The Economic Value of Weather Forecasts in Spraying for the Oriental Fruit Moth (OFM) Affecting Apple Orchards in South-Central Pennsylvania

This project aims to compare methods used to determine when to spray for destructive pests, for example, the OFM. Assuming that temperature directly affects the stage transition in the life cycle of agricultural pests, farmers can determine when to start spraying for pests using growing degree days (GDD) and more complex egg hatch models. An example from Hull and Krawcyzk (2001) for the OFM applies treatment at 150-170, 1125-1150, and 2250-2280 GDD after the first sustained moth captures.

The economic interest for the farmer lies in not spraying too early or too late. If they spray too early, then they might need to spray again later. This will go to increase the cost allocated for pesticides. On the other hand, if they spray too late, some of the pests might have already impacted the crop. This will reduce the quality and quantity of the final crop product, and the farmer will have to sell the produce for cheaper and have a decreased harvest available for sale.

Using Bayesian inference, straightforward utilization of a GDD model such as the one above is updated to probabilities using information from an egg hatch model with precipitation. The respective probabilities are used in decision and economic models created with input from area growers to calculate the dollar value of using the egg hatch model.

Hull & Krawczyk. 2001. Penn State University, Penn Fruit News Vol 81(2):23-36