104 AMERICAN GRAPE GROWING 



drops. In seasons when the weather is dry, and the air 

 pure, mildew will not appear. It is most prevalent in 

 locations with a tenacious subsoil and where malaria 

 abounds, being less frequent in soils with good drainage 

 and in high, exposed situations. Under-draining is also 

 a partial preventive, as excess of moisture about the roots 

 and in the air is, no doubt, its principal cause. 



The Gray Rot, or " Grape Cholera" (so-called), gen- 

 erally follows the mildew, and I think the latter its prin- 

 cipal cause, as it is generally found on berries of which 

 the stems have already been affected by mildew. The 

 berry first shows gray streaks and marblings ; in a few 

 days it turns to a grayish-blue color, withers, and drops 

 from the bunch. It will continue to affect berries until 

 they begin to ripen and color, but is confined to a few 

 varieties only, the Catawba, Diana, and a few others. 



The Spotted, or Brown Rot, has been most destructive 

 of late among the Concord, Martha, Rogers' Hybrids; in 

 short, nearly all of the Labruscas, with the exception of 

 the Ives, Perkins, and a few others, too poor in quality 

 to be very desirable. It appears like a small puncture 

 on the berry, which will take on a liver-colored hue and 

 spread very rapidly. In 1878 it destroyed almost the 

 whole Concord crop along the lower Missouri and Missis- 

 sippi. Longer fall pruning and heavier bearing of the 

 vine will prevent it to some extent, also close and early 

 summer-pruning, as it is worse on vines with a rank 

 growth, and on poorly drained soil. Training on the 

 trellis higher than is generally followed (which is a 

 natural consequence of longer pruning), will also be 

 found a partial preventive, in short, anything which will 

 give a freer circulation of air and more exposure to the 

 light will be of aid. 



There is another form of rot, appearing mostly on 

 the Herbemont, Lenoir, Hermann, and sometimes on the 

 Taylor, which generally comes after frequent showers, 



