ANNUAL REPORT, ]929 343 



a 1:1 ratio is the best, and three grams of the mixed chemicals for a six- 

 inch pot of soil proved the most efficient rate of application. Before this 

 method can be demonstrated on a commercial scale, there are certain 

 problems that must be solved by the laboratory method. 



Eggplant Wilt. (E. F. Guba, Waltham). Addition of chemicals to the 

 hills at planting time, with the object of sterilizing the soil about the 

 roots, gave no control of the wilt disease. Negative results were also 

 obtained with the use of a paper mulch. Studies in several fields of the 

 New York Purple variety indicate that the eggplant tolerates a high de- 

 gree of soil acidity, and that this cortdition usually is accompanied by an 

 insignificant amount of wilt. These findings point to the changing of 

 soil reaction as a means of controlling wilt, and efforts are being directed 

 toward this objective. 



Onion Blast. Several departments cooperated in work on various 

 phases of the problem presented by the disease of onions known as blast. 

 A field survey and spraying and dusting experiments were conducted by 

 A. I. Bourne (Department of Entomology) and W. L. Doran (Depart- 

 ment of Botany). Weather conditions were unfavorable to the develop- 

 ment of blast, and the trouble did not occur. Drought injury and thrips 

 injury were severe in many fields. Because of the absence of blast and 

 downy mildew, no data were obtained on the effect of dusts and sprays 

 on these diseases. The joint effects of chemicals and mechanical injuries 

 were such that it was concluded safe to spray six times with 4-4-50 Bor- 

 deaux, but not nine times; three times with 8-4-50 Bordeaux, but not five 

 times; and six times with milk of linie, but not nine times. Copper-lime 

 dusts proved more injurious than any of the Bordeaux mixtures. 



L. H. Jones (Department of Botany) worked on the physiology of 

 onion blast. Growing onions under conditions of reduced light and high 

 humidity tended to reduce root growth and to produce tender tops. Sub- 

 sequently, when exposed to hot sunshine and drying wind, these plants 

 were injured in a manner resembling the condition known as blast. 



Carnation Blight. (E. F. Guba, Waltham). The toxicity of fungicides 

 to spores of the causal fungus (Alternaria dianthi S. & H.), the preven- 

 tion of infection of potted plants which were artificially inoculated with 

 spores of the pathogene, and the control of the disease in the field have 

 been studied. In the toxicity tests with spores, naphthalene dust proved 

 the most effective of twelve fungicides employed. In an experiment on 

 the prevention of infection, five fungicides were used, each applied alone 

 and in combination with fish oil. Calcium arsenate with fish oil and 

 Bordeaux mixture with fish oil gave the best results. Results of a sec- 

 ond experiment substantiated those of the first and indicated no advan- 

 tage in the use of saponin as a spreader. Thirteen distinct treatments 

 were compared in a spraying experiment in the field. Bordeaux com- 

 bined with calcium arsenate and fish oil was the most effective of the 

 fungicides used. Copper-lime dust and calcium arsenate proved the least 

 effective. Calcium arsenate, alone or in combination with lime-sulfur, 

 caused injury to the plants. 



Forcing Gladiolus with the Aid of Artificial Light. (L. H. Jones). 

 The embryonic flowers of the gladiolus are formed a few weeks after the 

 corms are planted. Under normal out-of-door cultural conditions this 



