Disease Forecasting

Note to readers, attached is the complete final report for FNE94-063.

Fungal diseases like black rot and powdery mildew are a chronic problem in vineyards. Over the course of the growing season the incidence of disease varies with the weather, but since growers usually apply fungicides according to an invariant schedule irrespective of the weather, it is likely that much fungicide is applied at other than the optimal times, with diminished effect.

Mr. Mohart used his SARE grant to experiment with an alternative spraying schedule. He installed a system in his vineyard to monitor and electronically record weather data. He used a computer expert system called SPOTTS to examine the weather data, and predict when outbreaks of fungal disease were most likely. He sprayed Nova, a fungicide, on part of his vineyard at those times when SPOTTS indicated this was most opportune, while on the rest of the vineyard he maintained a traditional, calendar-based schedule.

Mr. Mohart ran this experiment for three years in succession, and each time found that the computer-based schedule permitted the elimination of one application of fungicide. In 1996, for instance, his control area received five applications, while the test area received only four, and in no year did he observe a higher incidence of disease in the latter. Each application that he did not have to make represented a saving, according to Mr. Mohart, of $32 to $36 per acre.

• FNE94-063 Final Report