This study was conducted to evaluate the comparative effectiveness of different methods to suppress fruit fly in Central Extension Resources Development Institute (CERDI), Gazipur. in rabi season, 2004-2005. The treatments used were (a) covering of tender fruits by porous polypropylene bag, (b) soil treatment with Diazinon 14G), (c) cover spray with fenitrothion (Sumithion 50EC), (d) bait spray prepared with molasses and Hilthion 57EC, (e) spraying neem oil and (f) control/untreated. The study was conducted with Randomized Complete Block Design (RCBD) with 4 replications arranged in field plots. The whole plot was divided into 24 equal sub plots of 3m x 2m size with an inter plot distance of 2m. Two pits of 30cm x 30cm x 20cm were dug in each plot at a distance of 2m between pits.
Cow dung and chemical fertilizer were applied as recommended by Rashid (1993) for cucumber at a rate of 10,000, 150, 125 and 100 kg of cow dung, urea, TSP and MP per hectare respectively. The half of cow dung, TSP, MP, and one third of urea were applied as basal dose during land preparation. The remaining cow dung, TSP and MP were applied in the pit 15 days before transplantation of seedlings. The rest of urea was top dressed after each flush of flowering and fruiting in three equal splits.
Seeds of improved cucumber were collected from the farmers of Narshingdi. The seedlings were raised in polypropylene bag containing 50% well-decomposed cow dung and 50% sandy loam soil. A 20-day old single healthy seedling was transplanted in each pit of the experimental plots and necessary measures were taken for their survival and creeping. Before flowering some red pumpkin beetles were found and were controlled by hand picking. Irrigation, weeding and mulching in the plots were done whenever necessary.
Treatment Application In the morning hours (8.0 am to 9.30 am ) the hand pollinated and naturally cross pollinated flowers were checked and recorded the pre-treatment infestation data and then covered by transparent polypropylene bag (20 x 10cm) having a few holes. This bagging operation was completed in the early morning before the beginning of frequent visit by the fruit fly. At the harvesting period, the bagged fruits were collected and the post-treatment infestation data were recorded along with other fruits harvested from the other treatments. These operations were undertaken continuously throughout the reproductive stages of the plant with the appearance of new fruits up to the last economic harvest.
Dazinon 14G @ 2.0g per pit was broadcasted in soil around the root zone of the plants. The insecticide was mixed with the soil properly followed by a light irrigation. Foliar application of Sumithion 50EC @ 2.5ml per liter of water was used. The spraying was done in the afternoon to avoid bright sun and drift caused by strong wind. The bait was prepared and sprayed by mixing 15g of molasses, 2.5ml of Hilthion 57EC and 2.5 liters of water. The required spray volume was prepared by mixing neem oil (2%) in water. A few drops of liquid detergent were used to break the surface tension of water and to help the solubility of neem oil in water. Each treatment was applied 4 times at 15 days interval at flower initiation, early, mid and late fruiting stages of the plants. The rest 4 plots were kept untreated. Before flower initiation the red pumpkin beetle and aphid observed on the plots were controlled by hand picking.
Data Collection and Analysis: The whole reproductive period of cucumber was divided into four stages as flower initiation, early, mid, and late fruiting stages. Data were collected on the basis of some pre-selected parameters viz., percent fruit infestation by number, weight, fruit yield, percent weight reduction over healthy fruit etc. Infestation of fruit and fruit weight reduction were calculated in percent using the following formulae:
% Fruit Infestation = Number of IF / Number of HF+ Number of IF x 100
% Weight Reduction =. Weight of HF- Weight of IF / Weight of HF x 100
Data were analyzed by MSTAT soft ware. The per cent data were transformed into ArcSin SIX/100 for the accuracy of the results. The range test of the means was done by using Duncan's Multiple Range Test (DMRT).