OBSERVATIONS ON SOME VINE DISEASES IN SONOMA COUNTY. 



13 



of other diseases, the North Sonoma plot, and a few side excursions to 

 other vineyards, were, however, of valuable assistance as soon as some 

 knowledge of the characteristics of the Red-leaf disease had been 

 obtained. By their aid the limits of variability of these characteristics 

 were established with considerable accuracy. 



In the following discussion of the effect of our spraying experiments 

 in controlling the Red-leaf disease, together with the observations on 

 its progress and development in the vineyard, the data collected at the 

 South Sonoma experiment plot form the basis of our discussion. 



Details of the Work at the South Sonoma, Experiment Plot. The plot 

 was established among old Mission vines which had been more or less 



HflY TlEU) 



FIG. 1. Map of South Sonoma Experiment Plot. 



diseased in 1902 and 1903 and were beginning to cause some concern. 

 By referring to the map (Fig. 1) the reader will at once see the manner 

 in which the plot was laid off and sprayed. The times at which the 

 sprayings were given have already been mentioned. The interval 

 between the sprayings with the Bordeaux mixture was so timed as to 

 always keep the leaves well covered with a film of the fungicide. The 

 Bordeaux was observed to cause a certain amount of burning in the 

 young leaves, especially in the earlier part of the season. This burning 

 of the tissues, which occurs between the veins and in stripes, the leaves 

 becoming, as a consequence, somewhat crinkled and distorted, should 

 not be confused with the characteristics of the Red-leaf disease. The 



