350 EXPERIMENT STATION RECORD. [Vol. 26 



No constantly associated organism has been found, but the rapid spread of the 

 disease through fields is considered to indicate that it is highly infectious. As a 

 result of field experiments, the disease was succesfuUy produced through inocu- 

 lation experiments in which the broken ends of diseased petioles were touched 

 to wounds on cucumber vines, the injection of expressed and filtered juice, 

 insertion of fragments of diseased tissue, etc. Experiments carried on in 

 Michigan indicate that insects, particularly the melon aphis {Aphis gossypii), 

 play an important part in the transmission of this disease. Successful inocu- 

 lations have also been made on pumpkins and muskmelons. In laboratory ex- 

 periments, a type of infection characterized by the entire wilting of the plant 

 appeared, but it has not been observed in the field. 



Experiments with the cucumber mosaic disease, I. C. Jaggee (Phytopa- 

 thology, 6 {1916), No. 2, pp. 148-151). — The results of experiments carried out 

 in a greenhouse in the vicinity of Rochester, N. Y., are described. 



Successful inoculation was secured when the expressed juices of leaves, 

 stems, and fruits, either filtered or not, were injected into sound cucumber 

 plants. Similar results were obtained by crushing diseased leaves in the hand 

 and then rubbing sound ones, or by growing sound and diseased plants so that 

 the foliage intermingled. Cucumber plants in contact only through their roots 

 did not develop the disease. 



In addition to the cucumber, the author reports successful inoculations on 

 the summer squash, pumpkin, and two varieties of gourd. 



Rotting of greenhouse lettuce, I. C. Jagger {West. N. Y. Hort. Soc. Proc, 

 60 {1915), pp. IJfl, 148). — A discussion of the rots of lettuce ascribed respectively 

 to Botrytis, Rhizoctonia, and Sclerotinia concludes with the statement that the 

 first two can be largely prevented by securing a vigorous growth, keeping the 

 plants and soil surface free from superfluous moisture, and maintaining moder- 

 ate temperature and humidity. Rhizoctonia and Sclerotinia can be temporarily 

 controlled by sterilization with steam in the autumn. 



Tomato blight, F. D. Heald {Rpt. Wash. Hort. Assoc, 12 {1915), pp. 35-42, 

 fig. 1). — Investigation during 1915 is stated to have shown that the tomato 

 blight, ascribed by Humphrey (E. S. R., 32. p. 444) to one or more species of 

 Fusarium, is really caused by a Rhizoctonia. The name Rhizoctonia disease is 

 selected as most appropriate. The fungus is said to be almost omnivorous. 

 Clean soil, abundant moisture, liberal fertilizer, correction of acidity with lime, 

 deep setting of plantlets, and early fall plowing of suspected soils are recom- 

 mended as protective measures. 



A troublesome disease on winter tomatoes, J. E. Howitt and R. E. Stone 

 {Phytopathology, 6 {1916), No. 2, pp. 162-166) .—It is stated that in the spring 

 of 1914 tomatoes in forcing houses near Hamilton, Ontario, showed a markedly 

 diseased condition of the leaves, stems, and fruit. Later in the year the 

 trouble reappeared, causing almost complete failure of the crop. This disease, 

 the symptoms of which are described, seems to be rather widely distributed. 

 Repeated microscopic examinations, culture tests, and inoculation experiments 

 have failed to disclose a causal organism. 



From the position and nature of the lesions and the fact that the disease 

 fails to develop in allected fruits when they are removed from the plant, the 

 authors have been led to conclude that the disease is a physiological trouble. 

 Experiments with sterilized soil are believed to indicate that the disease is in 

 some way connected with soil conditions. 



Powdery mildew demonstrations on the apple, grape, and peach during the 

 season 1915, L. Powell {Rpt. M'ash. State Hort. Assoc. 12 {1915). pp. 42-46).— 

 It is stated that in tests made in Benton County, Wash., following out the in- 

 structions given by Ballard and Volck (E. S. R.. 31, p. 748), satisfactory results 



