Bacterial leaf streak (BLS) was found in several winter wheat fields scouted this week. This continues to be the main disease currently observed in winter wheat, whether a fungicide was utilized.
With the recent frequent rains for some areas and rain in the forecast, the risk for Fusarium head blight (FHB) or scab has changed. Areas in the south central and east now have a moderate to high risk for scab.
We have started to received reports of true armyworm caterpillars showing up in South Dakota wheat fields. So far, the reports have originated from winter wheat fields in Central South Dakota.
A few wheat fields scouted last week were found with white (bleached heads). Several factors can lead to white heads in a wheat field. The most common cause of white heads is wheat stem maggot feeding.
Most of the winter wheat in the state is at flowering or will soon be flowering. A fungicide application is usually done at this wheat growth stage to control Fusarium head blight (FHB) or scab.
Wheat stem maggot adult activity has been observed in winter wheat fields in South Dakota. Researchers at SDSU Extension are working collaboratively with researchers from North Dakota and Nebraska to determine peak wheat stem maggot adult flights.
Winter wheat fields scouted this week in Brookings, Beadle, Hand, Hughes, Lyman and Tripp Counties show varying growth stages from jointing to flag leaf. At flag leaf growth stage, a fungicide may be applied to protect the flag leaf from fungal diseases because the flag leaf is the largest contributor to grain yield.
Many wheat producers in South Dakota have adopted more intensive management practices in the last few years, including an early season application of fungicide and, in some cases, insecticide.
The prolonged winter conditions and rainy cool spring have resulted in delayed spring wheat planting and as a result delayed plant progress. According to the May 13 USDA-NASS Crop Progress Report, only 28% of spring wheat has emerged compared to 81% during the same time last year and the 5-year average of 58%.
Winter wheat growers will soon be applying herbicides to manage weeds in their wheat fields. This is usually also the time when a fungicide may be tank-mixed with herbicide to save on the application cost.