1472 



ENCYCLOPEDIA OP PRACTICAL HORTICULTURE 



white varieties. It causes black circular 

 spots on the bulbs. Store in a dry cool 

 place and avoid piling too deeply in the 

 bins. - '• ' 



See Bmudae, 



Bacterial Diseases. See Herat Rot, 

 this section. 



Black Neck. See Dry Rot, this section. 



Blight 



Leaf blight or scald of onions during 

 mid-season, when the weather is warm 

 and dry, is rather a common occurence. 

 While often attributable to insects, spe- 

 cies of fungi, especially molds, are abun- 

 dant. It may be possible to check these 



molds by spraying. 



A. D. Selby, 



Wooster, Ohio. 

 Onion Brittle 



This disease causes many young seed- 

 lings in the field to die suddenly and 

 others to curl up and present a spotted 

 appearance. The cause of the disease is 

 unknown. The trouble usually starts in 

 spots which become larger year after 

 year until the land becomes worthless for 

 onions. Treating the land with formalin 

 has been recommended. 



Damping Off. See Cabhage Diseases. 



Dry or Black IVeck Rot 



Sclerotium cepivorum Berk. 



A serious disease of white onions. The 

 white onions are grown for somewhat 

 special markets and it is the eustom to 

 gather early before the tops fall over, to 

 top at once, and put up in crates in or- 

 der to preserve the white color of the 

 onion. As a rule this is not practiced 

 with black, red or yellow sorts, so that 

 this neck or dry rot is not so common 

 with them. This trouble appears to be 

 clearly different from the smudge fun- 

 gus which also disfigures the exterior of 

 white onions. The losses are very serious 

 between the gathering of the white onions 

 and time for winter storage while the 

 crates are piled in buildings or in covered 

 ricks in fields. 



It appears at this time that the early 

 topping of the white onions, leaving a 

 green neck, offers an inviting way for 

 the disease to enter; that the invasion is 

 in this direction appears from the sclero- 



tia of the fungus which forms in this 

 region. The disease appears to grow 

 worse with continuous cropping of on- 

 ions and the losses have been so large in 

 storage as to render storage of white 

 onions unprofitable. It has been suggest- 

 ed that the white onions should be gath- 

 ered and ricked in crates at once, either 

 in buildings or covered with tent or tem- 

 porary enclosure of building paper, and 

 disinfected or treated with formaldehyde 

 gas. The enclosure should not be opened 

 for 24 to 48 hours after treatment. In 

 this manner it is hoped to keep down the 

 infection of the white onions as well as 

 of any others from similar troubles. 



Fig. 1. The Result of Mildew on the Foliage. 



