Beans are an important vegetable crop in Bangladesh. It is rich in protein, fiber, vitamins and minerals. Beans are cultivated commercially all over the country from home to field. In the financial year 2018-19, the amount of land under beans in Bangladesh is 2082 hectares and the total production is 144050 metric tons (Agricultural Statistics Yearbook 2019). Different types of insects and diseases directly and indirectly affect bean production and their attack destroys a significant portion of the crop. In this situation, it is very important to gain knowledge about the type and management of various insects and diseases to protect the crop. The following is a discussion on the attack and management of major pests and diseases in bean crops.
Pod borer: Insect larvae pierce flowers, flower buds and fruit and eat the inner part. Their attack destroys large quantities of fruit and makes them unsuitable for sale in the market. One larva can destroy multiple flowers. As a result, insect bites and feces can be seen. Excessive attacks cause the fruit to fall off and the yield to decline.
Insect larvae are first located inside the flower. Infected flowers and fruits should be collected and killed along with insect larvae. Beneficial insects on the land need to release Bracon Habitat. For one hectare of land, 1 Banker Bracon (800-1000 insects) has to be released every week. Organic pesticides (MNPV @ 0.2 g / liter) should be applied. Spinosade (Tracer 45 SC 0.40 ml per liter of water or Success 1.2 ml) should be sprayed as soon as the infested area is attacked.
Aphid: Both adult insects and nymphs suck sap from new tips, young leaves, flower buds, flowers and fruits. If the number of insects in young trees is high, the trees may die. In older trees, the leaves crumble, turn yellow, and slow down growth. When the tree is attacked in flowering and fruiting stage, the flower buds and young fruits fall off and the young tips die. They spread the mosaic virus on the trees.
Insects are grouped on tips and leaves in the early stages. In this case they have to be crushed by hand. Neem seed solution (1 kg half-broken neem seeds should be soaked in 20 liters of water for 12 hours) should be sprayed. In case of excessive infestation, Malathion 57 EC should be sprayed at the rate of 1 ml per liter of water or Lambda Cyhelothrin (Cyclone 2.5 EC or Carat 2.5 EC) at the rate of 1 ml per liter of water.