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, J. Bixby, Program Assistant, NYS IPM Program. Cooperators: T. Martinson, Dept. of Entomology, NYSAES, Geneva, and J. Kovach, Fruit IPM Coordinator, NYS IPM Program INTRODUCTION       Alternative management strategies for grape berry moth have been part of Grape IPM implementation and demonstration projects in New York State since 1990. The Grape Berry Moth Risk Assessment (GBM RA) protocol developed by Hoffman and Dennehy, Department of Entomology, NYSAES, Geneva, NY, has since been widely implemented by growers and has been shown to significantly reduce, or eliminate insecticide use for grape berry moth (GBM) in a majority of vineyards in the Lake Erie grape growing region. While there has been annual demonstration and implementation projects with Isomate-GBM™, a phermonal mating disruption product, growers have been slow to implement this practice. Work with Isomate-GBM™ has involved grower vineyards encompassing all the GBM risk classifications. In the first year of the Macro-scale Implementation of IPM for Grapes in NY and PA: On-Farm Demonstration we applied Isomate-GBM™ to 100 acres of contiguous acres within a 2000 acre 'sea of grapes'. These vineyards were considered low risk and GBM damage levels were never close to the economic threshold of 2% damaged berries. Vineyards during the 1995 project had Isomate-GBM™ applied at 200 dispensers per acre as recommended by researchers and representatives of Pacific BioControl, distributor of the product.

METHODS

A project evaluation conducted during the dormant season gathered input from participating growers and the processing industry. Points raised during the meeting exposed some of the weaknesses Isomate-GBM has when compared to widespread grower implementation of the Grape Berry Moth Risk Assessment protocol.

The main barriers to adoption of Isomate-GBM expressed by growers are: 1) Economics of product and application, 2) Having to treat the entire vineyard when insecticide treatments are generally applied to only the outside rows or post-lengths, 3) Treatment is in vineyard and not where most mating takes place (in the wooded edge) and 4) Application of product comes during a busy time of year (Around May 15) Using this information. Growers felt that Isomate-GBM™ should will not be widely implemented in low risk vineyards where the need to apply insecticide has been greatly reduced by scouting using the GBM RA protocol. The constant need for insecticide application for management of grape berry moth in high and intermediate risk vineyards was thought to be a better target for Isomate-GBM™ implementation. The project was adjusted to demonstrate Isomate-GBM™ in high risk vineyard settings.

A vineyard in Westfield, NY was chosen as the project site. The vineyard was approximately 30 acres and was broken down into 4 blocks of similar size, divided North and South by an access road and East and West by a small stream. Lake Erie is adjacent to the vineyard on the North side with woods bordering the East, West and North edges.

Three different treatments were used. Treatment 1 consisted of Isomate GBM™ placed in the edge of the vineyard as well as in the woods. Treatment 2 involved placing Isomate GBM™ in the edge of the vineyard only and Treatment 3 had no Isomate GBM™. In accordance with previous research, a double rate (two dispensers per post length) of Isomate GBM were placed in the vineyard edge with the same rate used in the woods. Each block contained all three treatments in random order. A total of 12 plots were established (Click to see Fig. 1).

The rows in Block 1 were perpendicular to the wooded edge. The woods were 31-33 feet away from the end vines. In this block the Isomate GBM was placed 75 feet (3 post lengths) into the vineyard for Treatments 1 and 2. Each treatment was 25 rows wide.

The rows in Blocks 2, 3 and 4 were parallel to the woods. In these blocks the vineyard treatments of Isomate GBM ran in 4 rows, 28 feet, from the edge of the block. The treatments were each 8 post lengths wide. Block 2 was between 15 and 18 feet from the edge of the woods. Block 3 varied from 14 to 34 feet, and Block 4 was 15-29 feet from the woods.

Treatment 1 required the placement of Isomate GBM 50 feet into the woods. The woods in some areas around Block 1 and 2 were very thick and the Isomate GBM™ extended only 28 feet in some areas. On the eastern edge of the vineyard there was a cliff. This cliff allowed Isomate GBM™ to be placed in only 3 feet of woods in some areas.

