This model tracks predicted percent of egglaying and predicts the start of second and third generation egglaying (810, 1620 and 2430 GDD Base 47F from the biofix of wild grape bloom, respectively). Record the date of wild grape bloom at your location to use this model.
Degree day accumulation (Base 47F, from 3/1) on 5/19/2013: 380.4
Locate the Biofix Date (date of wild grape bloom) on the top row.
Make a note of this date for future use. Follow that column down to determine
the Base 47F Growing Degree Days (GDD) that have accumulated between the biofix
date and the current date, listed at the left side of that row. Forecast data is
provided (where available) to help with planning in the near-term. Depending on the
level of vineyard infestation, peaks of egglaying are predicted to start at 810 and
1620 GDD from the biofix date.MSU Grape Berry Moth oviposition and treatment model:
- Use date of wild grape bloom (50% clusters with 50% flowers open) as biofix date.
- Note biofix date for your vineyards.
- Consider timing applications of insecticides with good residual activity for 810 and 1620 degree days (base 47F) from the biofix date.