Biological Control of White Rot of Onion (Sclerotium cepivarum) by Coniothyrium minitans

Abstract

SUMMARYThe fungus Coniothyrium minitans is pathogenic to Sclerotium cepivorum, the causal agent of white rot of onion. In a glasshouse experiment, pycnidial dust prepared from C. minitans was used in soil treatments and as a seed dressing to protect onion seeds sown in S. cepivorum infested soil. Comparison was made with seed dressed with calomel, the standard fungicide used for white rot control. Seed dressing with C. minitans or soil dusting with C. minitans protected the onion plants from white rot as well as did calomel dressing. The calomel‐treated plants showed markedly poorer development than those treated with pycnidial dust, presumably because of phytotoxicity. The pycnidial dust appears equally effective against white rot, is much safer than calomel and should be very much cheaper. It is recommended for development for practical control of white rot.