Bitter gourd is a popular vegetable in Bangladesh and is now grown all year round. Growers face a number of pests and diseases: fruit flies and pumpkin beetles in particular damage the crop. These pests bore into the gourds, making them unfit to eat and causing them to rot, and farmers count the losses.

The fruit fly is one of bitter gourd's main enemies. The female fly inserts her ovipositor into the underside of a young fruit and lays eggs. A watery liquid oozes from the egg-laying spot and dries to a brown colour. The larvae that hatch feed on the flesh of the fruit, which turns yellow, rots and drops.

If fruit flies attack, affected gourds or flowers should be collected and destroyed or burnt. The land should be ploughed well so that birds can eat the pupae. In the jackfruit season, jackfruit cores can be placed here and there in the field: female flies will lay their eggs in them instead of the gourds, reducing the damage. Pheromone traps should be set up as soon as the first flowers appear, three traps for every 10 decimals.

During the mango or date-juice season, a little poison can be mixed with the juice and kept in bottles with a window cut into the side, placed around the field; flies that enter will die. Alternatively, 100 grams of ripe sweet pumpkin or another gourd-family vegetable can be chopped finely and mixed with a little poison (for example 0.25 grams of Sopsin) to make a poison bait, placed in earthen pots around the field. A cypermethrin-group insecticide can be sprayed at 1 ml per litre of water. The vegetable must not be eaten or sold within 15 days of spraying.

The white fly also attacks bitter gourd. The female lays eggs in young fruit; the larvae that hatch eat the flesh, and the fruit rots and falls early. Control measures should be taken quickly if white flies attack.

• Keep cultivation clean, and collect and destroy affected parts.
• Use sex pheromone traps and poison bait traps together.
• For the bait, mix 0.25 grams of Sevin 85 powder with 100 grams of mashed ripe sweet pumpkin, and change the bait every three to four days.

The pumpkin beetle also does serious damage. It eats holes in the leaves of seedlings, damages roots and can kill mature plants. Adult beetles should be picked off affected plants by hand and killed.

Seedlings should be kept covered with mosquito netting for 20 to 25 days. Sevin or Carbarin-85 can be sprayed at 2 grams per litre of water. To control the larvae, 2 to 5 grams of Basudin or Diazinon 10G should be applied at the base of each plant, followed by irrigation. The vegetable must not be eaten or sold within 15 days of spraying.

The viral mosaic disease of bitter gourd is also very harmful. Affected plants show leaves with a mosaic of yellow and dark green patches.

To protect the crop, disease-free seed should be sown, fertiliser used in balanced doses and infected plants pulled out of the field. Aphids and white flies carry the disease, so they should be controlled with an imidacloprid-group insecticide such as Admire, sprayed at 1 ml per litre of water. The vegetable must not be eaten or sold within 15 days of spraying.

Information: Krishi Batayan.

Source: Jagonews24. First published in Bengali on The Agro News.