Abstract
Background
High losses of sorghum crops due to fungal diseases, such as grain mold and stalk rot, are economically harmful and cause increased use of environmentally damaging chemical fungicides, which also are detrimental to human health. Hence, finding safe and effective ways to manage fungal diseases of sorghum is urgently needed.
Results
In the present study, the antagonistic activities of
Trichoderma viride
and
T. harzianum
against different pathogenic fungal strains were evaluated in vitro using a dual culture assay. Furthermore, the anti-mycotic activity of
Trichoderma
spp. culture filtrates was evaluated against different fungal strains using a food poisoning technique. Additionally, the antifungal activities of ethyl acetate extracts of
T. viride
and
T. harzianum
against different pathogens were evaluated using a disk diffusion method. As indicated by the dual culture assay,
T. harzianum
suppressed 66.8, 69.5, 68.7, 54.6, 84.12, and 71.39% of the mycelial growth of
Curvularia lunata
,
Exserohilum rostratum
,
Fusarium chlamydosporum
,
F. incarnatum
,
F. proliferatum
, and
Macrophomina phaseolina
, respectively.
T. viride
was more effective for controlling the growth of these pathogens, inhibiting 81.0, 89.0, 63.0, 70.7, 84.4, and 71.8% of mycelial growth, respectively. Both
E. rostratum
and
M. phaseolina
showed resistance to carbendazim fungicide at all tested concentrations, whereas the fungicidal concentrations of carbendazim against
C. lunata
,
F. chlamydosporum
, and
F. incarnatum
strains were 2.50, 1.50, and 2.00 ppm, respectively. Furthermore,
F. proliferatum
was sensitive to carbendazim fungicide at all tested concentrations. Antifungal assays of the ethyl acetate extracts of
T. viride
and
T. harzianum
indicated the potent activity of these extracts against fungal phytopathogens with different susceptibility patterns.
F. chlamydosporum
was the most sensitive to the extracts of
T. viride
and
T. harzianum
with minimum inhibitory concentrations of 0.5 and 1.0 mg/disk, respectively.
Conclusion
The potent suppression of sorghum phytopathogens by
T. viride
and
T. harzianum
makes them potential sources of safe and effective natural fungicides compared to carbendazim fungicide.