..Ji/ER!VMENT DOC!
COLLECTION
SEP 2 2 7986

FROM:

Elizabeth Anne Bourque, Ph.D.

RE:

Review of Alternatives to Herbicide, Amitrole

DATE:

May 9, 1985

Massachusetts has 36 a ctj_yj&— ingredients in 89 products registered for
poison ivy control. The EPA listed the contact herbicide dicamba, 2,4-D, MCPP
and glyphosate and the residual herbicides MSMA, simazine, picloram, duiron,
bromacil, tebuthuiron and velpar as alternatives to Amitrole. There is a
possibility of MSMA being a thyroid oncogen and the possibility of ground
water problems with simazine and picloram. There are data gaps in the
information on duiron , bromacil and velpar (1). Further these herbicides were
not listed alternatives by the Department of Agriculture at the January 1985
meeting. Therefore of the remaining five EPA listed alternatives as well as
ammate were reviewed: 2,4-D, Dicamba, Glyphosate, MCPP and Tebuthiuron. All
six herbicides have gaps in the data base for which EPA has requested
information (EPA, personal communication April 17, 1985). You will note that
the gaps are in critical health areas. These herbicides are all general use
herbicides .

An alternative method to herbicide control of weeds is Integrated Pest
Management (IPM). As it appeared that one of amitrole' s main uses was for
poison ivy control the possibility of I. P.M. was reviewed. This approach
would reduce the adverse health effect concerns or ground water contamination
concerns associated with the use of herbicides. I. P.M. for poison ivy is
clearly outlined in the enclosed review by Bio-Intergral Resource Center.

A final alternative method to consider is the complete elimination of
spraying of herbicides. The successful tio Spray policies in effect in Maine
and Vermont are summarized. A Cost of Comparison of Right-of-Way Treatment
Methods prepared for Empire State Electric Energy Research Corporation, June
1984 showed that on the basis of a single treatment hand cutting has a cost
advantage over other types of treatment regardless of the density of the
capable stems.

bj

REVIEW OF THE ALTERNATIVES TO AMITROLE

page

1. Herbicides:

a. Ammate 1

b. 2,4-Dichlorophenoxy Acetic Acid 2

c. Dicamba 4

d. Glyphosate 5

e. Mecoprop 6

f. Tebuthiuron 7

2. Integrated Pest Management 8

3. Hand Cutting 37

a. Evaluation Summary of Right-of-Way Treatment Methods 38

b. Estimated Cost per Acre for Single Treatment 39

c. No Spray Programs 4D

A, Bihliography 42

Digitized by the Internet Archive

in 2014

https://archive.org/details/reviewofalternatOObour

-1-

AMMATE

Action: A post-emergent herbicide that kills plants on contact or

after translocation within the plant.

Observation in Man: ACGIH recommends a TLV of 10mg/m3 (la) while OSHA's

permissible airborne exposure limit is 15mg/m3 (OSHA,
personal communication April 25, 1985).

Acute Effects: LD50 oral rat 3900 mg/kg (2)

LD50 oral mice 5760 mg/kg (2)

Mobility in Soil: Ammate is highly soluble 2 1 6g / 1 00 ml in water. Konnai

et al . (1974) showed that ammate was very mobile in
the soil. It moved 14 cm and 50 cm after application of 2
cm and 50cm of water (2). The EPA reviewed the data
submitted for registration of ammonium sulfamate and
determined that there was insufficient data to predict the
fate of ammate in the environment (2).

Summary of Toxico- Insufficient information is available to assess the
logical Literature: carcinogenic, teratogenic or mutagenic potential

of ammonium sulfamate (2). EPA has requested a
large range of tests but few have been received by EPA
(EPA, personal communication, April 12, 1985).

Mutagenicity: Negative results were noted in an Ames/Salmonella Assay

(2).

2,4-D

Action :

A post-emergent, selective herbicide which

kills plants by causing them to grow too quickly,

Route of Exposure

inhalation and dermal absorption (2)

Observations in Man

There have been a few cases reported of ingestion of
2,4-D. The lethal dose is estimated to be over
90mg/kg. The clinical picture indicative of 2,4-D
poisoning includes fibrillary twitching and muscular
paralysis . (3 ) During the field application of 2,4-D,
several cases of illness were reported to the American
Medical Association. Symptoms included burning
sensations in the throat and chest, weakness, loss of
appetite and weight, and slight albuminuria. This
brings into question whether the ACGIH TLV of 10mg/m3,
based wholly on ingestion, is sufficiently low to
prevent the effects by inhalation (la). OSHA has a TLV
of 10mg/m3. (OSHA, personal communication April 25,
1985).

Metabolism:

Khanna and Fang ( 1 966 ) found that the time necessary
to eliminate 2,4-D from the body was dose-dependent.
Rats eliminated 1-20rag within 24 whereas lOOmg
required 144 hours for 75% recovery. Fang et al
(1973) reported that small amounts of phenoxy
herbicides were passed through mother's milk to the
young. (2 )

Acute Effects

LD50 oral range from 100mg/kg dog to

541mg/kg chicks
the salts and esters were less toxic (2)

Chronic Effects

Rats fed 30 or 100mg/kg 5 times per week showed a
depressed growth rate, liver pathology and
gastrointestinal irritation. Rats fed 300 mg/kg died
within a 4 week period. Khera and McKinley (1972)
noted an increase in f etopathology and fetal skeletal
anomalies in pregnant rats fed 100 Or 1 50 mg/kg/day.
Bage et_al.(1973) observed teratogenic and embryotoxic
effects in NMRI mice that were injected with 50 or 110
mg/kg 2,4-D on days 6-14 of gestation (4)

-3-

Mobility in Soil: The physical and ^hemical properties of 2,4-D are

dependent on the form of the active ingredients (2)
High mobility was shown in a study of 2,4-D amine and
ester applied to a silty loam soil reached a depth of
40 cm after 5 days. (2) Low mobility was noted by
Smith (1975) who found only negligible amounts of
2,4-D below 5 cm at the end of one growing season (2)
Most 2,4-D residues breakdown in the soil in 6 weeks
(4)

Summary of Toxico-

logical Literature The EPA has requested data under 3C2B of FIFRA (1)

that agency required a fairly significant number of
tests from the registrants as the data base was so
deficient as to quality and presence of data. A
neurotoxicity and subchronic feeding study are
presently being reviewed by EPA. A reproductive study
and a long term chronic study are due in the summer of
1985 and late 1986, respectively .( EPA , Personal
Communication April 12, 1985) I" 1981, a state
advisory committee of DEQE and DPH said of 2,4-D:
"The scientific data are sufficiently suggestive of a
carcinogenic effect... that 2,4-D use should be
restricted to areas in which human exposure can be
kept to a minimum ... Broadcast methods of application
that potentially expose the general population should
be stopped."

-4-

DICAMBA

Action :

A pre-and post emergent, selective herbicide. It kills
plants by interfering with protein synthesis (2).

Route of Exposure: Inhalation and dermal absorption

Metabolism: Studies on rats and a holstein cow fed radiolabeled

dicamba showed 73-99% of the administered radioactivity
was excreted in the urine in 3-7 days (4).

Acute Effects: LD50 oral rat 757-2,900 mg/kg (4)

LD50 oral rci-e 1,189 mg/kg (4)

Signs of acute dicamba poisoning in animals include muscle
spasms, bradycardia, and inhibited voluntary and
involuntary reflexes. Death occurs in 3 days(4).

