Click on Titles: Grower Adoption of Grape IPM Disease Management Strategies Implementing GBM Risk Assessment and Leafhopper Scouting in Lake Erie Region Vineyards Exploring Alternative Methods of Implementing ISOMATE-GBM™ in High Risk Vineyards Reexamination of Grape Berry Moth Management Practices in the Lake Erie Region I Reexamination of Grape Berry Moth Management Practices in the Lake Erie Region II Postemergence Vineyard Weed Management Program I Postemergence Vineyard Weed Management Program II Food Quality Protection Act Back to GIPM Home Page Back to Lake Erie Regional Grape Program Home Page

Principle Investigators: T. Weigle, Sr. Area Extension Educator, NYS IPM Program, and J. Bixby, Grape IPM Summer Assistant, NYS IPM Program. Cooperator: A. Muza, Departments of Entomology and Plant Pathology, Penn State University. INTRODUCTION      The Grape Berry Moth Risk Assessment (GBM RA) protocol was developed by Hoffman and Dennehy (1987) to address the possibility of reducing the number of insecticide applications necessary to manage grape berry moth damage to economically acceptable levels. This program was initiated by the processors' desire to reduce pesticides due to public concern and the growers' desires to reduce production costs Martinson et al. (1991). The GBM RA protocol calls for a 10-day post bloom spray in high and intermediate risk vineyards. Low and intermediate risk vineyards are then scouted the third week of July to determine if an insecticide application is necessary during the first week of August. In high risk vineyards an early August insecticide application is made without sampling. Sampling during the fourth week of August is used in high risk vineyards to determine if a third insecticide application in late August is required.

METHODS

     Growers were responsible for classifying their vineyard blocks as High, Low, or Intermediate for risk of damage by GBM using the GBM RA protocol. Once a vineyard is classified the scouting and spray protocols are known. High and intermediate risk vineyards receive an automatic 10-days post bloom insecticide application for grape berry moth. This single application is often adequate to keep leafhopper populations below economic levels for the remainder of the season. High risk vineyards then receive an insecticide treatment in early August for GBM with a early September insecticide application determined by scouting the third week in August. Early August applications for GBM in low and intermediate risk vineyards are made only if scouting during the third week in July indicates it is necessary. This is also the timing for leafhopper scouting. Leafhopper scouting is only necessary if scouting for GBM shows no treatment is necessary as an insecticide applied for GBM will provide management of leafhopper as well.

     Low risk vineyards receive another scouting for leafhopper during the period immediately prebloom. Low risk vineyards do not receive an automatic insecticide application 10-days post bloom so scouting is accomplished during the immediate prebloom period to determine if leafhopper feeding is present in the upper canopy. The presence of feeding by leafhopper during this period of time warrants an insecticide to be applied. Growers could use any of the available leafhopper scouting protocols during this project. Spray records were examined and compared with scouting records for verification of the use of IPM protocols. Sample vineyards were also scouted by the IPM Program Assistant to help growers understand the scouting protocols and to provide information for use in code-a-phone messages and newsletter articles to ensure wider distribution of information to growers.

RESULTS AND DISCUSSION

     Spray records from 18 growers representing 1214 acres were used in evaluating this project. Growers assigned risk categories to their vineyard blocks and followed protocols for scouting for GBM and/or leafhopper. While some growers did not use the scouting protocols strictly as written, the time frame of when to accomplish the scouting was fairly well maintained and was the timing of insecticide applications.

     Grower spray records were evaluated for appropriate timing of insecticide applications, appropriate rates of insecticide for the primary pest listed on the spray record, total insecticide applications per block and total pounds of pesticide and active ingredient applied per vineyard block (see Table 1). This information was then compared to the conventional program of 3 insecticide applications per year used prior to the introduction of the GBM RA.

     As shown in Table 1, if all growers in this project used the conventional 3 spray program of the insecticide Sevin at 2.5# per acre (the most common material and rate for GBM in this project) it would have resulted in just over 4.5 tons of pesticide and 3.68 tons of active ingredient being applied to the 1214 acres. This would be an average of 7.5 pounds of Sevin and 6 pounds of active ingredient being applied per acre. If this information is extrapolated across the 33,000 acres in the Lake Erie Grape Belt it would result in 125 tons of pesticide and 100 tons of active ingredient applied each year.

     Table 1 shows that project participants decreased the total number of insecticide applications by 54% (25 instead of 54) and the total pounds of insecticide by 45%. The reduction in pounds of pesticide used is even more striking when you take into account that grower 11, the only vineyard with 3 insecticide applications, is responsible for 28% of the participating acreage. When compared to the conventional three spray program, the 45% reduction in pounds of pesticide would compare to a decrease of 56.25 tons of pesticide applied across the 33,000 acre Lake Erie Grape Belt.

     In addition to decreasing the number of insecticide applications, insecticide applications made specifically for leafhopper constituted 8 of the 25 applications made by project participants in 1996. This is significant because leafhopper requires only half the rate of insecticide needed for management of GBM. The column in Table 1 titled leafhopper sprays provides the number of one-half rate applications made specifically for leafhopper or other secondary pests. Seven of the eight leafhopper applications were the only insecticide applications made in that vineyard block in 1996 with no insecticide applied for GBM. These results indicate a more dramatic decrease in insecticide use. For example, grower eight applied only one insecticide which was the reduced rate specifically for leafhopper, While the number of applications in this block was reduced from three to one (67% reduction), the reduction in pounds of pesticide and active ingredient used was 83%.

     The Grape Berry Moth Risk Assessment protocol has become an extremely valuable tool in a vineyard IPM strategy. It allows growers to not only apply insecticides only when necessary, but has been easily adopted by growers because of it's ease of use and the fact that it is viewed by growers as relatively low risk. The addition of leafhopper scouting has reduced the perceived risk of using GBM RA by providing growers with a tool to help them determine if, and when, insecticide applications solely for leafhopper are warranted.

     The implementation of a pictorial scouting protocol for leafhopper is looked upon as the next step to reducing applications solely for leafhopper by reducing the time it takes to scout. Future implementation and research projects are planned to increase the use of both GBM and leafhopper scouting in the Lake Erie Grape Belt and to address the sporadic, but economically important, third generation of grape berry moth that has been difficult to predict the past few years.

This report provides a portion of the results from the project, Macro-scale Implementation of IPM for Grapes in NY and PA: On-Farm Demonstrations, funded by the Extension Service/United States Department of Agriculture Grants Program.

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