1910.] PUBLIC DOCUMENT — No. 31. 49 



door diseases also. In wet seasons certain diseases are common 

 which may be entirely absent in dry seasons. The presence of 

 dew, even in dry periods, may bring about infection by furnish- 

 ing favorable conditions for spore germination. If the moisture 

 conditions out of doors could be controlled as easily as they are 

 inside, a very large percentage of so-called blights could be 

 eliminated. 



CuCTJMBERS AND MeLOjSTS. 



Experiments made with melons and cucumbers, covering a 

 period of many years, have demonstrated that by proper regula- 

 tion of the moisture in well-ventilated houses Anthracnose 

 (C oUetotrichum) , downy mildew (Plasm o para), AUernaria and 

 powdery mildew (Erysiphe) can be held absolutely in check. 



At the time some of our exj)eriments were being carried on, 

 melons which were growing out of doors, within a few feet of 

 our greenhouse, were infected with all of the above diseases 

 except powdery mildew, but not a trace of infection could be 

 found from any of these diseases inside. During the many 

 years we have grown cucumbers and melons under glass we have 

 never had any infection from the above diseases excej)t the pow- 

 dery mildew, which was introduced into our house at one time 

 and encouraged to spread for a special purpose. All of these 

 diseases are more or less common each year in cucumber houses, 

 and cause much injury. 



Downy mildew affects cucumbers during July and August, 

 and Anthracnose in the spring. Most greenhouses growing cu- 

 cumbers are kept too moist and are often poorly ventilated. 

 There is no reason whatsoever why these crops cannot be grown 

 without infection from the above-mentioned diseases. Experi- 

 ence has shown us that in order to control blights it is necessary 

 that the air moisture should be held down, and if syringing of 

 the foliage becomes necessary, it should be done only on bright, 

 sunshiny mornings, when the foliage will dry off quickly, thus 

 preventing the spores from germinating and affecting the crop. 



Tomatoes. 



There are a large number of troubles associated with tomatoes 

 under glass which arise from improper handling of the crop. 



