Biological Control of Groundnut Stem Rot and Collar Rot Pathogens under in vitro Conditions

The experiment was conducted under laboratory conditions by using native isolates. These were tested against stem rot (S. rolfsii) and collar rot (A. niger) pathogens of groundnut under in vitro conditions by using dual culture technique. The fungal and bacterial bioagents which are inhibitory against these pathogens were identified by 18S rRNA (fungi) and 16S rRNA (bacteria) techniques and were compared with those from the GenBank using the BLAST program. Among fungal isolates T. harzianum (MBNRT-1) was superior in inhibition of S. rolfsii and A. niger and the per cent inhibitions were 70.5% in case S. rolfsii whereas; in A. niger the inhibition was 72.9 per cent. Among native bacterial isolates the isolate B. amyloliquifaciens (MBNRB-3) and is significantly superior over the other isolates in inhibiting the pathogens S. rolfsii and A. niger under in vitro conditions and the inhibitions were 66.6 per cent and 63.0 per cent respectively. Further, compatibility of effective fungal and bacterial bioagents T. harzianum (MBNRT-1) and B. amyloliquifaciens (MBNRB-3) with six fungicides and eight herbicides indicated that among the fungicides the azoxystrobin was highly compatible with both the bioagents T. harzianum (MBNRT-1) and B. amyloliquifaciens (MBNRB-3) whereas, among the herbicides imazethapyr + imazamox was found to be compatible with both the bioagents with all the concentrations. While, tebuconazole, thiram, mancozeb+carbendazim (fungicides) and quizolofop-p-ethyl and pendimethalin (herbicides) were highly inhibitory to the T. harzianum (MBNRT-1) and B. amyloliquifaciens (MBNRB-3) under in vitro conditions.