July IS, 1920 



Presoak Method of Seed Treatment 



383 



the table, indicating so far a satisfactory degree of control under actual 

 field conditions through the use of the presoak method as formulated. 



Plants collected from the western experimental plots March 27 to 

 April 3, 1920, were examined microscopically for the presence of oozing 

 bacteria in suspected blackchaff lesions and in dead leaves. Platings 

 were made later from similar lesions where abundant oozing bacteria 

 were found, and these developed the typical blackchaff colonies. Table 

 XI summarizes the results obtained. 



Table XI. — Condition of western experimental plots in the spring of ig20 



"Seeds presoaked 6 hours, then treated with formalin i to 330 for 10 minutes, drained, covered 6 hours 

 and dried. 



* Seeds presoaked 6 hours, then treated with copper sulphate i to 80 for half hour (soaked), and dried after 

 dipping a moment in milk of lime. 



A marked increase in blackchaff was observed in the untreated plots, 

 evidently due to wind and rain spreading the disease during the resump- 

 tion of growth. The spreading effect was especially noted in the Abilene 

 plots where the treated area adjoins the untreated. Other treated areas 

 at Hays and Ames, more isolated, show from 2 to 4 per cent of infection, 

 as compared with 17 to 25.5 per cent in untreated plots. 



Observations made at Hays and Abilene, Kans., in the latter part of 

 May, 1920, are summarized in Table XII. At Abilene the plants were 

 I to 2 feet tall, at Hays over 2 feet high. Heads had not yet emerged. 

 Microscopic examination and confirmation of diagnoses by platings were 



