184 Diseases of Greenhouse Crops 



of the tomato. A few days later, the water-soaked 

 spot becomes black and leathery and ceases to make 

 further progress. Complete rotting of the fruit may 

 be brought about by secondary invasions. 



Plants subject to frequent slight wilting produce 

 a greater number of defective fruits. There seems 

 no doubt but that the water supply in the soil is an 

 important factor in limiting or increasing blossom 

 end rot. The factors of drainage and cultivation 

 are, therefore, important considerations. Although 

 dry soils and drought favor the increase of the dis- 

 ease, the state of health of the plant itself seems 

 equally important. 



The use of fertilizers, too, seems to influence the 

 trouble. Heavy applications of manure or of pot- 

 ash seem to increase the rot, as do fertilizers in the 

 form of ammonium compounds. This is especially 

 true on sandy loams. On the other hand, nitrate 

 of soda or lime acts as a check. In controlling blos- 

 som end rot, the moisture of the air in the green- 

 house seems also an important factor. On bright, 

 sunny days, it is not advisable to keep the air dry. 

 However, care should be taken not to keep the air 

 of the house dry during the night, as this encourages 

 numerous fungous diseases. 



Sunburn 



Tomatoes are often burned while they are on the 

 vines by strong sunlight beating on the exposed fruit. 

 This results in a scalding of certain parts, loss of 



