A Report to the Apple Research & Development Program

EVALUATION OF NOVEL SPRAYING TECHNIQUES TO APPLY PESTICIDES AND GROWTH REGULATORS TO APPLE TREES IN NEW YORK

A report to the Apple Research & Development Program

Andrew Landers

Harvey Reissig

Jim Schupp

Kevin Iungerman

Dave Combs

Jane Barber

Cornell University

13th February 2002

Evaluation of novel sprayers to apply pesticides and growth regulators to apple trees in New York

Drift of pesticide spray is an important and costly problem facing growers. Drift results in damage to susceptible off target crops, environmental contamination to water courses and a lower than intended rate to the target crop, thus reducing the effectiveness of the pesticide. A number of novel spraying techniques have been developed which improve deposition and reduce drift, once such is system is air induction nozzles. The objective of these trials was to determine the efficacy of standard airblast nozzles to that of air inclusion nozzles used in an airblast sprayer.

1. Trial in the Lake Champlain valley

Procedure:

In the Growing season of 2001 an FMC 590 sprayer, built in 1991, was fitted with Lechler ID nozzles to compare their biological efficiency at controlling disease in an orchard in Northern New York. A cooperating grower kindly gave his time, trees, tractor and sprayer for the trial.

The sprayer was also fitted with hollow cone nozzles to apply 100 gallons of spray per acre. The mature apple trees were probably unpruned for two or more previous dormant seasons. Tree Row Spacing / Density: 16ft x 24ft; approx 110 trees/acre

Materials applied:

May 15th: 5 ounces Nova fungicide + 3 pounds Manzate fungicide;

May 24th: 3.25 ounces Sovran fungicide;

June 6th: 3.0 ounces of Sovran fungicide.

Lechler ID 110-04 nozzles were used, applying 100 gallons/acre. Hollow cone nozzles were also used for comparison. Control trees were included in the trial.

The data were analyzed as a completely randomized design with four replications.

As an indication of drift from the sprayer/ trees the adjacent rows of trees was also assessed for disease.

Results

Table 1

Scab on sprayed trees
% infection terminal leaf
terminal leavesfruitseverity rating

Conventional nozzles 33.1 b 0.9 a 0.4 b
Air-induction nozzles 17.0 a 3.9 a 0.2 a

Probability that means are
not significantly different: P = 0.0009 0.131 0.0006

Numbers within columns followed by the same letter are not significantly different (P≤0.05). Data on percentage of fruit or leaves infected was transformed prior to analysis using the arc-sine square root transformation. Data was collected from four replicates.

Table 2 Adjacent rows

Scab on unsprayed trees in adjacent row
% infection terminal leaf
terminal leavesfruitseverity rating

Conventional nozzles 74.7 a 76.8 1.7 b
Air-induction nozzles 65.1 a 55.0 1.1 a

Probability that means are
not significantly different: P = 0.480 0.055 0.030

Rating system for severity of leaf scab:

0 = no scab per leaf

1 = 1-3 lesions per leaf

2 = 3-6 lesions per leaf

3 = >6 lesions per leaf

2. Trial in the Hudson valley

Objective

The main objective of this trial was to evaluate the efficacy of Apogee, a plant growth regulator, on McIntosh apple, using two types of pesticide delivery systems: conventional disc-core type cone nozzle, and (AI) air induction nozzles.

Procedure

A three point hitch John Bean air-blast sprayer was retrofitted with both conventional disc-core type cone nozzles and AI nozzles. The cone nozzles were calibrated with a Makenzie flow meter to operate at a pressure of 300 psi or 7.8 gallons per minute. The AI nozzles were calibrated to a pressure of 100 psi or 7 gpm. A rate of 10 oz/ 100 gal of Apogee was used. The overall spray material output was 155 gallons per acre for cone nozzles and 172 gpa for the AI nozzles. Four treatments were applied 1) Untreated control, 2) Apogee AI (seven) nozzles, 3) Apogee disc-core type cone (seven) nozzles, 4) Apogee conventional disc-core type cone nozzles (five) with two bottom nozzles closed.

