Experimental site and climatic condition
The experiment was conducted in the Field Laboratory of Agrotechnology Discipline, Khulna University, Khulna (22°47′57.84″N, 89°31′53.48″E), Bangladesh during December 2013 to June 2014. The experimental site was characterized by moderately high temperature and heavy rainfall during kharif season (April-October) and scantly rainfall with moderately low temperature during rabi season (November-March).
Raising of seedlings and transplanting
The seed of local brinjal variety named Makra was collected from local market Gollamari and raised as seedling in germplasm centre of Khulna University. Brinjal seedling was raised in seedbed of 3m×1m size. Weeding, mulching and irrigation were done when required. The experiment was laid out in the Randomized Complete Block Design (RCBD) with three replications. The entire experimental plot was divided into 3 blocks each containing 7 units plots. Totally there were 21 unit plots. The treatments were randomly assigned to each unit plot so as to allot one treatment combination once in each block. The unit plots were 3m×2m in size with 75 cm distance between the blocks and 50 cm between the unit plots. Each plot was contained 16 plants. Organic amendments and chemical fertilizers were applied in the field as recommended by Bangladesh Agricultural Research Council (Anon., 2005). Healthy seedlings were uprooted from the seedbed and were transplanted in the experimental plots during late afternoon on December, 2013. Immediately after planting, the seedlings were watered. Seedlings were also planted around the experimental area for gap filling and to check the border effect.
Preparation of neem leaf extract
Fresh leaves of Azadirachata indica (Neem) were collected from the plants at the Khulna University campus. Then the collected leaves were dried in shade and were ground with a domestic grinder. Fifty grams (50g) of the ground leaves were added with water and left overnight to make 1000 ml solution. The mixture was then filtered and the filtrate poured into a flat bottom flask as stock for the field spraying five grams of wheel powder was added to increase its adhesiveness (Murugesam and Murugesh, 2009).
Preparation of garlic extract
Bulbs of garlic were brought from the market, 30 g of garlic bulbs were chopped into pieces using knife and such material was ground thoroughly, mixed with 50 ml of water and the ground mixture was soaked in little quantity of water over night and squeezed through muslin cloth and the volume was made up to 1 liter to get 3 per cent extract five grams of wheel powder was added to increase its adhesiveness (Murugesam and Murugesh, 2009).
Preparation of tobacco leaf extract
Tobacco leaves were brought from the market, 30 g of tobacco leaves were chopped into pieces and such material was ground thoroughly in mixed with 50 ml of water and the ground mixture was soaked in little quantity of water over night and squeezed through muslin cloth and the volume was made up to 1 liter to get 3 per cent extract five gram of wheel powder was added to increase its adhesiveness (Murugesam and Murugesh, 2009). The neem oil, mahogany oil and mahogany cake were purchased from the local market of Khulna.
Treatment application
The treatments namely Untreated control (only water), Neem leaf extract (@ 50 gl-1 water), Neem oil (@ 40 ml l-1 water), Mahogany oil (@ 40 ml l-1 water), Mahogany oil + Mahogany cake (oil (@ 40 ml l-1 water + cake @ 250 kg ha-1), Garlic extract (@ 50 g l-1 water) and Tobacco leaf extract (@ 50 g l-1 water) were applied as foliar sprays starting after 20 days of transplanting and repeated subsequently at 7 days interval and mahogany cake was applied in the plot and incorporated with soil. Care was taken to avoid drifting of treatment to neighbouring plots. No pest control technique was applied in untreated control plots. However, an equal volume of water, which was used for other plots, was sprayed at 7 days intervals. After transplanting of seedlings, various intercultural operations were accomplished for better growth and development of the plants.
Harvesting and data collection
Harvesting of fruits was started at 60 days after transplanting and continued up to 150 days after transplanting with an interval of 7 days. Harvesting was usually done manually. In order to know the effects of the treatments on controlling BSFB. Data were collected on total numbers of shoot, total numbers of infested shoot, percentage of shoots damage, percentage reduction of shoots infestation, numbers of larvae per infested shoot, total numbers of fruits, percentage of fruits damage, percentage reduction of fruits infestation, numbers of larvae per infested fruits, cost of production, gross return and benefit cost ratio (BCR).
Data analysis
Data were analyzed by using MSTAT-C software for analysis of variance. ANOVA was made by F variance test and the pair comparisons were performed by Duncan's Multiple Range Test (DMRT).