Interactions Between Insecticides, Spray pH, & Adjuvants
John C. Palumbo, F.J. Reyes, L. Carey, A. Amaya, and L. Ledesma
Department of Entomology, Yuma Valley Agricultural Center
Abstract
Studies were conducted in the laboratory to investigate how the addition of a
insecticides to two sources of Colorado River water would effect the pH of spray
mixtures. In addition, we were curious what the effects of various labeled
concentrations of buffers, acidifiers, spreader/stickers, and foliar nutrient
sprays would have on the pH of spray water. Results showed that in most cases,
spray concentration remained alkaline following addition of insecticides and
adjuvants, with variations occurring primarily for the OPs. Buffering agents
dramatically lowed pH at concentration greater than 0.25% v/v. Studies were
also designed to evaluate the knockdown and residual mortality of Success
against worms when applied in an acidic spray solution. Bioassays of larval
mortality on field-treated foliage showed that knockdown mortality was not
affected, but residual efficacy was significantly reduced when Success was
applied using acidic (pH 4.2) spray solutions.
Introduction
Many factors can influence the performance of a pesticide. One factor that can be easily controlled is the pH of the
water used in foliar sprays. Water sources from the Colorado River used for pesticide applications are alkaline with
pH readings from the Yuma Valley typically ranging from 7.8 to 8.2. Use of high pH water, particularly above 8.0,
may affect the performance of many pesticides. This occurs due to a reaction called alkaline hydrolysis, and it can
occur when the pesticide is mixed with alkaline water or other materials that cause a rise in the pH of the spray
water. Hydrolysis is the splitting of a compound by water in the presence of ions. Water that is alkaline has a larger
concentration of hydroxide ions than water that is neutral; therefore, alkaline hydrolysis increases as the pH
increases. Insecticides are generally more susceptible to alkaline hydrolysis than are fungicides and herbicides, and
of these, organophosphates and carbamates are more susceptible than other materials.
Little information is available on the degradation rate of many of the new pesticides in high pH water; some
pesticides are relatively unaffected. Consequently, some pesticide labels recommend applicators to buffer spray
water with a suitable acid buffer down to a range of 6-7 pH. In addition, when tank mixes of more than one
pesticide or when fertilizer is combined with a pesticide, the final spray solution should be checked to determine pH.
Because of the unknown effects of alkaline water on many of the new products, we wanted to know how addition of
these insecticides at labeled rates/concentrations to Colorado River water would effect the pH of spray mixtures. In
addition, we were curious what the effects of various labeled concentrations of buffers, acidifiers, spreader/stickers ,
and foliar nutrient sprays would be on the pH of spray water. Please note however that some of these studies were
not designed to evaluate the insecticide performance, but rather to measure the alkalinity and acidity of final spray
solutions, and the potential need for buffering these solutions prior to application. However, recent reports from
Dow Agrosciences have suggested that the performance of Success ® (spinosad) is thought to be altered when
___________________
This is a part of the University of Arizona College of Agriculture 2001 Vegetable Report, index at:
http://ag.arizona.edu/pubs/crops/az1252/
mixed and sprayed under moderately acidic (pH < 6) conditions. Thus, we also designed a study to evaluate the
knockdown and residual mortality of Success against worms when applied in an acidic spray solution.
Methods and Materials
Effect of Insecticides and Buffering Agents on Spray pH
Formulated active ingredients of a number of insecticides were used in these studies. Rates and formulations for
each product are shown in Tables 1 and 2, and Figures 1-3. Water samples were collected from two sources and
tested on the same day as collected. Colorado River surface water was collected from the east main canal in the
Yuma Valley, about 1.5 miles east of the Yuma Agricultural Center. Ground water was collected from a well located
at the Barkely Company farm shop located at Co. 19th and Ave G. Final spray concentrations of 5 and 30 GPA were
selected for measuring the effects of insecticides and adjuvants on the pH of the water both before and after they
were added. Each insecticide was measured at concentrations of a final spray solution of 5 and 30 GPA. For each
water source, 1140 ml of water was placed in a 2 liter plastic bottle with the appropriate amount of insecticide to
provide the proper concentration relative to the desired GPA. Each water source-GPA-insecticide combination was
replicated 5 times. Prior to adding insecticides or buffers to each bottle, a pH measurement was taken and recorded
for each replicate. A pH value was measured again at ½ hr and 24 hrs after the addition of the insecticide and
buffer. All pH values were estimated by measuring a 40 ml sample of each concentration with a Mettler DL12
Titrator. All recorded pH values were averaged and presented in the following tables and graphs. Because the
average pH values only deviated by a maximum 0.2 pH for any treatment (CV < 5), a statistical analysis was not
conducted.
