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C / 2 Soil Science Department
Water Quality Initiative Series
Circular 995
May 1991
PEARS
MANAGING PESTICIDES FOR CROP PRODUCTION
AND WATER QUALITY PROTECTION
A Supplement to the IFAS Pest Control Guides
A. G. HORNSBY
and
T. M. BUTLER
Soil Science Department
T. E. CROCKER
Fruit Crops Department
R. F. MIZELL III
NFREC, Quincy, FL
R. A. DUNN
Entomology and Nematology Department
G. W. SIMONE
Plant Pathology Department
Institute of Food and Agricultural Sciences
University of Florida
Gainesville, FL 32611
Florida Cooperative Extension Service
Institute of Food and Agricultural Sciences
University of Florida, Gainesville
John T. Woeste, Dean for Extension
WATER QUALITY CONSIDERATIONS IN
PEAR PRODUCTION
Concern about the harmful effects of pesticides on
surface water and groundwater quality should
motivate pear growers to select pesticides with the
least potential to cause water quality problems.
Many pear growers live in rural areas near where
they and other growers raise pears, therefore, their
personal water supply is susceptible to
contamination. Unfortunately, information that
allows growers to select pesticides less likely to
affect water quality has not previously been readily
available.
Our purpose is to provide information that can help
growers select pesticides that will have a minimum
adverse impact on water quality. The procedure
considers the soil properties of the application site,
the mobility of pesticides in these soils, and the
toxicity of the pesticides in water to humans and
aquatic species. A proper selection will decrease
chances of adversely affecting surface water and
groundwater quality. Certain combinations of soil
and pesticide properties (along with weather
conditions) can pose a significant potential hazard
to water quality. Our goal is to identify and avoid
these circumstances. Information contained in this
report can help pear growers make better decisions
about the pesticides that they use. This document
in no way endorses any particular pest control
product. All products must be used in accordance
with the label.
MATERIALS NEEDED TO USE THIS
PROCEDURE
To effectively use this procedure you will need the
following source materials:
1. A copy of the current IFAS Pest Control Guides
or other appropriate information sources that
identify pesticides that control specific pests.
2. A copy of your county soil survey report to
identify the soil types found in your orchards.
3. A copy of the Soil Science Fact Sheet entitled
"[Name of your countv]:Soil Ratings for Selecting
Pesticides" for your county, available from your
county Cooperative Extension Office. The basis of
these ratings are given in the IFAS Extension
Circular 959 entitled "Soil Ratings for Selecting
Pesticides for Water Quality Goals," which is also
available from your county Cooperative Extension
Office.
Note: If your county has not yet been mapped by
the Soil Conservation Service, you will need to
contact the local SCS office for a site evaluation and
determination of soil types and ratings for leaching
and runoff of pesticides.
IMPORTANT FACTORS
PESTICIDE SELECTION
THAT AFFECT
How pesticides behave in the soil is determined by
many factors including properties of the pesticides
and of the soil at the application site. Some of the
factors that should be considered when selecting
pesticides with minimal potential for water quality
impacts are:
Pesticide properties 1) The organic carbon
adsorption coefficient, KI describes the relative
affinity or attraction of the pesticide to soil
materials and therefore its mobility in the soil. 2)
The biological degradation half-life, T,1 is a
measure of persistence of the pesticide in soil. 3)
The lifetime health advisory level or equivalent,
HALEQ, is a measure of health risk to humans of
pesticide contaminated drinking water. 4) Aquatic
toxicity, LC, is a measure of the ability of the
pesticide to cause 50% mortality in aquatic test
species.
Soil properties 1) Hydraulic permeability is a
measure of the soils ability to allow water to
percolate through it. 2) Organic matter is
important for providing binding sites for pesticides,
thus reducing their mobility and increasing their
opportunity to be degraded by soil microorganisms.
3) Slope affects the potential for water to run off
the land surface.
