Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

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Maize boil smut (046)

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Photo 1. Seeds of the maize ear transformed into black spore-producing structures of the boil smut fungus, Ustilago zeae.

Photo 2. A few of the seeds have been taken over by the smut fungus, Ustilago zeae, and transformed into black spore containing galls.

Photo 3. The one-time seeds, turned into galls of the fungus, Ustilago maidis, are starting to split and liberate black spores.

Photo 4. Outgrowths from the petiole caused by boil smut, Ustilago maydis.

Summary

• Worldwide distribution. On maize and sweet corn. A minor disease.
• Spores from soil infect seedlings, grow inside and distort the ears, turning seeds into galls with millions of black spores. Smaller galls on leaves.
• Spread long distances is by spores on wind and seed, but also on people, animals, fodder, and machinery.
• Cultural control: do not replant on land where disease has occurred (spores stay alive for many years in soil); do not injure plants during cultivation; remove plants with signs of disease before galls burst; do not over fertilise plants; resistant varieties.
• Chemical control: treat seed with carboxin or thiram.

Common Name

Boil smut, common smut of maize

Scientific Name

Ustilago zeae; previously known as Ustilago maydis

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