No insecticides were applied to any of the blocks. Risk assessment was done in the third week of July and again in the third week of August on each plot to determine percent cluster damage. The sampling procedure for Grape Berry Moth Risk Assessment was to select 4 sites in the plot: 2 on the edge (wooded) and 2 on the interior. At each site, 10 clusters were examined for GBM damage on each of 5 vines for a total of 50 clusters/site and 200 clusters per plot. Cluster ratings were made using as few as one damaged berry counting as a damaged cluster. At each site the 5 vines were also examined for eastern grape leafhopper damage using the same five vines. One shoot/vine was used with leaves 3-7 (1 being the basal leaf) given a leaf rating on a scale from 0-4 using the pictorial damage rating system developed by Tim Martinson, Entomology, NYSAES, Geneva. Rating ran from zero (no damage) to 4 (extensive stippling from feeding and the presence chlorotic area). The threshold for cluster damage from grape berry moth in July is 6% and during the August scouting period is 15%. The threshold for leaf damage is an average leaf rating of 2 at the July scouting.

In late September clusters were collected from each plot. Twenty-five clusters from the edge and twenty-five clusters from the interior. The number of berries, the number of berries damaged by the GBM and the number of GBM larvae were counted for each cluster. The percent cluster damage by the GBM was obtained from this data.

RESULTS

Grape berry moth damage was severe across the Lake Erie growing regions in 1995. Weather conditions proved to be favorable for a third generation of grape berry moth instead of the two generations seen in a 'normal' year. Scouting during the third week of July found all treatments were over threshold on the vineyard edge while the interior of the vineyard was at or below threshold. The participating grower was notified of the results and decided to follow the protocol of no insecticide applications to help determine season long damage levels using Isomate-GBM™ alone. Results were similar in the August scouting period will all treatments severely over threshold on the edge of the vineyard and below threshold in the interior. Some blocks were rated as high as 80-85% average cluster damage (one infested berry equals one damaged cluster). Again no insecticide treatment was applied.

Fifty clusters per treatment were examined for the presence of grape berry moth damage and live larvae. Twenty-five clusters were examined in both the interior and exterior of each treatment plot. Table one shows that all treatments on the vineyard edge exceeded the federal damage threshold which grape processors in the Lake Erie region use for grape berry moth damage. In contrast, the vineyard interior which received no insecticide applications were below the damage threshold.

DISCUSSION

No insecticide treatments were applied in this demonstration project. One of the weaknesses most mentioned by growers concerning Isomate-GBM™ is the recommendation to apply insecticide to the vineyard edge of high and intermediate risk vineyards in addition to the use of Isomate-GBM™ over the entire vineyard. Using the Grape Berry Moth Risk Assessment protocol growers can monitor vineyards to determine if there is a need for insecticide applications over their entire vineyards. Many growers participating in past implementation projects have broken their vineyards into blocks and treat the wooded edge of the vineyard as high risk with two insecticide applications/year while they treat the interior of the vineyard as low risk with no insecticide applications applied unless scouting indicates it is necessary.

The most frequently cited reason by growers for not using Isomate-GBM™ is economics. Due to the known edge effect of grape berry moth, growers are reluctant to apply a high cost material throughout the vineyard when an insecticide application targeting only the edge will provide satisfactory management. As shown in Table 5 the cost of Isomate-GBM™ is prohibitive if used across the entire vineyard when compared to an application of insecticide. Time of application has varied from 2 acres/hour to 2 hours/acre depending on whether distribution is accomplished by paid university staff or hourly farm workers, respectively. A better system of payment for distribution of Isomate in the vineyard, based on number of ties applied, is being discussed.

¹ One hour of labor/acre for application. Labor at $6.00/hour cash wage plus social security and workmen's compensation is approximately $7.06/hour.
² This application would be a dedicated trip through the vineyard applying insecticide only.
³ This application would have insecticide tank mixed as part of a fungicide application so only the cost of insecticide is used.

Secondary pests are also listed as a concern for growers using pheromone mating disruption. Eastern grape leafhopper populations did not reach the treatment threshold in 1995 but has been a problem in some years in the Lake Erie region in vineyards which have reduced or eliminated insecticide applications by using the grape berry moth risk assessment.

Future work with Isomate-GBM™ will be based on NYSAES, Geneva researchers interest as during a personal conversation with Don Thompson, representative of Pacific BioControl, it became apparent that the company is no longer marketing the product. The primary reasons given were the wide implementation of the Grape Berry Moth Risk Assessment and the corresponding decrease in insecticide use and the economic feasibility of using pheromone mating disruption for grape berry moth when compared to using the Grape Berry Moth Risk Assessment protocol. Work still needs to be done to determine the correct rate, if any, of material that needs to be applied in the wooded and vineyard edge to create a pheromone cloud. If future research is conducted with Isomate-GBM it should focus on the vineyard edge instead of treating an entire vineyard if it ever is to be widely accepted by growers.

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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