Management practices 1) Pesticide application
frequencies and rates determine the total amount
applied. Lower frequencies and rates reduce the
potential for contamination. 2) Application
methods affect the amount of pesticide subject to
transport by water. For example, if applied directly
to the soil, there is a greater probability that more
of the product will be available for leaching or
runoff than if applied to the foliage. If the product
is incorporated into the soil, leaching may be the
most important loss pathway. Pesticides applied to
the foliage may be lost to the atmosphere,
decomposed by sunlight, or absorbed by the foliage,
thereby reducing the amount available for wash-off
and transport to water bodies. Irrigation practices
can also determine the loss pathways of pesticides.
Pesticides often move with water, so the less excess
water that is applied the less potential there is for
a pesticide to move past the crop root zone or to
run off in surface water. Rainfall or overhead
irrigation can wash off significant quantities of
pesticides from foliage immediately after
application.
INDICES USED TO SELECT PESTICIDES
Table 1 contains two important indices, the
pesticide leaching potential (RLPI) and the
pesticide runoff potential (RRPI). Both indices are
relative. For a given soil, these indices rank the
pesticides by their potential to move from the
application site by the indicated pathway (leaching
or runoff). The indices are based on the organic
carbon sorption coefficient and degradation half-life
values of each pesticide. Values for these
parameters have been taken from scientific
literature, technical manuals, and company product
literature.
The Relative Leaching Potential Index (RLPI)
defines the relative attenuation (reduction in mass
as it moves through the soil) of each pesticide in
soil, and therefore its potential to leach to
groundwater. Pesticides that are very mobile, for
example, those that have Ko values less than 100 in
sandy soils, or 50 or less in fine-textured soils
should be used with caution. There is some
uncertainty in the data used to calculate this index.
However, since the values are relative they can still
be used. It is important to realize that the smaller
the RLPI value of a pesticide the greater is its
potential to leach.
The Relative Runoff Potential Index (RRPI)
defines the relative immobility and availability of
each pesticide in soil, and therefore its potential to
remain near the soil surface and be subject to loss
in the aqueous phase or sediment phase of runoff.
There is some uncertainty in the data used to
calculate this index. However, since the values are
relative they can still be used. The smaller the
RRPI value of a pesticide the greater is its potential
to be lost in runoff.
Table 1 also contains information on the toxicity of
pesticides to humans and aquatic species. This
information can be used as a secondary
consideration in the pesticide selection procedure.
The Lifetime Health Advisory Level or Equivalent
(HALEQ) provides a measure of pesticide toxicity
to humans. The lifetime health advisory level as
defined by the USEPA is the concentration of a
chemical in drinking water that is not expected to
cause any adverse health effects over a lifetime of
exposure (70 years), with a margin of safety. The
values in Table 1 are the USEPA lifetime health
advisory level, HAL, or an equivalent value,
HALEQ (denoted by a superscripted asterisk),
calculated using the same formula used by the
USEPA (HALEQ = RfD x 7000), where RfD is
the reference dose determined by the USEPA. For
non-carcinogenic pesticides the calculated HALEQ
should not differ by more than a factor of 10 from
the values forthcoming from the USEPA. The
HAL or HALEQ has units of micrograms per liter
(tg/1, or ppb). The smaller the value the greater is
the toxicity to humans.
The Aquatic Toxicity provides a measure of
pesticide toxicity to aquatic species. The values
given in Table 1 are the lethal concentrations at
which 50% of the test species die (LC, ). Unless
otherwise noted by a lower case letter following the
value, the test species was rainbow trout. The
smaller the value the greater is the toxicity to
aquatic species.
Data for K,, RLPI, RRPI, HALEQ, and aquatic
toxicity are given for the active ingredient (common
name) of a product. When using a product that is
a mixture of two or more active ingredients use the
RLPI, RRPI, HALEQ, and Aquatic Toxicity value
for the most restrictive active ingredient in the
mixture.
Important Note: The information presented in
Table 1 DOES NOT supersede or replace the
information on the pesticide container label or
product literature.
