128 Diseases of Greenhouse Crops 



are slender and curved. The conidia are broadly 

 elliptical, and the resting spores are globose and 

 smooth, becoming wrinkled with age. 



Control. In the seed bed, spraying with 4-4-50 

 Bordeaux will control the disease. The first applica- 

 tion should be given as soon as the disease makes its 

 appearance. Later the application will be governed 

 by disease conditions. Care should also be taken 

 to avoid sowing the seeds too thickly. Overwater- 

 ing, poor ventilation, and high temperature favor the 

 disease. 



Drop 



Caused by Sderotinia libertiana Fckl. 



Drop is a disease fairly common on cauliflower. 

 The trouble may be recognized by a drooping and 

 wilting of the leaves. The bases of the affected 

 foliage are covered with a white weft of mycelial 

 growth, later by sclerotia. For a more extended 

 discussion of the disease, see lettuce drop, p. 150. 



Ring Spot 



Caused by Mycosphterella brassicacola (Duby) 

 Lind. 



Symptoms. On the leaves, the disease appears 

 as numerous small spots and the affected foliage 

 turns yellow. Most of the spots are formed on the 

 laminffi, but others are also formed on the large 

 midribs. The spots are definite in outline, round 



