Data from 63 tests conducted between 1946 and 1948 show the value of seed treatment. The mean increase in surviving seedlings was 33, 30, and 26 percent when fuzzy, reginned, and acid-delinted seed, respectively, were compared with untreated seed.

Of a large number of materials tested, higher percentages of emerged seedlings were obtained with the organic mercury dusts, ethyl mercury chloride, ethyl mercury phosphate, and ethyl mercury p-toluene sulfonanilide, which are sold under the trade names of 2 percent Ceresan, New Improved Ceresan 5 percent, and Ceresan M 7.7 percent, respectively. Another material recommended by the committee is zinc trichlorophenate, 50 percent, in a suitable diluent. It is marketed under the trade name Dow 9-B.

The materials are applied at the following rates: Fuzzy seed, 1 1/2 ounces to a bushel; acid-delinted seed, 2 ounces to 100 pounds; and reginned seed, 3 ounces to 100 pounds. They also are wettable and may be applied by the slurry method, which has given emergence values of seedlings comparable to the dust treatment.

The slurry method involves the suspension of the disinfectant in water and its application to the seed in that form rather than as a dust or powder. The method eliminates flying dust during seed-treating operations, ventilation or dust exhaustion, and the use of masks by workmen. Another advantage of the slurry method over dusts is that it gives greater accuracy and uniformity of dosage.

Chemicals for treating seed may be applied as dusts or slurry in homemade rotary drums equipped with tight-fitting lids or in specially constructed motor-driven machines with treating capacities of 4 to 6 tons of seed an hour.

Reginning, or machine delinting of cotton seed, is done extensively in the Central and Southeastern States. The linters are removed in the process, so that planting is more uniform, hill dropping equipment can be used, and seed and chemical dusts are saved. Light reginning is preferable; close reginning may damage some seed. During certain years of the regional tests, reginned treated seed gave a higher emergence of seedlings than fuzzy treated seed, but in other years the differences were small.

In 1938, for instance, reginned, Ceresan-treated seed in 21 plantings gave a higher mean number of surviving seedlings than comparable fuzzy treated seed. In 1939 in 18 regional plantings, the increase in number of surviving seedlings from reginned seed treated with 5 percent Ceresan was much higher than fuzzy seed similarly treated. In other tests later, the number of surviving seedlings for reginned was highest in 1946, slightly higher for fuzzy in 1947, and practically the same for both seed sublots in 1948.

Acid delinting of cotton seed is used more extensively in the drier areas of Texas and Oklahoma and in the irrigated areas of the western cotton States. It is used to a lesser extent in the Mississippi Valley and the Southeastern States. Either sulfuric acid or hydrochloric acid gas is used for delinting.

With the sulfuric acid method, the seed is mixed with the acid in delinting machines, which do the work rapidly and efficiently. After the linters are dissolved, the seed is thoroughly washed in large vats to remove the acid. The lighter seeds, or floaters, are removed during washing. The heavier seeds, or sinkers, are given a final rinsing, usually in dilute limewater, dried, and retained for planting.

With hydrochloric gas, the linters are removed by the gas from the heated acid. It has the advantage over the sulfuric acid method in that the seed is kept dry throughout the treatment. The lighter seeds are removed with fans.

Acid-delinted seed usually give a higher emergence of seedlings than reginned or fuzzy seed if weather conditions are favorable. But we have instances in which seed so treated gave only poor to fair germination during cool, wet weather. In 13 regional plantings in 1946, the surviving seedlings at final count (as percentage of seeds planted) were 73.0 for delinted, 61.7 for reginned, and 60.0 for fuzzy seed of the same lot. While acid-delinted seed gives good stands and requires less seed to the acre, especially if hill-dropped, the method is more expensive than machine delinting.

BACTERIAL BLIGHT causes death of seedlings and loss of young plants because infected stems are weakened by blight and break during wind storms. The disease occurs throughout the Cotton Belt. It is most destructive in the Southwestern States.

First, small, round, water-soaked lesions develop on the cotyledons as they emerge from the seed coat. The lesions furnish inoculum for the developing true leaves, the bacteria later infecting the terminal bud and main stem.

Delinting cotton seed with sulfuric acid plus fungicidal treatment eliminates blight bacteria from the seed.

DAVID C. NEAL, a pathologist in the Department of Agriculture since 1928, has been engaged in research on cotton diseases in the Southern States since 1917. His contributions include physiological studies of fusarium wilt, techniques for studying varietal resistance, and the effects of nutrition upon the incidence of this disease. He has also investigated the morphology and life history of phymatotrichum root rot, seed treatment for stand improvement, and crinkle leaf found to be caused by manganese toxicity. While working on phymatotrichum root rot Of cotton in Texas in 1929, Dr. Neal discovered the sclerotium stage of that fungus in nature and thereby established its importance in the persistence and overwintering of the disease in the soil. He is a native of Mississippi, a graduate of Mississippi State College, and postgraduate of Washington University, St. Louis, Mo.