Chronic Effects: Moderate necrosis and vacuolization of the liver were seen

in rats fed dicamba at 413 ppm) , slight liver pathology in
rats fed (330 ppm dicamba) and no adverse effects were
seen in rats fed 206 ppm(4).

Mobility in Soil Dicamba is highly mobile in soil. It was found to be the
and Water: most mobile of 40 pesticides tested. Friesan applied

dicamba to a sandy loam and eluted it with 5 cm of water,
the herbicide reached a depth of 15 cm in 1 hour (2). It
is very soluble in water and persists in sods for 7-10
months. (4)

Summary of Toxico- Available tests are inadequate to assess carcinogenicity,
logical literature: teratogenicity and mutagenicity (2). A number of

studies on dicamba were conducted by Industrial Bio-Test
Laboratories (IBT). The following studies conducted by
IBT were determined by the EPA to be invalid:
mutagenicity, mouse; teratology, mouse; mutagenicity,
bacteria; reproduction, men; and chronic carcinogen,
mouse. All the tests listed above, except the
reproduction test in men are in progress and results are
due by September, 1987 (EPA, Personal Communication April
12, 1985). Thus, dicamba remains a herbicide with a large
number of data gaps still imposed by the IBT scandal.

Observations in Man:No available data (4).

-5-

GLYPHOSATE

Action: A post-emergent, broad spectrum herbicide that blocks cell

metabolism by inhibiting synthesis of aromatic amino
acids(2)

Acute Effects LD50 oral rat 1,568 mg/kg (6)

LD50 oral mouse 4,873 mg/kg (2)

Mobility in Soil Glyphosate binds tightly to soil particles. Half-lives in a

variety of soils range from 8 to 19 weeks. Highly soluble
in water. The half-lives in various water samples range
from 7 to 10 weeks. (2)

Summary of Toxico—

logical Literature: There were 23 tests conducted by IBT that were invalid. Only

two of these have been replaced and are presently being
reviewed by the EPA. (EPA personal communication, April 12,
1985). More publicly available information is needed to
allow a independent review of glyphosate(2 )

-6-

MECOPROP

Route of Exposure: Toxic by ingestion and inhalation, irritant to skin and eyes

(3)

Acute Effects LD50 oral rats 650mg/kg (6)

LD50 oral mice 650mg/kg (6)

Chronic Effects Mecoprop given orally to mice at days 6-15 of gestation was

embryotoxic and caused malformations of the skeleton (5)

Summary of Toxico- The EPA requested in 198^, data to test the potential for
logical Literature: contamination of groundwater. (EPA, Personal Communi-
cation, April 17, 1985).

TEBUTHIURON

Action: A pre-emergent , non-selective herbicide, applied by as

pellets, which must be washed into the soil by rain and
taken up by the roots.

Metabolism:

More than 85% of a radiolabeled single oral dose was
excreted in 96 hours according to Lilly Research
Laboratories (2).

Acute Effects

LD50 oral rat 579 mg/kg (2)
LD50 oral mouse 644 mg/kg (2)

Mobility in Soil: Soluble in water and appears to be very persistent. Three

studies note a half-life of more than 1 year. Precautions
on the label include the statement that "its presence in
the soil may prevent growth of other desirable vegetation
for some years to come" (2). Reed noted tebuthiuron moved
to 26 cm in a silty clay and to 30 cm in a sandy loam
after 6 weeks (2). Bauer (1978) found that 20 cm of rain
distributed tebuthiuron throughout a 20 cm soil profile.

Summary of Toxico- More publicly available information is needed
logical Literature: on tebuthiuron. The EPA in 1983 requested a tera-
togenic study and in 1984 requested an array of studies on
groundwater contamination (EPA, Personal Communication,
April 12, 1985).

!
I

I

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Integ rated Pest Management
for Poison Ivy

T — The B1o-Integral Resource Center (BIRC), a non-profit organization,
provides practical information on the least toxic methods of managing pests
and land resource problems. Since 1970 members of BIRC staff have designed
Integrated Pest Management (IPM) programs for community groups, public agen-
cies and private institutions throughout the U.S. and Canada.

IPM is a decision-making process. A key component is a monitoring program
to* determine the timing and placement of pest control treatments. A mix of
biological, horticultural, mechanical and chemical strategies are integrated
to suppress pest populations below levels causing economic, medical or aesthe-
tic damage. »

Portions of this report were produced under contract # CX-300-0-0036 from the
National Park Service to JMI, Inc. as an account of work sponsored by the
United States Government. Neither the United States, nor the National Park
Service, nor any of their employees, makes any warranty, express or implied,
or assumes any legal liability or responsibility for the accuracy, complete-
ness, or usefulness of any information, apparatus, product, or process
disclosed, or represents that its use would not infringe on privately owned
rights. Reference herein to any specific commercial product, process, or ser-
vice by trade name, mark, manufacturer, or otherwise, does not necessarily
constitute or imply its endorsement," recommendation, or favoring by the United
States government or any agency thereof. The view and opinions of authors
expressed herein do not necessarily reflect those of the United States
Government, the National Park Service, the Environmental Protection Agency or
any other agency thereof.

© 1984 Olkowski, Olkowski & Daar All rights reserved.

-10-

TABLE OF CONTENTS

Page No.

FLOW DIAGRAM SUMMARIZING RECOMMENDED IPM PROGRAM FOR POISON IVY i
1. TARGET PEST IDENTIFICATION AND BIOLOGY

1.1 Description of Target Pest and Related Species 1
Table 1: Distinguishing Poison Ivy from other Plants 2

1.2 Life History 3
Table 2: Major Subspecies of Poison Ivy 4

1.3 Natural Enemy Information 7

1.4 Host / Site Information 7

2. MONITORING

2.1 Target Pest Monitoring Techniques 8

2.2 Monitoring Timing and Frequency 3

2.3 Monitoring Natural Enemies and the Environment 9

3. DECISION-MAKING

3.1 Determining Injury Levels 10

3.2 Action Points 11

3.3 Timing Treatments 12

3.4 Spot Treatment 13

4. TREATMENTS

4.1 Indirect Suppression 13

4.1.1 Design or Redesign 14

4.1.2 Habitat Modification 14

4.1.3 Human Behavior Changes 14

4.1.3.1 Horticultural Controls and 14
Maintenance Activities

4.1.3.2 Education 15

4.2 Direct Suppression 15

4.2.1 Physical controls 15

4.2.2 Biological controls 18

4.2.3 Chemical controls . 19
Table 3: Herbicide Information 20

5. REFERENCES CITED 24

-11-

FLOW DIAGRAM SUMMARIZING RECOMMENDED IPM PROGRAM FOR POISON IVY

POISON IVY PRESENT? no >NO PROBLEM

I

yes

PRESEnJe TOLERABLE? yes >

(e.g. not growing on structures or
areas utilized by vi si tors/ staff )

l

no

BEGIN JonITOrInG F

«» ID subspecies, review biology 4 ecology
° Map location 4 density of growth

• Determine locations where injury

to people or structures likely to occur
o Decide frequency of monitoring needed

• ID maintenance/other activities at site
" Set injury level (variables include

proximity of ivy to people and struc-
tures, density of growth, season, etc.)
° Set action point (e.g. in high-use
areas action is needed early to limit
spread of plant; in remote areas,
action can be delayed or avoided as
injury is less likely to occur)

