An average emergence of 800 field bindweed seedlings per acre was observed in 1941 in a 14-acre field from which the original stand of bindweed had been eradicated in 1921. Scattered emergence of bindweed seedlings occurred in this field in each subsequent year, including 1948, when 48 seedlings per acre were observed. All bindweed seedlings developed from seed that had been in the soil since 1920 or earlier years. Annual observations were begun in 1938 in another field from which the original stand of bindweed had been eradicated in 1937. The average number of bindweed seedlings per square rod were 93, 62, 71, 13, 19, 96, 14, 7, and 13 in the spring of each year, respectively, from 1938 to 1947. An experiment was started in 1938 to compare the effectiveness in controlling bindweed seedlings of nine different crop rotations and cropping methods. Winter wheat and close-drilled sorghum grown every year or in rotation with summer fallow or row sorghum, supplemented by monthly cultivation when the land was not in crop, gave complete or satisfactory control of bindweed seedlings during a 10-year period. Row sorghum grown every year permitted slow reinfestation of the land from seedlings by an intensive method and rapid reinfestation by an ordinary method. Seeding to buffalograss proved entirely inadequate as a method of preventing reinfestation by bindweed seedlings.

Milo disease, caused by Periconia circinata (Mang.) Sacc., a malady of sorghum that kills the roots of susceptible varieties, has been present in the United States for about 20 years. The disease suddenly became widespread during the drought years of the 1930's and resistant strains were quickly found, increased, and distributed. Yield trials for 10 years at the Texas Agricultural Experiment Stations at Chillicothe and 9 years at Lubbock indicate that losses of 50 to 60% can be expected whenever a susceptible variety is grown on infested soil. Fortunately, resistant strains of susceptible varieties have been selected and such losses can be avoided if precaution is taken to purchase seed of the resistant strains.

The grain yields, stover yields, percentage of lodging, plant height, number of leaves of the main stalk, weight of 100 kernels, and the date of heading of 19 F1 hybrids and nine parental varieties are reported. The experiments were conducted at University Farm, Tucson Ariz., in 1941 and at Salt River Valley Experiment Station, Mesa. Ariz., in 1942 and 1943. Silage yields of the most promising hybrids and their parents also were obtained in 1942 and 1943. The silage was analyzed for total sugars, protein, fat, ash, and crude fiber. All of the possible F1 hybrid combinations between hegari, Ajax, Atlas, Kalo, Grohoma, and Double Dwarf milo 38 were grown in 1942 and 1943. All but three of the 19 hybrids had grain yields in excess of the means of the parents. Grohoma X Double Dwarf milo 38 and Ajax X Double Dwarf milo 38 produced the highest yields. Fifteen of the 19 hybrids yielded more stover than the means of the parents. Crosses involving hegari or Double Dwarf milo 38 gave the largest increases in stover yield. All of the hybrids had increases in plant height over the means of the parents, ranging from 6.2% to 113.8%. All of the hybrids with either hegari or Double Dwarf milo 38 as one of the parents had increases in the number of leaves of the main stalk. Many of the hybrids were so tall that they lodged excessively. The Ajax hybrids showed the least inclination to lodge. In the F1 hybrids, the average seed size was intermediate or was as large as or larger than that of the larger-seeded parent. The hegari-Atlas hybrid yielded 30.7 tons of silage per acre in comparison with 18.7 tons of the heavy producing Atlas variety. Such large yields are difficult to harvest mechanically. Most of the hybrids tested were too tall for ready machine harvesting of the grain crop, and had brown seeds, an undesirable color from the market standpoint. The commercial production of hybrid sorghum seed awaits the development of economical methods of hybrid seed production.