Research Bulletin (Iowa Agriculture and Home Economics Experiment Station)


Evidence has been presented indicating that Diplodia zeae in its normal growth produced an endocellular substance inhibitive to its own growth. This substance reduced by two-thirds the growth of Diplodia zeae on agar to which it had been added. Germination of spores of Diplodia zeae was greatly reduced.

The inhibitive action was not destroyed by correction of hydrogen- ion concentration or sugar concentration in the solution of the inhibitor.

The inhibitor retained its action after moderate dilution with distilled water and after boiling or autoclaving at 15 pounds pressure for 1 hour.

The action of the inhibitor was retained after acid and alkaline hydrolysis and after oxidation with potassium permanganate and hydrogen peroxide.

The inhibitor was non-volatile, was not extracted with ether, chloroform or acetone, and only partially extracted with 80- percent ethyl alcohol.

The tests indicate that the inhibitor is a complex substance which is liberated from the mycelium after 5 to 11 weeks in artificial culture and is present in infected portions of the host plant.



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