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Small Grains Disease Update

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While a 11-plus inch deluge made for national headlines in Duluth, much smaller but timely rains have helped stave a worsening of the drought stress in parts of northwest Minnesota. Drought stress is pretty evident is many fields as evidenced by differences in plant height across the field. On June 19, the majority of northwest Minnesota is still rated to be in a moderate drought while a large portion of west central Minnesota is still considered abnormally dry. Timely rains will be needed to allow grainfill not to be impacted by drought as the crop needs nearly a 0.25 inch of water daily at the beginning of grainfill.

Most spring wheat is passed anthesis and in to the grainfill period. Reports indicate that many of you applied a fungicide to protect against foliar diseases and protect against Fusarium Head Blight. The University of Minnesota scouts continue to report that BYDV, stripe rust, tan spot and Septoria spot blotch are the most commonly found diseases. Severe BYDV is being reported from the west and central areas of the state, with yellowing and sever stunting in many cases due to the early season infection this year. Cool wet conditions have seen the increase of Septoria spot blotch in the north west of the state becoming prevalent on the lower canopy. With low humidity and little rain forecast the disease is likely to be slow moving into the upper canopy. Stripe rust is present throughout the state to varying degrees. Faller being one of the most affected varieties with infection reaching mid to upper canopy in some fields, but some stripe rust has also been found on Vantage.

The risk of FHB as predicted by the disease forecast models indicated relatively low risk for most of Minnesota for much of the past 7 days. The exception being much of Kittson county in the extreme northwest corner of the State. The weather outlook for the next 3 to 5 days suggests that the risk is likely waning.

A few calls have come in about powdery mildew having been detected in the lower canopy despite an application of a fungicide at anthesis. Understand that most if not all of the spray volume was deposited on the head and the upper canopy. Consequently it will not give good control of powdery mildew despite the fact that tebuconazole and Prosaro give good control of powdery mildew. The warmer daytime temperatures should really slow down these infections. Powdery mildew will turn from gray white to a tan color when it gets too hot for it to flourish.

The first case of crown rust has been reported on oats in Renville County.

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