The experiment was conducted at the Plant Pathology Field Laboratory of Bangladesh Agricultural University, Mymensingh during Rabi season (October-March). The experimental area belongs to the old Brahmaputra flood Plain in Agro-ecological Zone-9 (area 7230 km2). The macro-climate of the experimental area (BAU farm area) is subtropical in nature. The Local variety of chilli cultivar Balijuri collected from the Horticulture Centre, Mymensingh, Bangladesh was used for this experiment. Cowdung at the rate of 20 t ha-1 and fertilizers Urea, TSP (Triple Super Phosphate) MOP (Muriate of Potash) at the rate of 250, 200 and 150 kg ha-1, respectively were used. The whole amount of TSP and half amount of urea and MOP were applied as basal dose before transplanting of seedlings. The rest amount of urea and MOP were applied at 30 Day After Transplanting (DAT). The experiment was laid out in a Randomized Complete Block Design. Treatments were assigned to each block at random. The space between the blocks and between the plots was 1.00 and 0.50 m, respectively. Thirty days old day seedlings were transplanted maintaining a row to row distance of 25 cm and plant to plant distance of 30 cm. Light irrigation was given immediately after transplanting.
The transplants were shaded for a few days with the half of banana leaf sheath to protect them from scorching sunshine. The transplants however were kept open at night to allow them to receive dew. The treatments were control (no spray), field sanitation, extracts of neem (Azadirachta indica), mahogany (Swietenia mahagoni), koromcha (Carissa carandas), garlic (Allium sativum) and combined extracts of neem-mahogany-koromcha and neem-mahogany-garlic and a broad-spectrum chemical fungicide Ridomil (active ingredient; metal axyl and copper oxychloride) 50 WP @ 0.2%, which was used as a positive control.
The plant parts listed were used in this study and these were collected from the Horticulture centre, Bangladesh Agricultural University, Mymensingh. Procedure of making the plant extracts and application rate to plants was followed as described by Kabir et al. (2014). In brief, plant parts were washed with distilled water, blended in a blender machine and these extracts were sieved through a thin cloth. The plant extracts were diluted with water at 1:10 (w/v) dilution. The prepared fungicide and plant extracts were sprayed first at 21 day after transplanting and after that sprayed at 15 day intervals. The symptom bearing diseased leaves/infected plants serve as a source of inoculums, which were collected, removed and destroyed maintaining zero tolerance, therefore field sanitation was used as a treatment. Disease reactions such as disease incidence and severity were calculated.The plants which had spot(s) at least one leaf was considered as infected. Total number of infected plants was recorder in each plot.
Plant infection (%)= (Number of infection plants/Total number of plants) x100
Disease severity was recorded as percent leaf area diseased. Eight infected plants were selected from each plot at random and twenty infected leaves of these infected plants were selected at random in each plot due to measure percent damaged area. The average values were used. The disease severity was calculated by the following formula:
Leaf area diseased (%)= (Area of plant tissue affected by disease/Total area) x1000
Flowerings of chilli plants were started at 40-45 day after transplanting. Plants were produced flowers and fruits continuously upto 3-4 months after transplanting. But all fruits didn’t mature and ripe at a time. Those fruits were ripened, were harvested and continued by turns. After 4 months of transplanting, rest of the chilli fruits were ripened, harvested and weighed.