CRITERIA FOR MATCHING SOIL RATINGS WITH PESTICIDE INDICES
Pesticides with less potential to adversely affect water quality can be selected by matching the soil ratings and
pesticides using the following criteria:
PESTICIDE SELECTION CRITERIA
IF SOIL RATINGS
ARE:
THEN
SELECT PESTICIDE WITH:
RUNOFF
LOW
LOW
LOW
MEDIUM
MEDIUM
MEDIUM
HIGH
HIGH
HIGH
Larger RLPI value,
Larger RLPI value,
Larger RLPI and
RRPI values,
Larger RLPI and
RRPI values,
Larger RLPI and
RRPI values,
Larger RRPI value,
Larger RLPI and
RRPI values,
Larger RRPI and
RLPI values,
Larger RRPI value,
AND Larger HALEQ value.
AND Larger HALEQ value.
AND Larger HALEQ and
Aquatic Toxicity values.
AND Larger HALEQ and
Aquatic Toxicity values.
AND Larger HALEQ and
Aquatic Toxicity values.
AND Larger Aquatic Toxicity
value.
AND Larger HALEQ and
Aquatic Toxicity values.
AND Larger Aquatic Toxicity
and HALEQ values.
AND Larger Aquatic Toxicity
value.
PROCEDURE FOR SELECTING PESTICIDES
TO REDUCE ADVERSE WATER QUALITY
IMPACTS
A "Pesticide Selection Worksheet" is provided as a
convenient way to organize the information needed
to select pesticides to avoid water pollution by
pesticides in a particular production or management
unit. Instructions for using the worksheet are
outlined below. The function of the worksheet is to
match the soil leach and runoff ratings at the
application site with the pesticide RLPI (leaching)
and RRPI (runoff) indices and toxicity values given
in Table 1.
This will indicate the relative potential for pesticides
to leach or run off from a particular site and
consider the toxicity of the pesticides to humans or
aquatic life if the pesticides leach into groundwater
or if runoff enters surface impoundments or
streams. The last two columns are for recording the
pear grower's choices and reasons for selecting
particular products.
Our intent is to provide a decision support tool for
the pear grower. The grower is responsible for
making the final choice. The completed worksheet
can serve as a permanent record of the selection
process used and decision made by the grower.
LEACH
HIGH
MEDIUM
LOW
HIGH
MEDIUM
LOW
HIGH
MEDIUM
LOW
USING THE WORKSHEET
1. TARGET PEST: Correct identification of the
pests that need to be controlled is essential! Check
with knowledgeable experts and utilize competent
diagnostic laboratories so that a proper diagnosis
can be made. Misdiagnosis results in the wasteful
use of unnecessary pesticides and needless increases
in production costs. List confirmed pests in column
1 of the Pesticide Selection Worksheet.
2. RECOMMENDED PESTICIDES: Use the
current IFAS Pest Control Guides, or other
appropriate information sources to identify the
pesticides that control the pests of concern. List
these pesticides in column 2 of the Pesticide
Selection Worksheet.
3. PESTICIDE PROPERTIES: For each pesticide
listed in column 2 on the Pesticide Selection
Worksheet, copy the numeric value for K, RLPI,
RRPI, HALEQ, and Aquatic Toxicity from Table 1
into columns 3, 4, 5, 6, and 7 of the Pesticide
Selection Worksheet.
4. SOIL PROPERTIES: Consult the County Soil
Survey Report soil map sheets to locate your
production orchards and to identify the soils that
occur in these orchards. Use the Soil Science Fact
Sheet entitled "[Your County]:Soil Ratings for
Selecting Pesticides" (available from your county
Cooperative Extension Office) to determine the
leaching and surface runoff rating of the soils in
your orchards. As you determine the soil leach
rating and the soil runoff rating for each soil in each
orchard, list the soil name, soil leach rating, and soil
runoff rating in columns 8, 9, and 10, respectively,
of the Pesticide Selection Worksheet.
5. SELECTION OF PESTICIDES: Using infor-
mation that you have compiled on the Pesticide
Selection Worksheet, select appropriate pesticides
using the selection criteria on page 4 to match soil
and pesticide properties. The selection made can
be recorded in column 11 and notes relating to the
selection can be recorded in column 12.
