Disease management in oats

Red Leaf

Cause: Virus (Barley yellow dwarf virus). Spread by aphids.

Symptoms: First, yellow blotches occur near tip of leaf. Next, areas enlarge and leaves become yellow-red, scarlet, orange or reddish-brown. This pattern progresses from tip of leaf to its base. Dwarfing occurs with early infections and death may result. Infected leaves tend to curl and twist. Patches in field may be affected.

Host Range: Barley, oats, rye, wheat, bermuda grass, sudangrass, bluegrass, and other grasses.

Control: Avoid planting prior to November 15 if crop is intended for grain. Earlier planted oats for grazing are more likely to have this disease as aphid populations tend to be higher in dry, late summer-fall periods.

Crown Rust (Leaf Rust)

Cause: Fungus ( Puccinia coronata )

Symptoms: Similar to leaf rust of wheat: 1 to 2 mm round or oblong raised, orange-red pustules (uredia) in leaf blades, leaf sheaths and sometimes in glumes and awns. They are found beginning in late winter to early spring up though the heading stage. Black pustules (telia) covered by leaf surface occur near heading time.

Host Range: Oats and certain wild grasses.

Control: Resistant varieties, if available. Florida 502, Chapman, Secretariat, and Harrison have some resistance. Early maturing varieties may escape some disease.

Leaf Blotch and Black Stem

Cause: Fungus [Helminthosporium avenae (Bipolaris avenae )]

Symptoms: a) Leaf blotches, � to 1 inch in length, blue-black to orange-brown spots which evolve from smaller brownish water-soaked spots. A severe epidemic gives plants a scorched appearance. These symptoms occur most commonly in the lower leaves during the latter part of the growing season (early April to harvest). b) Black stem, symptoms are characterized by pinkish-brown blotches in the leaf sheath. Large black necrotic areas occur in the stem where the sheath encircles the stem. Thus the black stem symptoms first appear near nodal areas. White mycelium occur in the stem cavity near the black stem area. Infections are followed by the breaking of the stem at the third or fourth internode.

Host Range: Oats.

Control: Seed treatment. Resistant varieties, if available. Crop rotation.

Loose Smut

Cause: Fungus ( Ustilago avenae )

Symptoms: Grain in panicle is replaced with a black powdery mass of spores within a delicate white-grey membrane. Smutted plants are shorter than normal plants.

Host Range: Oats.

Control: Apparently most varieties in the southeast are resistant. Epidemics have occurred with certain varieties developed in Texas. Use seed treatment with Vitavax.

Covered Smut

Cause: Fungus ( Ustilago kolleri )

Symptoms: Similar to loose smut: Grain panicle is replaced with a black powdery mass of spores within a delicate white-grey membrane. Smutted plants are shorter than normal plants.

Host Range: Oats.

Control: Apparently most varieties in the southeast are resistant. Use a seed treatment with Vitavax.

Pythium Root Rot

Cause: Fungus ( Pythium spp.)

Symptoms: Preemergence damping off. Postemergence damping off. Plants that emerge successfully are stunted, and rot at base of stem. Root tips appear water-soaked. Occurs most frequently during the fall. Lower leaves become yellow. Laboratory diagnosis should be used for this disease. Can be confused with or occur with nitrogen deficiency.

Host Range: Wheat, rye, barley, oats, ryegrass, peanuts, corn, sorghum, soybeans, tobacco, rice, bermudagrass, vegetables and many other plant species.

Control: Seed treatment with Apron aids in control up to emergence. Avoid planting before the first of October with wheat, barley and rye and first of September with oats. Cool temperatures will reduce the activity of this fungus. Serious losses may require replanting.

Seedling Blight

Cause: Fungi ( Pythium spp., Rhizoctonia spp., Helminthosporium spp., Fusarium spp.)

Symptoms: Pre or postemergence stunting, distortion or death of seedling. Rotting of young roots and culms present. Water-soaking of roots, reddish or brown lesions on young plant parts. May mimic nitrogen deficiency (yellowing of lower leaves).

Host Range: Wheat, rye, barley, oats, corn and many crop and weed species.

Control: Avoid deep planting of seed. Crop rotation with non-cereal crops. Bury stubble. See section. Avoid planting before the first of October. Cool soil temperatures reduce Pythium seedling blight in Florida.

Common Root Rot

Cause: Several fungi ( Helminthosporium spp., Bipolaris spp., Fusarium spp., Rhizoctonia spp.)

Symptoms: Stunted plants which may be accompanied by purpled leaves. Purplish coloration of leaves may also occur due to cold damage or some other stress factor. It may occur in patches or where small grains have been grown on same land for several years, it may be more general in field. Tan-brown lesions on roots, and basal leaf sheaths. Inner tissues of crown may be brown. May follow drought, nematode or insect damage.

Host Range: Wheat, barley, rye, oats, corn and many crop and weed species.

Control: Crop rotation with non-cereal crops. Bury stubble. Use seed treatment.