Use fungicide seed treatments to improve wheat health
Using seed treatments for winter wheat can help you manage the disease threat and optimize yield potential for next year’s crop. While there may be a higher initial cost for using clean/certified, treated seed, the cost is almost always exceeded by the benefit in yield.
Several wheat diseases are caused by fungal pathogens that are soilborne and/or seedborne.
- Soilborne pathogens include those that cause root and crown rots and seedling blights, such as Bipolaris, Fusarium, Pythium, and Rhizoctonia.
- Seedborne pathogens are associated with head diseases that affect the grain. These diseases include common bunt (also known as stinking smut, Figure 1), loose smut (Figure 2), Fusarium head blight (Figure 3), black point (Figure 4) and ergot (Figure 5).
Economic Importance of Soil- and Seedborne Diseases
Soil- and seedborne diseases reduce yields as well as grain quality. Grain contaminated by common bunt can be rejected at the elevator, often resulting in total loss. Although loose smut does not affect grain quality, yield losses of up to 40% can result from the disease.
Incidence of ergot in wheat is relatively low; however, in 2011 favorable environmental conditions (cool, wet weather during flowering) resulted in epidemic levels of the disease in several wheat fields in south central and southeast Nebraska. Sclerotia or ergots (compact masses of the ergot fungus) can lower grain quality. In addition, the ergots contain toxic alkaloids that can cause ergotism and death in humans and livestock.
Fusarium head blight can cause significant losses resulting from floret sterility, poor grain fill, and contamination of grain by mycotoxins. If seed contaminated with the Fusararium head blight fungus is sown, seedling emergence can be reduced by up to 80%.
Black point can significantly reduce the bread-making quality of wheat. Heavy contamination of grain with black point can result in discolored flour. This can be a cause for rejection of the grain by millers.
Effect of Drought on Soil- and Seedborne Pathogens
Soil- and seedborne pathogens can survive adverse environmental conditions such as drought and winter temperatures by becoming dormant or forming survival structures. Additionally, seedborne pathogens are protected by the seed and/or the environment in which the seed is stored. When favorable environmental conditions (moisture and ambient temperatures) return, the pathogens become active again. The drought of 2012 will not reduce the risk posed by soil- and seedborne pathogens. Management measures against these pathogens should be taken as they would in a normal year.