132 Diseases of Economic Plants 



Blue-mold rot ^^^ {Penidllium). — Grapes should be handled 

 to avoid wounds, carefully packed, and shipped or stored at 

 as nearly 0° C. (32° F.) as possible to prevent large loss due 

 to blue-mold. 



Minor diseases 



Crown-gall ^^^ (see apple) is common on the grape, with 

 a wide difference in susceptibility between varieties; Bitter- 

 rot comes late in the season on the fruit when nearly ripe, see 

 apple; White-rot (Charrina) , Scab {Cladosporium viticolum 

 Ces.), Gray-rot {Sclerotinia fuckelianxi (De Bary) Fcl.), and 

 Cercospora leaf-spot are usually of but little injury. 



HUCKLEBERRY. See blueberry. 



RASPBERRY. See blackberry. 



STRAWBERRY 



Leaf-spot ^•'^' ^''^ {Mycosphcerella fragarioe (Tul.) Lin,, 

 Ramularia) . — The most conspicuous disease of the straw- 

 berry, one nearly always present to some extent on both wild 

 and cultivated varieties in Europe and America, is recognized 

 by the presence of small, 4-6 mm., purple or red-bordered 

 spots upon the leaves, the older spots bearing white or ashen 

 centers. Late in the development of the spots the hyphse of 

 the causal fungus are barely visible with a good hand lens. 

 The spots, when numerous, may coalesce, forming large, 

 irregular blotches. The disease is also very injurious in its 

 attacks upon the fruit stems, resulting in diminution of food 

 supply to the fruit and its improper development. 



It attacks all varieties, precluding the use of especially 

 susceptible varieties in some localities, often killing the 

 plants, and in any event lessening their vigor and produc- 

 tiveness. In some localities entire plantings have been de- 

 stroyed. One grower reports a loss of $1500 on a six-acre 

 field in one season. 



