142 Lessons in Fruit Growing. 



ries are tliree-fourths grown, ammoniacal solution of cop- 

 per carbonate is preferable to Bordeaux mixture, as it 

 stains the fruit less.' In the north, where the attacks are 

 not so severe, the treatments need not begin until July 1st, 

 and two later sprayings at intervals of 2 or 3 weeks usu- 

 ally prevent damage. 



205. The downy mildew, also called brown rot and gray 

 rot, is more common than the black rot in the northern 

 states. Like the latter, it is most serious in warm, wet 

 seasons. Some of its symptoais are light-green patches 

 upon both sides of the leaves, which later become yellow, 

 and still later change to brown. As the spots become yel- 

 low upon the upper side of the leaf, a frost-like substance 

 projects from the discolored part on the under side. The 

 affectioQ of the leaf is often accompanied by brown, 

 slightly-sunken areas on the shoots. The fruit is often 

 attacked, if at all, before the berries are half-grown. Af- 

 fected berries first become brown and later are covered 

 with a whitish powder. 



Treatment. In localities subject to this disease, an ap- 

 plication of Bordeaux mixture should be made when the 

 shoots have grown 6 to 10 inches, to be followed by a sec- 

 ond application after the vines have blossomed, and later 

 sprayings should succeed each other at intervals of 2 to 4 

 weeks, depending upon the season. The later treatments 

 may be made with ammoniacal solution of copper carbon- 

 ate to prevent staining the fruit. 



206. The powdery mildew develops most rapidly in 

 rather dry weather. It is a surface-growing fungus which 

 appears mainly upon the upper surface of the leaves, form- 



' Directions for making Bordeaux mixture and ammoniacal solution of cop- 

 per carbonate are given in "Principles of Plant Culture," 



