Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu; @Delmarplantdoc
We had a run of wet weather that did spur an increase in the Fusarium Head Blight (FHB) risk in varieties flowering last week. A good portion of wheat in Kent and New Castle counties as well as counties at similar latitudes in Maryland still has not flowered. I expect we will see this wheat flower over the next 5-7 days. Rain is forecast during this period, and this, coupled with moderate temperatures may increase our scab risk for soon to be flowering wheat. After the start of flowering you will want to check back in about 18-21 days to assess fusarium head blight. Start by randomly assessing one spot per 10 acres per field. At this site, do not look at the plants and randomly pick 10 heads. Rate the heads for the percent of FHB. Glume blotch typically gives the glumes a grey appearance, whereas FHB will cause bleaching of florets or sections of the head. The florets will be pinkish.
Let’s use an example. Here is wheat an assessment of a single site may look like
FHB
0, 0, 0, 10, 30, 0, 10, 1, 50, 0
Average = add severities and divide by total heads assessed = 10.5%
Repeat this assessment at one spot per 2-5 acres of field. Fields with values greater than 10 may see some FHB related yield losses and may be more likely to have elevated DON levels at harvest. Fields in this category should be harvested first, and care taken to keep this grain separate from high quality grain from clean fields.