Effect of Different Levels of Black Pointed Seeds on Disease Incidence, Leaf Blight Severity and Healthy Seed Production of Wheat

The experiments were conducted in the Seed Pathology Laboratory and experimental Field of Plant Pathology Department, Sher-e-Bangla Agricultural University, Dhaka-1207, during the period from October 2008 to April 2009 to find out the effect of different levels of black pointed seeds on disease incidence, leaf blight severity and healthy seed production of wheat. Eight levels of black pointed seed samples namely T1 = 0% black pointed seeds treated with Bavistin 50 WP @ 0.25% of seed weight); T2 = 0% black pointed seeds treated with Provax 200 WP @ 0.25% of seed weight; T3 = 10% black pointed seeds; T4 = 15% black pointed seeds; T5 = 20% black pointed seeds; T6 = 25% black pointed seeds; T7 = 40% black pointed seeds and T8 = 55% black pointed seeds. Leaf blight severity showed significant variation at flag leaf stage, panicle initiation stage, flowering stage, milk stage and hard dough stage in respect of sowing different levels of black pointed seeds. Significantly lowest disease severity at flag leaf stage (0.09), panicle initiation stage (0.15), flowering stage (0.43), milk stage (1.14) and hard dough stage (2.30) were recorded when 0% black pointed seeds treated with Bavistin 50 WP were sown. On the other hand the highest disease severity of 0.45, 1.06, 1.32, 2.10 and 3.81 were recorded at the above mentioned growth stage of the crop respectively when seeds were sown with 55% level of black pointed seeds. Significantly the highest (3.67 t/ha) grain yield was obtained in Bavistin treated apparently healthy (0% black pointed seeds) whereas the lowest yield (2.25 t/ha) was obtained in sowing seeds having 55% black pointed seeds.