Watermelon {Citrullus vulgaris). 



The leaf spot (Cercospora citrullina) mentioned in the last report 

 (10) continues to be present and through the killing of the leaves is 

 most effective in reducing yields. Also reported from Mayagiiez (5). 



Blossom-End Rot. — This year a blossom-end rot of the fruit was 

 observed. The blossom end of a fruit attacked by this disease dried 

 up and turned brown, although the remainder of the fruit sometimes 

 continued to enlarge for some time. Fruit of all sizes were attacked. 

 Various fungi gained entrance and set up a soft rot with juice exu- 

 date. Diplodia sp. was found in several instances associated with 

 this rot and also as the apparent cause of a stem-end rot in one 

 ease. No studies have been made of this fungus. 



It was observed that this trouble was most prevalent during a 

 drouth, but that later when the plants were growing vigorously 

 under the stimulus of an abundant water Supply, it practically dis- 

 appeared. Irrigation or frequent cultivation will doubtless check 

 the disease fairly well. 



Yautia {Colocasia sp., Xanthosoma sp.) 



The yautias were quite subject to a disease known as ' ' El mal ' ' 

 and probably due to a vascular parasite, although there was no 

 opportunity to investigate it. Plants attacked by this disease failed 

 to thrive, the leaves remained small, and were generally yellow. The 

 yield was greatly reduced. The disease was favored by poor soil 

 and dry weather. It can be avoided by care in planting only healthy 

 "heads'" or offsets in uninfected soil. 



Phyllosticta colocasieola Hoh. has been reported (7) on Colocasia 

 sj). Other fungi {Fcriconia sp. and Gloeosporium sp.) are mentioned 

 as occurring in spots on yautia. Of minor importance. 



conclusion. 



Studies to date have been merely preliminary, a survey of the 

 held as it were. However, certain points liave become clear as re- 

 gards the presence of diseases. It can be taken for granted that 

 they will appear, and consequently all steps possible should be taken 

 to control or minimize their attack. Most of the problems must be 

 met by producing or introducing resistant varieties, a proposition 

 for the plant breeder and one that requires time. Much can be done, 

 however, and fair crops of most vegetables realized by following such 

 corrective measures as are now known, such as proper preparation 



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