Abstract:
Macrophomina phaseolina
(Tassi) Goid, causing charcoal rot disease of
soybean, is one of the major factors
threatening soybean production, especially
in dry years. This pathogen remains the
prevailing causal agent of charcoal rot
disease that significantly suppresses the
yield of a variety of oilseed crops. Its wide
host range and ability to survive under arid
conditions, coupled with the ineffective use
of fungicides against it, have spurred
scientific endeavours for alternative avenues
to control this phytopathogen. Hence, the
present study aimed to provide empirical
evidence of the efficacy of fungal isolates
of Trichoderma spp. as biological control
agents against charcoal rot in soybean
(Glycine max L.). In this study Trichoderma
harzianum strains 6, 14, 17, 21, 44,
T. asperellum 26 and T. virens 32 were
evaluated as potential biological agents for
control of this disease. Mycelial growth of
M. phaseolina strain h-7 was reduced by
cell-free and volatile metabolites of
Trichoderma strains by 16.4 to 64.8%.
T. harzianum strain Tj17 significantly
(p≤0.05) reduced the incidence (to 7.3%)
and severity (to 3%) of disease 42 days after
inoculation and increased the 1000 grain
weight (to 178 g) in greenhouse conditions.
For confirmation of the greenhouse tests,
the selected antagonists were re-examined
in field trials, where this isolate reduced the
disease incidence (to 10%) and severity (to
3%). The overall results of this study show
high capability of used antagonists in
reduction of disease severity and incidence,
and resulting in increased weight of the
product. Hence, the findings reported in the
present study supported the applicability of
Tj17 isolate as possible alternative to
fungicides for the control of charcoal rot in
soybean.
