The phenology-based degree-day model for managing GBM was made available during the 2010 growing season through the NEWA website. Results from the model were used in weekly reports in the LERGP electronic newsletter, "The Crop Update," as well as during discussions at weekly Coffee Pot Meetings held throughout the growing season. Since this was the first year the model was available while still being validated in small research blocks, there is no impact data for on-farm implementation.
impact statement issue
GBM is the key insect pest of grapes in the eastern United States due to loss from the larval feeding on developing berries or associated with secondary rots that use the feeding wounds as an avenue for infection. The Grape Berry Moth Risk Assessment Protocol developed by Hoffmann and Dennehy in the late 1980s has become the conventional means of GBM management in New York. (A complete description can be found at nysipm.cornell.edu/publications/grapeman/files/risk.pdf.)
The protocol worked well for many years. However, late season damage started to become a problem in the late 1990s, and the protocol, with the first spray based on the timing of temperature-driven bloom periods, has proved less effective at determining the need for later season applications. Meanwhile, "calendar" spray timings based on calendar dates permit 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 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 Fahrenheit. Using bloom date to start the accumulation of degree-days, the phenology model predicts the start of the second generation at 810 degree-days after bloom and the third generation at 1620 degree-days. This model has been tested at a few isolated sites but has not undergone evaluation under commercial vineyard conditions.
With the help of Greg Loeb, Department of Entomology, Cornell University, and Juliet Carroll, New York State Integrated Pest Management Program, the phenology-based degree-day model and supporting explanations of the decision-making process were created on the Network for Environment and Weather Applications (NEWA) website. Bloom times for vineyards in the Lake Erie region were recorded and used as the biofix to start the model. Training in using the model was presented at a NEWA meeting at Cornell Lake Erie Research and Extension Laboratory, the Lake Erie Regional Grape Program (LERGP) Industry Field Rep meeting and at Coffee Pot Meetings held weekly across the Lake Erie region. Results of the model were reported weekly through the growing season via the LERGP Crop Update.
impact statement summary
The goal of this project is to validate the use of a temperature-driven phenology model to time applications of insecticides to manage grape berry moths (GBM), the key insect pest of grapes in the eastern United States, as well as to inform the New York grape industry of the insect's existence. This multi-state project uses 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. The use of a temperature-driven phenology model to time insecticide applications for GBM has the potential to decrease the number of applications from three to two when compared with conventional timings provided by the Grape Berry Moth Risk Assessment Protocol in current use.
Other private funding
Lake Erie Grape Research and Extension Program, Inc., NY Wine & Grape Foundation
