Mite menace in blackgram

RED SPIDER mite Tetranychus cinnabarinus is a pest of field crops. It causes serious damage. The summer crop is often prone to attack by this mite species. The young and adult mites suck the sap of the leaves flowers and pods.

Symptoms of damage: The mites are negatively phototropic and seen on the undersurface of the foliage. But at times they are also seen on the upper surfaces. Inside the webs all the developmental stages of the species are found. Some are found either on the leaf lamina or in angles formed by the major veins on the leaf in case of severe incidence. The common symptoms are stippling, bronzing, defoliation, retardation of growth and reduction and in severe cases drying up of the crop with substantial yield loss.

Physiological changes: The mite penetrates the plant tissues by its mouthparts called chelicerae and sucks the exuding sap. This results in drying and dropping of leaves. The damage of mesophyll layer by feeding on the lower surface causes bronzing in leaves.

Biology of mite species: The mite develops through egg, larva, protonymph, deutonymph and adult. The life cycle (egg to adult) is 14 days. The longevity of adult is 4-14 days.

The pest can be effectively managed by:

Provide sufficient irrigation to avoid wilting of plants and mite buildup.

Adopt recommended spacing between plants to avoid the migration of mite.

Sulphur dust at 10 kg/ac or spraying of dicofol 600 ml/ac or wettable sulphur 1.0 kg/ac.

N. Raju, & S.Ramanathan

TRRI, Aduthurai 612 101

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