of spruce and fir have suffered at least 2 years
of severe feeding. Surveys carried out in 1957 indicate that these and
adjacent stands will be seriously defoliated in 1958.
Severe defoliation was reported in 1957 in Wisconsin for the first time:
Scattered small areas were observed from the air in Washburn and Polk
Counties. Populations in Michigan remained at a low level. In general,
the scattered occurrence and the variation in size, age, stocking, and
mixture of balsam fir in stands in Michigan and Wisconsin make the pos-
sibility of a widespread outbreak unlikely.
ONTARIO
Figure 1.--Areas
of defoliation
by the spruce
budworm in nor-
thern Minnesota,
1957; based on
aerial survey.
Jack=Pine Budworm--
Population Declines
The jack-pine budworm (Choristoneura pinus) populations declined in most
of the areas in Wisconsin and Minnesota. New areas of light defoliation
were found in the Upper Peninsula of Michigan. Many stands in the Lower
Peninsula sustained moderate to heavy feeding.
In Wisconsin high larval populations were largely controlled by natural
factors. The control program, which was originally set up for some
200,000 acres, was carried out on only about 40,000 acres. Aerial sur-
veys in August indicated that defoliation in the unsprayed areas nad been
light, except on the periphery of some of the sprayed blocks and in un-
sprayed scattered stands and areas along streambanks. No control opera-
tions are anticipated in 1958 in Wisconsin.
The infestation in Minnesota generally declined and in some instances
completely collapsed. Because of this, very little control work was con-
ducted. Approximately 500 acres was sprayed by air in Crow Wing, Hub-
bard, and Beltrami Counties by the Conservation Department. An addi-
tional 500 acres of State land was sprayed in the southern end of Hubbard
County by the Conservation Department. Most of this consisted of jack
pine plantations that had been severely defoliated in 1956 and contained
a high population again in 1957. DDT was used for all the aerial con-
trol. Feeding was observed for the first time in the Beltrami Island
State Forest and in the Superior National Forest north of Trout Lake and
northwest of Virginia. Defoliation was moderate, and no control is con-
templated for 1958.
A control operation in 1958, involving about 2,500 acres of jack pine
plantations as well as natural stands, has been proposed on the Tawas
Ranger District of the Lower Michigan National Forest. Surveys will be
carried out in the spring of 1958 to determine the actual acreage need=-
ing treatment.
European Pine Shoot Moth-=
Extends Range
The European pine shoot moth (Rhyacionia buoliana) is one of the most
serious pests of red and Scotch pine in Michigan and Wisconsin (fig. 2).
This pest has increased its range to additional counties in both States
during the past year (fig. 3). It can be found in most of the counties
in Michigan's Lower Peninsula and in Houghton, Mackinac, Schoolcraft,
Luce, and Chippewa Counties in the Upper Peninsula. Natural red pine
stands as well as plantations are being attacked.
Figure 2.--Damage to red pine caused by the European pine shoot moth.
Extensive research studies are being conducted on this insect in this
country and Canada. Control remains very difficult. Some of the tests
using varying amounts of insecticides show promise. The timing of appli-
cation, dosage rate, and method of application are important factors.
Chemical control on limited areas will be conducted in 1958.
Figure 3.--
General area of
European pine
shoot moth in-
festations,
Lake States,
E957 «
l
Saratoga Spittlebug--
Continues as Major Pest
The Saratoga spittlebug (Aphrophora saratogensis) continued as the major
pest in red pine plantations in northern Wisconsin and the Upper Penin-
sula of Michigan.
Aerial spraying was conducted on 5,552 acres of Federal land in this area.
In the fall of 1956 control was anticipated on about 12,000 acres, but
1957 spring nymphal surveys indicated that widespread population drops
occurred in the northern portion, including the Ottawa, Chequamegon, and
Upper Michigan National Forests. Only in the southern portion of the
Nicolet National Forest did the control acreage remain at the anticipated
level. It is believed that population drops in the more northerly area
may have been caused by a severe freeze occurring on May 16. Official
weather station minimum temperatures on that date ranged from 16° to 22°
F. throughout the area.
Heavy infestations in the northeast area of Wisconsin resulted in treat-
ment of 3,879 acres by the Conservation Department. Most of the spray-
ing was in Marinette County, with smaller acreages in Oconto, Langlade,
Florence, and Marathon Counties. In Douglas County 153 acres were
aprayed.
