OBSERVATIONS ON SOME VINE DISEASES IN SONOMA 

 COUNTY, CALIFORNIA. 



BY O. BUTLER. 



Introduction. In 1903 the Viticultural Department of the College of Agriculture of the 

 University of California took up the study of a disease that, for a few seasons, had been 

 observed in Sonoma County and was beginning to cause some anxiety among the vine- 

 yardists. After an inspection of the vineyards of Sonoma County from Santa Rosa to 

 Cloverdale, including those of Alexander Valley and Dry Creek, we found that the 

 "Red-leaf disease," as the malady was called, was sufficiently widespread to require 

 special attention. The "Red-leaf disease" was, at that time, associated by many per- 

 sons with the Anaheim disease, and by some with Anthracnose. The first theory was 

 set aside h priori, on account of the difference in the effect on the canes and grapes, and 

 also on account of the lack of virulence of the disease when attacking the Mission vines.* 

 The suggestion that it might be Anthracnose was easily set aside, as the markings of 

 the disease on leaves, canes, and berries are of an entirely different character; it is very 

 doubtful that the true Anthracnosef has ever been found in a vineyard of California. 



On my return from this trip of investigation, I passed through Xapa Valley to com- 

 pare the " Red-leaf disease" with a malady of similar character that had caused damage 

 in some sections, and, after a consultation with Dr. E. W. Hilgard, it was decided to 

 start a methodic study of the "Red-leaf disease," and Mr. O. Butler was appointed to 

 carry out the investigations. This bulletin gives the results of his preliminary obser- 

 vations. 



During the same season arrangements were made with several vineyardists to 

 establish experiment plots on their land during the following year. 



While investigating the "Red-leaf disease," Mr. Butler found that a number of mala- 

 dies, either parasitic or physiological, w r ere responsible in a measure for the weakness or 

 dying of the vines. Among these affections Phylloxera, Root-rot, Mildew, lack of affinity 

 between scion and stock, lack of adaptation of stock to soil, mechanical injuries, Erinose, 

 and Black-knot are quite prevalent in Sonoma County, as well as in most vineyard 

 districts of California. 



A description of some of these will be given in separate bulletins, while others have 

 been already discussed in former publications: Report of Viticultural Commission, 

 1893; Bulletins Nos. 127, 131, 146, 148, of the Agricultural Experiment Station of the 

 University of California.:}: 



Mr. Butler's observations seem to show that the cause of the Red-leaf disease is not 

 parasitic, but that it is more probably due to soil and atmospheric conditions. These 

 observations will be kept up during the coming season, and a careful examination of the 

 subsoil and moisture-contents of the experimental plots will be made through the grow- 

 ing season, so that definite conclusions may be drawn. 



E. H. TWIGHT. 



THE RED-LEAF DISEASE. 



In 1903, the attention of the public was aroused by the alarming 

 notices published in the Sonoma County papers about a new and mys- 

 terious malady, which was unanimously denominated Red-leaf disease. 

 Opinions were freely aired as to the nature of the disease, but the 



* N. B. Pierce, Bulletin No. 2, Div. Veg. Path., U. S. Dept Agr., page 7. 

 fSphaceloma ampelinum. 



JAlso, in "American Vines," by P. Viala and Ravaz ; translated from the French by R Dubois 

 and E. H. Tvvight. 



