Abstract:
Wheat (Triticum aestivum L.). an important cereaJ crop ... is produced aJI over the
country. Leaf blight caused by Bipolaris sorokiniana is a common constraint of
limiting wheal production in Bangladesh. Use of plant extracts as a biocontrol
agent against plant diseases is a relatively recent approach. Efficacy of plant
extracts in controlling leaf blight (Bipolaris sorokinianas of wheat was studied
during the cropping season 2006-2007. The experiments were conducted in the
Seed Health Laboratory. Department of Plant Pathology and in the farm of the
Sher-e-Bangla Agricultural University, Dhaka. Initially 33 plant species were
evaluated for their efficacy against Bipolaris sorokiniana by an in vitro test.
Among them 13 species were found promising and selected for field evaluation
against leaf blight disease. A remarkable reduction of the severity of leaf blight
was achieved by treating seeds with botanicals. The treatments showed significant
effect in respect of leaf blight severity (0-5 scale) for flag leaf and penultimate leaf
at flowering, milking and bard dough stages. The lowest severity of flag leaf and
penultimate leaf in every stage was found in the treatment T12 (Seed treatment
with turmeric rhizome extract) followed by treatment T
(Seed treatment with
garlic clove extract) whereas the highest disease severity was recorded under the
Ill
2
treatment T1 (untreated control). Significantly the highest plant height (93.09 cm)
was found in the treatment T2~ ear length (15.58 cm) in treatment Ts (Seed
treatment with kalijira seed extract) and the number of spikelets Ices (19.I 1) in
treatment T5 (allamanda leaf extract). The number of grains/ear, number of healthy
grains/ear, weight of grains/ear and weight of healthy grains/ear were increased by
using seeds treated with extracts of kaliji.ra (Ts), garlic (T2). allamanda(T
and
turmeric (T
Seed treatment with plant extracts significantly increased grain yield over untreated control. Among the plant extracts, turmeric rhizome extract
12).
treated seeds resulted the highest grain yield (3.60 t/ha) which was 39.44 % higher
over untreated control. Thus plant extracts have definite antifungal effect on
Bipolaris sorokiniana which could be employed as an ecofriendly approach in
controlling leaf blight of wheat.
