EVALUATION OF NOVEL PESTICIDE SPRAYERS TO CONTROL

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EVALUATION OF NOVEL PESTICIDE SPRAYERS TO CONTROL
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   DISEASE AND INSECTS ON GRAPES IN NEW YORK AND
                   PENNSYLVANIA




                   A report to the Viticultural Consortium




                                           By

                               Dr Andrew Landers
                                Dr Wayne Wilcox
                              Dr Greg English-Loeb
                               Dr Tim Martinson




                                                                       Cornell University
                                                                       2nd January 2002




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 EVALUATION OF NOVEL PESTICIDE SPRAYERS TO CONTROL
   DISEASE AND INSECTS ON GRAPES IN NEW YORK AND
                   PENNSYLVANIA

                                        Introduction
The deposition of pesticides from air blast sprayers gives rise to concern amongst all
associated with the countryside and food production. In the growing season of 2001 a
team of researchers from Cornell University conducted trials into the efficiency of four
novel sprayers, the Proptec, the ESS Electrostatic, the CIMA and Cornell deflectors in
comparison to a traditional air blast sprayer.

Objectives
  1. To improve the standard of crop spraying and the understanding of safer pesticide
     application

   2. To evaluate the efficiency and effectiveness of novel, directed deposition sprayers
      such as Proptec, CIMA and ESS Electrostatic at reducing disease and
      insect populations in vineyards.

   3. To evaluate the effectiveness of Cornell designed air deflectors (fitted to airblast
      sprayers) at reducing disease and insect populations in vineyards.

   4. Collect data to provide a greater understanding of how droplet size affects the
      control of disease and insects.

Materials and methods

Seasonal spray programs were applied by owners/growers in vineyards in the Lake Erie
region of New York and in the Finger Lakes region. In all cases, sprays were applied to
between 1-3 blocks of 0.5-5 acres (depending on farm) with a novel or modified sprayer
and to equivalent blocks using a traditional air-blast sprayer. Each operator chose his
own spray materials and timings, following the general guidelines published in the New
York and Pennsylvania Pest Management Recommendations for Grapes. On a given
farm, both machines, at the same per-acre rates and on the same dates applied the same
spray materials, but the volume of water varied by machine.

Deposition was measured throughout the canopy using either a metal micronutrient tracer
(Sequestrene Fe), incorporated into the spray solution, or water sensitive card targets. An
image analyser was used to quantify droplets. Samples of water sensitive cards were be
taken at representative times throughout the application season particularly early season,
immediate prebloom, and postbloom/midsummer.


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Differences in spray deposition were analyzed for their biological impact by evaluating
insect and disease damage. Both incidence and severity of the major fungal diseases--
i.e., Phomopsis cane and leaf spot, powdery mildew, downy mildew, and black rot—were
assessed shortly after fruit set and again 1-2 wk before harvest. Disease assessments
were made at four arbitrary locations in each block, by examining 25 clusters and all
leaves on each of 10 shoots per location .

Evaluation of effectiveness of sprays was done either by direct counts of insects
(leafhoppers, banded grape bug); proportion of clusters infested (berry moth) or injury to
berries (berry moth).

Equipment

1. A novel sprayer, the Proptec, manufactured by Ledebuhr Industries of Michigan USA,
uses a rotary cage to create droplets which can be directed into the crop canopy. Liquid is
fed into a high-speed spinning cage then centrifugal forces spread the liquid and throw it
from the periphery. Fitting the units to a boom and driving the rotary cage with a
hydraulic motor provides the centrifugal force. The majority of droplets, (95%
approximately), are the same size, depending upon flow rate and cage speed. A small
propeller provides air movement and the position of the unit on the boom dictates air
direction. We have compared the Proptec sprayer with an air blast sprayer for the past
three years. A Proptec mounted sprayer was fitted with a flow regulator plate no. 89 and
operated at 20psi and applied pesticides at 25gpa and 50 gpa in a vineyard owned by
Canandaigua wine Co at Naples, NY. In the vineyard at Valois a Proptec at 25 gpa
(100% a.i) was compared with a Proptec at 12.5 gpa (both at 100% & 75% a.i) on
Riesling.

