Fusarium head blight or scab disease of wheat has been a minor problem in Arkansas since 1991 when scab contributed to the record low state average yield of 22 bushels / acre. Given that there are more than one million acres of corn and sorghum in Arkansas this year, a significant portion this fall’s wheat is likely to be planted after these crops. Wheat after corn or sorghum is at higher risk for scab because the same fungus that causes wheat scab also causes stalk and grain rots of corn and sorghum, and the fungus survives on the crop debris left on the soil surface. In the spring under warm, wet conditions, the fungus can produce billions of airborne spores on one piece of corn or sorghum stalk. If these spores are produced when wheat is flowering, a scab epidemic is likely. The spores can be blown for several miles, so one field with corn or sorghum debris can provide inoculum for a lot of downwind wheat fields. Many wheat fields in 2014 are likely to be downwind from fields with corn or sorghum debris.
Given the potential increased risk of scab, wheat growers should avoid susceptible varieties and stagger planting dates or plant varieties with different maturities to avoid having all fields flowering at the same time. No varieties are completely resistant, but there is enough resistance among contemporary cultivars to make a significant difference in yield, test weight, and mycotoxin levels if conditions are favorable for scab. For more information, see the ScabSmart brochure at the link below.
The following scab ratings for contemporary wheat varieties are based on one or more years of testing in inoculated and misted scab nurseries in Arkansas.
Moderately resistant: Armor Rampage, Armor Ricochet, Dixie Kelsey, Dixie McAlister, Syngenta Oakes, and VA Jamestown.
Moderately susceptible: Croplan Genetics 8302, Delta Grow 7500, Delta Grow 7900, Pioneer brand 26R10, Progeny 308, Syngenta Beretta, Terral TV8861, USG 3120, and USG 3201.
Susceptible: AGS 2056, AGS 2060, Pioneer brand 26R15, Pioneer brand 26R20, Pioneer brand 26R22, Progeny 185, Progeny 870, Syngenta Arcadia, Syngenta Coker 9553, Syngenta Harrison, and Terral TV8848.
Very susceptible: Terral LA841.