THE DISEASES OF FRUITS. 235 



and the burning of the diseased parts is all the more impor- 

 tant. 



The Downy Mildew {Plasmopara viticola B. & C.) is a fungus 

 quite different in appearance from any thus far considered. 

 As its name suggests it 

 produces a downy coating 

 upon the affected part, usu- 

 ally the under side, with a 

 yellow discoloration of the 

 upper side of the leaf. The 

 affected fruits while half 

 grown turn brown prema- 

 turely, and for this reason 

 the term "brown rot" is 

 sometimes given to this 

 disease. The browned ber- 

 ries remain hard and never 

 become edible and rarely 

 show the fungus upon the 

 stirface. Sometimes the 

 canes are infested, when 

 they are coated with the 

 downiness common to the 

 leaves. The filaments of the 

 fungus come to the surface 



through the StomateS and ^^'^- 291— Shows threads of Grape Mildew 



then thev branch and subdi- ^'■'^*°^ through " breathing pore " of leaf, 



men tney orancn ana SUOai afterward branching and bearing spores 

 vide, producing the spores upon their tips. (From Scribner.) 



upon the tips (see Fig. 291). 



Remedies. — The same treatment is recommended here as for 

 the diseases of the grape already considered. As all these 

 troubles may be upon the same vine, or even sing\e leaf, it 

 follows that the remedy applied for one will answer for all. 



The Powdery Mildew (Uncinula necator Schw.) is another 

 fungus of the vine that while the leading enemy in Europe is of 

 secondary consideration here. This is a superficial mildew — 

 that is, it grows upon the leaf and does not penetrate the 

 tissue, and on this account may be easily controlled as by sul- 

 phur dusted over the vines. The sprayings recommended for 

 the other vine diseases will be sufficient for this one. 