Effect of Spray pH on Success Efficacy
Two separate field applications were made; one on romaine and one on head lettuce to investigate the influence of
spray pH on the residual efficacy of Success against beet armyworm and cabbage. Lettuce, ‘Van Mor ‘ head lettuce,
and ‘ PIC’ romaine were direct seeded into double-row beds on Dec 2 at the Yuma Valley Agricultural Center,
Yuma, AZ. Each plot consisted of two 30 ft long beds spaced 42 inches apart and bordered on each side by 2
untreated beds. Plots were replicated 4 times in a RCBD. Using data from the previous tests five treatments were
applied to the plots: 1. Success applied at 6.0 oz/acre with no buffering agent added (pH 7.9); 2. Success
applied at 3.0 oz/acre with no buffering agent added; (pH 7.9); 3. Success applied at 6.0 oz/acre with Buffer
Trend 0-8-0 added (0.5 % v/v ; pH 4.2) ; 4. Success applied at 3.0 oz/acre with Buffer Trend 0-8-0 added (0.5 %
v/v; pH 4.2) ; and 5. an untreated control.
A single foliar application was made to romaine lettuce on March 27th and head lettuce on April 6th t with a CO2
operated boom sprayer that delivered 30 GPA at 50 psi. A directed spray was applied to each bed by 3 nozzles/bed.
To measure knockdown mortality, individual leaves (3 / rep) were collected from sprayed plants at 6-hrs after
treatment and brought into the laboratory. To measure residual mortality, leaves were collected 5 days following the
spray application. The leaves were removed from the upper portions of the plant that had received adequate spray
deposition. Once in the lab, a leaf disk (70mm diam) was removed from each leaf and placed into petri dishes. On
head lettuce leaves , five 2nd –3rd instar beet armyworm were placed within each petri dish,; for romaine leaves, five
3nd instar cabbage loopers were placed within each petri dish. Larvae were obtained from a laboratory colony at the
USDA/ARS Western Cotton Research Lab in Phoenix. The dishes were placed at room temperature for a 5 d
duration of infestation (78-80 F). Mortality was scored on each day to calculate cumulative mortality. Foliage
consumption was estimated for each leaf with a dish at day 5 and % leaf consumption over was calculated for each
treatment. All means were analyzed using a two-way ANOVA and mean differences were estimated using a
protected LSD (p<0.05).
Results and Discussion
Effect of Insecticides, Buffering Agents and Adjuvants on Spray pH
The influence of old and new active insecticide ingredients at commonly applied dosages are shown in Table 1.
This data shows the measured pH values for two sources of Colorado River water at two concentrations following
the addition of insecticides. The insecticides measured include pyrethroids, Ops’ carbamates and several of the new
chemistries. The pH for both water sources prior to addition of insecticides was alkaline; pH values of canal
(surface) water ranged from 8.0-8.2, and well (ground) water ranged from 7.5-7.7. In general, pH values for the
pyrethoid formulations remained alkaline at ½ and 24 hrs, regardless of water source or concentration. However, the
most variability was seen with the OPps and Carbamates. A wide range in pH values were observed across the
range of OP’s measured. pH dropped significantly more at the 5 GPA concentration and in some cases, in the
surface water at 24 hr. Water became acidic after additions of several compounds (Dimethoate, MSR, Orthene,
Malathion), did not change much for others (Diazinon), and actually became more alkaline after addition of
Lorsban. Carbamates did not alter pH nearly as much, with water remaining alkaline for both compounds.
