201: STATE HORTICULTURAL SOCIETY. 



Prof. F. Lamson Scribner, of the Tennessee station, one of the highest 

 authorities on diseases of the grape, gives the best description in a well-illustrated 

 bulletin of black-rot of the grape (Lcestadia Bidwellii, Ellis) He tells us the dis- 

 ease is a plant consisting of mar y fine tubes which grow in the tissues of the 

 affected parts, absorbing their nourishment. They produce three kinds of repro- 

 ductive spores; two are formed during the growing season, and serve for the 

 immediate spread of the disease from one part of the plant to another, and from 

 plant to plant ; the third appears in the early spring, in berries that rotted the 

 year previous, and thus carries the disease from year to year. It is because the 

 spores are produced in such vast quantities during the entire early part of the sea- 

 son, and grow so quickly after they mature, that more than one spraying is neces- 

 sary. If only the early spring crop of spores were produced by the fungus, a 

 single spraying, about the time the leaves push forth, would prevent serious dis- 

 aster; but these early spring spores germinate and produce a plant that pierces 

 the skin of leaf or stem, or young fruit, on whichever part it has happened to fall, 

 and in a very short time the young plant begins to form the two kinds of summer 

 spores, each of which germinates within a few days of ripening; and thus spores 

 are being produced and infesting the new growth as rapidly as it is extended. As 

 the disease is safe against all remedies when it has penetrated the grape plant, we 

 must apply the fungicide in the hope of killing the spores as they fall on the vine. 

 As there are three kinds of spores in the beginning of the season, great vigilance 

 is necessary in spraying at that time. 



Heat and moisture are favorable to the development of the disease, and the 

 opposite conditions unfavorable. So too hot dry weather is not at all favorable for 

 it, as compared with moist hot weather; hence, a drouth year is attended with 

 little rot. All experimenters are agreed on the following points in fighting diseases 

 of the grape : 



1. A washing of the vines and trellises with strong solution of blue vitriol 

 before growth starts in the spring, to destroy spores attached to old wood. This 

 can be accomplished either by heavy spraying or by washing with brush. 



2. Either Bordeaux mixture or ammoniacal solution of carbonate of copper 

 should be used for spraying after growth starts. The strength of the former mix- 

 ture is reported variously, the general tendency being toward the use of a much 

 weaker solution than was thought necessary when the experiments began— the 

 Connecticut Station even recommeniing one pound Cu. S O 4, one pound lime, to 

 22 gallons water. The formula usually followed is three pounds Cu. S O 4. three 

 pounds lime, to 22 gallons water. As Bordeaux mixture discolors the fruit, most 

 experimenters advise that the last spray be of ammoniacal solution of carbonate 

 of copper. 



3. The importance of early applications is insisted upon. Under most favor- 

 able weather conditions, four sprayings are recommended, with additional ones if 

 the season is wet. The times of spraying are about as follows : 1, when the new 

 growth is not more than four to eight inches long; 2, just before blooming ; 3, just 

 after blooming; 4, when the fruit is the size of small shot. This will bring the 

 applications about two weeks apart. All agree that less time should elapse between 

 the earlier applications than the later. 



If Bordeaux mixture is used for all sprayings, it can be washed off in a solu" 

 tion of 2 quarts cider vinegar to 10 gallons of water— the fruit being dipped in 

 clear water after being submerged a few minutes in the solution. 



None of the experimenters claim that any of the fungicides now in use will 

 entirely prevent grape-rot, nor that the disease will not be most harmful in a wet 



