ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF ENFORCEMENT
EVALUATION OF 2,4-D DAMAGE
IN THE LOWER YAKIMA VALLEY, WASHINGTON VINEYARDS
March 1979
National Enforcement Investigations Center
Denver, Colorado
and
Region X
Seattle, Washington
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INTRODUCTION
The lower Yakima Valley, located in south-central Washington at
the confluence of the Yakima and Snake Rivers with the Columbia River
(Figure 1), is an area of diverse agricultural crops. Numerous crops
are grown, with wheat being the principal one. Also of considerable
importance in the region are grapes, both wine and domestic varieties.
Grape vineyards in the lower Yakima Valley have been damaged, alleg-
edly, by the herbicide 2,4-D (2,4-dichlorophenoxyacetic acid) for
the past 20 years. Greater damage has occurred since 1969, especially
• during the 1974 grape-growing season . There are at least three
possible sources of the herbicide contamination:
1. Low-volatile and amine 2,4-D used on grains in
Washington is translocated to sensitive grape crops
when weather conditions favor herbicide drift.
2. Illegal use of high-volatile 2,4-D in the State of Washington.
3. High-volatile 2,4-D drift entering Washington from treated
croplands in Oregon.
Whenever any agricultural pesticide is sprayed on a field by
either a groundrig or aircraft, there is an initial drift of some
active ingredient away from the target area. This takes the form of
droplet drift at the time of spraying, with the smaller size drop-
lets being carried downwind rather than depositing in the target area.
Following the application, and generally extending over several hours,
more pesticide may be carried from the target area through evaporation
if the active ingredient is volatile. This latter transport is termed
vapor drift.
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WALLA WALLA
•PENDLETON
LEGEND
Study Area
Grape-gro win g*A r e a
Limits of Grain-Growing
Area
Figure 1. Grape-growing Region of Washington State
and Surrounding Study Area
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2
Spray deposition studies done in Canada showed that, for high
volatile 2,4-D butyl esters, about 35% of the applied chemical
evaporated from the ground and drifted downwind as vapor. For the
less volatile octyl formulation, the figure for vapor drift was around
12%. Initial droplet drift from the esters, as well as from the non-
volatile amine formulation, was about 3-5%. Maximum drift distances
were not calculated but probably exceed 40 km (25 mi.).
Applying these research findings to the situation in the lower
Yakima Valley, it appears that vapor drift from high volatile (butyl
ester) 2,4-D applications is potentially very high. The only known
use of high volatile 2,4-D in the study area is in Oregon.
Although the vineyard damage is apparent, the cause of the damage
3
is controversial. Studies by researchers at Washington State University
allege that one mechanism of damage is airborne translocation associ-
ated with the use of high-volatile 2,4-D to control weeds in north-central
Oregon grain-growing areas. However, Oregon State University
4
researchers found it unlikely that high-volatile 2,4-D is trans-
located from Oregon into Washington in sufficient amounts to cause
such damage. Oregon investigators believe it is more likely that
vineyard damage in Washington is due to low or non-volatile 2,4-D,
other herbicides, or the illegal use of high-volatile 2,4-D within
Washington State.
Washington State Department of Agriculture has used the Washing-
ton State University research results to develop herbicide-control
regulations. Presently, restrictions on 2,4-D use that are enforced
in Washington State are as follows:
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1. High volatile 2,4-D is banned (since 1974).
2. The use of low-volatile 2,4-D is prohibited in
areas immediately surrounding the grape growing
region between April 5 and October 31.
3. Application of 2,4-D is not permitted when weather
conditions favor drift that could damage susceptible
non-target crops.
4. Spray-booms must be equipped with state-approved
nozzles to lessen the chance of drift. Minimum allow-
able oriface diameter is 9mm (0.036 in.)
Despite these restrictions, concentrations of 2,4-D continue to be
found in air samples collected by Washington State University in and
near Washington vineyards. EPA Region X, Seattle, Washington, requested
the National Enforcement Investigations Center (NEIC) to (a) determine
if 2,4-D or other herbicide applications are causing damage to vineyards
in the lower Yakima Valley, (b) determine, if possible, the mode of
translocation and the source of herbicides causing damage to the vine-
yards, and (c) evaluate appropriate control measures.
