Biological Control of Groundnut Stem Rot and Collar Rot Pathogens under in vitro Conditions
V. Divya Rani
*
Department of Plant Pathology, Professor Jayashankar Telangana State Agricultural University, Hyderabad, Telangana (500030), India.
Hari Sudini
International Crops Research Institute for the Semi-Arid Tropics, Patancheru, Telengana (502324), India.
P. Narayan Reddy
Anurag Agricultural University, Venkatapur, Ghatkesar Rd, Hyderabad, Telangana (500088), India.
G. Uma Devi
Department of Plant Pathology, Professor Jayashankar Telangana State Agricultural University, Hyderabad, Telangana (500030), India.
K. Sadaiah
Department of Genetics and Plant Breeding, Professor Jayashankar Telangana State Agricultural University, Hyderabad, Telangana (500030), India.
K. Vijay Krishna Kumar
Department of Plant Pathology, Professor Jayashankar Telangana State Agricultural University, Hyderabad, Telangana (500030), India and Department of Plant Pathology, Acharya N G Ranga Agricultural University, Guntur, Andhra Pradesh (522034), India.
*Author to whom correspondence should be addressed.
Abstract
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.
Keywords: Biological control, groundnut, stem rot, collar rot, compatibility, fungicides, herbicides