ACTION POINT
> REACHED? no >

yes

BEGIN MECHANICAL, BIOLOGICAL
OR HORTICULTURAL CONTROLS

0 Grub out seedl i ngs

° Prune out vines

0 Mow or cut/grub shrub forms

0 Graze area with goats or sheep

0 Mulch or replant cleared areas

0 Minimize soil disturbance

° Eliminate bird perches

ADDITIONAL ACTION

NEEDED? ' no >

I

yes

USE CHEMICAL CONTROLS

0 Ammonium sulphamate (Ammate®)

0 Weed Oil

0 Glyphosate (Roundup®)

° Mulch or replant cleared area

POISON IVY

By

Sheila Daar, Helga Olkowski and William Olkowski

1. TARGET PEST IDENTIFICATION AND BIOLOGY

1.1 Description of Target Pest and Related Species

Poison ivy (Rhus radicans L., or Toxicodendron radicans Kuntz) is a deciduous
woody perennial plant which is native to North America. It takes several
forms including a trailing vine, a subshrub to shrub from 2 inches to 4 feet
high, or a vine up to 50 feet tall climbing rough surfaces.

Leaves are 1/2 to 2 inches long, and are always borne in groups of three
leaflets. These leaflets, found alternately along the stem, may be glossy or
dull -green, are usually smooth, but occasionally may be somewhat hairy. The
edges of the leaves vary widely; some are smooth, others are toothed or even
deeply lobed. Unfurling leaves are red, becoming green during summer and
colored various shades of yellow, orange, red or bronze in autumn.

Leaves of poison ivy never occur in pairs along the stem. This "alternate"
leaf characteristic distinguishes poison ivy from other, more benign plants
such as Virginia Creeper, Parthenoci ssus quinquefolia L., which resemble
poison ivy. See Table 1 for details which distinguish poison ivy from plants
which resemble it.

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TABLE 1.

DISTINGUISHING POISON IYY FROM PLANTS WHICH RESEMBLE IT

RELATED SPECIES

POISON IVY

Virginia Creeper (Parthenoci ssus
qui nquefol i a) has leaves composed
of five leaflets; leaf scars are
circular with raised edge; fruits
are juicy and purpl e; aerial roots
contain suction disks.

Boston Ivy (Parthenoci ssus
tricuspidata) has leaves with
three lobes but rarely three
leaflets; leaves are up to 8"
wide; fruits are juicy and purpl e;
aerial roots contain suction disks.

Box Elder (Acer negundo) has leaves
composed of three leaflets but are
borne opposi te each other on the
stem; fruits are in flattened pairs
with "wings"; young stems are bri ght
green.

Leaves are composed of three
leaflets; leaf scars are
tri angul ar; fruits are hard and
whi te; no suction disks on aerial
roots .

Leaves are composed' of three
distinct leaflets'; leaflets
are narrow, rarely exceeding
1/2 inch in width; fruits are
hard and whi te ; no sucti on di sks
on aerial roots.

Leaves composed of three leaflets
borne al ternately on the stem;
fruits have a round, berry-1 ike
shape; young stems brown or dul 1
green.

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Stems are woody, ranging from 1/2 to 6 inches in diameter. Slender, creeping
rootstalks are produced from the base of the stem. These roots often travel
horizontally on top of or through the soil, giving rise to short, slender leafy
shoots several yards from the parent plant.

In early summer, small clusters of greenish-white flowers form where the leaf
and stem join. Each flower develops into a white or cream-colored berry about
1/8 inch in diameter. The berries are especially helpful in identifying
poison ivy during the winter.

Consistent variation in the appearance and growth habit of poison ivy is
recognized by the designation of certain subspecies. See Table 2 for a
description and geographical distribution of the major subspecies of poison
i vy .

A substance known as urushiol , which is toxic to most humans, is found in the
phloem cells of poison ivy, located just under the bark. The poison is not
carried,. in the xylem vessels, however, so the inner wood of the plant is not
poisonous (Gill is 1975).

Poison ivy is a member of the Sumac family, Anacardiaceae, which also contains
such familiar plants as Poison oak (Rhus diversiloDa) and Poison sumac (_R.
verni x) , the cashew nut tree (Anacardium occidentale) , and the lacquer tree of
China and Japan (Toxcicodendron vernici f] uum) from which oriental lacquerware
is made. The sap in each of these species contains urushiol which can
cause severe dermatitis in susceptible humans.

1.2 Life History

A. Reproduction

Poison ivy has male and female -flowers on separate plants (dioecious). Pollen
is distributed by insects and female flowers produce a high percentage of
one-seeded mature fruit (Mulligan 1977). Seeds mature in late summer or
early fall. They may remain viable for at least six years (Gillis 1971).

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TABLE 2.

MAJOR SUBSPECIES OF POISON IVY FOUND IN THE UNITED STATES

Latin Name

Descri ption

Distribution

Rhus radicans L.
subsp. radi cans
(Toxicodendron
radi cans subsp.
radi cans

Green, Mulligan.)

Shrub to vine form with
aerial roots climbing rough
surfaces; undersurface of
leaflets with tufts of hairs
toward bases of midribs;
hairs ascending along
lateral veins on undersur-
face of leaflets; usually 5
or more leaves on vertical
stems; leaflets entire or
mostly entire; surface of
fruits pubescent.

A lowland subspecies which is
essentially an Atlantic coastal
dweller that occurs from
southern Nova Scotia south to
the Florida Keys and the
western Bahama Islands and west
to eastern Texas. It is
separated from subsp. negundo
to the west by the Al 1 egheny
Ridge in PA. and NY., and
the Blue Ridge mountains to
the south. In the north R_.
radicans is separated from _R.
rydbergi'i along the 44th
parallel of latitude.

_R. radicans L.
subsp . negundo
(T. radi cans ,
subsp. negundo
Greene) .

Shrub to vine with aerial
roots climbing rough sur-
faces; hairs along midrib on
undersurface of leaflets not
tufted; hairs along sideveins
on undersurface of leaflets
spreading; usually 5 or more
leaves on vertical stems;
leaflets toothed or mostly
toothed.

Found in the central area of
the U.S. (the midwestern states
generally north of the Ohio
River). Eastern boundary is
Allegheny Ridge, most clearly
delimited in the vicinity of
Tuscarora Mountain in
Pennsylvania. On the east
flank of * the Alleghenies is
subsp. radicans.

R_. radicans L.
subsp. rydbergi i
(T. radi cans , subsp
rydbergi i Greene )

A trai 1 i ng vi ne , or a
subshrub to shrub lacking
aerial roots; hairs along
midrib on undersurface of
leaflets not tufted; hairs
along sideveins on undersur-
face of leaflets spreading;
usually fewer than 5 leaves
on stems; leaflets toothed.

Most widespread and uniform
all the subspecies. Occurs
from Central Arizona to the
Gaspe Peninsula and to the
Rockies in southern Canada.

of

R. radicans L.
subsp. verrucosum
(J_. radi cans subsp.
verrucosum Greene )

Aerial roots; glabrous
leaves and shoots except
for an occasional population
with small tufts of hairs in
major vein axils oh lower
leaflet surface. Has become
distinctive due to prominent
sharp lobes on the leaflets.

Found only in Texas

-16-

Few seeds fall directly to the ground, remaining instead encapsulated in the
fruits which are eaten by birds and other wildlife.