2. The ESS electrostatic sprayer is manufactured by ESS of Watkinsville, Georgia. The
sprayer uses an induction charging nozzle which applies a negative electrostatic charge to
the droplets. The fine droplets are propelled towards the plant by a low pressure air
stream. The small droplets, around 50 microns are attracted to the positive charge of the
plant (opposites attract). The sprayer uses very low application rates, 9gpa was applied in
our trials at 30psi air pressure and 30psi liquid pressure. At the Canandaigua Wine Co.
vineyard at Dresden, NY we compared the ESS electrostatic with an airblast (as 2000)
at 100%, 75%, 50% a.i on Aurore. We also compared the ESS electrostatic with an
airblast (as 2000) on Aurore & Castel. Last year there were concerns about gusts of wind
affecting disease control. A simple tunnel arrangement was constructed and deposition
and control was undertaken with an ESS tunnel system on Cayuga White

3. The Italian CIMA sprayer uses multiple outlets to direct the air and spray towards the
canopy. Individual outlets can be moved into various positions and upper and lower units
can be operated. Trials were conducted to compare an airblast at 100gpa with a CIMA at
100gpa and 50 gpa. Another trial compared the use of upper and lower applicators with
lower applicators only. Trials were conducted at the vineyard of Allan Davies in Hector,
NY.



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4. Last winter a set of air deflectors were developed at Cornell University and this
growing season a set were fitted to an airblast sprayer and compared to a conventional
airblast at Canandaigua Wine Co. at Pulteney, NY.

All sprayers were calibrated before use.
Results

It was a low disease and low insect activity year. Abundance of disease and grape
arthropod pests can vary greatly from vineyard to vineyard and year to year. Hence, it is
often difficult to find sites with sufficient pressure to adequately evaluate the efficacy of
these different sprayers and spray techniques.

1. Proptec

Table 1 in the appendix shows that the Proptec at Naples gave better control of
phomopsis at 30 gpa than at 50 gpa. This is a similar result as last year, see Year 2 trial
results reported in the Viticultural Consortium East, Report of 2001 Proposals received
and Reports to Grants 2000, NYSAES, September 2001.pp131-133. It indicates that the
correct volume is critical to get disease control, too much leads to run-off, too little is
insufficient for coverage. This year there was hardly any disease pressure, but the Proptec
at 30gpa was significantly better than the airblast at 50 gpa.

Comparing the Proptec sprayer at 50 and 30 gallons per acre with Airblast at 50 gallons
at Naples where vines were treated with carbaryl at around bloom period. The insecticide
was targeted against grape rootworm adults but would also have killed any leafhoppers or
grape berry moth present in the vineyard. An initial inspection of leaves and clusters
revealed very low numbers of leafhoppers and incidence of damage from grape berry
moth. Leaves did have some leaf chewing damage, most likely caused by grape
rootworm adults (earlier in the season) and also some injury from Japanese beetle (later
in the season). To evaluate beetle feeding injury we scored the proportion of leaves with
greater than about 0.8 cm2 of feeding damage for 125 leaves per replicate. Vines treated
with the airblast sprayer at 50 gallons per acre had 15 leaves out of 375 (0.04), vines
treated with the Proptec sprayer at 50 gallons had 27 damaged leaves out of 375 (0.07),
and vines treated with the Proptec sprayer and 30 gallons had 34 damaged leaves out of
375 (0.09). These differences were not statistically significant (P = 0.14) but do suggest
that the Proptec sprayer was somewhat less effective in controlling grape rootworm than
the airblast sprayer.

Trial results at very low rates on Riesling at Valois, at 25gpa or 12.5 gpa at 100% label or
75% label rate, may be found in TABLE 2. With very low disease incidence it is difficult
to give a definite opinion, further trials are necessary.