Control estimates on Federal lands for 1958 total about 8,000 acres.
Barring unfavorable weather conditions or other decimating agents, the
acreage in the 1958 control program should be about average compared with
the operations carried out over the last decade (fig. 4).
10,000
g |
é |
& Figure 4.--Acreage sprayed
& le | to control damaging Sara-
nN | | i toga spittlebug infesta-
oc es Paid = tions on national forests
3 5000 Be te. | in northern Wisconsin and
Pi Poi Se the Upper Peninsula of
a 7 i. | | LC Michigan, 1945-1957.
| ca
oo mI TiLiint
Mllm@ uli u
White-Pine Weevil--
Causes Degrade and Volume Loss
The white-pine weevil (Pissodes strobi) is a major pest of pine stands.
Trees are not killed, but loss in height growth and tree deformity with
resultant loss of quality are sustained. Weeviling of over 40 percent
of the trees in a stand is common. White pine, jack pine, Scotch pine,
and Norway spruce are favored hosts, and recently red pine has also been
severely attacked. In Michigan weeviling was reported on red pine in 8
counties in 1957 as compared to 3 counties in 1956. Damage was common
on red pine in the northern areas of Wisconsin.
Control by clipping and burning of infested tips was carried out on 300
acres of State land in Michigan in 1957.
Pine Sawflies--
Populations Increase in Some Plantations
Several species of sawflies of the genera Neodiprion and Diprion infested
pine plantations throughout the Lake States. On some areas chemical con-
trol was needed.
In Michigan the red-headed pine sawfly (Neodiprion lecontei) population
increased greatly during 1957, particularly in the western Upper Penin-
sula and northwestern Lower Peninsula. The Michigan Conservation Depart-
ment aerially sprayed with DDT 1,800 acres of red and jack pines on
State lands in Antrim, Emmet, and Missaukee Counties. Scattered infes-
tations of the red-headed pine sawfly were reported from several counties
in Wisconsin. Heavy damage to a few jack pine plantations resulted in
private control action.
The European pine sawfly (Neodiprion sertifer) remains the most important
defoliator of young hard pines in the Lower Peninsula. This insect is
important to Christmas tree growers, as it consumes the old needles. It
is not presently known to occur in Minnesota or Wisconsin.
A few specimens of the European spruce sawfly (Diprion hercyniae) were
collected from white spruce at Iron River, Wis. This is believed to be
the first collection of this species in Wisconsin. Other sawflies re-
ported doing damage in Wisconsin include the white pine sawfly (Neodiprion
pinetum), the jack-pine sawfly (N. pratti banksianae), the red-pine saw-
aly. (N. nanulus nanulus), and Diprion frutetorun.
The introduced pine sawfly (Diprion similis) caused heavy defoliation of
white pine in parts of Minnesota and Wisconsin. Heavy parasitism was re-
ported in Wisconsin. This insect was reported this year for the first
time in Michigan, small infestations being found in Antrim, Charlevoix,
and Kalamazoo Counties.
Larch Sawfly--
Defoliation Over Wider Area
The larch sawfly (Pristiphora erichsonii) was reported in most of the
tamarack stands in northern Wisconsin and Minnesota. Populations con-
tinued to build up in Wisconsin and Michigan.
Severe defoliation occurred in the western part of the Upper Peninsula
of Michigan. Defoliation also was reported in the eastern half of the
Upper Peninsula and in the northern half of the Lower Peninsula. The
buildup was not as rapid as in the previous 2 years, and no mortality
has been reported from this State.
Defoliation in Wisconsin was more conspicuous Over a larger area than
previously, ranging from heavy to complete over most of the tamarack
stands in the northern half of the State. Many stands in the east cen-
tral area were also infested, and some were severely defoliated.
