Evaluate Wheat Fields for Fusarium Head Blight (Head Scab) Prior to Harvest

Symptoms

Symptoms of Fusarium head blight (head scab) are present in Kentucky wheat fields with varying levels of damage being reported.  Heads often are partially affected, with both healthy green and affected bleached areas being present in the same head (Figure 1).  In some cases, masses of spores that are salmon-pink in color can be observed on affected heads.  Wheat growers may want to evaluate the level of Fusarium head blight in their fields before harvest.  It is easiest to observe this disease before heads completely mature.  Growers with moderate to high levels of Fusarium head blight should consider making adjustments to their combine that would allow low test-weight, scabby kernels to be blown out the back of the combine.  Research conducted at The Ohio State University indicated that adjusting the combine’s fan speed between 1,375 and 1,475 rpms and the shutter opening to 90 mm (3.5 inches) resulted in the lowest discounts that would have been received at the elevator due to low test weight, percent damaged kernels, and level of the mycotoxin deoxynivalenol (DON; vomitoxin) present in the harvested grain (Salgado et al., 2011).

Figure 1. Symptoms of Fusarium head blight on a wheat head (Photo: Carl Bradley, UK)

Figure 2. Obvious Fusarium head blight symptoms on a susceptible wheat variety grown at a UK research trial in 2019 (Photo: Carl Bradley, UK)

Figure 3. Very low incidence of Fusarium head blight symptoms on a moderately-resistant wheat variety grown at a UK research trial in 2019 (Photo: Carl Bradley, UK)

Management

Management of Fusarium head blight begins with growing the most resistant wheat varieties available.  In trials conducted at the University of Kentucky Research & Education Center (UKREC) near Princeton, KY this year, obvious differences in severity of Fusarium head blight can be observed between susceptible and moderately-resistant wheat varieties (Figures 2 and 3).  Information on the most resistant wheat varieties available in Kentucky can be found on the UK Small Grain Variety Testing Program website and on the ScabSmart website

Reference

Salgado, J. D., Wallhead, M., Madden, L. V., and Paul, P. A. 2011. Grain harvesting strategies to minimize grain quality losses due to Fusarium head blight in wheat. Plant Disease 95:1448-1457.

 

Carl A. Bradley, Extension Plant Pathologist

 

 

 

Posted in Grains