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Smut

Causal organism: Fungus
Important species:

  • False smut on rice (Ustilaginoidea virens, Entyloma oryzae)
  • Sorghum smut, Broom-corn smut (Sporisorium sorghi)
  • Corn smut, Common smut of corn (Ustilago zeae, U. maydis)
  • Host plants

    Corn, rice, sorghum, wheat, sugarcane, and other grasses

    Affected plant stages

    All growth stages

    Affected plant parts

    Grains or kernels, but it will also infect all above ground plant parts

    Symptoms

    False smut on rice

    Infected grain has greenish smut balls with a velvety appearance. The smut ball appears small at first and grows gradually up to the size of 1 cm. It is seen in between the hulls and encloses the floral parts. As the fungi growth intensifies, the smut ball bursts and becomes orange then later yellowish-green or greenish-black in color. Infection usually occurs during the reproductive and ripening stages, infecting a few grains in the panicle and leaving the rest healthy.

    Sorghum smut, Broom-corn smut

    Infected grain is covered with a whitish to gray or brown, or gray and brown striped smut spores that appear like cone-shaped galls or elongated sorghum seeds. As the disease progresses, the galls erupt and may infest other kernels. Severe head infection during the reproductive and ripening stages usually result in economic losses.

    Corn smut, Common smut of corn

    An infected kernel is enclosed with spongy, white-silvery or greenish-white coating and as the disease intensifies, the coat bursts and a brown or black, powdery mass of spores is exposed. The tassel and corn ear infection is the most noticeable but the fungus may infect any aboveground parts at all growth stages. An infected corn ear is enclosed partially or wholly by the smut gall on the outer corn husk.

    Conditions that favor development

    1. Diseased seeds.
    2. Warm rainy days with high humidity.
    3. Insect pests.

    Prevention and control

    1. Use of diseased-free seeds that are selected from healthy mother plants.
    2. Control insect pests.
    3. Split nitrogen application.
    4. Removal and proper disposal of infected plant debris.
    5. Avoid field activities when the plants are wet.



    External links


    References


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