A fungal substance of selective action on plant growth produced by Pyrenochaeta sp.

The effect of the pink substance extracted from mycelia of Pyrenochaela sp. on growth of 10 kinds of plants was examined by germination test in the light. The substance inhibited the growth of germinating seedlings of 5 monocotyledonous plants (upland rice, sorghum, wheat, barley, and oat) at a concentration higher than 10 ppm of the partially purified pink substance, while it rather stimulated that of 5 dicotyledonous plants (chinese cabbage, cucumber, radish, turnip, and burdock) at 10-100 ppm. When the substance was sprayed on shoots of upland rice and Chinese cabbage germinated in pot, it inhibited the growth of seedlings of the former and stimulated that of the latter.