The Vegetable Leafminer (Liriomyza sativae) is an important pest on a wide variety of hosts. Overwintered Vegetable Leafminer pupae typically emerge as adults in spring. Depending on weather and location, there may be many generations in a season. The Vegetable Leafminer Growing Degree Day Model, developed by researchers, and available on the Pest Prophet app, is a tool growers can use to predict larvae emergence from leaves and egg hatch after adults have been observed, based on 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 this type of model the biofix date should be set when first adults are observed in the field, and should be re-set to predict to following generations.

Growing Degree Day Accumulation and Treatment

After the biofix is set, growing degree day accumulation can begin, using a lower threshold of 10C  and an upper threshold of 35C. This can be done using daily high and low temperatures, or using hourly temperature data using the Pest Prophet app. 50% egg hatch occurs at approximately 39 GDD (C) after biofix date. Larvae emerge at approximately 95 GDD(C) following the biofix date.

Source:

Petitt, F. L., J. C. Allen, and C. S. Barfield. 1991. Degree-day model for vegetable leafminer (Diptera: Agromyzidae) phenology. Environ. Entomol. 20: 1134-1140.