It has been shown that the principal factor in natural cross-pollination of cotton was the insect and that wind pollination does not take place in Lyallpur. Three species, Apis dorsata Fab., Anthophora confusa Smith, and Elis thoracica Lepel, were the prinicipal pollen carriers. The insects usually preferred to stay in the same cotton field, and in the case of sorghum barrier the few exceptions preferred to cross through the barrier rather than above it.

A study was made on the symptomatology and etiology of weak neck of sorghum. This is a physiologic or nonparasitic disease characterized by gradual disintegration of the tissues of the peduncles, which often break at or near their bases, and by poorly developed grain with absence of normal luster. Weak neck was induced by subjecting Colby plants to one or more drouth-stress periods, by artificial defoliation, and by partial shading of the leaves during the growing season. Sterilization of the soil and the addition to the soil of superphosphate had no effect on the control of the disease. The resistant varieties Pink kafir and White Yolo maintained a higher concentration of carbohydrates in the peduncles throughout the growing season than did the susceptible varieties Colby and Day. It is suggested that weak neck of milos may be controlled best by breeding combine varieties with inherent characteristics of peduncles similar to the kafirs.

1. From highly variable material consisting of bulk lots from a variety of points in Oklahoma and Texas, selections for specific agronomic types were made and placed in isolation blocks. Seed harvested from each block was used to establish sample populations in which reselections for type were made. Second generation progenies were established from seed produced by the reselections under isolation. Fourteen matched plants of each type were isolated in the first generation, 12 in the second generation. 2. Eighteen types were used, including a series of growth forms, late flowering, broad leaves, narrow leaves, heavy stems, fine stems, abundant leaf production, abundant culm production, and rapid basal spread. 3. The isolation blocks were 25 feet square and 28 feet apart in each direction. The intervals were planted to a thick stand of sorghum. Genetic isolation was quite satisfactory for this type of breeding system, but was probably not complete in so short a distance. 4. Considerable progress toward fixation of some of the types was evident in a single generation. Some types bred reasonably true to type after two generations; other types were less readily fixed. 5. Characters easily fixed in a population are broad leaves, narrow leaves, fine stems, heavy stems, and late flowering. 6. Types involving abundant leaf production showed the least progress toward fixation. 7. Certain characters appeared to be closely associated in the sample populations, e.g., broad leaf and late flowering, fine leaf and rust resistance, broad leaf and blue-green color, narrow leaf and yellow-green color.