Similarly, pH values remained alkaline for endosulfan . The chloronicotinyls did not alter much with pH values
remaining alkaline at ½ and 24 hrs, regardless of water source or concentration. In most cases, the pH values for
water sources and concentrations remained alkaline after addition of the new compounds. Avaunt and Aphistar
appeared to drop the pH the most, whereas Fulfill, Confirm and Knack resulted in very little change in pH.
The data in Table 2 shows the measured pH values for Colorado River surface water at two concentrations following
the combination of multiple insecticides and adjuvants. The combinations measured include several insecticides and
spreader/stickers commonly used in tank mixtures for vegetable insect control. The pH for the surface water prior to
addition of the insecticides was alkaline (pH 8.2). For the Success-Ammo tank-mix, no significant changes in pH
values were measured after the addition of either individual compounds or mixtures. pH values remained alkaline at
½ and 24 hrs, regardless of spray volume concentration. Similarly, pH values remained alkaline at ½ and 24 hrs in
the Confirm+Warrior or Lannate +-Mustang mixtures bit in some cases, some of the compounds and mixtures
actually slightly increased pH values.
The effects of two common buffers on the pH of Colorado River surface water sources without the addition of
insecticide are shown in Fig 1and 2. The pretest pH values for the surface source was 8.1 and 7.8 for the ground
water. Both of the buffers used contained or were derived from phosphoric acid. For Buffer-Trend 0-8-0, pH values
dropped immediately to an acidic nature at the low concentrations (0.06 and 0.125% v/v) staying within a range 6-7
pH for up to 6 hrs. Concentrations greater than 0.25 % resulted in a significant drop in pH (>4), regardless of water
source. Similarly, pH values in Buffer P.S. dropped immediately to an acidic nature at the low concentrations (0.06
and 0.125% v/v) staying within a range 6-7 pH for up to 6 hrs. However, concentrations at 0.25 % resulted in a pH
(~6), similar to lower concentrations. Concentrations greater than 0.25 % resulted in a significant drop in pH,
regardless of water source, but tended to drop less in ground water at 0.5%.
The effect of Success combined with buffers, an acidifier and soluble sulfur on the pH of Colorado River ground
water sources are shown in Figures 3 and 4. The pre-test ph value for the surface source was 7.9. Both of the
buffers used contained or were derived from phosphoric acid. The active ingredient for Success is spinosad,
formulated as a soluble concentrate with 77% inert ingredients. Buffer concentrations for the Buffer-Trend and
Buffer P.S. greater than 0.25% resulted in highly acidic conditions. However, we saw no significant changes in pH
levels after the addition of Success, regardless of the buffer concentration. Similarly, the addition of LI 700 resulted
in acidification of the water. Addition of Success did not result in any additional effect on pH. Concentrations
greater than 0.06 % v/v resulted in pH values less than 6.0. The addition of Flowable Sulfur, or in combination with
Success did not significantly alter the alkalinity of the spray water. It was projected that sulfur would acidifiy the
water, but SulPreme is 52% elemental sulfur and in this state will not acidify water. However, once elemental
sulfur is microbially activiated, as in the soil, sulfuric acid will lower alkaline conditions.
The results of this information should serve as a useful guideline for growers, PCAs and applicators when
considering the use of insecticide and buffers. The OPs appear to be most susceptible to changes in pH, whereas
most spray solutions appear to remain at a fairly consistent pH after the addition of spray materials. However, this
data should only serve as a baseline, as water pH levels from different sources or times of the year could change
significantly. Furthermore, the need to buffer spray solution is commonly indicated on the label, or available from
the manufacturer. In addition many of the newer compounds are stable in a fairly alkaline water and won’t require
buffering. However, prior to mixing spray solution it is a good idea to measure the pH of the water before and after
mixing. Again, refer to the label for specific guidelines on using additives to spray mixtures.