Vines were treated twice with carbaryl insecticide (postbloom and mid-August).
Leafhoppers were very rare at the Valois site and not evaluated. Some damage from
grape berry moth, especially near the western edge of the trial near some woods was
found. To compare treatments we quantified the number of clusters out of 100 that had
evidence of berry moth damage. For the two no spray rows we evaluated 50 clusters per
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replicate. On unsprayed rows we found 6 infested clusters out of 100 (0.06 infestation
rate) which is below the established economic threshold of 0.12 but not insignificant. For
vines treated with the Proptec sprayer at 25 gallons and 100% ai we found 12 clusters
infested out of 300 (0.04 infestation rate). For vines treated with the Proptec sprayer at
12.5 gallons and 100% ai we found 11 clusters infested out of 300 (0.04 infestation rate).
For vines treated with the Proptec sprayer at 12.5 gallons and 75% ai we found 9 infested
clusters out of 300 (0.03 infestation rate). Overall, we found no marked differences in
damage among the three treatments (P = 0.6). Thus, using less water and decreasing
amount of active ingredient did not result in reduced control. However, because pressure
was light, even in unsprayed rows, it is difficult to draw definitive conclusions.

2. Electrostatic sprayer
Results in Appendix Table 3 indicate that the ESS worked best when fungicide
applications were made at 100% label recommendation. At such small quantities of water
per acre, it appears it is imperative to apply the recommended amount of pesticide to
ensure good pesticide action. When comparing ESS electrostatic (variable a.i.) in Aurore
at Dresden where vines were treated with carbaryl at about bloom, we found very low
pest pressure from grape berry moth or leafhoppers. No evaluation was made.
        Aurore vines were treated at with carbaryl at about bloom. We assessed
leafhopper densities on the Aurore grapes on 29 August 2001. Out of 750 leaves we
found no leafhopper nymphs. This includes an assessment of 300 leaves along no spray
rows. Thus, overall leafhopper densities, even on unsprayed vines, were very low. We
were unable to compare treatments. Damage from grape berry moth was also rare and
not evaluated.
        Castel vines were treated with carbaryl at about bloom. In the Castel grapes,
which were evaluated on 29 August, 2001, we found 2 leafhopper nymphs out of 375
leaves for vines sprayed with an airblast sprayer and 4 leafhopper nymphs out of 375
leaves for vines sprayed with the electrostatic sprayer. These densities are very low and
it is impossible to draw definitive conclusions concerning efficacy of the two sprayer
systems. Damage from grape berry moth was rare and not evaluated.

3. CIMA sprayer
CIMA Applying Different volumes, Compared to an Airblast
The test comparing the Air-blast at 100gpa and the CIMA working at either 100 or 50
gpa showed that considering just treatment type it was the volume applied that caused
differences in deposit rather than the machine type. The CIMA working at 50gpa applied
less than the CIMA and Air-blast working at 100gpa (52, 70, and 72.9 % cover
respectively P<0.001 LSD 8.28). The CIMA operating at 50gpa, deposited significantly
less chemical to the lower leaf surface compared to the upper (P=0.035), whilst the other
two treatments applied similar quantities to both leaf surfaces. Significant interactions
were also observed at the treatment leaf and canopy level, which is best described
graphically in Appendix Figure 1

CIMA With only bottom units spraying compared to both bottom and top units
Overall there was no significant difference between deposits measured for the different
unit load, only between canopy depth and leaf side. Interaction analysis however, showed
that there was significantly less chemical deposited to the centre of the canopy compared
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to the top of the canopy when both units were used. When only the lower units were used
significantly less chemical was deposited to both the top and the centre of the canopy
compared to the bottom; with the top receiving less than the centre. See Figure 2 in the
Appendix.

Concord vs. Aurora
There was a significant difference between the treatment type and leaf side. The
application of 100gpa to the concord crop resulted in significantly lower percent covers
on the underside of the leaf (P<0.001). An increase in canopy density should explain why
half the quantity of liquid per acre should result in higher percent coverage for Aurora
compared to the Concord crop; the application rate per unit leaf area was probably
similar.

