Loose Smut of Wheat
Causal Agent: The fungus Ustilago triticiHosts: Wheat.
Symptoms: The name "loose smut" is very descriptive since fungus spores, which make up each black head, adhere loosely and are knocked off easily by wind or rain leaving only the naked rachis. Loose smut is recognizable as soon as the affected heads emerge from the boot. Usually the entire head will be diseased. Infected seed does not show any outward symptoms, and seed germination is not affected.
Control: Unlike many other seed-borne pathogens, loose smut is internal, not surface-borne; therefore contact seed protectant fungicides are infeffective. To be effective, the control method must kill the fungus inside the seed without injuring the germ. The only seed protectant materials effective against loose smut are those with systemic activity. Certified seed should be relatively free of loose smut infections. Please contact your local county extension office for current information.
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