Effect of Spray pH on Success Efficacy
The results of this study clearly showed that acidic spray solutions had a negative impact on the residual efficacy of
Success against beet armyworm and cabbage looper in lettuce. On romaine lettuce, initial knockdown mortality was
not affected by Success rate or the pH of the spray solution. As expected, the 90% mortality was observed after 2
days of exposure in the bioassay dishes (Figure 1A). However, acidic pH conditions had a significant impact on the
residual mortality of larvae in the 3.0 oz/acre Success treatment, where we observed about a 40% reduction in
efficacy. Residual efficacy in the higher Success rate was not apparently affected by lower pH. A significant
increase in foliage consumption was also observed (Table 3). Beet armyworm on treated head lettuce responded
similarly , but affects of pH on residual mortality were seen at both high and low rates. Consequently mortality did
not differ significantly between the untreated check and the two Success rates sprayed in acidic solutions. Larvae
exposed to acidic spray solutions fed significantly more than those feeding on leaves treated with non-acidic sprays.
Dow AgroSciences has reported problems with the residual efficacy of Success at pH levels below 6. This data
certainly corroborates the anecdotal reports of poor Success residual performance when applied in acidic spray
solutions. The reasons for this breakdown in residual centers around how spinosad is formulated. Success is
formuatled as a suspension concentrate made up of suspended granules, each granule containing many spinosad
monomers. When Success is mixed in spray solutions at a pH above 6, the Success granules remain intact, thus
protecting it from UV degradation However, when in a acidic environment (pH < 6), the granules break, exposing
the spinosad monomers to rapid degradation. Thus knockdown mortality is not immediately affected, but residual
mortality becomes reduced as the sprayed product is exposed to UV light for a length of time. In this study 5 days of
exposure in March/April was enough to significantly reduce residual mortality. Under normal conditions in Yuma
using Colorado River water, buffers or acidifying agents should be avoided, unless extremely alkaline or for other
reasons. The product should not be mixed in acid spray solutions if possible. This can be particularly important for
growers and PCAs who use the product in tank-mixes with phosphorus-based foliar nutrient sprays like (0-8-0).
When used as a foliar fertilizer, recommended rates range from 1-2 qts / 30-50 gal (0.5-1.0 % v/v) by ground and 1
qt / 10-15 gal (1.7-2.5%) by air. All of these concentrations resulted in highly acidic water conditions in our study.
Furthermore, tank mixing with other insecticides like MSR or dimethoate could result in problems if pH is not
