Horticulture, a text book for high schools and normals, including plant propagation; . Fig. 176.—A winter cover crop m THE GRAPEVINE ROOT-BORER 249 The grapevine phylloxera attacks both the leaves and the rootsof the grapes. It is seldom serious except in California and inforeign grape growing regions. This is true at least of the rootforms. Leaf-galls are often found on American grapes in othersections. When the roots are seriously attacked, they are appa-rently poisoned by the insect and decay follows. The vines are. Fig. 17; -Downy mildew disease causes green fruit to become hard and dry; t
Horticulture, a text book for high schools and normals, including plant propagation; . Fig. 176.—A winter cover crop m THE GRAPEVINE ROOT-BORER 249 The grapevine phylloxera attacks both the leaves and the rootsof the grapes. It is seldom serious except in California and inforeign grape growing regions. This is true at least of the rootforms. Leaf-galls are often found on American grapes in othersections. When the roots are seriously attacked, they are appa-rently poisoned by the insect and decay follows. The vines are. Fig. 17; -Downy mildew disease causes green fruit to become hard and dry; the riperfruits shrivel and turn brownish in color. (Minnesota Station.) frequently killed. Resistant varieties must be used for stocks inorder to control the root form of this pest. If European grapes aregrafted upon American stocks, they are usually not seriouslyaffected by this enemy. The grapevine root-borer feeds on the roots of the grape somedistance under the ground. Its work is not usually noticed until 250 GRAPES the vine dies or is nearly killed. It is believed that the muscadinegroup of grapes is not affected by this pest. It has been suggestedthat these vines be used as stocks for the grafting of other grapeswhere this enemy is serious. Diseases of the Grape.—The black rot is doubtless the worstdisease of the grape. Downy mildew (Fig. 177) is also very destruc-tive in some sections. The methods required in preventing blackrot disease will effectively control several other diseases which mayotherwis
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectgardeni, bookyear1922
