Family Cucurbitaceae 237 



toms in both diseases are very much alike. The only 

 disparity consists in the difference of the two causa- 

 tive organisms. For a further study of Rhizopus 

 nigricans, see soft and ring rot of the sweet potato, 

 pp. 156-159. 



POWDERY MILDEW, see CUCUMBER, p. 232. 



ANTHRACNOSE, see WATERMELON, p. 240. 



LEAF SPOT, see CANTALOUPE, p. 224. 



WILT OR YELLOWS 

 Caused by Fusarium cucurbitcz Taub. x 



One of the greatest drawbacks to squash culture 

 in many of the Southern States, especially in Texas, 

 is a disease known as wilt (fig. 41 i) or yellows. The 

 symptoms of the squash wilt are identical with those of 

 the watermelon wilt, see p. 244. However, the organ- 

 ism F. cucurbitcE is different and distinct from the three 

 species of Fusarium which are capable of producing a 

 wilt on watermelon. The name Fusarium cucurbi- 

 ts n. sp. is therefore given to the squash wilt 

 organism to distinguish it from other species of Fusa- 

 rium. From investigations by the writer there has 

 been found no variety which is resistant to wilt. On 

 the other hand, the pumpkin Cucurbita pepo, and the 

 "sugar through" gourd Lagenaria vulgaris will 

 thrive in soils where squashes are known to fail from 

 wilt. Watermelons, cowpeas, cotton, and okra will 

 also thrive well in Fusarium-sick soil of squashes. 

 Occasionally it is found that cowpeas and okra will 



1 From unpublished data of the author. 



