[Vol. 10 



164 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



The fungus was grown on 



per cent agar containing M/50 



dextrose, M/50 KN0 3 , M/100 KH 2 PO<, M/500 MgS0<, and 5 



drops of M/1000 FeP0< per 1000 cc. of solution. The medium 



was sterilized in 100-cc. quantities and the reaction was then 



adjusted 



0.5 N H,P0 4 or 0.5 N KOH. After it had stood for several days, 



it was then poured into large petri dishes and the Ph values were 



determined. The petri dishes were inoculated by placing a 



the addition of appropriate quantities of sterile 



TABLE II 



GROWTH OF MYCELIUM ON AN AGAR MEDIUM OF DIFFERENT INITIAL 



H-ION CONCENTRATIONS 



Culture 



P 



Av. diam. of colonies in mm . 



Remarks 



No. 



value 



7 da. 



10 da. 



Gain 



1 



2.9 



20 



32 



12 



Mat floccose 



2 



3.5 



35 



61 



26 



Mat floccose 



3 



5.2 



62 



92 





Mat less floccose 



4 



6.0 



67 



92 





Mat less floccose 



5 



6.8 



58 



92 





Mat less floccose 



6 



7.2 



60 



92 





Mat less floccose 



7 



8.2 



51 



92 





Mat less floccose 



single pycnidium at the center of each and the cultures were then 

 placed in light in a glass incubator maintained at 25-30° C. As 

 shown in table II, the diameters of the colonies were measured at 

 2 different times. Under such conditions, growth was found 

 to be most rapid when started at Ph 6 and to fall off at either end 

 of the range used. The colonies in the plates having an initial 

 i of 2.9 and 3.5 grew comparatively slowly but eventually 



Ph 



reached the margins of the plates. 



Control 



No experimental work has yet been done on the control of this 

 disease. However, the life history of the causal organism, its 

 relation to its host plant, and the course of the disease in the field 

 suggest certain measures by which losses may be minimized, if 

 not entirely prevented. Halsted reported encouraging results 

 from spraying with Bordeaux mixture for control of pod blight 

 of lima beans, and Harter ('17) recommends that spraying begin 



