By Blake Jackson
Symptoms of Fusarium head blight (FHB) have started appearing in wheat fields across Pennsylvania. Although multiple Fusarium species can cause this disease, Fusarium graminearum is the most common in the state.
As grain fill progresses, accurately identifying FHB symptoms and assessing its impact is critical to managing yield and grain quality.
Identifying FHB in the Field
FHB shows a variety of symptoms. Infected spikelets may appear bleached while surrounding ones remain green. As the infection advances, stems below the head may turn brown or gray.
A notable sign of the disease is the presence of orange to salmon-pink spore masses, often seen at the base of the head, between spikelets and the rachis, or even on the awns. Severely affected grain is typically shriveled, discolored, and lightweight.
It's important to note that some infected heads may still appear healthy, particularly when the infection occurs later in development these cases still present a risk of mycotoxin contamination.
Estimating Incidence and Severity
Accurate assessment of FHB levels is essential for making decisions about harvest and grain storage. Recent research from The Ohio State University suggests evaluating at least 100 heads per location in a field for a reliable estimate.
Check several spots across the field and assess both the percentage of infected heads (incidence) and the extent of damage on each (severity).
For example, if 51 out of 100 heads show symptoms, the incidence is 51%. An average wheat spike has 12-14 spikelets, so each infected spikelet represents about 7% of the spike’s area.
If more than 25% of heads are affected, consider using high fan speeds during harvest to remove lightweight, infected kernels-often high in vomitoxin.
You may also want to separate scabby grain from cleaner fields. Consult your crop insurance provider about testing procedures if you suspect contamination.
Despite using resistant varieties and fungicides, complete protection against FHB isn't possible, especially under favorable disease conditions.
Photo Credit: gettyimages-ygrek
Categories: Pennsylvania, Crops, Wheat