Abstract
Bavistin, Panoram, Calixin and Antracol were the most effective in that order in reducing sclerotial formation of Afacrophomina phaseolina. Rubigon exhibited intermediate effectiveness while Liromenzeb was the least effective in inhibiting sclerotial production. Panoram was the most effective in retarding sclerotial germi-nation followed by Bavistin. Antracol displayed intermediate action while Calixin was least effective in this connection. The most effective fungicide in reducing scle-rotial population in fungicide treated soil was Bavistin followed by Antracol, Panoram and Calixin in that order. Bavistin also proved effective in reducing per cent charcoal rot disease at all the rates ranging from 0.02 to 0,20%. Antracol was effective in controlling charcoal rot at 0.10 and 0.20% drench.
INTRODUCTION
Soybean crop suffers reduction in yield due to charcoal rot, caused by Macrophom-the phaseolina (Tassi) Goid (Dhingra and Sinclair, 1973) in this part of the world. The genetic resistance against the pathogen in the available commercial soybean cultivars is scarce (Anonymous, 1985), so chemothera-peutic control is the only hope to combat with this disease. Vir et al. (1974) tested some fungicides against M, phaseolina in the field on soybean and found that Topsin at 1000 ppm concentration gave the best re, suits. Ilyas et al. (1975) investigated the ef-fect of some fungicides against the mycelial growth, sclerotial production and germina-tion of Al. phaseolina on agar plates and on the green house grown soybean seedlings where the fungicides were used as soil drench.
MATERIALS AND METHODS
1. Isolation and Pathogenicity Test: The fungus was isolated from charcoal rot of-
(cued soybean plants by usual isolation technique (Pathak, 1987) and identified through morphological characters as de-scribed by Barnet and Hunter (1972). The purified culture of A!. phaseolinu was ob-tained by plating single sclerotium from the isolated fungus on potato dextrose agar (PDA). Mass culture of M. phaseolina was prepared on soybean seed. The pathogenic-ity of the isolate was confirmed on soybean seedlings grown in pots in the usual way, 2. Testing of Fungicides (in vitro): Antracol, Bavistin, Calixin, Liromenzeb, Panoram and Rubigon were tested at 5, 10, 20 and 50 ppm concentrations against the mycelial growth of M. phaseolina using a technique as de-scribed by Borum and Sinclair (1968). To each 90 mm petri plate containing calculated amount of fungicide and solidified potato dextrose agar, 4 mm agar plug of M. phase-olina mycelium was placed in the centre. Petri plates containing FDA and the pathogen culture but without the fungicide served as the check.
