428 Journal of Agricultural Research voi. vi, no. h 



None of the 30 varieties of cucumber were free from wilt, the diseased 

 plants in each variety ranging from 30 to 100 per cent. In the 7 varie- 

 ties of cantaloupe exposed to infection, the wilt ranged from 9 to 66 

 per cent. Of the 24 varieties of squash, 2 remained free from wilt 

 throughout the season, and in the remaining 22 varieties the disease 

 occurred in 10 to 100 per cent of the plants. Little hope of finding a 

 high degree of resistance is to be noted in the cucumber record. A 

 considerable difference in percentages of wilt is found, but whether 

 this will persist from year to year or is merely accidental can be ascer- 

 tained only by further trials in different localities and seasons. A 

 greater promise of resistance was evidenced by the squash varieties. 

 In his experiments Dr. Krwin F. Smith, Bureau of Plant Industry, 

 obtained infection in squashes with B. iracheiphilus obtained from 

 wilted squash plants, but with cultures obtained from cucumbers squash 

 infections were rare or where they did occur failed to extend beyond the 

 immediate vicinity of inoculation. 



Experiments relative to the infection of squash plants by means of 

 cultures of B. iracheiphilus obtained from cucumbers, cantaloupes, and 

 squashes are not yet completed. However, up to the present time, 15 

 strains from cucumber, i from cantaloupe, and 7 from squash have been 

 tested by inoculation into these three hosts. All the strains have proved 

 infectious on cucumber and cantaloupe. Of the 15 cucumber strains 

 inoculated into the Yellow Crookneck and Early White Bush squashes, 

 7 have given no infection, 2 (En66 and En68) have given doubtful 

 signs of incipient wilt, 4 (En68, Eniop, R305, and R307) primary wilt 

 (not extending beyond the inoculated leaves), and 2 (R308 and En 108) 

 wilt involving the entire plant. The single cantaloupe strain in most 

 cases failed to infect squash. In those cases where infection did occur, 

 the signs did not extend far beyond the inoculation punctures. All the 

 squash strains were infectious to squash, varietal differences, however, 

 being evident. 



Among the common cultivated cucurbits cucumbers appear to be the 

 most susceptible, and following them in succession should be placed 

 cantaloupes, squashes, and pumpkins, with watermelons (Citrullus vul- 

 garis) as most resistant. So far as the writers know, bacterial wilt has 

 been reported but once as occurring naturally upon watermelons, and 

 this case was reported without accompanying proof.^ The ordinary 

 watermelon wilt is caused by a species of Fusarium. 



Summarizing the season's work upon cucurbit varieties, together with 

 the general field obser\^ations of the senior writer, it may be stated 

 that there is little hope of controlling the disease in the cucumber through 

 host resistance to the parasite. The cantaloupe and squash, especially 



1 Selby, A. D. Certain troublesome diseases of tomatoes and cucurbits. In Ann. Rpt. Columbus Hort. 

 Soc. 1896, p. 113. 1897. 



