Studies on Root Rot/ Wilt of Soybean
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Date
2011
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Publisher
UAS, Dharwad
Abstract
Soybean Glycine max (L.) Merill is protein rich oilseed crop. It is considered
as a golden bean, miracle bean and wonder crop of the 20th century because of its
characters and usage. Wilt/root rot is caused by Sclerotium rolfsii, Rhizoctonia sp. and
Fusarium sp. are major constraints in soybean production. Isolates of all the
pathogens were obtained during the survey from different locations of northern
Karnataka and the disease incidence varied from 3.36 to 36.30 per cent.
The study on variability of the causal organisms was undertaken. Isolates of
all the pathogens showed marked difference in their growth rate and time taken for
sclerotial initiation and spore production.
Cultural studies on different media revealed that S. rolfsii and Fusarium sp.
grew well on Potato Dextrose Agar and Rhizoctonia sp. grew well on Sabouraud’s
Agar. Isolates varied in their growth in all the temperature tested. Maximum growth
rate and spore germination was observed at 30ºC while no growth at 40ºC.
In vitro studies revealed that Trichoderma viride, Trichoderma harzianum,
Azadirachtin, Neem oil, Mancozeb, Carbendazim, Thiophanate methyl,
Hexaconazole, Propiconazole, Carbendazim + Mancozeb and Carboxin + Mancozeb
were more effective in inhibiting the mycelial growth of all the three pathogens.
Glasshouse studies revealed that soil drenching with Carbendazim, Carboxin +
Thiram, Thiophanate methyl, Hexaconozole, Neem oil, Nimbicidine, T. harzianum
and T. viride helped to manage the disease successfully.