adjusted. Finally, we recommend that pH levels of all spray mixes should be measured before these type of products
are used.
Table 1. Influence of Insecticides on pH levels of aqueous spray concentrations (gpa) before
(Pre-test), and at ½ and 24 hours following addition of insecticide to water collected from two
local sources
pH
Insecticide
Rate,
(Product/acre)
Warrior T
3.8 oz
Ammo 2.5EC
Mustang 1.5EC
Ambush 25W
Capture 2EC
Dimethoate 267E
Diazinon 3EC
Endosulfan 3EC
MSR 2EC
Lorsban 50W
Orthene 97S
Malathion 8EC
Lannate SP
Larvin 3.2EC
5.0 oz
4.3 oz
12 oz
5.1 oz
16 oz
16 oz
42 oz
30 oz
2.0 lb
1.0 lb
32 oz
0.8 lb
32 oz
Canal water
Well water
Spray Vol,
(GPA)
Pre-test
½ hr
24 hr
Pre-test
½ hr
24 hr
5
8.0
7.2
7.6
7.6
7.0
7.5
30
8.0
7.8
7.7
7.6
7.6
7.3
5
8.0
7.9
7.8
7.6
7.7
7.6
30
8.0
8.0
7.9
7.6
7.6
7.6
5
8.0
7.8
7.7
7.7
7.7
7.5
30
8.0
8.0
7.9
7.7
7.8
7.7
5
8.0
7.9
7.7
7.7
7.8
7.6
30
8.0
8.0
7.9
7.7
7.8
7.6
5
8.0
7.7
7.7
7.7
7.6
7.5
30
8.0
7.9
7.8
7.7
7.7
7.7
5
8.0
4.0
3.4
7.5
5.5
4.4
30
8.0
6.8
6.2
7.5
7.0
6.5
5
8.0
8.0
7.9
7.5
7.3
7.2
30
8.0
8.0
8.0
7.5
7.8
7.7
5
8.0
7.8
7.6
7.6
7.6
7.6
30
8.0
7.9
7.9
7.6
7.6
7.7
5
8.0
2.4
2.5
7.6
2.6
2.8
30
8.0
5.9
6.3
7.6
6.2
6.4
5
8.0
8.4
8.6
7.7
8.3
8.5
30
8.0
8.2
8.4
7.7
7.3
7.5
5
8.0
5.8
5.7
7.7
6.0
5.9
30
8.0
6.4
6.4
7.7
6.4
6.4
5
8.0
3.9
3.6
7.7
5.4
5.2
30
8.0
6.6
6.5
7.7
6.8
6.7
5
8.0
7.9
7.7
7.7
7.8
7.7
30
8.0
7.9
7.9
7.7
7.8
7.8
5
8.0
7.2
7.3
7.7
7.4
7.4
30
8.0
7.7
7.7
7.7
7.6
7.7
Table 1.
continued.
pH
Insecticide
Provado 1 6F
Admire 2F
Actara 25W
Platinum 2SC
Cryolite Pro96
Success 2S
Avaunt WG
Proclaim 5SG
Agrimek 0.15EC
Fulfill 50WG
Confirm 2F
Knack EC
Applaud 70WP
Pirimor 50 DF
Aphistar 25W
Canal water
Well water
Rate,
(Product/acre)
Spray Vol,
(GPA)
Pre-test
½ hr
24 hr
Pre-test
½ hr
24 hr
3 75 oz
5
81
77
76
77
76
75
30
8.1
7.8
7.9
7.7
7.7
7.7
5
8.1
7.8
7.7
7.7
7.7
7.6
30
8.1
8.0
7.8
7.7
7.8
7.6
5
8.1
8.1
7.8
7.7
7.7
7.3
30
8.1
8.1
7.4
7.7
7.6
7.2
16 oz
5.5 oz
8 oz
12 lb
6.0 oz
5.8 oz
3.2 oz
12 oz
4.5 oz
8.0 oz
8.0 oz
8.0 oz
8.0 oz
4.0 oz
5
8.1
8.0
8.0
7.7
7.6
7.5
30
8.1
7.9
7.8
7.7
7.6
7.4
5
8.1
7.0
6.9
7.7
7.1
6.9
30
8.1
7.0
6.9
7.7
7.2
7.0
5
8.3
7.9
7.5
7.7
7.5
7.5
30
8.3
7.9
8.0
7.7
7.5
7.6
5
8.3
7.0
7.0
7.7
7.1
7.1
30
8.3
7.5
7.4
7.7
7.4
7.4
5
8.0
7.8
7.6
7.7
7.6
7.4
30
8.0
7.8
7.3
7.7
7.7
7.4
5
8.2
6.6
6.7
7.7
6.8
7.0
30
8.2
7.6
7.5
7.7
7.4
7.3
5
8.0
8.2
8.2
7.7
8.3
7.8
30
8.0
8.2
8.2
7.7
7.7
7.7
5
8.0
8.2
8.0
7.7
7.9
7.8
30
8.0
8.2
8.2
7.7
7.5
7.5
5
8.0
7.9
7.9
7.7
7.6
7.7
30
8.0
8.1
8.1
7.7
7.7
7.6
5
8.0
7.1
7.1
7.7
7.0
7.1
30
8.0
7.6
7.4
7.7
7.4
7.3
5
8.0
7.9
8.1
7.7
7.7
8.3
30
8.0
8.0
7.9
7.7
7.7
7.6
5
8.0
7.3
7.1
7.7
7.3
7.1
30
8.0
7.8
7.2
7.7
7.5
7.2
Table 2. Influence of Insecticides mixtures on pH levels of canal water at two aqueous spray concentrations
(gpa) before (Pre-test), and at ½ and 24 hours following addition of insecticide.