Poison ivy also reproduces from alternate buds on horizontal rootstalks.
However, horizontal spread of poison ivy is slow, rarely more than 4
inches/year and frequently less (Mulligan 1977). Vertical growth of vining
stems is rapid, however. Despite its ability to propagate vegetatively ,
poison ivy rarely becomes established by plant fragments (Gillis 1971).

B. Growth and Devel opment

Colonization of new sites is primarily by seed dispersed by birds and ani-
mals during autumn, winter and early spring. The hard seeds pass through the
digestive tracts of birds and animals in a viable condition.

Seeds germinate when the soil warns up in the spring. They produce a primary
vertical stem -and basal roots. Horizontal rootstalks (rhizomes) are produced
from the base of the primary vertical shoot in the first or second growing
season, -and grow horizontally on or beneath the surface of the ground.
Rhizomes have buds which produce new vertical stems as well as adventitious
roots just below each bud. Each new vertical stem in turn produces additional
horizontal rhizomes, resulting in a large interconnected clone with many ver-
tical stems and horizontal rootstalks, both above and below ground.

Flower and leaf buds are formed on new growth on vertical stems in late summer
and early autumn, and are carried overwinter on the stems. Leaves appear. on
the year-old stems as soon as the soil warms up in the spring. Flower buds
formed the previous year open in late spring through mid-summer, depending on
location. Maximum flowering occurs in June and July in most areas with some
additional flowering occuring sporadically until early autumn.

Poison ivy often grows intertwined with ornamental plants and may be mistaken
for a desirable landscape plant due to its attractive foliage and striking
reddish-bronze fall color.

-17-

When growing in full sunlight poison ivy usually takes the form of a shrub,
assuming a vine form when growing in more filtered sunlight. The vine form of
poison ivy is most common. Vines grow for many years, becoming several inches
in diameter and quite woody. Slender vines may run along the ground, grow
with shrubbery, or take support from a tree.

The vine forms roots readily when in contact with the ground or with any
object that will support it. Aerial roots attach the vine securely to the
tree or post supporting the vine. According to Crooks and Klingman (1967),
the vines and roots apparently do not cause injury to trees except where
growth may cover the supporting plant and exclude sunlight. The vining nature
of the plant makes it well adapted to climbing over stone walls or on brick
and stone houses. See Section 3.1, Oeterminining Injury Levels, for a
discussion of the impact of poison ivy vines on buildings and other struc-
tures.

C. Benefits of Poison Ivy

Despite the toxicity it poses to humans, poison ivy plays a number of benefi-
cial roles in the natural environment. For example, poison ivy is of con-
siderable wildlife value. Fruits are eaten by many birds. Martin et al .
(1951) report that poison ivy fruits make up a quarter of the diet of some
flickers and wrentits. Fruits, stems and leaves are eaten by bears, muskrats,
rabbits, small rodents and deer, and a number of small mammals use it for
cover. Bees can make a nontoxic honey from its nectar (Rostenburg 1955).

As a colonizer of disturbed soils, poison ivy appears to play a significant
role in erosion control and soil stabilization. In the Friesland Province of
Holland, poison ivy is used to stabilize dykes (Gill is 1975). In park set-
tings, poison ivy (properly posted with signs) could be used to discourage
human trampling of sensitive areas.

-18-

1.3 Natural Enemy Information

Mulligan (1977) lists arthropods in the following orders as feeding on poison
ivy: Lepidoptera, Hymenoptera, Diptera, Coleoptera, Homoptera (Aohididae) and
Acarina (Harrison 1904; Tissot 1928, 1933; Steyskal 1951; Gil lis 1971;
Richards 1972). Criddle (1927) considered the larvae of Eoioaschia zelleri
Grote (Leoi doptera) the most destructive of all insects to poison ivy.

Conners (1967) lists the following fungi as infesting poison ivy in Canada:
Cercospora rhoi na Cke . & El 1 . Man . , Cyl i ndrosoori urn i rregul are ( Pk . ) Dearn . ,
Cyl indrosporium toxicodendri (Ell. & Mart . ) , Phyl 1 osticta rhoi col a Ell . & Ev . ,
and Pileolaria brevipes Berk. <S Rav. Parmelee and Elliott (1974) also list
Pileolaria brevipes from British Columbia and Arthur (1934) states that this
rust infects poison ivy throughout its range.

1.4 Host/Si te Information

Poison fvy is usually found where soils have been repeatedly disturbed in
connection with construction projects, forest clearing operations, etc. It
does not grow where repeated agricultural cultivation occurs, since these
operations remove seedlings before they can become well -establ i shed. Poison
ivy grows in association with many other native and introduced plant com-
munities and is most often found growing at woodland edges or openings, along
roadsides and fenceposts, and adjacent to watercourses. Because poison ivy
fruits are eaten by a wide variety of birds, the plant is common around trees,
fencerows, under telephone wires, and wherever birds are likely to perch.

Its wide distribution throughout the north-and south-eastern U.S. and exten-
sions into Canada and south into Central America indicates that poison ivy is
adapted to a wide variety of climatic conditions.

-19-

Poison ivy grows on a variety of soils. According to Gill is (1971), calcium
is the most important element in the soil for the growth of poison ivy. The
maximum root development is in the A horizon of the soil and poison ivy is
virtually absent from soils that are highly leached of minerals, especially
calcium and magnesium.

2. MONITORING

2.1 Target Pest Monitoring Techniques

In park settings where poison ivy is or has been present, begin monitoring in
mid-to-late spring when new seedlings have germinated and the leaves have
opened on older, established clumps. Use the distinctive 3-part leaves to
identify the plant. To decide on levels of effort needed for monitoring,
determine which growth form (sub-species) of poison ivy is present at the
site. With the relatively low shrub forms which tend to spread hori zonal ly
only very slowly — approximately 4" per year (Mulligan 1977), monitoring can
be kept to a minimum.

2.2 Monitoring Timing and Frequency

The most important thing is to time the first monitoring visit(s) early enough
in the season that both seedling and established poison ivy stands are visible
and can be accurately noted on a map. This is usually mid-to-late May in most
parts of its range.

For the vining forms of poison ivy which are capable of rapid and extensive
vertical growth (six to twenty feet in one season is not unusual), more fre-
quent monitoring might be desirable in order to determine the need for treat-
ment before growth is excessive. Since most vertical growth of poison ivy
occurs prior to flowering, it is desirable to monitor poison ivy vines once
per month between foliation in the spring (April-May), and onset of flowering
(June-July in most areas) and again at the end of the growing season.

-20-

If monitoring indicates that no treatment is required, subsequent visits
should be necessary only at the end of the summer before plants lose their
leaves. At this time any changes in park use patterns near the poison ivy, as
well as the height and width of the clump can be recorded. By reviewing this
data over time, park managers can determine relative growth rates of poison
ivy in their area as well as the likelihood of park visitors or workers coming
in contact with it. Decisions about injury (tolerance) levels and treatments
can be based on this data.

If a treatment is warranted, monitoring must occur frequently enough to deter-
mine when the plants are at the optimal stage for treatment. For example
pruning treatments on poison ivy are most effective if applied just before .the
plant blooms; herbicide treatments on mature plants should be applied during
or just after flowering (see section 4.2). Since chemical and mechanical
treatment methods prescribed for poison ivy usually require more than one
application, it is important that monitoring occur frequently enough after the
first treatment to detect if and when a second treatment is needed.

