Results of the first two years of this project were very encouraging in that the phenology model provided similar GBM control at harvest as the GBMRA protocol, with one less insecticide applied.
impact statement issue
Grape Berry Moth (GBM) is the key insect pest of grapes in the eastern United States due to loss from the larval stage feeding directly on developing berries and also to loss associated with secondary rots that use the feeding wounds as an avenue for berry infection. The Grape Berry Moth Risk Assessment (GBMRA) Protocol developed by Hoffmann and Dennehy in the late 1980s has become the conventional means of GBM management in New York. (A complete description of the protocol can be found at: http://nysipm.cornell.edu/publications/grapeman/files/risk.pdf.) The GBMRA protocol worked well for many years. However, late season damage started to become a problem in the late 1990s, and the GBMRA has proved to be less effective at determining the need for later season applications. With the first spray based on the timing of the bloom period, which is driven by temperature, the other spray timings are based on calendar dates with no correction in years that are much warmer or colder than average.
impact statement response
The degree day requirements (use of daily high and low temperatures to determine heat accumulation) for development of each generation of GBM has been investigated under laboratory conditions (Tobin et al. 2001, 2003). Based on these data we estimated that the number of degree-days for GBM to develop from eggs to egg-laying adult females is approximately 810 degree-days (degrees Fahrenheit) using a base temperature of 47 degrees F. Using bloom date to start the collection of degree-days, a phenology model would predict the start of the second generation at 810 degree-days after bloom and the third generation at 1,620 degree-days after bloom. This model has been tested at a few isolated sites but has not undergone evaluation under commercial vineyard conditions. Experiments were conducted at vineyard sites each in New York (Finger Lakes and Lake Erie regions), Pennsylvania (Lake Erie region), and Michigan (Southwestern region), using Labrusca or hybrid vineyards with a high risk of GBM damage. At each site we established six-vine plots located at the vineyard edge where GBM pressure is greatest using a random block experimental design and 4-6 replicates per treatment. Treatments compared in this experiment were: (1) treated with GBM insecticide following GBMRAP at 5-10 days post-bloom, at the beginning of August and end of August (commercial standard); (2) treated with GBM insecticide following GBM phenology model of Tobin et al. (2001) at 810 degree-days after biofix (bloom of the wild grape V. riparia) (predicted start of second generation), and 1,620 degree-days after biofix (predicted start of third generation); and (3) untreated control.
impact statement summary
The goal of this two-year study is to validate the use of a temperature-driven phenology model to time the application of insecticide for the control of grape berry moth (GBM), the key insect pest of grapes in the eastern United States. This multi-state project used replicated plots in vineyards in the Finger Lakes and Lake Erie Regions of New York, the Lake Erie Region of Pennsylvania and the Southwestern region of Michigan. This report details first-year results from the Lake Erie region of New York. The use of a temperature-driven phenology model to time insecticide applications for grape berry moth resulted in a decrease in the number of applications from three to two when compared with the conventional timings provided by the Grape Berry Risk Assessment Protocol.
Other private funding
Lake Erie Grape Research and Extension Program, Inc., NY Wine and Grape Foundation
