Michigan potato late blight forecast – July 11, 2018

No late blight reported. Risk remains moderate throughout Michigan growing regions.

July 11, 2018 - Authors: Jaime Willbur, Lee Duynslager

Michigan late blight forecast
Figure 1. July 11, 2018 – Michigan late blight forecast based on accumulation of disease severity values (DSVs) since early May emergence. Yellow pins indicate medium risk areas.

The Michigan Late Blight Forecast Tool is currently calculating 2018 risk predictions. No potato late blight has been reported this season in Michigan. Late blight risk remains at moderate levels in most areas (Fig. 1).

Late blight is caused by Phytophthora infestans, which favors 60-80°F temperatures, high humidity, and frequent rainfall. This online forecasting tool calculates disease severity values (DSVs) based on the duration of temperature and relative humidity conditions that are favorable for disease development. Accumulated DSVs (based on early May emergence) are used to determine the local late blight risk level, indicated by the color of the map marker pins:

Low risk
(Green)

Medium risk
(Yellow)

High risk
(Orange)

Late blight detected within 2-5 miles
(Purple/Pink)

Late blight detected within 1 mile
(Red)

This tool was developed by Baker et al. 2002 and weather data used in this model is provided by the Michigan State University Enviroweather. A customizable tool for early to late emergence scenarios is currently in development.

Please visit the MSU Potato Disease website for more information. Answers to frequently asked questions about this forecast tool are available.

Tags: late blight forecast, msu extension, potato late blight


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