MARKET DISEASES OF VEGETABLES. 33 



CUCUMBER AND MUSKMELON; ANTHRACNOSE. 



Cause: A fungus (Colletotrichum lagenarium). 



On cucumbers the anthracnose lesions are found in the 

 market as circular, sunken, water-soaked spots which 

 usually bear a slimy, orange-pink coating of spore masses. 

 As the rotted tissue dries out, the surface may crack. 



On Honeydew muskmelons the oval, light gray lesions 

 with concentric rings of pink or black dots (acervuli) are 

 very conspicuous. Large lesions become sunken, and the 

 central tissue often cracks open, affording a port of entry 

 for other fungi. 



On netted cantaloupes, the lesions are sharply sunken but 

 not very conspicuous until the salmon-colored spore masses 

 appear. 



The same fungus causes anthracnose of watermelon (dis- 

 cussed elsewhere). 



Anthracnose is a field disease occurring on leaves, stems, 

 and fruits. Infection proceeds from infested seed or soil, 

 and the disease spreads during wet weather. Fruit infec- 

 tion takes place in the field and the lesions enlarge in transit, 

 causing serious blemishing. Frequently, secondary rots 

 enter through the anthracnose spots. 



Anthracnose is of widespread occurrence. In the market 

 it has been noted commonly on Louisiana cucumbers and 

 Colorado Honeydew and Osage muskmelons. 



Affected fruits are unsightly and rapidly become un- 

 salable. 



The disease can be controlled by crop rotation, use of 

 disease-free seed, and spraying with Bordeaux mixture. It 

 is advisable not to ship fruits showing any signs of the dis- 

 ease because of its rapid development in transit. 



Ref. (21). 



CUCUMBER: BACTERIAL SPOT. 



Cause: Bacteria (Bacterium lachrymans). 



The lesions of bacterial spot appear as small greasy or 

 water-soaked spots, usually showing a small whitish dot in 

 the center. The diseased spots may enlarge and lead to a 

 secondary soft rot of rather large areas. Often a jelly-like 

 mass of exudate is formed on these lesions. Under certain 

 conditions, such rotted tissue may dry out, leaving cavities 

 in the surface of the fruit. 



Bacterial spot is a common and widespread disease of the 

 vines causing what is known in the field as angular leaf spot. 

 The disease is carried with the seed and spreads in the field 

 in wet weather. Fruits become infected in the field, and the 

 disease may progress but does not spread during transit. 



The disease may be controlled by seed disinfection, crop 

 rotation, and spraying with Bordeaux mixture. 



Ref. (6); (62); (8). 



