By Alyssa Collins and Paul D. Esker
Many barley varieties are heading in the southern parts of PA, and others are not far behind. Disease pressure in our region has been low up to now with cooler temperatures, low humidity, and high winds, but these conditions are changing rapidly with lingering rain showers coupled with warmer temperatures. We should expect to see increased levels of common foliar diseases like powdery mildew and leaf blotches, and a greater threat of Fusarium head blight (a.k.a. head scab). As many of you know, this is a disease of wheat and barley that can lead to the production of vomitoxin (DON) in grains.
If you intend to protect your barley from scab using a foliar fungicide, it is important to be prepared to spray at 50% heading or shortly thereafter. Once your crop begins heading, there is approximately a 5-to-6 day window to apply a fungicide. Current labels state that the last stage of application is mid-flower and there is a 30-day harvest restriction. Do not use any of the strobilurins (Quadris, Headline), or strobilurin/triazole (Twinline, Quilt, Stratego) combination products at flowering or later. There is evidence that they may cause an increase in mycotoxin production.
Caramba, Miravis Ace, and Prosaro all provide very good scab suppression. The Miravis Ace label allows for earlier application than Caramba or Prosaro, but best results are still achieved when application is timed at heading in barley. Spray nozzles should be angled at 30° down from horizontal, toward the grain heads, using forward- and backward mounted nozzles or nozzles with a two directional spray, such as Twinjet nozzles. Additionally, a fungicide treatment at heading using any of these products will also give you excellent control of most leaf diseases as well.