Biological control of Rhizoctonia solani by binucleate Rhizoctonia spp. and hypovirulent R. solani agents
1995
Herr, L.J.
Despite research on biological control dating back to the early 1930s, reliable, economical biocontrols of diseases caused by Rhizoctonia solani are not generally available commercially. New approaches for detection and use of novel agents and development of broadly applicable biological control management systems are needed, especially for field crops. During the past 10 years, new sources of agents from within the diverse groups of binucleate Rhizoctonia spp. and hypovirulent R. solani isolates have been demonstrated to be effective in biocontrol of a range of host--R. solani disease combinations. Although these agents include isoiates from several different binucleate Rhizoctonia anastomosis groups (AG) and hypovirulent R. solani AG. neither mycoparasitism nor antibiosis is involved in biocontrol of R. solani by any of these isolates. Postulated mechanisms of biocontrol include induction of systemic host resistance, and/or competition for recognition and invasion sites or nutrients. Tested collections of binucleate Rhizoctonia spp. and hypovirulent R. solani differ markedly in effectiveness as biocontrol agents for diseases caused by R. solani. Reportedly, plant surface-colonizing isolates (i.e. on or superficially within outer tissues of roots, crowns, hypocotyls, stems or petioles) are effective biocontrol agents, whereas, non-colonizers are ineffective.
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