Menu

Assess for Scab in Winter Wheat

A number of winter wheat fields in central South Dakota were scouted last week. Fusarium head blight (scab) severity was at low to moderate levels in several fields. Very few fields had severe scab. The level of scab in a wheat field depends on whether flowering coincides with rainfall, the susceptibility of the cultivar planted, and whether a fungicide is applied at flowering. Winter wheat is at ripening in most fields and this is when scab symptoms are most obvious. Once wheat starts to senesce and dry up, it may be difficult to differentiate between scab infected and non-infected wheat heads.

It is important to assess the level of scab in the field in order to determine the best approach to use when harvesting affected fields. It is also important to differentiate between bleached heads due to scab or due to other causes like insect damage or crown and root rots. For scab infected heads, look for bleached spikelets or entire heads with the peduncle still green. Occasionally, infected spikelets may have a pink-orange mass of spores at the base of the spikelet. For insect damaged plants or plants infected with root and crown rot pathogens, the entire plant may be killed and/or the peduncle is also bleached.

In addition to causing direct yield losses from shriveled scabby seed, the scab fungus also produces mycotoxins (mainly deoxynevalenol [DON]). Depending on the level of DON in grain, this can lead to dockage or even rejection of the grain at the elevator. The federal guidelines for acceptable DON levels in grain depend on the final use of the grain (human or animal consumption) and range from 1.0 ppm to 10.0 ppm.

Approaches for reducing scabby grain while harvesting infected fields include:

  • Adjusting the combine fan speed to blow out scab infected kernels. Scab infected kernels are lighter than healthy kernels.
  • Harvesting fields with high scab last to avoid contaminating grain from fields with less scab.
  • Extra cleaning may be required if harvested grain is still scabby.
  • Blending scabby grain with less infected grain to lower DON concentration.

Source: Emmanuel Byamukama, South Dakota State University 

Recent News

For Safety’s Sake, Don’t Take Drying Shortcuts with Stored Corn
10/29/2020

Wet weather conditions are causing concerns with the 2020 corn crop going into storage. Proper management of stored grain will be the key to eliminating risks to human health and safety later in the season. Grain that goes into the bin with higher moisture content presents a host of possible issues. It can freeze or […]

Planting Fall Cover Crops
10/29/2020

We are now approaching the time of year to think about planting fall cover crops. Cover crops can serve many purposes, ranging from erosion control to nutrient sequestration. Depending on the type and species of cover crop, benefits range from providing a Nitrogen source, scavenging nutrients to decrease leaching potential, acting as a soil builder, […]

Revised 2021 Crop Budgets Lead to Higher 2021 Return Projections
10/29/2020

The 2021 Crop Budgets have been revised from the original August release. Corn and soybean prices have been increased in revised budgets, leading to higher corn and soybean return projections for 2021. In most years, soybeans have been more profitable than corn since 2012. In 2021, soybeans again are projected to be more profitable than […]

Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now