Rooting of cut shoots of cotton in culture filtrate of Fusarium vasinfectum

A study was made of the toxicity of culture filtrates of the cotton-wilt pathogen, Fusarium vasinfectum Atk., grown in synthetic Czapek's medium, to cut shoots of cotton. This indicated that, under laboratory conditions, the culture filtrate (fourteen days old) when dialysed against distilled water at 4-5°C. for four days to rid the crude filtrate of metabolites-earlier observed to be toxic to the plant-brought about typical wilt symptoms, which have been described in detail elsewhere. Higher dilutions of this dialysed neat filtrate did not produce any symptoms of toxaemia, but induced rooting. However, the dialysed filtrate autoclaved at 15 lb. pressure for 15 min. (with the view of inactivating the toxin) induced profuse rooting in the cut shoots of cotton at all concentrations, and in no case were there any typical wilt symptoms