An aerial survey in Minnesota indicated that the total area of defolia-
tion was about the same as in 1956. Tamarack mortality apparently
Figure 5.--Left;: A red pine blown over after attack by the
pine root collar weevil. Right: A closeup of damage to
a second red pine caused by larval feeding of the root
collar weevil.
caused by larch sawfly defoliation was first observed in 1954. Since
that time surveys have been conducted by the State Entomologist's Office
in cooperation with the Lake States Forest Experiment Station to deter-
mine the extent and location of mortality. The percent of dead trees
for each stand was obtained by 2-inch diameter classes in 1/10-acre
plots. The results are summarized in table 1. Tamarack mortality is
evident in most of Minnesota's north central bogs. The associated tree
species, black spruce and northern white-cedar, have not shown compara=
ble mortality. Death of some trees due to competition and adverse site
factors occurs annually, but many of the dead tamaracks are codominants
on good sites, indicating that repeated defoliation will cause mortality.
Table 1.--Tamarack mortality in Minnesota, 1957
Tot ae eaous j Number of ‘Total number * Number of Percent
*1/10-acre plots’ of treesl/ “dead trees’ mortality
Warroad 1 24 6) 1)
Williams 1 34 O 1)
Spooner 1 74 agah 15
Big Falls 2 104 fal ll
Littlefork 1 34 2 6
Hines a 72 iG 24
Dixon Lake Lookout al 28 5 18
Whipholt af 75 ao 35
Boy River ak 40 at 3
Deer River af 64 26 41
Talmoon Li 9 8) 0
Orr 1 68 6 9
Cook at 28 10 36
Florenton 2 aS 38 33
Aurora 1 23. 8 35)
Ely 1 25 (6) 6)
Laporte 3 225 ts 32
TOTAL 21 1,042 233 22.4
1/ Includes only tamarack.
Root Collar Weevil--
Becoming More Important
The pine root collar weevil (Hylobius radicis) has caused heavy damage
to Scotch, jack, and red pines in plantations and natural stands (fig. 5).
High populations have been reported from the sandy soil types in north-
western and central Wisconsin. Heavy infestations were found in jack
and Scotch pine plantations in Shawano County. Extensive plantations of
jack and red pines were badly damaged by this insect in Burnett County.
TEA
Damage has been reported in windbreaks and shelterbelts of red and Scotch
pines in Minnesota and Michigan. Minnesota also reports heavy infesta-
tions in some jack pine plantations.
White pine is rarely attacked severely and therefore the damage to this
species is not economically important.
Gypsy Moth--
Control Program Successful
The following report covering the gypsy moth (Porthetria dispar (L.))
trapping and control program in Michigan was prepared by the Bureau of
Plant Industry, Michigan State Department of Agriculture.
"The aerial spraying phase of the 1957 Gypsy Moth eradication pro-
gram commenced on May the fifth. Due to unceasing winds and ex=-
tensive rainfall the job was not completed until the twenty-third.
"The original contract called for the aerially spraying of 7,573
gallons of a 12-1/2 percent DDT solution applied at the rate of
one gallon per acre. After operations were well under way a re-
appraisal was made of the amount of wooded acres to be sprayed
and the final gallonage applied amounted to 11,025. Of the 19,840
acres treated, 17,280 were on private lands and 1,600 on State
lands. In addition to the 19,840 acres treated to eradicate the
Gypsy Moth, the contractor also applied the same material at the
same dosage and rate of application over local subdivisions and
communities for the relief of mosquitos. The total area treated
amounted to 11,238 acres, and it is felt that this should also
be included as Gypsy Moth control spraying. The total acreage
sprayed with a 12-1/2 percent DDT solution would then total 22,348.
"The trapping phase began on the 17th of June and was conducted in
the following central Michigan counties: Gratiot, Ionia, Clinton,
Shiawassee, Barry, Eaton, Ingham, Livingston, Calhoun, Jackson,
and Washtenaw. The current survey was conducted by placing 4,911
traps over an area of 1,977 square miles. An average of 80 square
miles was covered by each trap tender. About 200 traps were placed
in each of the trap tender's district. These were patrolled at
least once each week and new traps were placed when necessary. For
the first time since the infestations were found in Michigan no
moths were recovered. It is interesting to note that not a single
moth has been caught in any of the areas that were aerially treated
since 1954. If the next two years are as successful as the year
1957, it will be relatively safe to assume that the Gypsy Moth has
been eradicated in Michigan."
