1»20] DISEASES OF PLANTS. 845 



The treatment of certain seed-carried diseases, G. W. Wilson (Abs. in 

 Srinice, n. set:, 52 (1920), No. 1S3.',, p. 87).— Tlie author reports that he and his 

 associates have perfefted a method of treating cotton seed for the prevention 

 of certain seed-carried diseases. The method is deemed practicable on a com- 

 mercial scale, and bids fair to be of considerable value in the treatment of seed- 

 carried diseases of otlier crops. 



Diseases of grains, sorghums, and millet, and their control in Texas, 

 J. J. Taubenhaus (Texas Sta. Bui. 261 (1920), pp. 3-3//. figs. 15). — A nontechni- 

 cal account is given of the more common diseases occurring on w^heat, oats, rye, 

 barley, sudan grass, corn, sorghum, and millet, and so far as definite means are 

 linown suggestions are given for their control. 



Greenhouse lettuce disease (Kentucky Sta. Rpt. 1919, pt. 1, pp. Jf5, 46). — 

 It is reported that experiments conducted by the department of horticulture in 

 the growing of head lettuce iu the greenhouse failed in 1918 and again in 1919, 

 and an iuvestigation has been begun to determine the cause of the trouble. Be- 

 lieving that the disease was due to soil organisms, some of the benches were 

 treated with a 1 : 100 solution of formalin at the rate of 4 qts. per square foot 

 of bench space. Other benches were untreated to provide check plants. 



After varieties of lettuce became well established in the soil, many of the 

 plants were observed to show various irregularities of growth, such as stunting 

 of the midvein and wrinkling of the leaf blade, irregular distribution of 

 chlorophyll, tip burning, etc. Examination of the root systems of about 400 

 plants showed numerous lesions on the roots, and in many instances stubs were 

 observed wliere the roots had completely rotted off. Cultures from the roots 

 yielded a species of Fusarium, and experiments are under way to determine 

 the specific organism and methods of control. Surface sterilization of seeds 

 proved of no value as a control measure. 



In addition to the foregoing, Sclerotinia libertiana, Botrytis cinerea, Rhigoo- 

 tonia sp., and Septoria consimilis are reported as causing damage to greenhouse 

 lettuce. 



The comparative rate of desiccation of tubers from normal and diseased 

 potato plants, A. L. Bakke (Phytopathology, 9 (1919), No. 12. pp. 5Jfl-5-'f6, fig. 

 1). — The results are given of a study of the rate of desiccation of tubers of the 

 varieties Rural New Yorker and Eureka, the latter known to be very susceptible 

 to the curly dwarf disease. It was found that curly dwarf potato tubers on 

 being desiccated reached an equilibrium with the evaporating power of the air 

 before the normal potatoes of the same variety. The diseased tubers contained 

 more suberin at the beginning, but later fissures developed which caused the 

 tubers to reach the equilibrium earlier. Curly dwarf potatoes on being placed 

 in water showed a greater absorption than desiccated normal tubers similarly 

 placed. 



Tobacco diseases, G. H. Chapman (Massachusetts Sta. Bui. 195 (1920), pp. 

 itSSl). — In a report on tobacco investigations the author gives a summary of 

 experiments on the control of tobacco diseases carried on since 1916. In the 

 seed bed control is largely through the practice of sterilization. In the field 

 a considerable number of diseases have been observed, the most important of 

 which is the root rot caused by Thielavia hasicola. Other diseases observed 

 are the mosaic, leaf .spots, rusts, damping-oflf, stem canker, root rots Induced by 

 various species of Fusarium, sun scald, bud .scald, etc. 



In connection with the investigations, a root rot which Is more or less similar 

 In Its effect to that caused by Thielavia was observed. In this rot there were 

 no pronounced black lesions on the roots but a uniform browning and dirty dis- 

 coloration, most of the injury being confined to the fine, feeding rootlets. A 