Notes:
1. If the pesticide product selected is a formulated
mixture or a tank mix, each active ingredient must
be considered. The most restrictive pesticide in the
mixture will determine the choice. Trade names in
Table 1 followed by (M) are formulated mixtures.
2. Sometimes there may not be a clear choice from
among the alternative chemicals available to control
a particular pest. In these cases, first order
screening using the RLPI or RRPI only can suffice.
3. Depth to groundwater and local geohydrology
may influence your final selection. Shallow
groundwater is more vulnerable to contamination.
Deep water tables with intervening impermeable
geologic layers are much less vulnerable.
4. Distance to surface water bodies may also
influence your final selection. Surface waters
adjacent to or near the pesticide application site are
more vulnerable to contamination than those further
away. If surface runoff from the application site
usually infiltrates into the soil off site before
reaching a surface water body, then the HALEQ
should be considered as the secondary screening
index.
IRULE Irears-resrCIle 1ra.ieer niLi IA ISU Ot cC-Il rr--- n re--o nmL.s o moet no-LI cS r- uus u.&. u0jUILY1
Sorption Relative Losses Toxicity
Application Type2 Coefficient3 Leaching Runoff HAL or HALEQ8 Aquatic LC,7
Trade Name1 Common Name Soil Foliar Koc (ml/g) RLPI4 RRPI5 (ppb) (ppm)
Herbicide
Casoron dichlobenil x 400 E 67 42 4 6.3
Devrinol napropamide x x 700 100 20 700 30b
Dowpon M dalapon x 1 1 1 200 500a
Fusilade fluazifop-butyl x 5,700 >2,000 12 70 1.6
Gramoxone paraquat x 1,000,000 E >2,000 1 30 15
Karmex diuron x x 480 53 23 10 4.9
Princep simazine x 130 22 22 1 2.8
Roundup glyphosate x 24,000 E >2,000 1 700 8.3
Sinbar terbacil x 55 5 5 90 42.6
Solicam norflurazon x 700 233 48 300 6
Surflan oryzalin x x 600 300 83 400 3.26
Treflan trifluralin INC 8,000 1,330 2 5 0.041
Insecticide/Miticide
Ambush permethrin x 100,000 >2,000 1 400 0.0041
Apollo clofentezine x nd nd nd 90 non toxic
Asana esfenvalerate x 5,300 1,510 5 nd 0.00069j
Carzol formetanate hydro. x 1,000,000 E >2,000 1 10 2.8
Cygon 400 dimethoate x 20 29 29 1 6.2
Cythion malathion x x 1,800 >2,000 556 100 0.2
Dipel Bacillus thuringiensis x nd nd nd nd 95b
Di-Syston disulfoton INC x 600 E 200 56 0.3 1.85
Dusting Sulfur sulfur x nd nd nd nd non toxic
DZN diazinon diazinon INC x 1,000 E 250 25 0.6 0.09
Ectrin fenvaterate x 5,300 1,510 5 200 0.0006
Guthion azinphos-methyl x 1,000 1,000 100 9 0.0043
HAL or HALEQ6: Lifetime Health Advisory Level or Lifetime Health Advisory Level Equivalent.
