Wheat growth stages vary across Indiana, but many fields are heading and beginning to flower in areas in central and northern Indiana. These regions are at low to moderate risk for Fusarium head blight (FHB) development for wheat that will flower during the next few days, however intermittent rains and increased temperatures will likely increase the risk for disease development. Producers in areas where wheat is beginning to flower should carefully monitor the risk map over the coming week. If temperature and humidity increase, the risk for disease development could increase in other northern and central counties in the state.
Fungicide applications for FHB suppression 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.
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. 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.
The foliar disease Septoria/Stagonospora leaf blotch (Figure 1) has been observed in fields throughout the state, but is still at relatively low levels in northern Indiana. Symptoms of this disease are now visible on the leaves just below the flag leaf in areas we scouted in southern and central Indiana, and fungicides applied at flowering for FHB suppression will also provide some level of protection from foliar disease on the flag leaf. Producers in northern IN who are considering a foliar fungicide application for Septoria/Stagonospora leaf blotch control through boot stage should keep in mind that applications made prior to flowering will NOT suppress FHB or the associated mycotoxin deoxynivalenol, or DON. If the risk for FHB increases after foliar fungicide applications are made, it may be necessary to make another application at flowering for FHB suppression.
Very low levels of stripe rust (low incidence and severity) were first reported in southern IN last week in Posey county. We have not seen or heard of additional confirmations of stripe rust, but we will continue to monitor fields for this disease.