12
Forest tent caterpillar--
Population Increase Predicted
in Scattered Areas
The forest tent caterpillar (Malacosoma disstria) infestation in Minne-
sota covered about 255,000 acres in 1957 in south central St. Louis
County. The egg mass survey conducted in October 1957 indicates that the
population of this insect will probably increase in some stands in 1958.
In Gogebic County, Mich., the infestation remained about the same as in
1956. Feeding by the large aspen tortrix (Archips conflictana) in the
same stands added to the severity of defoliation.
Heavy feeding in Wisconsin was centered in parts of Sawyer, Rusk, Price,
and Iron Counties. Scattered areas of defoliation were common in the re-
mainder of the aspen areas of northern Wisconsin. Winter egg-band sur-
veys indicate that heavy feeding will be sustained in scattered areas
throughout the northern counties in 1958 but the overall population will
probably decline slightly. Heavy defoliation of basswood occurred at the
Fort Totten Indian Reservation and the Sullys Hill Game Refuge in North
Dakota; very high egg-band counts indicate heavy larval populations in
1958.
Hardwood Defoliators--
Five Species Are Active
The fruit tree leaf roller (Archips argyrospila) defoliated oak on 350,000
acres in the central Lower Peninsula of Michigan. Infestations of this
insect were reported as light to medium in Florence, Marinette, and Lang-
lade Counties, Wis. Heavy parasitism was reported from both States, and
a population decline is expected.
The red-humped oakworm (Symnerista albicosta) defoliated oak on 44 ,800
acres in Oceana, Lake, Newaygo, and Muskegon Counties in Michigan's Lower
Peninsula. This pest is an annoyance to residents but is not expected to
have much effect on the trees.
The large aspen tortrix (Archips conflictana) often occurred with the
forest tent caterpillar in aspen stands in Michigan and Wisconsin. Some
areas in Michigan's Upper Peninsula were defoliated up to 75 percent® by
this insect.
A leaf roller (Sparganothis pettitana) and a webworm (Tetralopha sp.)
have combined to cause severe defoliation in maple stands in northeastern
Wisconsin, especially in Florence County. Feeding in 1957 was apparently
lighter than the 2 previous years. Refoliation does not normally occur
unless the defoliation is nearly complete. Predator and parasite popula-
tions were heavy this past year, and it is believed that the infestation
is declining. This is the same area in which many maple trees are dead or
dying from a cause as yet unknown.
13
THE MOST IMPORTANT FOREST DISEASES IN 1957
The following pages discuss briefly some of the important tree diseases
in the Lake States. The discussion is limited to those diseases which
are new or showed a definite change in prevalence or for which new in-
formation on their status was obtained.
Maple Blight
Is Causing Much Concern
Some dying-back of tops in hard maple has been noted in Wisconsin for
several years. This dieback did not seem to be particularly serious in
forest stands. In 1957, however, a rapid dying of hard maple appeared
on an area in Florence County, Wis. All maple from seedlings to sawlog-
size trees in rather small localized patches died during the year. A
rough estimate has been made that, in aggregate, all maple died on about
1,000 acres. The cause has not been determined, and it is therefore not
known whether this quick dying is related in any way to the less serious
dieback noted elsewhere in Wisconsin in previous years. Definite infor-
mation on the extent to which the problem may occur in other areas of
the region has not yet been obtained. A few scattered large maple with
similar symptoms died at Dukes, Mich., and a few other areas are sus-
pected of having the blight.
Since the cause is unknown, it is not possible to forecast the future
impact of this disease on the northern hardwood type. If the mortality
was caused by a pathogen that will increase and spread in future years,
the situation is alarming. Plans are being made to investigate the
problem. Research will be conducted to determine whether a pathogen is
involved, surveys made to determine the distribution of the disease and
to evaluate the problem, and studies made of the influence of insects
and environmental factors.
