Source: Kiersten Wise, Purdue University
Wheat in southern Indiana is heading out and beginning to flower. The recent rainy weather may have caused concern about development of Fusarium head blight, or scab, but the majority of the state is still at low to medium risk for Fusarium head blight according to the wheat scab risk model that was discussed in last week's Pest and Crop article. This risk assessment tool can be accessed here.
There is a slight chance of rain later in the week in southern Indiana, followed by cool, sunny weather. The periods of sunny and dry weather after rainfall are not favorable for infection by the fungus that causes Fusarium head blight. This fungus, Fusarium graminearium, infects wheat during flowering, beginning at Feekes 10.5.1, and prefers rainy, warm and humid weather conditions for infection and disease development.
Producers in areas of medium risk that are wary of model predictions and have Fusarium head blight-susceptible varieties planted may choose to apply a fungicide. Fungicide applications need to be made at Feekes 10.5.1, or early flowering. There are several fungicides available for Fusarium head blight control, and these are listed in the foliar fungicide efficacy table developed by the North Central Regional Committee on Management of Small Grain Diseases or NCERA-184 committee: here.
Caramba, Prosaro and Proline were given a rating of "good" based on a designation system from the Regional Wheat Disease Committee. Products containing only tebuconazole (Folicur, others) were rated as fair, and propiconazole alone (Tilt, others) was rated as poor for management of Fusarium head blight. Remember, fungicides that have a strobilurin mode of action are not labeled for Fusarium head blight suppression. Be sure to follow label restrictions on how many days must pass between fungicide application and harvest.
Low levels of foliar diseases such as Septoria/Stagonospora leaf blotch have been observed in some fields, but overall, foliar disease levels are low. We will need to continue to monitor the level of risk for Fusarium head blight development in wheat in central and northern Indiana as the crop approaches heading in these areas.