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SUMMARY
The field study was conducted from April 20 to May 5, 1978, and
included: (1) environmental sampling of soil, water and vegetation
(grape leaves) for herbicide residue analysis; (2) ambient air sampling
to determine aerial concentrations of 2,4-D; (3) determining the amounts,
types, and locations of herbicide use in the study area during the field
study; and (4) recording weather conditions of the study area via a
network of meteorological stations. In addition, an unsuccessful aerial
gas tracer study was conducted to provide additional information on air
movements from Oregon into Washington.
Grape leaves in the lower Yakima Valley of Washington State were
contaminated with as much as 0.28 pg/g of 2,4-D by April 21, 1978.
A second visit in late June, 1978 revealed extensive herbicide damage
in several vineyards, but the 1978 grape yield remained good. Growers
believe prospects for another good crop in 1979 are poor because the
herbicide damage of 1978 will reduce overall plant vigor next season.
Apparently, 2,4-D drifted by air into the vineyards prior to the
NEIC study. Because of incomplete records of application in Oregon and
the fact that no 2,4-D was found in air samples collected by the NEIC,
the specific source of the 2,4-D drift remains unknown.
Droplet drift into vineyards from any 2,4-D application in Oregon
or Washington could be reduced also if applicators were required to:
(:1) spray only under the lightest winds, not under weather inversions,
(2) reduce hydraulic pressure on sprayers, (3) apply more total solution
volume, (4) use thickeners, or (5) use low pressure nozzles.
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STUDY METHODS
Ambient air, soil, water and vegetation samples were collected
from seventeen stations in the lower Yakima Valley [Figure 2 and
Table 1]. Seven sampling stations (2,4,5,6,9,10 and 15) were
located in vineyards. The remaining 10 stations were sited in the
vicinity of Pasco, which is the center of the grape growing area.
To adequately define meteorological conditions in the survey
area, data were obtained for wind speed, wind direction, horizontal
wind direction variation, stability, mixing depth, temperature,
humidity, and barometric pressure. In addition to three meteorological
stations established by the NEIC [Figure 2], data were also obtained
from the National Weather Service and Battelle Northwest Laboratories,
Richland, WA and Portland General Electric, Portland, OR for the period
from April 16 to May 6, 1978. Weather forecast support was provided
by the Portland, OR and Yakima, WA National Weather Service offices.
This information was used in planning an SF, (sulfur hexafluoride)
gas tracer study; however, a malfunction in sampling equipment
prevented usable results from being obtained.
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Table 1
Sampling Station Locations
1. Murch-Land vineyard near Grandview, WA
2. Handling Farm near Mabton, WA
3. Washington State University (WSU) Experimental Farm
near Prosser, WA
4. Parcel 1 home near Benton City, WA
5. Bacchus-Dionysis vineyard near Pasco, WA
6. Conner vineyard near Pasco, WA
7. Neff farm near Ice Harbor Dam, WA
8. Fire station near Hoffman Ranch at Eureka, WA
9. Snake River vineyard near Ice Harbor Dam, WA
10. Lutke vineyard near Kennewick, WA
11. 1 mi. south of Cemetery Road on Travis Road near
Kennewick, WA
12. Clodfelter Farm near Kennewick, WA
13. Blair Ranch in Horse Heaven Hills near
Kennewick, WA
14. Lynch Ranch near Touchet, WA
15. Cripe vineyard near Hermison, OR
16. Carty Meterological Tower near Boardman, OR
17. Pebble Springs Meteorological Tower near Arlington, OR
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rse Heaven Hills
WASHINGTON
1"
'$'.
«¥•'•
.i
.
i..
Sampling Static ns
M=| Meterological Stations (NEIC)
Figure^ 2, Samp/ing Stafionsl
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At the seven vineyards included in the study area, samples of
irrigation water, soil and vegetation were collected for analysis of
2,4-D and dicamba. Air samples were collected by use of a porous
polystyrenedivinyl-benzene copolymer resin, Amberlite XAD-2*, a solid
absorbent which selectively retains organic compounds in air while
allowing water vapor to pass through the collection column. Twice
daily (on an 8- and 16-hour schedule) the resin columns were retrieved,
wrapped in aluminum foil, packed in separate plastic bags, labeled and
shipped to the NEIC laboratory for analysis of phenoxy herbicides.
