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Commonly Asked Fusarium Head Blight (FHB) Questions (07/09/20)

During the last week, I have received questions pertaining to Fusarium head blight and would like to summarize some of the most commonly asked questions.

During the last week, I have received questions pertaining to Fusarium head blight and would like to summarize some of the most commonly asked questions.

Question: I have been dry all year and received my first rain since May. What is my scab risk?

Answer: The Fusarium pathogen needs to be “activated” with prolonged periods of moisture before it releases spores from inoculum sources (ie: corn residue). Therefore, a rain event does not automatically increase scab risk in a field. It is important to monitor environmental conditions prior to and throughout the heading and flowering growth stages to assess scab risk.

Question: What is the best time to apply a fungicide in barley?

Answer: Research conducted at NDSU suggests the best time to apply a fungicide for barley is at full-head and up to seven days after full-head has occurred (Figure 1). When a fungicide is applied shortly after the boot stage when awns first become visible, fungicide coverage becomes an issue. The fungicides used for FHB are not fully systemic and will protect plant tissue that has been covered with a fungicide. When applied too early, the flag leaf sheath may act as a barrier to getting good coverage on a barley head.

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Question: Do both ground and aerial applications work for FHB?

Answer: Yes. Both ground and aerial applications work for management of FHB. For ground applications, water volumes should be between 10-20 gallons per acre. For aerial applications, it is recommended to have 4-5 gallons per acre.

Question: Will a FHB fungicide application help protect the flag leaf?

Answer: The fungicides commonly used for FHB will provide suppression of fungal leaf diseases. However, they will not eradicate or cure fungal lesions that have already appeared on the flag leaf.

Andrew Friskop

Extension Plant Pathology, Cereal Crops

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