This usually means that treated plants should be visited again a minimum of
two-to-four weeks after initial control efforts. If a second treatment
appears to be needed, another post- treatment monitoring visit should be sched-
uled, with a final visit at the end of the growing season to determine the
overall effectiveness of the treatment program. Plants believed to be dead
sometimes resume growth after many months; thus an area under treatment must
be watched fairly closely for at least a year to determine if retreatment is
necessary (Crooks and Klingman 1967).

2.3 Monitoring Natural Enemies and the Environment

As a native plant, poison ivy tends to enjoy a stable relationship with the
herbivores and pathogens that, feed on it. Thus, suppression of its growth by
native natural enemies is not likely to be significant. However, livestock,
particularly penned goats and sheep can severely reduce and sometimes elimi-
nate stands of poison ivy by their browsing and trampling activities. Thus,

These variables may differ from site to site depending on the location,
overall maintenance objectives, role or value of the plants in the environ-
ment, opinions and experience of managers, level of complaints by visitors or
staff, etc. In the case of poison ivy, the adverse health effects that con-
tact with the plant pose to humans usually render tolerance levels very
low.

Similarly, the potential damage to buildings posed by poison ivy may also
justify low tolerance levels. Like 3oston Ivy (Parthenoci ssus tricusoi data)
and English Ivy (Hedera helix) (Warnock et al . 1983), Poison Ivy attaches
itself to stone masonry, wood and other building materials by means of aerial
rootlets which are capable of penetrating and enlarging small cracks in the
structure. This habit can result in water damage and general weakening of the
building. The dense foliage and thicket of roots produced by poison ivy arso
can visually obscure the building surface so that damage goes undetected.

Tolerance for poison ivy growing on trees, however, may be high due to the
fact that vines' and roots apparently do not cause injury to trees except where
growth may. cover the supporting plant and exclude sunlight (Crooks 1967).

In summary, in areas of high use near buildings, within campgrounds, and on
major trails, tolerance levels would be low since the likelihood of human con-
tact or damage to buildings is high. In low use and remote areas of the park,
tolerance levels for poison ivy could be quite high, since human contact is
less likely. In general, poison ivy should only be controlled in developed
sites where the plant is likely to come in contact with humans or damage
structures .

3.2 Acti on Poi nt

The action point is that point in time when weed suppression must take place
to prevent the injury level from being reached (or the tolerance level from
bei ng exceeded) .

-21-

where livestock are corralled in the vicinity of poison ivy, early and late
season monitoring visits should be made to document levels of control achieved
by the livestock.

The environmental conditions conducive to poison ivy growth (e.g., sites where
soils have undergone severe disturbance) should be monitored several times per
season in order to spot new infestations of the plant. Examples of such areas
include construction sites, trenching operations, heavily used trails, eroding
streamsides, and even rodent mounds. Monitoring of these areas can consist of
casual observation until poison ivy is found to be present, at which point
written records should be initiated.

3 . DECISION-MAKING

3.1 Determining Injury (To! erance ) Level s

Injury level refers to the point in the growth of the pest population when the
numbers of pest organisms are sufficient to cause some unacceptable kind or
degree of structural, economic, aesthetic or medical damage (injury). When
applying the injury level concept to weed problems, it is useful to substitute
the phrase "tolerance" levels as a synonym for "injury" levels. In other
words, to determine how much weed growth can be tolerated before action is
required to prevent aesthetic or other injury (damage) from taking place.

Several variables should be considered in establishing any weed tolerance
1 evel . These i ncl ude:

a. species and growth habit;

b. location of weed problem;

c. weed population size;

d. type of actual or potential damage caused by weed;

e. degree of invasiveness of growth;

f. costs of managing the weed problem (including lost work time,
responding to complaints, education of staff and visitors,
etc.) .

-23-

Like injury/tolerance levels, weed action points are based upon an
understanding of how fast the plant is likely to spread in a given period of
time and the need to treat early enough in the plant's growth to prevent
injury to people, structures, ornamentals, etc.

With poison ivy, the point when action is needed primarily depends on whether
it is the shrub or vine form to be dealt with, and whether it is the young
seedling stage or established perennial rootstalks that are to be treated.

If it is the shrub form, growth is slow enough that several seasons may pass
before action is required to keep the plants from exceeding tolerance levels.
The only interim action required may be monitoring and the posting of warning
signs to keep humans away from the plants. With the vining form, however, its
rampant growth habit may indicate the need to treat as soon as it is observed
growing in order to prevent the tolerance level from being exceeded.

3.3 Timi ng Treatments

Seedling: The timing of treatments is a function of the. growth stage of the
plant to be treated and the technique to be used. Poison ivy is most easily
removed when in the seedling stage in early spring (Crooks, and Klingman 1967).
Such timing permits the use of mechanical methods — primarily grubbing out the
plants — and occurs at a time when the soil is still wet and all parts of the
plant including the roots can be removed by cultivation. Careful workers with
proper protective clothing can dig out small plants with minimal hazard to
themsel ves.

Clumps: If the plants to be removed are established clumps supported by
mature rootstalks, treatments by mowing should be applied just before the
plants bloom, usually in early to mid-June. Herbicides are most effective
when applied at the full -bloom stage when poison ivy plants are translocating
sugars (and the herbicide) down to the roots. Subsequent treatments should be
delayed until the resprouts are in full leaf. Treatment of mature plants by
physical means (hand removal) or pruning, might best be done in late fall when
plants have lost their leaves, thus reducing the potential exposure of workers

to the poisonous resins. At this point in the season fall rains have again
soaked the soil, making physical or mechanical removal of rootstalks easier to
achieve. Herbicide use can be kept to a minimum by first pruning off the
leaves and stems with a weed eater or lopping shears followed by spot-treati ng
the stumps with a hand-sprayer, wick applicator or injection device.

During the early part of the growing season, the leaves of poisonous plants
usually tend to stand conspicuously apart from those of adjacent plants, and
treatments can be targeted to poison ivy alone if done carefully. Later the
leaves become intermingled, and injury to adjacent species is unavoidable.

3.4 Spot Treatment

The purpose of spot treatments is to confine the material or activity to
the target plant. Spot treatments when plants are small can solve problems
early and avoid more extensive control efforts later on. When treatments
are applied, unnecessary soil disturbance should be avoided as it provides
habitat for new infestations of poison ivy.

4.0 TREATMENTS

4.1 Indi rect suppression

Indirect suppression strategies and tactics are those that change the con-
ditions that create or define the pest problem. Examples are:

a) design or redesign of the landscape or the plant care system for
the purpose of reducing or eliminating weed growth;

b) modifying the habitat in some major way to discourage growth of
a particular weed species;

c) human behavior changes including the alteration of use patterns
or maintenance practices contributing to weed growth, or educa-
tion to increase tolerance levels for the "weed" species.

-26-

B. Competi ti ve PI anti ng

Where significant soil disturbance has occured due to construction projects,
acts of nature, or physical removal of poison ivy plants, it is important to
seed in or plant fast-growing soil colonizing plants such as grasses or
groundcovers in a effort to limit the soil space and nutrient reserve other-
wise available to poison ivy. Although this tactic has not been documented
specifically for poison ivy in the weed literature, it is a well-established
weed control tactic for similar species (Daar, 1983b) and is worth testing on
poison ivy.

