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Small Grains Disease and Pest Update for 06/25/21

I attended small grain plot tours at six locations across the southern half of the state. The wheat across the southern half of Minnesota is now far enough along in the grainfill period that wheat stem maggot and latent infections of common root rot/fusarium crown rot can be found. These are the individual heads that ripen prematurely and then turn completely white while the rest of the crop is still green.  The incidence of both was low. Likewise, the scouts and I found loose smut in wheat and barley at low incidence. 

The only other fungal disease I found (much to my surprise) was net blotch in a production field of Pinnacle barley near New Ulm.  We know that Pinnacle is very susceptible to net blotch but nine days ago - when it reached Feekes growth stage 9 and the grower and I had discussed whether to spray a fungicide  - this field was absolutely spotless. 

Cereal aphids number remain highest in the west-central portion of Minnesota and the southern/central portion of the Red River Valley.  Grasshopper numbers are holding steady but reports of spraying against grasshoppers are reaching my desk.

The immediate weather forecast remains void of any substantial precipitation. That means that the drought will worsen and, depending on the amount of available water left in the soil profile, further stress the crop.  Growers have commented to me that even half an inch of precipitation will keep the soil surface noticeable wet for mere hours.

Henceforth, my recommendation remains the same as it was last week: there is little reason to apply a fungicide to suppress FHB and/or control the leaf diseases.  

Meanwhile, I do ask you to continue scout for aphids and grasshoppers as the scouts found that week-over-week incidence of aphids and grasshoppers increased again across all of Minnesota. Apply an insecticide as soon you find one or more aphids on 80% of the individual stems across the field. However, do not apply an insecticide after the crop reaches anthesis nor not apply an insecticide if you expect the field to yield less than the level of crop insurance coverage elected times your APH yield.  


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