To determine the types, amounts and locations of herbicide appli-
cations during the period of April 15 to May 5, 1978, a questionnaire
was prepared and distributed to aerial applicators operating in
east-central Washington and Oregon [Fig. 7]. However, because limited
data were received from the questionnaire, a subsequent review of state
'pesticide use records was conducted, in October, 1978. Senior officials
within the Washington and Oregon state agricultural departments were
also contacted at that time.
STUDY RESULTS
In March, 1978, during a reconnaissance of the lower Yakima Valley,
woody portions of selected grapevines and soil samples were collected
from vineyards, allegedly affected by 2,4-D. A grapevine sample collected
on April 1, 1978 contained 0.06 ug/g of 2,4-D. One soil sample, collected
on March 15, 1978, contained residues of a benzoic acid herbicide (0.005
yg/g dicamba). At no other time during the reconnaissance in March or
the full-scale study in 'April and May did an analysis reveal detectable
levels of dicamba.
*Mention of commercial products does not constitute endorsement by
the U.S. Environmental Protection Agency.
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Vegetation (grape leaves), soil, irrigation water, and ambient air
were collected from the vineyards during the April 20 to May 5, 1978
study. Grape leaves contained from <0.13 to 0.28 ug/g 2,4-D (Table 2)
with no other pesticide residues being found. Analytical methods used
did not specifically identify the type of 2,4-D on the grape leaves
(e.g. high, low or non-volatile); however, 2,4-D at an intermittent con-
centration of 0.1 y/g over a 60 hour time period is known to damage
c
grape plants . No 2,4-D or other phenoxy-type herbicides were found in
air, soil or irrigation water samples.
To determine the possible means by which 2,4-D was translocated to
vineyards, published literature was reviewed.
Pesticide studies conducted in Canada and Washington state
reaffirmed that 2,4-D contact with exposed plant surfaces, via air (not
soil or water) is the most effective method to apply the herbicide and
kill plants. Soil incorporation or mixing with irrigation water are
methods not used in WA or OR. Based on these facts, it was concluded
that airborne deposition of the 2,4-D appears to be the most likely way that
the vineyards of the Yakima Valley become contaminated.
In late June, 1978, damage to grape leaves was noted during a visit
to several vineyards in the Pasco, WA area, with local grape-growers
(Figures 3,4,5,6). Figure 4 shows a grape vine alledgedly contaminated
with 2,4-D; however, other herbicides cause similar malformations. These
vineyard owners stated that 1978 crop prospects ranged from fair to
good, but that 1979 crop production may suffer because of a loss of
plant vigor during the 1978 growing season.
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Fig. 3. Normal near-mature Concord grape leaf.
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Fig. 4. Emerging Concord grape shoot contaminated with 2,4-D.
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Fig. 5. Typical 2,4-D symptoms on Concord grape leaves.
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Fig. 6. Poor set of wine grapes caused by aerial 2,4-D
contamination. (Courtesy of W.J. Clore)
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Table 2
Results of Analyses of Vegetation Samples
for 2,4-D*
Date
4/1/78
4/21/78
4/21/78
4/21/78
4/21/78
4/22/78
5/2/78
5/2/78
5/2/78
5/2/78
5/3/78
Time
—
0640
0730
0937
1000
1430
0715
0800
0840
1021
0900
2,4-D**
0.06*
0.28
0.11*
0.15
0.09
<0.13
0.10
0.03
0.05
0.11
0.08
*Confirmed by GC/MS
**Expressed as yg/g of the methyl ester
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Information provided to the NEIC by several grape-growers following
the 1978 harvest indicated that yields were good, probably the best
within the last 5 years. The apparent anomoly between severe plant
damage and a good crop yield is not clearly understood.
