Rhizoctonia solani, one of the causes of eyespot, can produce other symptoms. In closely planted turf its cobwebby mycelium spreads radially, rotting the leaves and forming brown patch areas. We sometimes find brown patch in pastures. Occasionally it also causes some stunting by attacking the roots themselves; then it is often associated with common root rot fungi, and the symptoms are blended in one complex. R. solani has at least four races that can be distinguished more or less by their capacity to attack a number of grass, cereal, and leguminous and vegetable crops. One race in western Oregon and Washington is especially virulent on the basal parts of the stems of cereals and some grasses but is scarcely parasitic on legumes. Other races in the Midwest and eastern seaboard are actively parasitic on both grasses and legumes.

Crop rotation to control Rhizoctonia is difficult because of its adaptability to numerous hosts and because of the complexity of its races.

CROWN ROTS usually develop on older plants. The interior of the crowns show brown, dry rot. Such plants are probably affected with common rot, the same as occurs in cereals. An abundance of pink Fusarium spores may be present. Sometimes the less Conspicuous brown ones of Helminthosporium are found.

On Kentucky bluegrass a crown or foot rot occurs. It is caused by a distinct fungus (Helminthosporium vagans), which usually attacks the leaves and causes a dark spot.

The roots of plants suffering from crown rots usually are decayed and serve as poor anchors for the plants, which are readily removed from the ground. Old, sod-bound stands especially are subject to crown rots. They also may suffer from root browning, caused by the same fungus that causes seedling blight in young plants (Pythium graminicola). Root browning and crown rots often work together in the old stands. Sometimes the plants may be kept producing for a few more years by use of fertilizer to balance the activity of the Pythium.

5. Snow molds. Some soil-borne fungi attack all above-ground parts of grasses as they lie under the snow in late winter. For many years field workers confused these diseases with winter injury, which is due to low temperature. It has been shown, however, that the elimination of the parasitic mold permitted the plants to survive without injury despite the winter weather. In other words, the parasitic snow mold fungi prefer to live at a temperature approximating that of melting snow.

THERE ARE two common groups of snow mold the pink snow mold, caused by Fusarium nivale, and the speckled snow mold, caused by species of Typhula.

Pink snow mold attacks field and turf grasses in late winter, either under the snow or during raw winter weather. The leaves in the prostrate winter rosette stage are killed and formed into pink or straw-colored mats, which later dry to papery films. Sometimes plants recover from the disease if the crowns are not deeply injured. The color of the dead leaves is due partly to the masses of pinkspores that are formed. The spores sometimes cause a secondary leaf spot in early spring if cold, wet weather follows melting of the snow.

Pink snow mold is especially common in the Pacific Northwest on cheatgrass brome (Bromus tectorum), which serves as one of its carriers.

SPECKLED snow mold, more restricted than pink snow mold, is a true snow mold in that it cannot thrive without the semi-refrigeration of melting snow. It causes a slimy, gray rot of grass and cereal leaves under the snow in midwinter or late winter. The gray mold soon forms many tiny, black, hard sclerotia, which dot the white dried leaves after the snow has gone hence the name speckled snow mold. The sclerotia, which form on the leaves in March to April in the Pacific Northwest, germinate the following November. They produce small, fragile, club-shaped fruiting bodies. The bodies shoot off spores into the air.

Speckled snow mold is controlled by fall applications of mercurials and several organic chemicals, such as PMAS. Chemical control is not at all practical on grasses because of cost, except on greens and other turfs of relatively high value.

HERE is a list of some groups of grasses, their more important diseases, and their general geographic distribution:

Bermuda-grass (Cynodon dacyllon): Rhizoctonia rot (Southern States).

Bluestems (Andropogon): Seedling blight (Great Plains); seed rots (Great Plains).

Brome grasses (Bromus): Seedling blight (Great Plains); seed rots (general); snow molds (Northwest and Northeast); rhizoctonia rot (general); common root rot (general):

Dropseeds (Sporobolus): Seedling blight (Western States); common root rot (Western States).

Foxtail millet (Setaria italica): Seedling blight (general), seed rots (general, North); root necrosis (general).

Grama and buffalo grasses: Seed rots (Great Plains); seedling blight (Great Plains).

Indian ricegrass (Oryzopsis hymenoides): Seedling blight (far West); common root rot and crown rot (far West); rhizoctonia rot (scattered); snow molds (Pacific Northwest); seed rots (general); root necrosis and crown rots (far West).

Kentucky bluegrass (Poa pratensis): Dollar spot (Northeast); brown patch (general); foot rot,

Helminthosporium (general).

Lovegrass (Eragrostis): Sometimes seedling blight and common root rot (Southwest and Plains).

Orchardgrass (Dactylic) : Root necrosis (general); seed rot (general); seedling blight (scattered).

Panicum grasses: Seedling blight (Great Plains); root necrosis (Plains and South).

Redtop and bents (Agrostis): Seed rots (general); rhizoctonia rot (general); damping-off (coastal areas).

Ryegrasses (Lolium): Common root rot (general); root necrosis (general); rhizoctonia rots (general); seed rots (general).

Timothy (Phleum pratense): Seedling blight (general); seed rots (general); root necrosis (general).

Wheatgrasses (Agropyron): Seedling blight (Western States); common root rot and crown rot (Western States).

Wild-rye grasses (Elymus): Seedling blight (general); common root rot and crown rot (general).

Stipa grasses: Seedling blight (Plains and far West); common root rot and crown rot (Western States).

RODERICK SPRAGUE, a pathologist at the Tree Fruit Experiment Station, Wenatchee, Wash., has been investigating soil-borne fungi in the Western States since 1929. He was with the Bureau of Plant Industry, Soils, and Agricultural Engineering until 1947, when he returned to Washington State College. He holds degrees from that institution and from the University of Cincinnati. He has written many technical articles and a reference manual on diseases of the grass family.