To be most effective, the planting should occur as soon as possible after the
soil disturbance has occured. Native plant species are most desirable for -
such areas as they are best adapted to existing soil conditions and weather
patterns and best able to establish themselves with minimum maintenance.
Consult local soil conservation and native plant organizations for recommended
plant species!

4.1.3.2 Education

In a park setting, it is important to educate visitors and staff on methods of
identifying poison ivy so they can avoid contact with the plant. To the degree
human contact with the plants can be avoided, treatments of the pest will be
unnecessary. Signs, pamphlets and displays can be located at trail heads,
campgrounds, visitor centers and similar areas where visitors are frequent.

4.2 Pi rect Suppression

4.2.1 Physical controls

A. Grubbi ng Out

Seed! i ng: Physical removal with digging and cutting tools is often the most
effective means of thorough removal of poison ivy. Seedling plants can be dug
out most easily in early spring after leaves have unfurled, but while the soil

-25-

4.1.1 Design or Redesign

Poison Ivy is primarily a problem in landscapes that have not been designed by
humans originally, or that have been left to revert to a more "natural" state
after previous human management. Redesigning the area is rarely a desirable
strategy because of the basic objective of keeping the area as "natural" as
possible.

However, in developed park areas designers of latrines, visitor centers,
campgrounds, fence! ines, etc. should be encouraged to avoid creating bare
areas beneath likely bird perches as these conditions optimize the establish-
ment of poison ivy.

4.1.2 Habitat Modification

No examples of using habitat modification to manage poison ivy. could be found
in the literature. However, ecological information on the pest suggests that
application of deep mulches to bare soil could restrict germination of ooison
ivy seeds (see "Mulching", Section 4.1.3.1C).

4.1.3 Human Behavior Changes

4.1.3.1 Horticultural Controls and
Mai ntenance Activities

A. Mi nimi zi ng Soil Pi sturbance

Poison Ivy is opportunistic, taking advantage of areas where the soil has been
disturbed and laid bare, and there is less competition. Where the pest plant
and the wildlife that feeds upon and spreads it are common, every effort
should be made to minimize soil disturbance as a part of construction projects
or staff and visitor traffic.

-27-

is still wet. By summer or fall of the first year, seedlings usually have a
well -devel oped vertical and horizontal root system and are more difficult to
remove.

Mature: Late fall, after poison ivy has dropped its leaves and rains have
saturated the soil, is usually the best time to dig out mature poison ivy.
Since root systems may travel horizontally for 20 feet, extensive digging may
be necessary. However, the roots do not appear to grow more than a foot or so
deep, so extensive vertical digging is usually not required. After the ini-
tial grubbing has occured, treated areas should be monitored on a monthly'
basis to check for resprouts from rootstock inadvertently left in the soil. .

In addition to shovels and mattocks, other tools useful when grubbing out
poison ivy include brush hooks, McLeods (a double-edged digging tool),
Pulaski's (a forester's axe), and gas-powered weedeaters with blade attach-
ments. Hydraulic winches mounted on pick-up trucks are often useful in
removing stems and roots of" poison ivy growing in dense thickets. These tools
can be found in most forest equipment supply catalogues.

B. Mowi ng

Seedling and young plants can be kept within an inch or two in height by fre-
quent mowing (probably twice per month during the growing season). This regular
removal of leaves and stems will restrict (but not eliminate) the development
of horizontal roots. If a mowing program is adopted, it is important to
collect clippings and dispose of them in a plastic bag or bury them to prevent
the clippings from being spread over large areas and inadvertently contamin-
ting park workers or visitors. Mowing is not recommended for poison ivy
control in a lawn area used for picnicing or other recreational activities.

C. Reseated Cultivation

Poison ivy can be removed by repeated cultivation with a hoe, disk, spring-
toothed harrow, or duck-foot cultivator. To be effective, cultivation has to
occur frequently enough to remove new seedlings or young plants before they
are able to form extensive perennial roots. The actual cultivation frequency
required is a function of several factors including extent of growth of poison
ivy, soil conditions, type of adjacent vegetation, etc.

D. Pruni ng and Gi rdl i ng

It may be possible to kill poison ivy by girdling stems or trunks. To do
this, cut an incision through the bark into the sapwood in a continuous line
around the circumference of the stem. The incision cuts the sap transport
vessels thus halting the movement of nutrients and water up and down the
plant, causing eventual death.

Poison ivy growing as long vines on trees can be killed by severing their
stems near the soil line with an axe or saw (Grant 1929). Care should be
taken to chop completely through the viney stem which is often found fitting
in a groove of the bark of the tree. To minimize damage to the tree bark, the
final cut should be made with a knife.

The severed vine can be pulled from the tree at the time the cut is made, or
it can be left to dry on the tree over the summer and be removed in the fall
when the dried leaves have dropped off and the remaining wood is less toxic to
handle. After a month or six weeks, the new tops that spring from the lower
portion of the vine may be pulled up (Grant 1929), injected or painted with
an herbicide, or cut off repeatedly in hopes of starving the root system and
achieving the eventual death of the plant.

E. Mul ching

Once poison ivy has been removed from an area, it is desirable to cover the
soil with a temporary groundcover, to reduce the ability of poison ivy

-29-

seedlings to recolonize the open ground. A deep mulch (6-12 inches) of
hardwood chips is most likely to provide protection against poison ivy
seedling emergence. Hardwood chips in the 1" x 2" size range are more effec-
tive than mulches made from bark. The small particles size of bark mulches
and their easy decomposition by soil microbes limits their effect.

NOTE: Never burn any part of the poison ivy plant. Tiny droplets of the oil
will be carried on ashes in the smoke and can be breathed into the lungs.
The throat may swell up and the whole body can break out in an extreme rash.
Whenever possible, dispose of treated poison ivy by burying. Plant pieces
should be covered with at least 12" of soil to prevent sprouts from
developing. If burying is not feasible, enclose plants in plastic bags for
disposal in a landfill.

4.2.2 Biological controls

A. Arthropods and pathogens

A number of arthropods, micro-organisms and viruses are reported to feed on
poison ivy (See Section 1.4). However, researchers are reluctant to pursue
biocontrol programs on poison ivy because so little is understood about the
beneficial roles played by poison ivy and other native plants in the eco-
system. The unknown risks to the environment caused by . non-sel ecti ve
suppression of native plant species by biological control organisms could out-
weigh the benefits.

B. Livestock

Suppression and even eradication of shrubby stands of poison ivy can be
achieved by intensive grazing of livestock in areas where the plant is growing
(Grant and Hansen 1929). While few studies exist on using livestock specifi-
cally for poison ivy control, there is extensive experience with goats
controlling similar brush species such as poison oak (Rhus diversiloba L.) in
the western U.S., and useful extrapolations to poison ivy are probably in
order (Daar 1983a; Green and Newell 1982).

-30-

Where appropriate, Angora, Spanish or other non-dairy goat breeds or sheep can
be concentrated in an area containing poison ivy by use of lightweight, por-
table, electrified plastic fencing called Flexinet', powered by a 12 volt car
battery or solar cell which generates sufficient current to keep livestock in
and predators out. Fencing fabric is supported on non-conductive fiberglass
fence posts. Flexinet' is available from the Waterford Corporation, Fort
Collins, CO and costs approximately 5100 for 150 feet in 1983.