Insecticide
Success 2S
Ammo 2.5EC
Silwet
Rate,
(Product/acre)
Spray Vol,
(GPA)
6 oz
5 oz
0.12% v/v
Success+Silwet
Ammo+Silwet
Success+Ammo
Success+Ammo+Silwet
Confirm 2SC (8 oz)
Warrior T (3.8 oz)
Latron CS-7 (0.12% v/v)
Confirm + Latron
Warrior + Latron
Confirm + Warrior
Confirm + Warrior + Latron
8 oz
3.8 oz
0.12% v/v
pH
Pre-test
½ hr
24 hr
5
8.2
7.9
7.9
30
8.2
8.1
8.1
5
8.2
8.1
8.1
30
8.2
8.1
8.2
5
8.2
8.2
8.2
30
8.2
8.2
8.1
5
8.2
7.9
7.5
30
8.2
8.1
8.0
5
8.2
8.1
8.0
30
8.2
8.2
8.1
5
8.2
8.0
8.0
30
8.2
8.2
8.0
5
8.2
7.9
7.9
30
8.2
8.1
8.1
5
8.2
8.3
8.3
30
8.2
8.3
8.4
5
8.2
7.9
8.1
30
8.2
8.2
8.3
5
8.2
8.2
8.3
30
8.2
8.2
8.3
5
8.2
8.0
8.0
30
8.2
8.2
8.1
5
8.2
7.9
7.9
30
8.2
8.2
8.2
5
8.2
7.9
7.9
30
8.2
8.2
8.2
5
8.2
7.8
7.8
30
8.2
8.2
8.1
Table 2. Continued
Insecticide
Rate
(Product/acre)
Spray Vol,
(GPA)
Lannate
0.8 lb
Musang
Kinetic
Lannate+Kinetic
Mustang+Kinetic
Lannate+Mustang
Lannate+Mustang+Kinetic
4.3 oz
0.12 % v/v
pH
Pre-test
½ hr
24 hr
5
8.2
8.1
7.7
30
8.2
8.3
8.1
5
8.2
8.0
7.9
30
8.2
8.3
8.3
5
8.2
8.4
8.3
30
8.2
8.4
8.3
5
8.2
8.2
7.8
30
8.2
8.3
8.2
5
8.2
8.0
8.4
30
8.2
8.3
8.2
5
8.2
7.6
7.4
30
8.2
8.2
8.0
5
8.2
8.0
7.7
30
8.2
8.2
8.0
Table 3. Cumulative Residual Mortality to Success and Foliage Consumption on treated lettuce at 5 DAT.
Larvae were allowed to feed on treated foliage for 5 days.
Cabbage Looper
On Romaine Lettuce
Treatment
Beet Armyworm
On Head Lettuce
Larval
Mortality
(%)
Foliage
Consumption
(%)
Larval
Mortality
(%)
Foliage
Consumption
(%)
Success 6 oz + Buffer
(pH 4.2)
94.4 a
9.2 c
30.0 bc
42.5 b
Success 6 oz
(pH 7.9)
85.9 a
10.8 c
75.3 a
9.2 c
Success 3 oz + Buffer
(pH 4.2)
27.8 b
40.5 b
20.0 c
45.8 b
Success 3 oz
(pH 7.9)
90.3 a
16.7 c
56.7 ab
18 c
Untreated
0.0 c
98.3 a
16.7 c
61.5 a
Means within column followed by the same letter are not significantly different (protected LSD., P<0.05)
Fig 1. Impact of Buffer on the pH of Colorado River
surface water (West Main Canal).
