274 PLANT DISEASES 



DROP or ROT (Sclerotinia libertiana) . Base of the leaves or stem 

 rots off, allowing leaves to drop. 



Control. Sterilize the soil with steam before planting. See 

 under Steam in Chapter XV, p. 253. 



ROSETTE (Rhizoctonia sp.). A rotting or damping-off of the stem. 

 Late affected plants have a resetted appearance. 



Control. Start seed in steam-sterilized soil, and transfer to 

 beds that have been sterilized with steam, a.s for DROP. 

 Muskmelon. ANTHRACNOSE ( Colletotrichum lagenarium) . Dead spots 

 on the leaves and stems and sunken pits on the fruit. Thorough 

 and frequent spraying with bordeaux mixture will hold this dis- 

 ease in check. 



DOWNY MILDEW. The same disease as on cucumbers (p. 270) . Often 

 very destructive. 



Control. A satisfactory method is not known. Spraying as 

 for cucumber mildew has not proved effective. 

 WILT. See CUCUMBER. 



Nectarine. Yellows, etc. See under PEACH, p. 276. 

 Nursery Stock. Foliage on young trees is apt to be attacked by 

 various leaf-spot fungi. The damage comes in reducing growth, 

 thus often making seconds. Several applications of bordeaux 

 mixture to keep the new growth protected are beneficial. 

 Oats. RUST (Puccinia coronata). A red rust of the blades. 



Control There is no known method of control. 

 SMUT. See under SMUT OF CEREALS, p. 260. 



Onion. MILDEW (Peronospora schleideniana) . Causes a wilt or 

 blight of the leaves. 



Control. Spray with bordeaux mixture, 5-5-50, to which has 

 been added one gallon of resin-sal-soda sticker. The first applica- 

 tion should be made when the third leaf has developed, and the 

 application should be repeated every ten days until the crop is har- 

 vested. 



SMUT ( Urocystis cepulce). Forms black pustules on the leaves and 

 bulbs. Seedlings may be killed outright. 



Control. Onions from sets or from seed started in soil free 

 from the disease seldom have the smut. Practice crop rotation. 

 Drill into the soil with the seed 100 pounds of sulfur and 50 

 pounds of air-slaked lime to the acre. 



