OBSERVATIONS ON SOME VINE DISEASES IN SONOMA COUNTY. 21 



now and then they may occur just above and below the diaphragms, 

 and without regularity; at other times a slight discoloration of the pith 

 may be traced from the base of the shoot up several nodps. In the 

 spurs the woody tissue of the previous year is brown and often, more 

 especially near the edge, zoned with darker lines. In the arms we have 

 the same general appearance as in the spurs, with this difference that, 

 in cross-section, the darker areas may be more suffused. In the trunk 

 the discolorations of the wood are less pronounced and, in longitudinal 

 section, appear as striations which become less numerous as one nears 

 the stock (the diseased vines are grafted on Lenoir), which they rarely 

 penetrate to any extent; or, if no decay or dead tissue is present, the 

 live wood may be suffused with a faint brown tinge, from which the 

 striations stand out less boldly. The bodies of the vines have, however, 

 in most cases suffered more extended disorganization than just described. 

 One finds, whenever large limbs have been at one time removed, decay 

 and dead tissues occupying a large part of the body of the vine and 

 eating gradually down toward the stock, which is rarely affected, how- 

 ever, to any serious extent. 



The roots are always healthy, even in sickly vines. 



Generalities regarding the Work at the East Sonoma Experiment Plot. 

 This plot was established in a vineyard reconstituted some twenty years 

 ago. Lenoir was the grafting stock originally used; but from time to 

 time, as vacancies occurred, other stocks mostly Rupestris of the Fort 

 Worth type were used to fill in the missing places. In that part of 

 the vineyard selected for the experiment plot (the only really diseased 

 portion) the Lenoirs are carrying Semillon grafts. 



The plot, however, is not free from admixture. A few Zinfandels are scattered here and 

 there and were evidently accidentally introduced when refilling the vacancies. When the 

 vineyard was reconstituted the grafting was well done and the grafts were not allowed 

 to strike root. Furthermore, there was never any great disparity of growth between 

 the stock and graft, and consequently the unions are smooth. The vines were pruned 

 short prior to 1902, and, in consequence, had never produced much of a crop,, the 

 Semillon being one of the grapes that demands long pruning to produce fully. The 

 vines, however, under, this regime, were moderately healthy and sufficiently vigorous. 

 In 1902 the system of pruning was changed from short to long. Following the adop- 

 tion of the long pruning the vines began to show disease. In 1903 they were already 

 much affected. This new disease was then supposed to be the Red-leaf disease. We 

 now know that it was the Grape-shrivel. 



Acting on the assumption that the disease in this vineyard was the 

 Red-leaf, arrangements were made in February, 1904, to carry out there 

 the same spraying experiments as at the other two plots. The East 

 Sonoma plot was divided into twelve sections, containing four rows of 

 vines each. Sections 1 and 7 were sprayed with acid iron sulfate, * 

 sections 3 and 9 with acid iron sulfate and Bordeaux mixture; sections 

 2, 4, 6, and 12 were left as witnesses. Sections 1, 3, 7, and 9 were 



*For the method of preparing this fungicide, see page 12. 



