244 EXPERIMENT STATION BECORD. 



DISEASES OF PLANTS. 



Report of the plant pathologist and superintendent of southern California 

 stations, July 1, 1906, to June 30, 1909, K. E. Smith {California Sfa. Bui. 

 203, pp. 5-63, figs. 23).— An account is sivon of the pathological work of the 

 stations and particularly of the investigations which have been carried on in 

 connection with the southern California stations at Whittier, Riverside, and 

 Santa Monica. After describing the establishment of the new lalxn-atories, the 

 author gives accounts of some of the investigations, which include studies of 

 pear blight, walnut blight, lemon rot, sugar-beet blight, peach blight, rose dis- 

 eases, apricot diseases, olive knot, onion mildew, brown rot of stone fruits, 

 celery blight, apple mildew, and tomato diseases. 



In connection with the pear blight work, which is carried on in cooperation 

 with this Department, the author thinks that sutiicient work has been done to 

 demonstrate the method of combating the disease and that further work on as 

 large a scale as the past few years would not be profitable. In these investiga- 

 tions some peculiarities of the pear blight in California have been brought to 

 light. Among these are the large amount of infection that takes place through 

 the twigs and green shoots, and the number of trees which become infected in 

 the body near the ground or just under the ground. Insects seem to play an 

 important part in infecting these portions of the trees, and the point of attack on 

 the lower part of the trunk seems to be the buds or young sprouts. As some of 

 the stocks used for growing Bartlett pears tend to send up root shoots, it is 

 suggested that other stock should be employed that has little or no tendency 

 to low branching or the sending up of suckers. 



Investigations with walnut blight have shown the presence of immune varie- 

 ties, and the author believes that the solution of the problem of walnut culture 

 will be the use of innnune varieties grafted upon resistant stocks. 



In the investigation of the apricot disease the author reports that much of 

 the trouble has been caused by the fungus Coryneum hcycrinkii. This fungus 

 not only attacks the foliage but destroys many of the fruit buds. In- addition, 

 a physiological effect somewhat resembling that produced by the fungus is 

 described. From experiments in spraying peaches it is believed that the 

 Coryneum disease may be controlled by one spraying of Bordeaux mixture in 

 November followed by a second in February. 



Investigations are being continued on the olive knot, a previous account of 

 which has been given (E. S. R., 10, p. 55). These investigations are being con- 

 ducted to learn the source and method of infection. 



In cooperation with the Orange County Celery Growers' Association suc- 

 cessful experiments have been carried on for the control of the celery blight, 

 caused by Scptoria petroselini apii. This fungus in 1908 caused very serious 

 losses, but as a result of general spraying the disease was practically controlled 

 during the season of 1908-9. 



The report concludes with a list of diseases of plants that have been observed 

 since the last report. 



[Notes on plant diseases], G. E. Stone {Massachusetts »S7«. Rpt. 1908, pt. 

 1, pp. Ji3, Jfli, J16-6I, pi. 1). — Notes are given on bacterial rot of the cabbage and 

 cauliflower, crown gall, onion rot, onion smut, a disease of the radish, celery 

 crown rot, and a disease of lettuce due to nematodes and methods of control. 

 These different diseases are discussed in a popular manner and suggestions 

 given for their prevention. 



In connection with the treatment for onion smut, the author devised a simple 

 and inexiiensive api>l lance for attachment to the onion drill, by which the seed 

 can be moistened with formalin at the time of planting. It was found that if 