Black Spruce Root Rot
Caused Severe Losses
Three nurseries--2 in Minnesota and 1 in Michigan--lost about 50 percent
of their black spruce transplant stock this summer. There is no record
of such losses occurring in the past. The symptoms are those of a root
rot, with the mortality scattered throughout the transplant beds. The
mortality is progressive, occurring throughout the growing season. This
fall many of the surviving trees showed early symptoms, indicating that
further mortality can be expected in this stock next year.
The cause of the root rot is not known. No definite forecast can be
made, therefore, as to whether similar losses will occur in the transplant
14
beds planted in succeeding years. No evidence was found that indicates
the losses were caused primarily by physical factors such as weather or
nursery practices, although too deep planting appears to have contributed
to the situation in one nursery. Some tests will be made with soil fumi-
gants and fungicides. These should provide some indication as to whether
a pathogen is involved and may also suggest a control measure.
Leaf Blight of Honeysuckle
Is Common in North Dakota Nurseries
A leaf blight of honeysuckle was found to be quite severe in some North
Dakota nurseries. Affected foliage turns brown and usually becomes
rolled or twisted. Foliage loss was severe enough to probably have a
considerable effect on growth. This disease was found to be caused by a
rather unusual fungus usually referred to as Glomerularia lonicerae. This
fungus is a basidiomycete belonging to the genus Herpobasidium.3/ The
basidia emerge from the stomata on the diseased leaves. Although no con-
trol has been tried, it is believed that a fungicidal spray would be ef-
fective.
A Root Rot of Russian Olive
Was Found in North Dakota
A root rot of Russian olive was noted in a North Dakota nursery. This
root rot was characterized by the occurrence of localized necrotic lesions
on the root systems. Although a high percentage of the stock was affected,
little damage resulted. A few of the trees died, but during the growing
season most of the trees callused over the lesions and appeared to have
completely recovered. When first noted about a year ago there was con-
siderable concern about possible damage, but the experience this growing
season tends to indicate that the injury was transient in nature.
An Unidentified Canker
of Jack Pine Was Found
A high prevalence of long, narrow cankers was found on pole-size jack
pine in a localized area on the Chippewa National Forest. The cause of
the cankering has not been determined. Apparently it does not kill pole-
size trees, but it does cause some deformation. The distribution of this
3/ Gould, Charles J., Jr. 1945. The parasitism of Glomerularia
lonicerae (PK) D. and H. in lonicera species. Iowa State Jour. Sci. 19:
301-331.
15
disease and whether it occurs on smaller trees where it might cause more
serious damage are not known. Plans are to give this problem more atten-
tion next year to ascertain whether it is of practical importance.
The Vigor of Many Elms
Was Below Normal
An appreciable reduction in vigor was noted for many elms this year.
This was especially true in the southern half of Minnesota and adjacent
areas. Many of the trees produced an abnormally heavy seed crop and had
small, sparse foliage throughout the growing season. No cause for this
condition was immediately apparent. The Canadians have reported what ap-
pears to be similar symptoms on elm in the Prairie Provinces .= Their
investigation suggests that the injury was due to deep frost penetration.
Frost penetration was unusually deep last winter in the Minnesota areas
where the injury was noted, and it is assumed to be the probable cause.
A Sudden Growth Reduction Was Noted
in Some Red Pine Plantations
A sudden and drastic growth reduction was noted in some red pine planta-
tions in the Upper Peninsula of Michigan. The affected plantations had
been putting on very satisfactory growth in previous years. This year
height growth was limited to from 1 to 3 inches. The condition occurred
over the entire area of the plantations, and all trees were affected. A
Similar but not as drastic a growth reduction was noted in many other
plantations. No symptoms of disease or insect injury were seen on the
trees. It is not known what caused the condition or whether the condi-
tion will persist in the affected plantations. The growing season was
unusually dry in some parts of the Upper Peninsula, and it is possible
that this may be involved, although no other species showed similar ef-
fects.