Principal formulations of 2,4-D used as reported by aerial appli-
cators [Fig. 7] and by review of state records in both Washington and
Oregon were the low-volatile amine (Washington) and the high-volatile
butyl ester (Oregon). Commercial applicators reported crops treated
with 2,4-D and other closely related produces included wheat, corn,
clover, alfalfa and barley, while a variety of other herbicides were
used on peas, corn, barley, alfalfa, mint and wheat, the latter being
the principal crop treated with 2,4-D in 1978.
The questionnaire completed by applicators revealed 2,4-D was
sprayed on 8 to 1860 hectare (20 to 4,600-acre) fields at a rate of
28 to 94 liters/hectare (3 to 10 gallons/acre) using .0.3 to 1.8
liter/hectare (0.25 to 1.5 pt/acre) active ingredients. In Washington,
the state data were detailed enough to determine that 16,000 hectares
(39,000 acres) were treated with approximately 643,000 liters (170,000
gallons) of 2,4-D during the April 20 to May 5, 1978 study; treated
sites were as close as 8 Km (about 5 miles) to vineyards. Data
supplied by Oregon provided information only on total amounts sprayed
on a daily basis within the Oregon Columbia Basin wheat growing area;
the specific locations and number of treated acres were not made
available.
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Additionally, the data revealed that: (1) in Washington and
Oregon most spraying of herbicidal material occurred after April 20,
and (2) about 4,800 Kg (10,500 Ibs) of high volatile 2,4-D was sprayed
on Oregon wheat fields during the course of the NEIC study. The use
of high volatile 2,4-D is not permitted in Washington.
2
While the high volatile 2,4-D has a propensity to drift , no
2,4-D was found in air samples during the NEIC study (April 20 to
May 5, 1978); therefore, the NEIC was unable to determine the specific
source of 2,4-D found earlier in Yakima Valley vineyards.
In order to estimate the possible downwind hazard resulting from
pesticide .drift and in particular to determine ways by which the
hazard can be reduced, it is essential to distinguish between droplet
and vapor migration from the target area.
Recommendations
Because drift of 2,4-D may cause herbicide damage in vineyards,
it is appropriate to maintain controls on 2,4-D applications in
Oregon and Washington sites upwind from Yakima Valley vineyards.
Applicators in both states should be advised to spray 2,4-D only
under the lightest winds, particularly when upwind of susceptible
grape vineyards. Spraying should not occur under inversion conditions,
when the upward dilution of the drift cloud is much reduced.
Applicators should also be advised that drift from 2,4-D applications
is effectively diminished by: (1) reducing the hydraulic pressure
on sprayers; (2) applying more total solution volume; (3) using
thickeners and (4) using, low pressure nozzles.
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FIGURE 7
Example of Herbicide Application Record
Questionnaire Sent to all Aerial Applicators in
North-central Oregon and South-central Washington
HERBICIDE APPLICATION RECORD
Applicator (Firm) Date Time to_
Location of Field (Hwy/Route-Nearest Town & Distance)
Area of Field (Acres) Application-Aerial/Ground Herbicide Applied_
Application Rate (Gal/Acre) Crop Treated
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REFERENCES
1. Personal Communication from C. Brown, Washington
State Department of Agriculture. March, 1978.
2. Maybank, J., et al_. 1977. Spray Drift and Swath
Deposit Pattern from Agricultural Pesticide Appli-
cation: Report of the 1976 Field Trial Program.
SRC Rept. No. P77-1, Jan., 1977.
3. Anon. 1977. Studies of 2,4-D Drift Problems in
the Lower Yakima Valley-1976. Report No. 77-13-32.
Washington State University. 27 pp.
4. Farwell, S.O., F. W. Bowes and D. F. Adams, 1977.
Evaluation of XAD-2 as a Collection Sorbent for
2,4-D Herbicides in Air. J. Environ. Sci. Health
B12(l): 71-83.
5. Weigle, J.L., e_t al_. 1970. 2,4-D as an Air
Pollutant: Effects on Market Quality of Several
Horticultural Crops. HortScience 5(4):213-214.
6. Maybank, J., et al. 1978. Spray Drift from
Agricultural Pesticide Applications. J. Air Pollut.
Conf. Assoc. 28(10):1009-1014.
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