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Agronomic Crops Network

Ohio State University Extension


Early-May Wheat Disease Update

Wheat fungicide chart

The wheat crop in Ohio is now at or just past Feekes 8 (flag leaf emergence), the growth stage at which we usually recommend fungicide application for foliar disease control. However, conditions have been fairly hot and dry over the last 7 to 10 days, slowing down the development of early-season diseases such as powdery mildew and Septoria. Septoria tritici leaf spot usually shows up first on the lower leaves as yellowish flecks that later develop into irregularly-shaped, brownish-gray lesions, with dark-brown to black spots in the center. The disease is usually spread from the lower to the upper leaves by rain splash; so, unless it rains and becomes cool (50 to 68oC) over the next week or so, Septoria leaf spot may not become a problem this year.

Cool temperatures and high relative humidity are also required for the development of Powdery Mildew, another early-season disease that so far is at very low levels this season. As it warms up, both Septoria and powdery mildew will become even less of a concern, but continue to monitor your crop over the next several days. Remember, if the variety is susceptible and conditions become favorable, a fungicide can be applied to prevent the diseases from reaching the flag leaf (the upper-most leaf of the plant) before grain-fill. Follow the link for fungicide options and also see the chart below.

Management of Small Grain Diseases Fungicide Efficacy for Control of Wheat Diseases

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.