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  • Writer's pictureWendell Koehn

Aphids found: prepare for a management application

Updated: May 18, 2019



Wheat Stage: Feekes 8, the flag leaf, the last leaf is out on most fields checked in our area. Even wheat planted late has largely narrowed the gap in maturity. The next stage Feekes 9 will be when the flag leaf is completely emerged. This is defined when the ligule at the leaf collar is visible. Keep this in mind through this report. The persons on these fields were Wendell Koehn & Alex Long, our Beck's agronomist for Missouri.


Insects Some aphids are being found. Although, the thresholds are barely being met; I believe an insecticide application will be necessary as the cost to risk ratio of this management practice is heavily weighted in favor of profitablility.

Disease No rust or powdery mildew was found in the several fields we walked in. However; with the rain forecasted causing an increase in humidity will increase the likelihood of disease pressure. Especially, keep a lookout for striped rust. Depending on the your goals from here on, consider a good strobi fungicide at Feekes 9 (see above for staging) like Quilt, Delaro, Twinline, or Stratego YLD. Note: at this point it would be a good time to spray the insecticide in this fungicide application to cover the aphids, too. As you know the aphids will vector the Barley Yellow Dwarf Virus, which will be present later on.



Looking ahead to flower: When the half of the field is at 10.5.1 will be a time when the plant is at risk for head scab. This is probably the most critical application in wheat management from this time forward. In years of high humidity with little drying taking place this disease can wipe an astronomical amount of yield and reduce grain quality severely.


I am including below pictures of the difference between dry fertilizer vs streaming liquid N onto wheat. The top is the dry spread and the bottom is the liquid. Note that if Nitrogen is not at critical levels in the fall, this may not be so noticeable. Wheat fields are like High Definition screens with many pixels per square foot. It is possible that the spinner was not calibrated properly. Certainly, a wheat field will be the crop that reveals this error with HD quality. Streaming liquid nitrogen on can be a more even application for this crop.



As always, if you need anything, please feel free to reach out to 417-684-5301 or wendell@topagservices.com


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