Leafhopper pressure was very high on unsprayed rows at the west end of the trial.
Leaves showed extensive feeding injury (stippling) and we counted 328 nymphs on 75
leaves (4.4 nymphs per leaf). Densities of leafhoppers, however, were much lower on
vines within the trial, even on unsprayed control rows. Out of 150 leaves inspected from
the two unsprayed control rows we found 27 nymphs (about 0.2 nymphs per leaf).
Densities of leafhopper nymphs were even lower on sprayed vines. We found only 2
nymphs out of 225 leaves from vines treated with the airblast sprayer (0.009 nymphs per
leaf). We found a few more leafhopper nymphs on vines treated with the Cima sprayer
using 100 gallons per acre (11 out of 225 leaves = 0.05 nymphs per leaf). For vines
treated with the Cima sprayer at 50 gallons we found 8 nymphs out of 225 leaves (0.04
nymphs per leaf). There was no statistical difference among treatments (P = 0.56). Given
the high leafhopper pressure in the vineyard, it appears both the Cima and the airblast
sprayers were effective in controlling leafhoppers in this trial.

4. Cornell deflectors

Low disease incidence lead to very difficult trial conditions. Figure 3 in the Appendix
shows how the deflectors placed an even 55% coverage throughout the canopy as
opposed to the erratic 20 and 40 % throughout the top and centre with the traditional
airblast. It was only at the bottom of the canopy was there an equal deposition. Figure 4
in the appendix confirms this more even distribution on the drift pole measure. There was
no significant difference in disease control, see Table 6 in the appendix.

Acknowledgement

We would like to acknowledge the willingness and support of the growers, Tom Collins
and Bill Dunn of Naples, Valois, Pulteney and Dresden and Allen Davis of Hector who
gave their time and equipment for these trials. I wish to thank Jane Barber and members
of the Finger Lakes Grape Program for their technical assistance. Funding for this project
was provided by the Viticultural consortium, Lake Erie Regional Grape Program, Grape
production research fund, New York wine growers, and the Wine and Grape foundation




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                                       APPENDIX
TABLE 1 PROPTEC cv. ‘NIAGARA’: PHOMOPSIS CONTROL AT NAPLES

Treatment         % Clusters infected
Airblast, 50 gpa                      2.6 ab
Proptec 30 gpa                        0.7 b
Proptec 50 gpa                        7.7 a
_______________________________________________________

COMMENTS: Values represent the means for 50 clusters per location, 3 replicate locations per treatment,
rated 29 August 2001. Values not followed by a common letter are significantly different (P = 0.05,
Waller-Duncan). Low disease pressure.

TABLE 2 PROPTEC: RIESLING: DISEASE INFECTION AT VALOIS
Disease was rated on Oct. 2 and Oct.4.

Powdery Mildew Leaf Infection

Treatment                            % Leaf Area Infected                  Probability*
25 GPA 100% A.I.                           10.4 %                            p=0.28
12.5 GPA 100% A.I.                          7.6 %
12.5 GPA 75% A.I.                          11.0 %                            p=0.15
Control                                    42.5%

Powdery Mildew Fruit Infection

Treatment                            % Cluster Area Infected                Probability*
25 GPA 100% A.I.                             0.2 %                            p=0.24
12.5 GPA 100% A.I.                           0.5 %
12.5 GPA 75% A.I.                            0.5 %                             p=0.96
Control                                     39.3 %

Botrytis Bunch Rot Fruit Infection

Treatment                            % Cluster Area Infected                Probability*
25 GPA 100% A.I.                            14.6 %                            p=0.28
12.5 GPA 100% A.I.                          11.4 %
12.5 GPA 75% A.I.                           10.5 %                             p=0.79
Control                                      5.5 %

*A two sample t-test was performed comparing the treatment 12.5 GPA 100% A.I. to 25 GPA 100% A.I. or
12.5 GPA 75% A.I. The probability reported is for the hypothesis that the difference between 12.5 GPA
100% A.I. and the other respective treatments are not different from 0. The Control is reported but not
analyzed.




