Efforts to breed improved, disease-resistant strains of grama grasses have been started at agricultural experiment stations in Kansas and Oklahoma.

MOUNTAIN BROME (Bromus marginatus) and related species are subject to at least 25 diseases. Foliage troubles include several leaf spots, anthracnose, powdery mildew, snow mold, gray leaf spot, tar spot, bacterial chocolate spot, scald, leaf rot, char spot, leaf speckle, brown blotch, brown stripe, rusts, and bacterial blight. Ordinarily the important leaf diseases are scolecotrichum leaf stripe, rhynchosporium scald, and bacterial chocolate spot.

Rescuegrass, Bromus catharticus, is subject to fewer and different diseases, including bacterial leaf streak.

Chocolate leaf spot, or bacterial blight, is caused by a bacterium, Pseudomonas coronafaciens var. atropurpurea. The lesions, circular to elliptical and water-soaked at first, later turn brown and coalesce to form purplish-brown areas on the leaf blade and sheath. Bacterial slime is absent on the surface of the leaf spots. Spots on the panicles are smaller and restricted. In severe attacks the upper nodes may be killed by secondary infections of the organism. In such plants the panicles wither and die, as though injured by frost.

The disease attacks many grasses. It is important on wheatgrasses. We do not know how to control it. The bacteria are believed to overwinter in the lesions on dead grass. Careful burning before spring growth should reduce the disease.

Upper left: Anthracnose (Colletotrichum graminicola) on leaves of Johnsongrass. Upper right: Sweet Sudan (tan spots) and common Sudan (red spots) infected by the leaf blight fungus. Lower left: Net blotch on tall fescue. Lower right: Leaves of Starr (wide) and common (narrower) millet affected with cercospora leaf spot.

BUFFALOGRASS (Buchloe dactyloides) suffers from 11 diseases. One of them is a leaf and glume spot, frequently called false smut and caused by cercospora seminalis.

The fungus forms a compact, olive-green mass held by the spines that enclose the seed spikelets. Fungus mycelium penetrates the seed and replaces it with a mass of spores. False smut occurs sporadically in dry areas, although it is abundant in wet years. The disease is especially troublesome when buffalograss is grown under irrigation for seed.

Because it reduces yields of seed, false smut has caused a shortage of seed of improved strains. Regrassing programs in which buffalograss is the chief grass used have therefore been retarded. No strains highly resistant to false smut are available, but we hope plant breeding work at several State and Federal stations in the southern Great Plains will develop some.

WILD-RYE GRASSES (species of Elymus) are heir to some 75 ills. Common leaf diseases are rusts, leaf smuts, powdery mildew, ascochyta leaf spot, fusarium head blight, phyllachora tar spot, scolecotrichum brown stripe, selenophoma stem speckle, bacterial chocolate spot, septogloeum tar spot, septoria leaf spots, stagonospora purple brown blotch, and epichloe choke or cattail disease.

Cattail disease is named for the whitish body of the fungus, Epichloe tvphina, which surrounds grass stems with a tight sleeve like the heads of the cattail plant. It occurs sparingly on a large number of grasses in North America. It is sometimes abundant on blue-grasses in the North Central States. Patches of wild-rye sometimes are heavily infested in Northern and Central States. The disease is apparently restricted to sections that have cool seasons and mild winters or in places where the plants are protected by snow. It may severely damage seed-producing stands. It is much more important in Europe than in North America. It is relatively common on prairie junegrass, Koeleria cristata, over our prairies and on blue-grasses and wheatgrasses in limited regions.

The fungus produces a perennial mycelium in the crown buds. In summer the mycelium forms a white felt over the surface of late tillers and often covers the seed heads as they emerge from the sheath. The fungus body usually encloses all the seed spike or else parts of the panicle in this type of inflorescence. In late-flowering grasses, such as timothy, tillers may be trapped and delayed or destroyed. As the fungus increases in thickness, it becomes yellow, then orange, and forms the collar around the leaf sheath or stem.

The disease is transmitted in seeds of red fescue, Festuca rubra, and possibly in other grasses in which diseased plants produce seed.

The disease was introduced into Pennsylvania in red fescue seeds from Hungary. Growers of grass seed should look for cattail disease in grass-seed crops. With all the present traffic of grass seeds from domestic and foreign sources, this and other diseases could be introduced and become new problems. No adequate control for cattail disease has been developed although roguing is partly successful.

A fusarium head blight has caused serious seed losses in Russian wild-rye, Elymus junceus, in New Mexico. Bacterial leaf spots are common on the wild-rye grasses in the northern Great Plains. Powdery mildew is fairly serious on Russian wild-rye in North Dakota.

CANARYGRASSES (Phalaris species) have nearly 30 diseases, but most of the leaf diseases are not serious.

Reed canarygrass, Phalaris arundinacea, is adapted throughout the Western States, but it grows mainly in locations with abundant moisture, such as swampy spots, lake shores, and stream banks. Even so, it generally is free of injurious leaf diseases.

A fungus, Stagonosporafohicola, causes a tawny spot on leaves. The lesions, which may be brown, wine-colored, tawny, or buff, sometimes cover the entire leaf blade. The disease has been prevalent in late summer at Mandan, N. Dak., in years of abundant precipitation. The trouble was found in plots and native stands in the Missouri River bottom lands and is common in marshes in Minnesota and South Dakota.

Distinct differences in susceptibility of reed canarygrass plants have been noted in upland plots at the Northern Great Plains Field Station an indication that varieties resistant to the disease are possible.

FIFTY RECOGNIZED PARASITES occur on the western bluegrasses mutton bluegrass (Poa fendleriana), alkali bluegrass (P. juncifolia), Nevada bluegrass (P. nevadensis), big bluegrass (P. ampla), and related species. Their more important leaf disorders are rusts, scolecotrichum leaf stripe, selenophoma leaf spot, septoria leaf spot, and powdery mildew. Control must be sought for by breeding disease-resistant strains of bluegrass.