INSECTS AND DISEASES 89 



in Colorado, Ijrought to the moister climate of the 

 Ohio valley, developed the old tendency to disease 

 again, but by careful selection after the second or 

 third generation, under its new environment, it 

 again became as resistant as before. And so, with 

 only our present knowledge of these fungous and 

 wilt diseases to guide us, it would seem that the 

 only satisfactory remedies which may be safely 

 recommended are a long rotation of crops and care- 

 ful selection and breeding of varieties which are im- 

 mune to the disease. 



There are a few other diseases which are more or 

 less common on cucurbitaceous plants and which 

 aflFect the melon with the others, such as the 



Scab (Cladosporiu)ii cucumcrinum. Ell. & Arth.). — 

 On melons it produces small, sunken spots, mostly 

 on the fruit, but sometimes on the stems. It is 

 mostly present during very wet weather. 



Anthracnose (Collctotrichiiin lagcnarium, Pass.). — 

 This disease affects both fruit and leaves, produc- 

 ing brown spots on the leaves and small sunken 

 spots which cause the fruit to rot. 



Downy Mildew (Plasmopara cuhensis, B. & C). — 

 Most common on cucumbers, but it affects all kinds 

 of cucurbits. A full account of this disease may be 

 found in Bulletin No. 119, New York Experiment 

 Station. (Fig. 20,) 



