Second season paddy crop in Alappuzha faces black bug threat

The Kerala Centre for Pest Management (KCPM) has issued an alert over black bug (karinchaazhi) infestation in paddy fields under four Krishi Bhavans in Alappuzha district.

Officials say the presence of the pest has been confirmed in Punnapra, Nedumudi, Kainakary and Champakulam. The bugs have been found in fields undergoing second season paddy cultivation, around 25 days after sowing.

The KCPM warns that the black bug, which sucks sap from plants, could damage crops and urges farmers to remain vigilant. The pest is typically found on leaves. It is also seen in the soil or at the base of plants. It injures leaves and midribs, causing leaves to tear off and midribs to wilt.

Wounds caused by the black bug might also facilitate the spread of bacteria responsible for leaf blight. In cases of severe infestation, symptoms such as stunted growth, yellowing of leaves, and wilting of midribs might appear.

Officials suggest controlled flooding of fields to help destroy the pests. “If water is flooded to the extent that the base of the plants is submerged, the bugs will climb upwards. This prevents them from sucking sap from the lower parts of the plant. Furthermore, if the lower leaves remain submerged for more than six hours, the egg clusters laid on them will be destroyed. The bugs that climb upward will be eaten by birds and other natural predators. Predatory insects such as tortoise beetles also feed on and destroy egg clusters,” says an official.

The bug population usually increases in the days following the full moon. Officials say that insecticide application could be carried out in severely affected areas. “If large numbers of pests are found and symptoms appear on paddy plants, insecticides can be applied as per technical advice,” the official adds.

Biocontrol agents

In fields practising organic farming, Azadirachtin 1500 PPM can be sprayed at the rate of one litre per acre. The pest population can also be controlled by applying biocontrol agents such as Metarhizium and Beauveria.

If the use of chemical insecticides is required, granular formulations are recommended. Granules can be applied along with chemical fertilisers. To ensure better results, optimum soil moisture should be maintained during application.

For more details, farmers could contact the following phone numbers: 8547865338 (Nedumudi), 9074306585 (Punnapra), 9961392082 (Kainakary) and 9567819958 (Champakulam).