The nature of the problem underlines the need for field burning and supplies a basis for evaluation of alternate methods for grass disease control. Grass seed production is inherently trashy farming that unavoidably creates conditions favorable for maximum development of diseases. A build-up of diseases in fields is inevitable when inoculum is allowed to accumulate during several years of continuous grass culture. These unavoidable difficulties are compounded by the impracticality of major methods used for control of diseases of other plants. Breeding for disease resistance is usually impossible. Crop rotation is not possible in the culture of long-term perennials. Seed treatments have only limited value. Except for our chemical control of rust diseases, chemical control of grass diseases generally has not been feasible. All of this, aggravated by low-acre returns from most grass crops which dictate that control methods must be inexpensive. Under these circumstances, maximum sanitation is imperative and simple removal of straw and stubble would generally be nadequate. Burning fulfills the low-cost requirement and by the generation of sterilizing heat furnishes the most effective control of grass diseases through effective field hygiene probably ever developed in the culture of perennial plant. Field burning was recommended first for control of blind-seed disease and ergot in perennial ryegrass. About half the acreage was burned afterthe 1948 harvest, and nearly all fields have been burned since 1949. Remarkable control was immediately obtained on both blind-seed and ergot. Burning was extended to tall fescue and other perennial grasses for control of ergot and other major diseases as listed in Table 1.