Family Cucurbitaceae 235 



FRUIT ROT 



Caused by Choanophora cucurbitarum (B. and Rav.) 

 Thax. 



Fruit rot is a common disease of the summer 

 squashes. It has been found in North and South 

 Carolina, Massachusetts, New York, Ohio, Michigan, 

 Connecticut, Florida, and Texas. The disease is of 

 little importance in dry seasons. It is, however, 

 favored by conditions of high humidity and excessive 

 rainfall, or by heavy dews at night. 



Symptoms. It usually attacks the flowers, or 

 especially the remnants, of the old calyx (fig. 41 a). 

 The latter when affected become shriveled and cov- 

 ered with a thick crop of brown conidiophores of the 

 causative fungus. From the floral parts, the my- 

 celium works downward and into the young squash, 

 which wilts very rapidly, turning into a soft rot and 

 later covered by a gray growth of conidiophores 

 (fig. 41 b). As far as is known, the fungus does not 

 attack any other part of the squash plant except the 

 floral parts and the fruit. 



The varieties of squash most affected by fruit rot 

 are the "patty pan" types, commonly known as 

 cymblings. Wolf 1 has found Choanophora cucurbi- 

 tarum on fading flowers of cucumber, Althea, scarlet 

 hibiscus, okra, and cotton. 



The Fungus. The conidiophores when young are 

 whitish, but at maturity take on a metallic luster. 



1 Wolf, F. A., U. S. Dept. of Agr., Jour. Agr. Research, 8 : 319-328, 

 1917. 



