The Olive knot disease : its inception, development, and control.

Abstract does not appear. First page follows. Introduction In 1931 the College of Agriculture was asked to investigate the olive knot disease, caused by Bacterium savastanoi E. F. S., then becoming serious in various districts of the Sacramento Valley. Despite the excellent work of previous investigators, information on many cardinal points in the development of the disease was lacking; and no specific control measures, aside from the removal and destruction of knots, were known. A knowledge of the circumstances under which the knot passes from a rather innocuous, occasionally occurring disease into a widespread and destructive malady was considered important. Consequently, the several factors that might be instrumental in predisposing the host to attack and in favoring the inception and development of the disease were particularly studied. In addition, the possibility of control was considered. The control data, though admittedly not of sufficient extent or diversity to warrant detailed recommendations, are promising bases for trials in various localities. Most of the work reported herein was done in orchards near Corning, California. History of the Disease in California In 1898 Bioletti(3), (4) reported finding the disease in Merced County and stated that it had been present since 1893. R. E. Smith(23) mentioned its prevalence in the Sacramento Valley in 1907. It did not, however, become serious until 1909, when Smith(24) stated that studies were being initiated. In 1912, Horne, Parker, and Daines(10) investigated a serious outbreak in Sacramento County. Then followed a period when no account of serious damage appears in the records except in isolated cases. One such outbreak developed in Butte County 10 or 15 years ago, although no published record shows how long this lasted or how severe it became.