The Light Brown Apple Moth (Epiphyas postvittana) is an important pest on grapes in Australia and New Zealand and is an invasive species in California. Overwintered Light Brown Apple Moth larvae typically emerge in late winter/ early spring and the first adults may be seen soon after. There can be 3-4 generations in a year, depending on the weather. Insecticide treatments targeting 1st or 2nd generation larvae are typically the best way to control Light Brown Apple Moth populations for the entire growing season. The Light Brown Apple Moth Growing Degree Day Model, developed by researchers at Oregon State University, and available on the Pest Prophet app, is a tool growers can use to predict egg hatch based on adult trap catches and field-specific temperature data.

Initiating the Biofix

To properly use the model, the biofix must first be set. This is the date that will serve as the starting point for growing degree day accumulation. For Light Brown Apple Moths, this biofix is the first date of consistent, sustained adult moth catches using pheromone traps in the orchard or vineyard. Traps should be placed in early spring, or late winter, and checked on a regular basis. Once adult moths have been trapped for a few weeks in a row, the date of the first catch should be used as the biofix.

Growing Degree Day Accumulation and Treatment

After the biofix is set, growing degree day accumulation can begin, using a lower threshold of 45F and an upper threshold of 88F. This can be done using daily high and low temperatures, or using hourly temperature data using the Pest Prophet app. The first egg hatch will peak at approximately 390 GDD (F) after adult moth catch and the larval stage will be between 756 and 1400 GDD (F). The optimum timing for a single insecticide treatment is approximately 1,100 GDD(F) after the adult moth catch. After 1400 GDD (F) the next generations of adults will be seen in flight.

Adjusting Biofix for Each Generation

For best results in second generation of Light Brown Apple moths in a given season, the biofix should be reset when new pheromone traps have successfully capture adult moths in late spring/ early summer. Approximately 1,100 GDD(F) following the readjusted biofix is, again, the optimum time for insecticide treatment.

Source:

Light Brown Apple Moth, Epiphyas postvittana (Walker), Phenological Model Analysis by Len Coop, Integrated Plant Protection Center, Oregon State University, Jun 18, 2012