5.2.73
SCLEROTINIA STEM ROT OF BISHOP WEED AND ITS MANAGEMENT BY BIO-AGENTS

SB SINGH

Dept. of Plant Pathology, CS Azad University of Agriculture and Technology, Kanpur - 208 002, India

Background and objectives
Bishop weed (Trachyspermum ammi) is one of the important herbal spices and medicinal plants of the world. Recently, this crop was found to suffer from stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary [1] in Uttar Pradesh. it is posing a serious threat to cultivation of this important condiment due to heavy incidence. This disease was hitherto unknown in India. Therefore, detailed studies ae being carried out on the disease and its management.

Results and conclusions
The affected part of the stem becomes water-soaked, brown and finally straw-coloured. There is thick, white mycelial felting on the surface of the stem, followed by formation of sclerotia both on and in the stem. While taking isolations, using sclerotia, it was observed that Coniothyrium minitans and Bacillus subtilis were constantly associated with them. Both the organisms were screened for antagonism against S. sclerotiorum and their strong inhibitory activity was investigated in vitro. It was found that C. minitans and B. subtilis parasitized sclerotia formed by S. sclerotiorium and led to their decomposition. Thus both the organisms significantly affected survival of sclerotia of S. sclerotiorum. Bishop weed seeds were slurry treated with C. minitans and B. subtilis, and both sown in pot-soil artificially infested with sclerotia ofS. sclerotiorum. Also, there was significant reduction in disease severity by treatment of seeds with the test organisms. Further, it was observed that under laboratory conditions, both the organisms reduced sclerotia formation on stem pieces of the host. Thus both organisms not only exhibited inhibitory activity against S. sclerotiorum in vitro, but were also effective in the management of the disease in field conditions.

Reference
1. Kohn LM, 1979. Phytopathology 69, 881-886.