The degree to which poison ivy is suppressed or eradicated by goats or
sheep depends on a number of factors including herd size, duration of penning,
state of succulence of vegetation, etc. Goats and sheep will graze or trample
most of the vegetation in the area in which they are penned, so valuable vege-
tation such as specimen trees and shrubs should be protected by fencing or
other barriers to keep the livestock at a distance. Goats eat both foliage*
and stems of poison ivy.

4.2.3 Chemical controls

A. Herbici de Appl i cation Timing and Techni ques

Typically, at least two herbicide applications are needed to kill all parts of
the plant (Grant and Hansen 1929; Crooks and Klingman 1967). Seedlings should
be treated in the spring as soon as new leaves are fully opened (Daar 1983b).
Translocated herbicides such as ammonium sulphamate (=Ammate*) or glyphosate
(=Roundup®) should be applied on mature plants during or just after the bloom
1 stage as that is the point when sugars are being translocated to the roots and
will carry the herbicide throughout the plant system. If monitoring indicates
retreatment is needed, a second application is best made as soon as resprouted
leaves are fully expanded (Crooks and Klingman 1967). See Table 3 for a list
of herbicides registered for use against poison ivy.

B. Protection of Workers

Poison ivy is toxic at all stages of growth — and even when dead from severed
roots or herbicide spray (Crooks and Klingman 1967). Thus protective

-31-

TABLE 3.

A COMPARISON OF EFFICACY, TOXICITY, MOBILITY I PERSISTENCE
OF COMMON HERBICIDES USED AGAINST POISON IVY

HERBICIDE

EFFICACY TOXICITY MOBILITY PERSISTENCE COMMENTS
(LD50)1 SOIL/WATER'1

Ammonium Sulphamate
( Ammate®)

H L L S= 4-12 wks Degrades to

W= nd nitrogen and
sulfur in soil

Aminotriazole
(Amitrol-T®)

H M M S= 7 weeks Potentially

W= 201 days carcinogenic
in humans^

Glyphosate
( Roundup®)

H L L S= >8 wks§

W= nd

Sodium Chlorate
(Chlorate/Borate
mix is fire-retar-
dant)

H L L-H S= 12-52 wks

W= nd

★ „
Herbicides from Herbicide Handbook. 1979. Weed Science Soci-ety of America.

"'"Ibid, Herbicide Handbook.

"'"'"pimentel , D. 1971. Ecological Effects of Pesticides on Non-Target Species.
Office of Science and Technology. USGPO. NOTE: This data is dependent on
many variables including soil type, available moisture, rates of applica-
tion, etc. Figures presented here should be considered approximations.

'iARC monographs on the Evaluation of the Carcinogenic Risk of Chemicals to
Humans, Supplement I, 1979. IARC, Lyon, France, p. 22.

^Herbicide Handbook, op.cit., p. 226.

KEY:

Efficacy: H = High; M = Medium; L = Low

Toxicity: H = LDso's of 1-99 mg/kg; M = 100-1000; L = >1000.*

Mobility: H = High; M = Medium; L = Low

Persistence: S = soil; W = water; nd = no data

-32-

clothing should be worn no matter which treatment is selected. Workers should
cover as much of the body as possible. Canvas or leather leggings over work-
pants provide extra protection when working in dense stands of the plants..
Hands should be protected with thick canvas, rubber or leather gloves. A
beekeeper hat with veil can be used to protect the face when clearing dense
stands of poison ivy. An industrial respirator mask should be worn when
chopping or sawing plants to prevent breathing in sawdust particles, or when
in the vicinity of burning poison ivy (burning is not a recommended method of
control or di sposal . )

Poison ivy sap can adhere to clothing, tools, and the coats of pets and
livestock for very long periods of time, and therefore serve as reservoirs for
recontami nation . For example, Shelmire (1941) reports that gloves stored a-t
room temperature for 16 months still can cause poison ivy dermatitis. Thus it
is important that clothing worn while working in or near poison ivy be care-
fully removed (use gloves), washed in hot, soapy water, and hung in the air to
dry for several days in order to insure that all sap is deactivated (Gill is
1975). Repeated washing may be needed. Do not wash with other clothing.
Using rubber gloves, clean tools used on poison ivy after each use with a rag
containing an oil solvent such as gasoline, alcohol, or turpentine. Rags and
gloves should be enclosed in a plastic bag and discarded after use to prevent
recontami nation.

Contaminated skin should be washed several times with water and a strong soap.
The soap dissolves the oily sap and enables it to be removed from the skin.
If soap is not available, cotton balls soaked in vinegar (2 tablespoons in 1
cup water) or alcohol (1/2 cup alcohol to 1/2 cup water) can be dabbed on the
contaminated skin to dissolve the sap. Calamine lotion or a paste of baking
soda can be topically applied to the dermatitis to relieve itching.

C. Protecti ng Adjacent Vegetation

Since both shrub and vining forms of poison ivy usually grow in association
with desired ornamental or native plant species, great care must be taken not
to permanently damage such plants when using herbicides on poison ivy.

-33-

To keep damage to desirable plants to a minimum, use injection, frill or
basal spray techniques where possible. Herbicide injection tools are
available from forestry supply catalogues or other equipment sources. Frill
methods consist of making shallow axe cuts around the circumference of the
stem and applying herbicides into the cuts. Basal sprays involve coating
the bark on the lower 12" to 24" of trunk or stem with herbicide.

When foliage sprays are required, spray nozzles which produce fairly large
herbicide droplets should be used to limit drift of the herbicide. It may be
useful to include an anti -drift product in the spray tank. Drift also can be
minimized by using moderate pressure thus producing relatively large spray
droplets, rather than high pressure which produces a driving mist (Crooks and
Klingman, 1967).

Another application tool useful in confining herbicides to the target weed
(spot-treatment) is a wick applicator. These tools absorb the herbicide on a
rope, sponge or carpet wick and permit the applicator to wipe the herbicide
directly onto the poison ivy. The applicators are made from common PVC
plastic pipe and commercial rope, sponges or carpet pieces. They can be
custom designed (or easily retrofitted) with long handles" allowing the worker
to stand some distance from the poison ivy yet still apply the herbicide.
Manufactured, hand-held or machine-mounted wick applicators can be purchased
from commercial sources.

The "jar method" is another technique of limiting drift. To implement this
method, cut the tip off a trailing stem of the poison ivy plant. Discard
the severed tip and place the cut end into a quart jar containing an herbicide
solution for at least one hour. Jars (or other containers) should be stabi-
lized so they don't tip over. It also may be necessary to use a wedge or
fastener to hold the immersed shoot in position. The herbicide will be
translocated throughout the plant's vascular system and the plant (or substan-
tial portions) will die.

The herbicides ammonium sulphamate, sodium chlorate or glyphosate can be used
in the jar method. Use at the highest concentration permitted on the label.

-34-

Bates (1955) found that a 40 percent concentration of sodium chlorate was rnore
effective at killing woody plants than were weaker solutions of 5 to 10 per-
cent. Mote that sodium chlorate is highly combustible and should be used with
extreme caution.

