Preparing to Manage Barley Disease

Alyssa Collins, PhD and Paul Esker, PennState Extension

Barley development is progressing,
so remember to protect it from disease.

An overcast and cool spring has kept small grains short in many areas, but that hasn’t stopped crop development. Some barley varieties are heading in the southern parts of PA, and others are not far behind. The environment has been generally unfavorable for the development of many of the fungal diseases we usually deal with at this time of year.

 





 

Nonetheless, now is the critical time to prepare to control Fusarium head blight (a.k.a. head scab). If you intend to protect your barley from scab be prepared to spray a fungicide at 50% heading or shortly thereafter. As many of you know, this is a disease of wheat and barley that can lead to the production of vomitoxin (DON) in grains. Only the most susceptible varieties of barley currently heading are at a medium to high risk of scab infection in Fayette, Somerset, York, and Lancaster Counties at this time.

Once your crop begins heading, there is about a 5-to-6 day window to apply a fungicide. The labels state the last stage of application is mid-flower and there is a 30-day to 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.

At this point in the season, the only way to reduce the scab problem is to spray. But in general, do not rely solely on fungicides, as they will provide at most a 50–60% reduction in scab severity and vomitoxin. Start with selecting resistant varieties, and time sprays properly to achieve greater control.

 





 

A newer fungicide, Miravis Ace, has been labeled for the control of head scab in barley and wheat, and university trials have found it to provide disease suppression similar to existing products, but using a different chemistry. Caramba or Prosaro are our traditional scab products and, along with Miravis Ace, give good control of most leaf and head diseases, in addition to suppressing scab. The Miravis Ace label allows for earlier application than Caramba or Prosaro, but best results are still achieved when application is 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. A fungicide treatment at heading using any of these products will also give you excellent control of most leaf diseases as well.

As our season progresses, keeping an eye on the FHB Risk Assessment Tool will become critical for those farmers who are trying to make the decision to spray small grains. This forecasting site, called "Fusarium Risk Tool", is an online model that helps us predict infection risk levels everywhere in the state. It is undergoing major revisions this year to serve the industry better, so you’ll notice a different look. Stay tuned to Field Crop News for updates on the new functionality of the FHB Risk Assessment Tool.

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