Birch Decadence
Was Less Severe in 1957
In past years a rather severe dying-back of yellow birch crowns has ap-
peared in some areas in the Upper Peninsula of Michigan. Limited obser-
vations during 1957 did not reveal any further decline of affected trees.
Trees that had died back to some extent in previous years seemed to be
holding their own or recovering.
4/ Hord, H. H. V., Van Groenewood, H., and Riley, C. G. 1957.
Low temperature injury to roots of white elm. Forestry Chron. 33; 156-163.
16
Needle Droop of Red Pine
Was Unusually Severe
Severe symptoms of needle droop were noted in some northern Minnesota,
Wisconsin, and Upper Peninsula of Michigan plantations (fig. 6). In the
affected areas practically all of the trees showed symptoms, but serious
damage was found only on trees less than 4 feet tall growing in heavy
sod. In some of the areas examined this year many buds had died, and in
one area 100 percent of the trees were dead by fall. Needle droop is be-
lieved to be caused by a rather sudden drop in available moisture. It is
not known whether the needle=droop type of symptoms noted in the area
where 100=percent mortality occurred was actually the disease called
needle droop or similar foliage symptoms resulting from some undetermined
cause. The heavy mortality was limited to trees located in open depres-
sions.
A Gradual Deterioration
and Dying of White Pine
Was More Prevalent Than Usual
A condition which results in serious deterioration of scattered, indi-
vidual white pine trees appeared to be more common in 1957 than in pre-
vious years. This condition is referred to by some persons as needle
blight. Needle blight does occur in this region, and the typical symp-
tom is a partial dying-back of the needles on individual trees intermixed
with normal~appearing trees. This disease is transient and does not ap-
pear to cause any appreciable damage.
The decline referred to here appears to
be a different disease that has much
more serious effects. The symptoms are
similar to those for the chlorotic dwarf
Figure 6.--Needle-droop symptoms
on red pine.
Figure 7.--Cross=section of
60-year-old jack pine with
jack pine - sweetfern rust
cankers causing severe de-
formation of the bole.
Note advanced decay caused
by Fomes pini.
disease of white pine®?/ except that damage occurs on larger trees in
natural stands. The decline is progressive, and the trees die within a
few years after the first appearance of symptoms. The principal symptom
is the sparse and chlorotic foliage. Even during the present year only
a few trees are affected in most areas. In Grand Rapids, Minn., a high
percentage of the white pine has developed these symptoms and died during
recent years. It is not known whether the cause of the condition in
Grand Rapids is the same as for that occurring in forest stands.
Jack Pine - Sweetfern Rust
Is Common in Some Plantations
During the year a number of small pole=-size jack pine in plantations were
examined, and jack pine - sweetfern rust (Cronartium comptonia) was preva-
lent in some plantations; as many as 20 to 40 percent of the trees had
rust cankers on the lower portion of the bole. Although this rust usually
does not kill pole-size trees, it does cause serious deformation and very
possibly early development of red rot (fig. 7). The age of the infec-
tions and their basal location suggest that the trees were infected at
an early age, either as nursery stock or shortly after planting. It was
noted that some of the affected plantations had been planted in the same
5/ Swingle, Roger U. 1944. Chlorotic dwarf of eastern white
pine. Plant Disease Reporter 28: 824-825.
18
year with stock from the same nursery. This rust can kill small trees,
and nursery infection could cause considerable early mortality in planta-
tions. The rust apparently does not produce obvious symptoms on 2-0
stock; hence, culling of nursery stock would be difficult. Studies are
under way to determine the importance of this rust and the role of nur-
sery infection.
Jack Pine - Comandra Rust
Was Found in One Area
Cankers caused by the jack pine - comandra rust (Cronartium comandrae)
were found on a few trees in one locality in Minnesota. This rust does
not appear to be common or widespread in the region. The alternate host
is bastard toad flax. The cankers are quite similar to those caused by
the jack pine - sweetfern rust, but the rust can be distinguished by the
unusual shape of the aeciospores. In areas where bastard toad flax is
present it should not be assumed that all rust cankers on jack pine are
caused by the jack pine - sweetfern rust, which has sweetfern as the
usual alternate host.
