102 THE RAISIN INDUSTRY. 



other side of the trench. What few crawl up can easily be kept down 

 by hand-picking. 



If certain attractive flowers, such as honey-suckles or petunias, are 

 planted on a small bed in the vineyard, say near the house, the moths 

 will come to them to feed from all the surrounding neighborhood. 

 Only one small bed should be planted on every vineyard. A boy with 

 a butterfly net, posted at each flower bed at sundown, can catch hun- 

 dreds of moths every evening, and considerably reduce their number 

 and prevent them from breeding. 



BLACK-KNOT. 



Characteristics. The woody or spongy excrescences which appear on 

 the vines, and which are known as black-knots, are really only a wart- 

 like growth, the origin of which is entirely unknown. It is supposed 

 that an insufficient outlet for the sap in the spring caused by too 

 close pruning is the chief cause. Certainly closely pruned vines are 

 more subject to the black-kn6t than long pruned vines, but on the other 

 hand neglected vines which have had no cultivation, and which accord- 

 ingly could hardly have had too rapid a flow of sap, suffer more than 

 any others. The woody warts appear quite frequently on the ends of the 

 spurs of the old wood, or on places of last year's growth which have 

 been wounded or injured in some way, but never on the green wood. 

 They vary in size from that of a pea to that of lumps weighing several 

 pounds. When present in small quantities, the warts cause no injury, 

 but when they become larger the vines may even die. These black- 

 knots always die with the year, and never survive to the next sea- 

 son. At the end of the season, they burst open and then often dis- 

 play black spores of fungi, which, however, are only parasitical growths 

 on the already decayed wood, and not the cause of the disease. As I said, 

 it is generally supposed that the flow of sap is during spring time so 

 great that it ruptures the cells of the vine and causes the warts to 

 form. Under the microscope, however, there are no such ruptured cells 

 visible. It is more natural to suppose, that through the accumula- 

 tion of sap an irritating poison is originated, which causes the warty 

 growth to form in a manner similar to the formation of galls. On 

 sandy soil the black-knot is the most common, probably on account of 

 the earliness and the natural warmth of this kind of soil. 



Remedies. So far no decidedly successful remedy has been found. 

 Some growers advise leaving plenty of spurs on the vine, so as to give 

 a sufficient outlet to the sap, but it remains to be seen if this will 

 mitigate the evil. If the black-knot should be very destructive, a cut- 

 ting out of the same in summer time while they are forming would 

 be beneficial. This could best be done in 'June and July. Mixtures 

 of coal-oil and lime, etc., have been used during the winter after the 

 vines were already pruned, but, as the black-knot is then already dead, 

 no advantages can result from this remedy. 



GRASSHOPPERS. 



General Notes. While grasshoppers cannot be considered as a 

 common pest in the vineyard, still they are at times greatly destructive. 



