Seed Rot and Seedling Blight (fungi – Pythium spp., Fusarium nivale, Rhizoctonia sp., Helminthosporium sp., Fusarium spp.): Germinating seed of all grass varieties may be attacked and rotted. Small sprouts may be killed before or soon after they come through the soil by the same fungi that cause seed rot. Where the problem has been serious, treat seed. (See seed treatment.) Avoid planting too deeply.
Root Rot and Crown Rot(fungi): Most fungi that cause seed rot and seedling blight are involved. Yellow to brown discolorations appear on affected root and crown tissue. The lower leaves may become yellow and die, and finally, nearly all infected plants either die or are retarded severely. Weakened plants are killed by short periods of drought or winter injury. Control is the same as for seed rod and seedling blight. Use good management practices.
Powdery Mildew (fungus – Erysiphe graminis): White to gray mold growth develops either in blotches or uniformly over the entire leaf surface. Dried out areas of dead leaf tissue may develop and kill the whole leaf. Severely infected plants may become weakened and die. In pastures where the grass is either closely grazed or cut, the symptoms are not as conspicuous. On ranges and pastures, control methods are impractical. For grass nurseries and grass crops for seed production, see Chemical Control section. Grasses most severely affected by powdery mildew are wheat grasses (Agropyron), bent-grass (Agrostis), fescue (Festuca), and bluegrass (Poa). Common rescuegrass is very susceptible. Other strains of rescuegrass seem more resistant. The disease is apt to be more severe during cool weather with frequent showers or following application of irrigation water.
Ergot (fungus – Clavicepsspp.): Dark brown to nearly black, spurlike bodies (sclerotia) extend beyond the floral bracts in diseased florets. One to many ergot bodies may develop in a single head. When grass matures, most of the sclerotia drop to the ground. They be harvested with hay or seed or consumed by grazing livestock. Ergot in Dallisgrass is prevalent in Southeast Texas. Occasionally, it can be found on Bahiagrass. The disease affects production of grasses very little, but it does have serious consequences on livestock that feed on diseased grass. When ergot is consumed in quantities too small to manifest pronounced symptoms of ergotism, it affects the general health and vigor of the animals. When ergot is consumed in considerably larger quantities over a long period, ergot results in either spasmodic or gangrenous ergotism. In the latter phase of the disease, hoofs, tips of ears, and tips of tail may slough, teeth may drop out, and hair may shed excessively prior to death. There is no effective control on host plants. The following will help to avoid losses of livestock due to ergotism: Employ a crop rotation where none of the host plants follow each other. Do not plant ergot-infested seed. When ergot appears in pastures, either clip the heads or wait until the grass matures and the sclerotia have fallen to the ground before using it for grazing purposes. Mowing borders and fence rows before heading will help eliminate secondary infestation. The disease is sometimes worse in these areas. Do not harvest ergotized crops for hay. Removal of sclerotia from ergotized cereal or grain prior to feeding it, is essential to avoid the ergot disease of livestock. To make ergotized grains safe for feeding, the sclerotia should be removed by the brine sedimentation process. By this method, the ergotized grain should be placed in a vat of salt solution (4 pounds in 25 gallons of water). When the grain is stirred, the sclerotia rise to the surface and can be skimmed off. Destroy screenings and skimmings. Grain treated by this method should be dried before storing.
Leaf Rust (fungus – Pucciniaspp.): See leaf rust of oats and wheat for description. Many different leaf rusts damage grasses.
Brown Leaf Blight (fungus – Colletotrichum graminis): Apt to occur in Southeast Texas during August on coastal Bermudagrass. Grayish brown to dark brown streaks occur on leaf blades. No chemical control is recommended.