Department of Plant Pathology, Physiology and Weed Science

Wheat Scab

Location: Head Diseases -> Wheat Scab

Scientific Name: Fusarium graminearum













Description:

Scab is early identified in the field when healthy heads are green. Scab-infested spikelets appear prematurely bleached. Often spikelets in one-third to one-half of the head are affected. In several cases the entire head may be colonized. The bleached spikelets are either sterile or contain shriveled and discolored seed. Close examination of affected spikelets may show superficial pink mycelia at the base of the colonized spikelet. The fungi that cause scab overwinter on infested crop residues such as cornstalks, wheat stubble, and stubble from other grasses. During flowering of the wheat, spores are produced on these scab-infested residues. During moist, warm weather the wind-borne scab spores infect and colonize the spent anther cases (pollen producing sacks) of the flowering wheat and go on to invade the spikelet and developing seed.


The grain harvested from wheat fields heavily infested with scab is of poor quality, low test weight, and often contains mycotoxins (toxins produced by fungi) that make the grain less palatable to livestock and humans. Some of these mycotoxins induce vomiting and muscle spasms in man and non-ruminant animals. Other mycotoxins can cause sexual reproductive dysfunction.



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