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. METHODS Spray records were collected from 18 of the 26 growers who originally participated in the weather network and applications of fungicides were examined to see how they coincided with infection periods (post-infection disease management strategy) and/or the primary season disease management protocol. The post-infection disease management protocol requires application of the fungicide Nova within 72 hours after the start of an infection period. This program typically results in 4 fungicide applications in a "normal year", 3 sprays in a dry year and 5 applications in a wet year. The primary season disease management protocol starts at 10- 12-inches of shoot growth and continues until primary inoculum is exhausted, typically resulting in an average of 4 fungicide applications a year. Scouting took place during the last week of July. This timing was chosen to coincide with the exhaustion of the primary inoculum of black rot and powdery mildew. Scouting at this time should give growers a good indication of the status of primary infection in a particular vineyard block and help in determining disease management strategies for dealing with secondary inoculum. The scouting protocol was developed for the two primary diseases of concern in 'Concords', black rot and powdery mildew. However, due to the frequent rainfall experienced during the 1996 growing season Phomopsis Cane and Leaf Spot and Downy mildew infections were also accessed to ensure that these diseases did not adversely impact crop quality. Both cluster and leaf infections were evaluated using a scouting method similar to the Grape Berry Moth Risk Assessment Protocol. This protocol consists of scouting four areas in a vineyard, two on the vineyard edge and two in the interior of the vineyard.

RESULTS AND DISCUSSION

Twelve of the 18 growers surveyed accessed weather information from machines located in, or near, their vineyards on a regular basis during the period of primary infection by black rot or powdery mildew. Comparing grower spray records to the post-infection or primary season disease management protocol showed that none of the growers chose to use the post-infection protocol, without adaptation, during 1996. A survey of growers prior to harvest provided several reasons for the post infection protocol not being followed in 1996. The most common reasons given by growers were: 1) Frequent rainfall during 1996 created the need for fungicide applications to be made on a protectant basis during the period of primary infection by black rot and powdery mildew, 2) The Post-infection protocol is difficult to implement on a large acreage due to the restriction of having fungicides applied within 72 hours after the start of an infection period, 3) Overwintering inoculum of powdery mildew, when combined with early infection periods, made the option of the primary season disease management strategy less of a risk in their minds, and 4) reliability of receiving daily weather information was questioned as lightning damage to weather and communication equipment was a problem at some sites in 1996.

As seen in Table 1., spray records were evaluated using several variables. Growers who accessed weather information applied an average of 3.5-4 fungicide applications (range 2-7) while growers who did not access weather information applied an average of 4.5 fungicide applications (range 2-6). Both groups are below the average for fungicide applications determined prior to the demonstration/implementation phase of the two IPM disease management strategies used in this project. A Grape Pesticide Matrix has been created with a starting date of 1989. The average number of fungicide applications in 1989 was 5 with a range from 2-9. The type of growing season also needs to be taken into consideration when comparing years as 1989 is considered a 'normal' year while 1996 was a very wet year. This data indicates that the implementation and educational elements of the Grape IPM program have moved growers to apply fungicides earlier in the growing season during the period primary inoculum is available while decreasing the number of fungicide applications.

¹ Rescue treatment is defined as a fungicide (typically copper or JMS Stylet Oil) applied after 7/31 and with an interval between sprays of 21 days or longer.
² Spray interval during the period when primary inoculum of powdery mildew or black rot is available.
³ Number of applications vary due to spot treatments of vineyard blocks.

The number of acres a grower operates did not significantly affect the number of fungicide applications made. Growers records were split into three categories 1) 30 acres or less, 2) 31 - 99 acres and 3) 100 acres or more. Growers operating 30 acres or less or 31-99 acres used an average of 4 fungicide applications in 1996. Growers operating 100 acres or more applied an average of 3.75 - 5 fungicide applications. While there were very few variables among the spray programs examined which showed a big advantage to using the previously described IPM disease management programs and weather equipment, there were growers who used IPM strategies to reduce cost and pesticide applied. In the above example using grower size, the growers who operated 100 acres or above had an average number of fungicide applications from 3.75 - 5. In these two cases (growers 3 and 11) fungicide applications were made on an as needed basis rather than on the entire acreage as 'insurance'. This saved grower 3 $1,757 and reduced the pesticide applied by 157 pounds. Grower 11 saved $2,784 dollars while reducing the pesticide applied by 205 pounds (See Table 2.).

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¹ Represents the number of acres in which a grower did not apply a fungicide due to scouting, vineyard history, which the remaining acres received.
² This acreage was presented as a range of figures due to the many different spray protocols used. Fungicides were applied on a block by block basis. Spray records were not detailed enough to provide information on a block by block basis.

Another IPM practice which was difficult to evaluate with the survey methods used in this project is knowledge of vineyard history and determination of over wintering inoculum. Grower 9 applied less fungicide applications than were called for in 1996 using the IPM disease management protocols. However, powdery mildew has never been a big concern in this vineyard and over wintering inoculum was judged to be low. This grower, as with all the others, was able to ripen the crop and deliver it to the processor.

Table 2. shows the amount of pesticide and active ingredient applied per acre along with total pesticide cost per acre (product only). Once again there are no trends which can be picked out other than historical. Growers are applying fungicides earlier in the season to try and limit primary infections rather than applying fungicides in an attempt to eradicate existing infections after bloom. The more expensive fungicide programs typically had either JMS Stylet Oil ($11.75 gallon) or more frequent applications of the sterol-inhibiting class of fungicides used in place of less expensive fungicides.

Evaluation of the disease management portion of this project was very difficult due to all the variables which affect vineyard disease development. Training systems play a large role in vineyard disease development through differences in canopy density and crop load. The biggest differences are seen between hand pruned and minimally pruned vines. Hand pruned vines typically have a less dense canopy and lower tons per acre. Vineyard nutrition also plays a large part in what levels of a pest a vine can tolerate while still ripening the crop. Vines with adequate nutrition typically have delayed senescence of leaves in the fall and are able to withstand higher populations of powdery mildew.

Future programs will have to take these variables into consideration. More wide spread implementation of Grape IPM practices is currently under discussion with National Grape Cooperative, the largest processor in the Lake Erie Region. Meetings have been held with Cornell Faculty, Extension Educators, New York State IPM Program staff and representatives of National Grape Cooperative to take the promising aspects of this project and develop a set of IPM elements which their growers can implement in their vineyards. An emphasis is being placed on the use of the manual, Grape IPM in the Northeast, which was developed in conjunction with this project. This project should greatly expand the use of IPM practices in Lake Erie Region vineyards in the near future.

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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