A Canker Is Very Prevalent
in Poor Red Pine Plantations
Poor survival and a generally unsatisfactory condition of the remaining
trees is characteristic of some red pine plantations in the Upper Penin-
sula of Michigan. Observation indicates that the trees commonly are af-
fected with a canker disease, with many of the trees having multiple in-
fections. The cause of the cankers is unknown. Whether the canker is
primarily responsible for the poor condition of these plantations or
whether it has developed because of poor tree vigor resulting from other
factors has not been determined. The cankers are difficult to detect,
as there are no easily recognized superficial symptoms. The necrotic
cankered areas are not surrounded by callus formation, which indicates
that they apparently develop rapidly.
Heart Rot Appears Important
in Russian Olive
Russian olive is a preferred species for shelterbelt plantings in North
Dakota. Although the tree grows very satisfactorily on the Plains, the
life span of the species does not appear to be as great as it should be
in many situations. This apparently is a result of early development of
heart rot, which weakens the stem and eventually causes the tree to break
off. It is believed that this heart rot is caused by Fomes ellisianus
(Polyporus fraxinophilus var. ellisianus).
19
S10 1d
ASAYNS
SLO 1d
NO!ILVI104350
PERCENT OF TREES INFECTED
= fo Ww +
OSé6él
eS6l
bG6l
Figure 8.--Hypoxylon
canker population
trends, Lake States,
1950-1957. The plots
for 1953 to 1957 are
called "defoliation"
plots because they
were also used to
SS6
study the forest tent
caterpillar.
9S6
256
Hypoxylon Canker Continues
to Cause Severe Mortality
Additional survey information on Hypoxylon canker of aspen caused by
Hypoxylon pruinatum was obtained during the year by remeasurement of many
permanent sample plots. The data substantiate previous findings that
this disease kills about 1 to 2 percent of the standing aspen volume per
year. The annual loss probably exceeds 1,000,000 cords per year. The
prevalence of cankers in aspen stands was the same as for 1956 (fig. 8).
Probably the most outstanding factor noted during the year was the low
population of new infections found on the pilots. If the current low rate
of infection continues, there will be a decline in canker population.
There is no basis, however, for predicting future trends. As far as is
known, a buildup such as was experienced in 1955 could occur again at any
time.
White Pine Blister Rust Prevalence
Is Related to Microclimate
Studies of the white pine blister rust (Cronartium ribicola) are provid-
ing substantial evidence that prevalence of the rust varies appreciably.
In southern Wisconsin blister rust causes serious damage only tin very
20
localized situations that are characterized by a microclimate unusually
favorable for rust infection. In other locations white pine can be grown
with little danger of serious damage. In this area the high-hazard loca-
tions can be recognized by topographic features and the characteristics
of the tree crown canopy. Elevation above sea level is also very impor-
tant. Below 800 feet there is little rust anywhere. Between 800 feet
and 1100 to 1200 feet rust is localized by microclimatic factors, and
above 1200 feet it tends to be general, occurring on all sites, and some-
times is severe.
Observations indicate that a similar situation apparently prevails in
much of the Lower Peninsula of Michigan and in southeastern Minnesota.
In the northern parts of the region, rust infection is much more general
and severe. Apparent long-distance dissemination has been noted in some
localized areas in this part of the region. Studies of the problem have
provided tentative conclusions indicating that the air circulation pat-
tern is such as to carry rust spores far greater than usual distances
from Ribes in nearby swamps.
Oak Wilt Damage
Is Intensifying
No change in the distribution of oak wilt, caused by Ceratocystis
fagacearum, has been reported during the past year. A 3-year survey of
counties in Minnesota and Wisconsin where oak wilt is well established
indicates a relatively constant rate of intensification from year to year.
An average of about 1.6 new infection centers became established each
year per 100 acres of oak type. Over 50 percent of the old established
infection centers show active wilt in any given year, and the average ra-
dial spread of all infection centers is about 4 feet.
