Abstract
Efficacy of plant extracts, BAU-Biofungicide (a Trichoderma based preparation) and
chemical fungicide Tilt (0.1%) were evaluated to manage leaf blight of wheat caused
by Biopolaris sorokiniana in cv. Kanchan and Prodip. The field experiments had been
conducted in Dhanna Rampal Block, Tangail sadar, Bangladesh for three successive
years during November, 2015 to July, 2018. Wheat seeds harvested from the
experimental plots were evaluated for seed health and quality in 'Professor Golam Ali
Fakir Seed Pathology Centre', BAU, Mymensingh. Three years of field trials, seed
treatment with BAU-Biofungicide (3%) resulted significant effect in increasing the
field emergence, reducing seedling mortality and increasing plant stand in both
cultivars. In all the three years of field experiments, the lowest disease severity was
observed in plots where Tilt was used as spray followed by seed treatment with BAUBiofungicide plus BAU-Biofungicide spray (3%). According to final field experiment
in the year 2017-18, seed treatment with BAU-Biofungicide plus BAU-Biofungicide
spray, yielded the highest plant height and length of ear in comparable to Tilt and
other treatments. BAU-Biofungicide showed excellent effect in producing the number
of healthy grains/ear (37.6 in Kanchan and 40.3 in Prodip), where Tilt produced (39.7
in Kanchan and 40.7 in Prodip). Maximum number of grade-0 seeds (91.50%) in
Kanchan and (93.67%) in Prodip were observed in Tilt followed by BAU-Biofungicide
seed treatment plus BAU-Biofungicide spray (90.17%) in Kanchan and (91.83%) in
Prodip. The prevalence of seed borne fungi were investigated by blotter method. The
identified seed borne fungal species were Bipolaris sorokiniana, Fusarium moniliforme,
Fusarium oxysporum, Curvularia lunata, Alternaria tenuis and Aspergillus flavus. The
highest reduction of seed borne infection by Bipolaris sorokiniana was observed
(93.24%) in Kanchan and (88.89%) in Prodip over control in harvested seeds where
plots were sprayed with Tilt; while, seed treatment with BAU-Biofungicide plus BAUBioungicide spray resulted (87.84%) in Kanchan and (83.33%) in Prodip over control.
Maximum increase in seed germination (97.50%) in Kanchan and (97.25%) in Prodip
were observed in Tilt as spray followed by seed treatment with BAU-Biofungicide
plus BAU-Biofungicide spray resulting (96.50%) in Kanchan and (96.00%) in Prodip
which were 15.57% and 11.63% higher increase over control. In tray method, the
highest increase of normal seedlings in Kanchan (20.00%) and in Prodip (16.35%) were
observed in BAU-Biofungicide seed treatment along with spray. Tilt resulted higher
increase in vigour index over control (50.38%) in Kanchan and (44.90%) in Prodip
while, BAU-Biofungicide seed treatment plus BAU-Biofungicide spray resulted
46.39% in Kanchan and 41.98% in Prodip. The highest grain yield in Kanchan (3.44
t/ha) and in Prodip (3.92 t/ha) were obtained by applying Tilt followed by seed
treatment with BAU-Biofungicide plus BAU-Biofungicide spray resulting (3.18 t/ha)
in Kanchan and (3.69 t/ha) in Prodip which were 37.26% and 43.38% higher grain
yield over control. The highest Benefit -Cost Ratio (BCR) was obtained in Kanchan
(2.80:1) and in Prodip (3.33:1) when plots were sprayed with Tilt followed by seed
treatment with BAU-Biofungicide plus BAU- Biofungicide spray in Kanchan (2.58:1)
and in Prodip (3.13:1).