BULLETIN 231] WALNUT CULTURE IN CALIFORNIA. 363 



per cent. Dilution plates were made after three hours' time, using 

 four loopfuls from each tube to inoculate the agar tubes. In seven 

 days the following results were given: Growth in 1/10000 per cent 

 and the weaker strengths. 



Carbolic Acid. The following per cents were made, using distilled 

 water to properly dilute the 5 per cent stock solution of carbolic acid 

 (Merck) : 1/2, 1/4, 1/10, 1/25, 1/50, 1/100 per cents, four tubes of each 

 and three check tubes of distilled water. Tubes were inoculated 

 with three loopfuls of walnut blight culture and dilution plates were 

 made after three hours. After six days 1/2 and 1/4 per cents showed 

 either no growth or at least not walnut blight. The other lower per 

 cents 1/10, 1/25, 1/50, and 1/100 showed some growth. The 1/10 per 

 cent developed 12 and 7 colonies in two of the plates, while the other 

 two showed no growth. 



An attempt wus at first made to use the carbolic acid with a solution 

 containing peptone, but the results are not exact because there was a 

 precipitate due to the chemical action of the acid with the peptone. A 

 series of tubes containing Dunham solution and carbolic acid was made 

 and the tubes inoculated with three loopfuls from a four days' growth 

 in meat bouillon. Growth and cloudiness of tubes occurred in 1/25, 

 1/50 and 1/100 per cents. No growth in tubes having 1, 1/2, and 1/4 

 per cents. Plates were made from the tubes and the results obtained 

 agree with the statements above. 



Formalin. A 1/25 per cent solution acting for three hours on the 

 organism was effective in killing. A solution of 1/50 per cent formalin 

 acting for the same time did not kill. 



Potassium Permanganate A solution of 1/500 per cent acting for 

 three hours killed the organism. 



Sodium Benzoate. This chemical was tested but showed poor germi- 

 cidal action. A solution of 1 per cent did not kill the organism even 

 after six days' time. This strength was sufficient to inhibit growth of 

 organism when used in Dunham solution, but when plates were made 

 from these tubes colonies of walnut blight developed. 



CONTROL OF WALNUT BLIGHT. 



Spraying. The earliest attempts at the control of this disease con- 

 sisted, as has been the case with most plant diseases, in spraying with 

 Bordeaux mixture. Pierce carried on a considerable amount of such 

 work and at his suggestion a number of growers gave this method of 

 treatment quite a thorough trial. As a result of his work Pierce recom- 

 mended spraying with Bordeaux mixture just before the trees came 