The "jar" method works on the principle of negative root pressure and,
according to 3ates (1955), the best results are obtained in hot dry weathe'-
and at the height of summer. Treatment with the "jar" method in mid-winter
and early spring seem to be the least effective and treatment of certain
plants was without effect in late March, but rapidly effective in July. Once
the plant is dead, the sodium chlorate, "does not appear to cause any injury
when the weed decays. Whether this is due to the small amount present or
whether it is due to the decomposition of the chemical, is not known (Bates-,
1955). Ammonium sulphamate degrades to the fertilizers nitrogen and sulphur.
If the "jar" method is used, workers must remain near the jars to insure that
visitors, pets or wildlife do not come in contact with the poisons.

end —

-35-

5. REFERENCES CITED

Annon. 1979. Evaluation of the carcinogenic risk of chemicals to humans.
Supplement I. IARC. Lyon, France, p. 22.

Arthur, J.C. 1934. Manual of the rusts in the United States and Canada.
Purdue Research Foundation. Lafayette, Ind. 438 pp.

Bates, G.H. 1955. Weed control. Farmer & Stock-Breeder Ltd. London,
pp. 193-199.

Connors, I.L. 1967. An annotated index of plant diseases in Canada. Can.
Dep. Agric. Publ . 1251. 381 pp.

Crooks, D.M. and D.L. Klingman. 1967. Poison ivy, poison oak and
poison sumac. Farmers Bulletin No. 1972. USDA. 16 pp.

Criddle, N. 1927. Lepi dopteras reared in Manitoba from poison ivy. Can. J.
Entomol . 59:99-10TI

Daar, S. 1983a. Using goats for brush control. IPM Practitioner 5(4):4-6.-

Daar, S. 1983b. Using IPM principles in weed control programs. IPM
Practitioner 5(2) :6-8.

Gill is, W.T. 1975. Poison ivy and its kin. Arnoldia 35: 93-123.

Gill is, W.T. 1971. The systematics and ecology of poison-ivy and the

poison-oaks (Toxicodendron , Anacardi aceae) . Rhodora 73: 72-159, 161-237,
370-433, 465-34H:

Grant, C.V. and A. A. Hansen. 1929. Poison ivy and poison sumac and their
eradication. Farmers Bulletin No. 1166. USDA. 14pp.

Green, L.R. and L.A. Newell. 1982. Using goats to control brush regrowth on
fuel breaks. General Technical Report PSW-59. Pacific Southwest Forest
and Range Experiment Station. 30 pp.

Harrison, G.D. 1904. Poison ivy caterpillars. J. New York Entomol. Soc.
12:249-250.

Martin, A.C., H.S. Zim and A.L. Nelson. 1951. American wildlife and plants.
A guide to wildlife food habits. Dover Publ., New York, N.Y. 500 pp.

Mulligan, G.A. and B.E. Junkins. 1977. The biology of Canadian weeds:
Rhus radicans L. Can. J. Plant Science 57:515-523.

Parmelee, J. A. and M.E. Elliot. 1974. Pileolaria brevipes. Fungi
Canadensis 50, Agrig. Canada, Ottawa, Ont. 2pp.

I

-36-

REFERENCES, CQMT.

Pimentel , D. 1971. Ecological effects of pesticides on non-target species.
Office of Science and Technology. USGPO. 220 pp.

Rostenburg, A. 1955. Anecdotal biographical history of poison ivy. A.M. A.
Arch. Derm. 72:438-445.

Richards, W.R. 1972. Aulacorthum rhusifoliae (Homoptera; Aphididae). A
new poison ivy inhabiting aphid from Ontario. Can. Entomol. 105:
173-174.

Shelmire, 3. 1941. The poison ivy plant and its oleoresin. J. Invest. Derm.
4:337-348.

Steyskal , G. 1951 - Insects feeding on plants of Toxicodendron section of
the genus Rhus. Col eopteri st 1 s 3ull.5: 75-77.

Tissot, A.M. 1928. A new aphid on poison ivy (Rhus radicans L. ) . Fla.
Entomol . 12: 1-2.

Tissot, A..N. 1933. Additions to the aphid fauna of Florida. Fla. Entomol.
17:37-45.

Weed Science Society of America. 1979. Herbicide handbook. Fourth Ed.
479 pp\ '

Warnock,' R.A. , L. Fendrick, 8. Hightower and T.D. Tatum. 1983. Vegetative

threats to historic sites and structures. Soil Systems, Inc. Alexandria,
Virginia.

-37-

ADVANTAGES OF HAND CUTTING

1. Cost: The basis of a single treatment, hand cutting has a

cost advantage over other types of treatment
regardless of the density of capable stems. In the
long-term program of treatment over several
treatment cycles, hand cutting may not be the least
expensive since this type of treatment eventually
leads to prolific sprouting and increased density.
All costs are based on utility billing rates for
labor, equipment and materials. Labor rates
include the wages paid to the worker plus overhead
and profit (lb).

Aerial herbicide treatment caused a net decrease (-6-
percent of shrubs. Selective ground foliar
spraying produced a low net increase (+3 percent)
of shrubs. The effect of hand cutting and the
other four treatments (listed on page 31) on ground
cover were similar. An increase in total herbaceous
cover was recorded for all treatments (lb).

3. Visual Effects: Undesirable brownout and more accumulation of dead

stems was seen with herbicide treatments than with
hand cutting (lb).

4. Health Affects: The adverse health effects of handling pesticides

was studied in the Maine Department of Trans-
portation and Pesticide Control Board. Of
the 38 persons tested 27 may possibly be responding
to occupational exposures. In some cases, liver
enzyme levels were slightly above normal, while in
others the cholinesterase values were somewhat
depressed. Maine is one of a handful of states that
has started such programs (Feb. 1985). It has begun
focusing on long-term toxicity of chemicals used,
instead of merely considering the acute effects. It
should be noted that there have been some reports
of accidents due to the use of chain saws in hand
cutting.

2. Maintenance of

Desirable Non-target
vegetation

-38

-39-

Estimate Cost per acre for Single Treatment
(Based on 1981 Dollars) (lb)

Density steins per acre 4 ft
2,000 6,000 12,000

10 ft

2,000 6,000 12,000

Hand Cutting

$82 $159

$274

$124 $201 $317

Mowing

$93 $128

$181

$210 $245 $298

Cut & Stump

$312

$648

$210 $434 $770

Dormant Basal $184 $345 $586
Treatment

$452 $613 $855

Summer Basal $206 $408

Treatment

$713

$314 $517 $821

Selective
Ground Foliar
Treatment

$104 $125

$155

$277 $297 $327

-40-

SUMMARY OF NO SPRAY PROGRAMS

STATE

RESPONSIBLE AGENCY OR COMPANY

Maine*

Dept . of Trans . (DOT)

Utility Company Agreement

1 . Town of Lebanon
signed agreement
2 years ago.

2. Town of Southport
presently discuss-
ing an agreement.

3. About 500 land-
owners have agree-
ments. 75% of the
landowners have
successfully com-
plied with the
program.

Maine Central
Power sent noti-
fication of No
Spray option to
all customers
with March bill.
To date about 75
people have re-
quested information
and about 20 have
signed agreements.

Landowner or landowner of
abutting property main-
tains land to specifica-
tions set by the Depart-
ment of Transportation or
Utility Company

4. DOT places metallic,

reflective, No Spray

signs on appropriate
_pr_opertv_1__

Vermont**

Public Service
Board (includes
all utility
companies)

1. Limited spraying, i.e.
cutting and stump treat-
ment free to landowner

OR

2. Landowner pays the
difference in cost be-
tween mechanical clearing
and spraying. This cost
is based upon a brush
acre, i.e. 500 stems per
acre. The cost has not
been set yet as there are
discrepancies in the cost
estimation among the
various companies.