A randomized block design was used on vigorous M.26 McIntosh trees with four replicates. Ten shoots were tagged in each lower and upper tree canopies for subsequent bi-weekly shoot measurements. A twenty fruit sample per tree was taken at harvest to evaluate fruit quality. Fruit size, weight, L/D ratio, chroma, and % blush or red fruit color was measured. Finally a late autumn upper canopy terminal shoot measurement was taken to evaluate effect of Apogee.

Results

Shoot growth control was excellent under both delivery methods. AI and disc-core type cone nozzle treatments significantly reduced shoot growth by 50%. AI nozzle efficacy was nearly identical to disc-core type cone nozzle application. Both delivery methods also significantly improved red fruit color by 25%. Overall fruit size (L/D ratio) was not significantly different among the treatments.

Apogee is an effective PGR that reduces shoot growth, increasing light penetration in tree canopies and thus improving red fruit color. Furthermore, Apogee is a highly effective material that reduces shoot growth and recent data (1999 +2000 on Northern Spy) suggests pruning time can be reduced by 20% per tree.

Table 3

3. Trial at NYSAES, Geneva

Procedure:

A FMC Economist sprayer was used for all applications, which started at petal fall (16 May) and continued through last cover (8 Aug). The NYSAES maintenance staff made the fungicide applications for the entire orchard (tree size ca. 15x10ft) starting at apple phonology half-inch green and ending after bloom, at which time the trial applications started. The test plots were sprayed on a calendar schedule of 14 days and consisted of Flint (2.0 oz/A) and Imidan (1.5 lb/A) for both the petal fall (16 may) and 1C (31 May) applications. The 2C (12 June) through 6C (8 Aug) applications consisted of Captec (3.0 qt./A), Bayleton (6.0 oz/A) and Imidan (1.5 lb/A). The 3C, 4C and 5C sprays were applied on 27 Jun, 11 Jul and 25 Jul respectively. The test plots were sprayed at 100 GPA in both treatments. This required changing the pressure to 350 psi for the standard nozzles and 100 psi for the air inclusion nozzles. Both treatments were sprayed at 3.0 mph.

Results:

The data in Chart 1 shows that the deposition attained from the air inclusion treatment was not as efficient as the standard nozzles. Although the reading at the bottom of the canopy was comparable, the remainder of the sections had vast differences.

Chart 1. Deposition data taken from the tree canopy for the standard and air inclusion nozzles.

This data suggests that the standard nozzle would then have better control because of the improved deposition characteristics. However, fruit damage (see Table 1.) taken at harvest did not statistically separate from either of the treated plots or the untreated control. This lack of efficacy in either of the two test plots was probably due to insufficient power provided by the sprayer used. The FMC Economist was not large enough to provide adequate coverage for the size of the trees in this trial.

Table 4. Mean percent fruit damage in each of the replicates.

TreatmentMean Percent Fruit Damage

Internal lep.Early lep. Late lep.PCTPB SJS% Clean

Air Inclusion 21.3 a 0.3 a 2.3 a 43.7 a8.7 a 58.0 a 10.0 a

Standard 18.3 a 0.3 a 4.3 a 40.0 a 11.3 a 61.3 a 12.7 a

Untreated Control 45.0 a 0.0 a 3.0 a 59.3 a8.0 a 44.3 a 6.3 a

Means within a column followed by the same letter are not significantly different(Fisher’s Protected LSD Test, P<0.05). data transformed Arcsin (SqrtX) prior to analysis.

Conclusions:

Air induction nozzles provided better control of scab in unpruned trees than did

conventional nozzles. The larger droplets from the air-induction nozzles were better able

to penetrate leaf canopies.

Based on unsprayed trees on the down-wind side of the sprayed row, it appears that there was more “drift” or coverage in the adjacent row with air-induction compared to conventional nozzles. However, differences were only significant at P≤0.05 for ratings of leaf severity. Differences in levels of fruit scab were very nearly significant (P=0.055).

The air induction nozzles gave similar coverage to the cone nozzle.