Continued---
~____ C--L------I- ~-- L-- Y^L---~ ~^- PIIU~;Y ~~~iCi~ ,A Yi~i~i~~ U~,~C rrMlih) ~CC~I~
f\C tf\* /
TABLE 1. Pears Pesticide Parameter Matrix---Continued:
Sorption Relative Losses Toxicity
Application Type2 Coefficient3 Leaching Runoff HAL or HALEQ6 Aquatic LC,7
Trade Name1 Common Name Soil Foliar Ko (ml/g) RLPI4 RRPI5 (ppb) (ppm)
Insecticide/Miticide
Imidan phosmet x 820 432 64 100 0.3
Karathane dinocap x 550 E 1,100 364 nd 0.0154
Kelthane dicofol x 18,000 E >2,000 1 7 0.52b
Lannate methomyl x 72 24 24 200 3.4
Lorsban chlorpyrifos x 6,070 >2,000 5 20 0.0071
Mesurol methiocarb x 300 E 100 100 90 0.436
Metasystox-R oxydemeton-methyl x 10 10 10 4 *6.4
Microthiol Special sulfur x nd nd nd nd non toxic
Mitac amitraz x 1,000 E >2,000 500 nd nd
Morestan oxythioquinox x 2,300 767 14 400 0.22
Niran parathion x 5,000 E >2,000 14 2 1.43
Omite propargite x 4,000 E 714 4 100 0.12
Penncap M methyl-parathion x 5,100 E >2,000 39 2 3.7
Pounce permethrin x 100,000 >2,000 1 400 0.0041
Pydrin fenvalerate x 5,300 1,510 5 200 0.0006
Savey hexythiazox x 6,200 >2,000 5 nd nd
Sevin carbaryl x 300 300 300 700 114
Spectracide diazinon x 1,000 E 250 25 0.6 0.09
Sulfur Alpha sulfur x nd nd nd nd non toxic
Supracide methidathion x 400 E 571 357 7 0.01
Thiodan endosulfan x 12,400 >2,000 2 0.4 0.0014
Thiolux sulfur x nd nd nd nd non toxic
Thiophos parathion x 5,000 E >2,000 14 2 1.43
Vendex fenbutatin oxide x 2,300 256 5 400 0.27
Volck Supreme petroleum oil x 1,000 G 1,000 100 nd nd
Vydate oxamyl x 25 63 63 200 4.2
HAL or HALEQb: Lifetime Health Advisory Level or Lifetime Health Advisory Level Equivalent.
Continued---
TABLE 1. Pears- Pesticide Parameter Matrix---Continued:
Sorption Relative Losses Toxicity
Application Type2 Coefficient3 Leaching Runoff HAL or HALEQ6 Aquatic LC,17
Trade Name1 Common Name Soil Foliar Koc (ml/g) RLPI4 RRPIs (ppb) (ppm)
Nematicide
Nemacur fenamiphos INC 100 20 20 2 0.11
Fungicide
Agri-mycin streptomycin x nd nd nd nd nd
Agri-Strep streptomycin x nd nd nd nd nd
Basicop copper sulfate x nd nd nd nd 0.14
Bayleton triadimefon x 300 115 115 200 14
Benlate benomyl x 1,900 79 2 400 0.17
Carbamate ferbam x 300 176 176 100 mod toxicity
Champion cupric hydroxide x nd nd nd nd 0.08
Copper FF copper sulfate,basic x nd nd nd nd nd
Copro copper oxychloride x nd nd nd nd nd
Copzin copper sulfate, basic x nd nd nd nd nd
CP Basic copper sulfate x nd nd nd nd 0.14
Cyprex dodine (acetate) x 100,000 E >2,000 1 30 0.53h
Karathane dinocap x 550 E 1,100 364 nd 0.0154
Kocide cupric hydroxide x nd nd nd nd 0.08
Kolospray sulfur x nd nd nd nd non toxic
Microthiol sulfur x nd nd nd nd non toxic
Super Six sulfur x nd nd nd nd non toxic
That Big sulfur x nd nd nd nd non toxic
Topcop copper sulfate x nd nd nd nd 0.14
Tribasic copper sulfate x nd nd nd nd 0.14
Wettable Sulfur sulfur x nd nd nd nd non toxic
HAL or HALEQ5: Lifetime Health Advisory Level or Lifetime Health Advisory Level Equivalent.
