There is a considerable amount of Fusarium head blight, or FHB, showing up in many wheat fields in the central and northeastern parts of Kentucky. With some exceptions, though, west and southern Kentucky are in pretty good shape overall.
I suspect many wheat fields east of I-65, especially in the more northern areas, were flowering during this period (week of June 10), which is about a week later than when most wheat fields flowered in the western half of the state. Flowering is the time when FHB takes hold in a crop if weather conditions are favorable. FHB Symptoms begin to show up in force about 3 weeks following infection.
About 40 percent to 45 percent control of FHB is about all one can expect from a FHB fungicide when the FHB risk is high and the variety is susceptible. In fact, it is common to have 80-90 percent incidence of diseased heads in a FHB- susceptible variety when the risk is high and a fungicide IS NOT deployed. Thus, 50 percent to 60 percent incidence may actually represent reasonable disease control.
Aside from the obvious yield and grain quality problems associated with FHB, the mycotoxin, deoxynivalenol, or DON, is most certainly going to be a factor in grain, silage, hay or straw harvested from fields with significant levels of FHB. DON affects both marketability and, potentially, end use. For example, grain destined for human consumption cannot have greater than 2 parts per million DON. Grain with greater than 2 ppm will be docked at the point of sale. Very high levels may be a cause for rejection at the elevator. For grain, silage, hay, or straw destined for animal feed/bedding, the allowable levels of DON are greater than 2 ppm, but maximum allowable levels vary according to the animal species.
High DON levels are most certainly going to be encountered in grain and miscellaneous harvested spike tissues are most certainly going to be encountered. For fields harvested for grain, turning up the air on the combine and blowing light-weight “scabby” kernels out the back of the combine has been shown to limit DON in harvested grain.
Fields destined for silage and hay should be harvested as soon as possible since DON levels will continue to increase while the crop is still in the field. Keeping track of grain from specific fields may be a good idea since it is probable that DON levels associated with various fields on the same farm will vary from field to field, depending on when the crop flowered and the weather conditions at flowering, among other factors.
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