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TABLE 3 ELECTROSTATIC cv. ‘AURORE’: POWDERY MILDEW CONTROL

Treatment                         Incidence                 Severity
                                               Clusters
ESS 100%                               3.3 b                0.1 b
ESS 50%                               22.5 a                3.2 a
ESS 25%                               18.3 a                3.2 a
                                       Foliage
ESS 100%                        49.2 b            7.9 b
ESS 50%                         69.2 ab          16.1 a
ESS 25%                         85.0 a           20.1 a
______________________________________________________

COMMENTS: Values represent the means for 40 clusters per plot and 40 leaves (5 leaves/shoot x 8
shoots) per plot, 3 replicate plots per treatment, rated 27-28 August 2001. Values not followed by a
common letter are significantly different (P = 0.05, Waller-Duncan). Low disease pressure. (Incidence =
% clusters or leaves infected; severity = % surface area infected)




Table 4 CIMA: Average percent cover for the two different units loads down through the
canopy


                                           Both Units     Lower Units
                               Top           53.4 c         28.6 a
                              Centre        34.3 ab         33.9 ab
                              Bottom        46.8 bc         53.1 c



P=0.005, SED=7.00 LSD=13.79.Overall the upper leaf surface received more than the
lower leaf surface with both application types (57.4 and 25.9 respectively P=0.002,
SED=4.04, LSD=7.96)
.
Table 5 CIMA: Average percent cover for different crop types at different application
rates P<0.001 , SED=5.16 , LSD=10.18
                                       Aurora 50gpa Concord 100gpa
                            Upper          86.5          85.2
                            Lower           88           53.1




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                               Percentage deposited by an Air blast 100gpa; and a CIMA operating at either 100 or 50gpa


            120                                              Air Blast       CIMA 100         CIMA 50
                                                             I = Least significant Difference 20. 29
            100



                 80
 .
 Percent cover




                 60



                 40



                 20



                      0
                                Upper            Lower              Upper             Lower             Upper             Lower

                                          Top                                Centre                              Bottom
                                                                         Canopy position




Figure 1 Average percentage deposited by an Air-blast 100gpa and a CIMA at 100, or
50gpa. Deposits were significantly different both down through the canopy and on the
upper and lower leaves.


                                Average deposits for Both full and reduced unit load, on both side of and all the way down
                                                                   through the canopy.


                      120
                              I = Least significant                Top Upper            Top Lower

                      100                                          Centre Upper         Centre Lower


                       80                                          Bottom Upper         Bottom Lower
      .




                       60
      Percent Cover




                       40


                       20


                          0
                                        Left                     Right                     Left                     Right

                      -20                       Both units                                          Lower unit

                                                                         Canopy position




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Figure 2 CIMA: % cover for upper/lower leaves throughout the canopy

4. Cornell deflectors

TABLE 6 CORNELL DEFLECTORS cv. ‘AURORE’: POWDERY MILDEW CONTROL

Treatment                                             Incidence         Severity
                                                               Clusters
Deflectors +                                              0.0             0.0
Deflectors – (Air blast)                                  0.9             0.1

                                Foliage
Deflectors +                3.4          0.1
Deflectors – (Air blast)    2.5          0.1
______________________________________________________
COMMENTS: Values represent the means for 60 clusters per plot and 60 leaves (5 leaves/shoot x 12
shoots) per plot, 3 replicate plots per treatment, rated 27 August 2001. No significant difference (P = 0.05,
t-test) between treatments. Low disease pressure, excellent control with both. (Incidence = % clusters or
leaves infected; severity = % surface area infected)



                          Comparison of percent cover achieved with a Cornell Deflector and a Traditional Air blast
                                      sprayer, recorded at three different zones within a vine canopy


                    100
                                                      Air blast              Deflector
                    90
                                                I = standard error of differences of means
                    80

                    70
    .




                    60
    Percent cover




                    50

                    40

                    30

                    20

                    10

                     0
                                      Top                           Centre                     Bottom
                                                                  Canopy zone



Figure 3 Cornell Deflectors: Comparison of % cover within the canopy between
deflectors and traditional airblast




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                          Average deposits on a drift tower for Airblast and Cornell deflector


                  14.25
                                      AirBlast Average      Deflector Average
                  12.75

                  11.25

                   9.75
      .




                   8.25
      Height ft




                   6.75

                   5.25

                   3.75

                   2.25

                   0.75

                      0.00        20.00       40.00        60.00        80.00       100.00       120.00
                                                          % Cover


                                Figure 4. Cornell deflectors: Deposits on drift tower

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