9
Buffer-Trend, 0-8-0
8
1/2 hr
6 hrs
pH
7
6
5
4
3
2
0
0.06
0.12
0.25
0.50
1.0
Buffer Concentration
(% v/v)
9
Buffer P.S.
1/2 hr
6 hrs
8
pH
7
6
5
4
3
2
0
0.06
0.12
0.25
Buffer Concentration
(% v/v)
0.50
1.0
Fig 2. Impact of Buffer on the pH of Colorado River
ground water (Co.19th and Ave G).
9
Buffer-Trend, 0-8-0
1/2 hr
6 hrs
8
pH
7
6
5
4
3
2
0
0.06
0.12
0.25
0.50
1.0
Buffer Concentration
(% v/v)
9
Buffer P.S.
1/2 hr
6 hrs
8
pH
7
6
5
4
3
2
0
0.06
0.12
0.25
Buffer Concentration
(% v/v)
0.50
1.0
Fig 3. Impact of Buffer and Success to the pH of Well Water
9
Buffer-Trend, 0-8-0
Buffer-Trend 0-8-0
Buffer-Trend + Success
8
pH
7
6
5
4
3
2
0
0.06
0.12
0.25
0.50
1.0
Buffer Concentration
(% v/v)
Buffer P.S.
9
Buffer P.S.
Buffer P.S. - Success
8
pH
7
6
5
4
3
2
0
0.06
0.12
0.25
Buffer Concentration
(% v/v)
0.50
1.0
Fig 4. Impact of an acidifier and sulfur combined
with Success on the pH of well water.
8.0
LI 700
LI 700
LI 700 + Success
7.5
7.0
pH
6.5
6.0
5.5
5.0
4.5
4.0
0
0.03
(4 oz)
0.06
(8 oz)
0.125
(1 pt)
0.250
(2 pt)
0.038
(3 pt)
2.0
(5 pts)
2.5
(6 pts)
Concentration - % v/v
( Product /100 gal)
8.5
Sul-Preme 52
Sulfur
Sulfur + Success
8.0
pH
7.5
7.0
6.5
6.0
5.5
0
0.8
(2 pts)
1.25
(3 pts)
1.6
(4 pts)
Concentration - % v/v
(Product / 30 GPA)
Figure 5.
Effect of Acidic Spray Conditions on Success Efficacy Against Cabbage Lopper
on Romaine lettuce
Cabbage Looper (Knockdown Mortality )
Larvae Infested 6-hrs After Treatment
Larval Mortality (%)
100
80
60
Success 6 oz + Buffer (pH 4.2)
Success 6 oz
Success 3 oz + Buffer (pH 4.2)
Success 3 oz
Untreated
40
20
0
1
3
Cabbage Looper (Residual Mortality )
Larvae Infested 5 Says Aafter Treatment
100
Larval Mortality (%)
2
Days After Infestation
80
60
40
20
0
1
2
3
4
5
Days After Infestation
Foliage Consumed (%)
Cabbage Looper - Residual Feeding Damage (5 DAI)
100
80
60
40
20
0
6 oz
Buffer
6 oz
3 oz
Buffer
3 oz
Untreated
Figure 6.
Effect of Acidic Spray Conditions on Success Efficacy Against Beet Armyworm
on Head lettuce
Beet Armyworm (Knockdown Mortality )
Larvae Infested 6-hrs After Treatment
Larval Mortality (%)
100
80
60
Success 6 oz + Buffer (pH 4.2)
40
Success 6 oz (pH 7.9)
Success 3 oz + Buffer (pH 4.2)
Success 3 oz (pH 7.9)
Untreated
20
0
1
5
Beet Armyworm (Residual Mortality )
Larvae Infested 5 Days After Treatment
100
Larval Mortality (%)
2
3
4
Days After Infestation
80
60
40
20
0
1
2
3
4
5
Days After Infestation
Foliage Consumed (%)
70
Beet Armyworm - Residual Feeding Damage (5 DAI)
60
50
40
30
20
10
0
6 oz
Buffer
6 oz
3 oz
Buffer
3 oz
Untreated