Research Projects

Integrating and Optimizing New Approaches To Meet Pest Management Challenges in Michigan Vineyards

PROJECT OBJECTIVES:

1. Determine the effectiveness of reduced risk
pesticides on grape pests and their impact on
biocontrol agents in vineyard-scale trials.
2. Determine the effect of wild grape removal from
habitats adjacent to vineyards on grape berry moth
and biocontrol agents.
3. Optimize sprayer technology to improve coverage
of grape clusters.
4. Characterize relationship between cluster
coverage and control of grape pests.

1. Determine the effectiveness of reduced risk pesticides on grape pests and their impact on biocontrol agents in vineyard-scale trials. Two ‘Concord’ grape vineyards with histories of grape berry moth (GBM) infestation were chosen at each of four farms in Van Buren and Berrien counties, Michigan. At each farm, one vineyard received a program consisting of reduced-risk insecticides (Intrepid®, Assail®, and SpinTor®) for insect control while the comparison grower standard vineyard received conventional broad-spectrum insecticides (Sevin®, Danitol®, Guthion®) according to the grower’s typical program. All vineyards received a post-bloom application of Danitol® 2.4 EC and program comparisons were targeted at second and third berry moth generations, when pressure is highest.

In the reduced-risk treatment, there was a significant reduction in the number of GBM that emerged from berries collected on 14 Aug and 13 Sept compared to samples taken on the same dates from conventional vineyards. On three sample dates, the parasitism rate of GBM was greater in GBM collected from the reduced-risk vineyards than in the grower standard vineyards. Unbaited yellow sticky traps were deployed in all vineyards, providing an overview of the natural enemy complex. However, in this first year there was no significant difference in the number or community of natural enemies between treatments.
Serenade was tested for control of late season sour rots, but was found to not provide any protection against this. However, disease pressure was very low at the sites where this was done.

2. Determine the effect of wild grape removal from habitats adjacent to vineyards on grape berry moth and biocontrol agents. One to ten acre paired-vineyards at five farms in southwest Michigan were used for this study. Wild grape vines in the woods adjacent to one of the paired vineyards was cut (to prevent fruiting), which removed a possible refuge for both GBM and their parasitoids. Samples of 100 GBM-infested berries (in 5 sub-samples) were collected from all vineyards on 19 Aug, 9 and 30 September. There was no significant difference between treatments in the number of GBM and parasitoids emerging. Unbaited yellow sticky traps were deployed in the vineyards and no significant difference in the number of adult natural enemies was found between treatments. We expect differences in GBM pressure and parasitoid abundance to become evident in the remaining two years of this research project.

3. Optimize sprayer technology to improve coverage of grape clusters. Three sprayers were compared for their ability to provide coverage of grape clusters in a juice grape canopy. During the second week of August 2003, a rotary fan assisted, tower, and airblast sprayer were each tested at three different water volumes. Six freshly-picked clusters were hung below the cordon in the canopy along a 7-vine row of Niagara grapes. Once installed, one of the sprayers at one of the water volume settings was loaded with a solution of kaolin clay, and driven along the row. Collected clusters were analyzed for their kaolin residue by determining the amount deposited, the % coverage, and the droplet size distribution.

Analysis of the samples is ongoing, but the data already indicate the importance of appropriate sprayer and water volume decisions for achieving cluster coverage. Even at high volume, some sprayers had difficulty penetrating the cluster with residue (Fig. 1), with kaolin visible only on the outer cluster surface. Research in 2004 will determine the significance of this for control of insects in clusters.

4. Characterize relationship between cluster coverage and control of grape pests. This objective was not conducted in 2003, but will start in 2004 and continue in 2005.

Acknowledgements

We gratefully acknowledge Project GREEEN, The Michigan Agricultural Experiment Station, and National Grape Cooperative for funding this research. We wish to thank members of the MSU Small Fruit Entomology Lab for their technical assistance and grower cooperators for granting access to their vineyards.