Dutch Elm Disease
Has Not Been Found in Minnesota
The presence of the Dutch elm disease, caused by Ceratocystis ulmi, in
Wisconsin has caused considerable concern in Minnesota. To date, however,
no evidence of the disease has been found in Minnesota.
During the past year 1,285 specimens were received for laboratory diag-
nosis in Wisconsin.2 Three hundred seventy-six were confirmed as Dutch
elm disease in trees from 46 communities in 7 counties. The 7 Wisconsin
counties now known to have the disease are Jefferson, Waukesha, Racine,
6/ Reported by E. L. Chambers, Chief, Division of Plant Industry,
Wisconsin Department of Agriculture.
21
Kenosha, Walworth, Rock, and Milwaukee. The laboratory diagnosis in Wis-
consin revealed almost as many trees infected with Verticillium sp. as
were infected with Dutch elm disease and about 50 percent as many infec-
ted with Dothiorella ulmi. Verticillium and Dothiorella are fungi that
cause symptoms that are easily confused with Dutch elm disease. The high
prevalence of these diseases emphasizes the need for laboratory diagnosis
of trees suspected of having Dutch elm disease. Wisconsin has an inten-
Sive control program under way and is quite optimistic about slowing up
the spread of the disease.
Michigan also has a strong Dutch elm disease control program and a con-
siderably larger population of infected trees to deal with.
Cause of Oak Mortality
in Northwestern Wisconsin Is Unknown
Oak have been reported as dying in localized patches in the following
northwestern Wisconsin counties: Burnett, Sawyer, Washburn, and Polk.—
The symptoms are similar to those of oak wilt, but the oak wilt fungus,
Ceratocystis fagacearum, has not been isolated. It is believed that the
mortality results from some other unknown cause. The disease has not
caused widespread killing, but its potential for damage is not known.
Mortality from this disease was first noted 3 years ago.
7/ Reported by Donald Renlund, Wisconsin Conservation Department,
and also observed by Station personnel.
22
Lv
:
ww
“i
SOME RECENT STATION PAPERS
The Market for Domestic Charcoal in Wisconsin, by John R. Warner and
William B. Lord. Sta. Paper 46, 15 pp., illus. 1957.
Natural Regeneration on a 2-Acre Mixed-Oak Clear Cutting Five Years
After Logging, by Harold F. Scholz and A. J. DeVriend. Sta. Paper
48, 21 pp; iltus. 957.
Deterioration of Sugar Maple Following Logging Damage, by Gene A.
Hesterberg. Sta. Paper 51, 58 pp., illus. 1957.
A Record of the Timber Cut from Forests of the Lake States, 1954, by
Arthur G. Horn. Sta. Paper 53, 47 pp., illus. 1957.
Marking Guides for Northern Hardwoods Under the Selection System, by
Carl Arbogast, Jr. Sta. Paper 56, 20 pp., illus. 1957.
Managing Red Pine for Poles in Lower Michigan, by Paul C. Guilkey.
Sta. Paper 57, 21 pp., illus. 1958.
Proceedings, Third Lake States Forest Tree Improvement Conference,
september 17, 18, 1957. Sta. Paper 58, 87 pp., illus. 1958.
Silvical Characteristics of:
Red Pine, by Paul ©. Rudoli. Sta. Paper 44, 32 pp., illus. 1957.
Black Spruce, by M. L. Heinselman. Sta. Paper 45, 30 pp., illus.
UCR
Rock Elm, by Harold F. Scholz. Sta. Paper 47, 16 pp., illus. 1957.
Quaking Aspen, by R. O. Strothmann and Z. A. Zasada. Sta. Paper 49,
26 pp., illus. 1957.
Sugar Maple, by R. M. Godman. Sta. Paper 50, 24 pp., illus. 1957.
Tamarack, by Eugene I. Roe. Sta. Paper 52, 22 pp., illus. 1957.
American Elm, by Paul C. Guilkey. Sta. Paper 54, 19 pp., illus.
POO
White Spruce, by Hans Nienstaedt. Sta. Paper 55, 23 pp., illus.
UEC
Slippery Elm, by Harold F. Scholz. Sta. Paper 59, 14 pp., illus.
1958.
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