Continued---
TABLE 1. Pears- Pesticide Parameter Matrix---Continued:
Sorption Relative Losses Toxicity
Application Type2 Coefficient3 Leaching Runoff HAL or HALEQ6 Aquatic LC,57
Trade Name1 Common Name Soil Foliar Koc (ml/g) RLPI4 RRPIS (ppb) (ppm)
Fumigants for Control of Soil Fungi and Nematodes
Brom-0-Gas methyl bromide INJ 22 4 4 7 2.5
Busan 1020 metham-sodium INC,INJ 10 E 14 14 nd 0.36 b
Chlor-0-Pic chloropicrin INJ 62 620 620 nd nd
Dowfume MC2 methyl bromide INJ 22 4 4 7 2.5
Telone II 1,3-dichloropropene INJ 32 32 32 0.2 5.5
Telone C-17(M) chloropicrin INJ 62 620 620 nd nd
Telone C-17(M) 1,3-dichloropropene INJ 32 32 32 0.2 5.5
Terr-O-Gas(M) chloropicrin INJ 62 620 620 nd nd
Terr-O-Gas(M) methyl bromide INJ 22 4 4 7 2.5
Vapam metham-sodium INC,INJ 10 E 14 14 nd 0.36 b
Vorlex(M) 1,3-dichloropropene INJ 32 32 32 0.2 5.5
Vorlex(M) M.I.T. INJ 6 9 9 nd 0.37
1Trade Name:
2Application Type:
3Sorption Coefficient:
4Relative Leaching Potential Index (RLPI):
5Relative Runoff Potential Index (RRPI):
6HAL or HALEQ:
7Aquatic Toxicity LC50:
(M) indicates that the product is a mixture of two or more active ingredients.
INC: incorporated INJ: injected x: applied to soil surface or foliage
E: estimated G: educated guess
Smaller number indicates greater leaching hazard.
Smaller number indicates greater runoff hazard.
Lifetime Health Advisory Level or Lifetime Health Advisory Level Equivalent.
*: Lifetime Health Advisory Equivalent
value is for rainbow trout 48 or 96 hr exposure time, unless otherwise specified
a=channel catfish b=bluegill h=harlequin fish j=fathead minnows
nd: no data available.
PESTICIDE SELECTION WORKSHEET
Landowner/Operator
Name-
County:
Date:
Farm ID: F
field ID Sheet of
IFAS Relative Losses Toxicity Soil Soil
Target Pest Recommended Ko Leaching Runoff Lifetime Aquatic Soil Leaching Runoff Selected Comments
Pesticides Value RLPI RRPI HALEQ* Toxicity Type Rating Rating Pesticide
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)
If the Ko value is 100 or less or if the RLPI value is 10 or less and the soil leach rating is high, then the pesticide has a high potential for leaching and should
be used with extreme caution. Alternative pesticides and reduced rates should be considered if possible. Apply pesticide during periods with low potential for rainfall
if possible.
Crop:
Name:_
Farm ID
PESTICIDE SELECTION WORKSHEET
C
Landowner/Operator Name:
Crop:
county:
Farm ID: F
Date:
ield ID Sheet of
IFAS Relative Losses Toxicity Soil Soil
Target Pest Recommended K, Leaching Runoff Lifetime Aquatic Soil Leaching Runoff Selected Comments
Pesticides Value RLPI RRPI HALEQ* Toxicity Type Rating Rating Pesticide
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)
If the K. value is 100 or less or if the RLPI value is 10 or less and the soil leach rating is high, then the pesticide has a high potential for Leaching and should
be used with extreme caution. Alternative pesticides and reduced rates should be considered if possible. Apply pesticide during periods with low potential for rainfall
if possible.
Acknowledgements:
The development of this document was supported by the USDA/ES Water Quality Initiative Project
#89EWQI-1-9134 and the IFAS Center for Natural Resources, University of Florida, Gainesville, FL.
COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, John T. Woeste,
Director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of the May 8 and June
30, 1914 Acts of Congress; and is authorized to provide research, educational information and other services only to individuals and institutions that
function without regard to race, color, sex, age, handicap or national origin. Single copies of extension publications (excluding 4-H and youth
publications) are available free to Florida residents from county extension offices. Information on bulk rates or copies for out-of-state purchasers
is availablefromC.M. Hinton, Publications Distribution Center, IFAS Building 664, Universityof Florida, Gainesville, Florida32611. Before publicizing
this publication, editors should contact this address to determine availability. Printed 11/91.
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