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Sci Tech
Useful tips to check red palm weevil in coconut
Red palm weevil is the most destructive pest of coconut. The adult weevil is reddish brown in colour with longevity of 70-130 days. The female weevil lays its eggs in soft tissues of young palms and in the wounds present on the stem or leaf stalk.
The grub tunnels its way into the trunk and feeds on the internal tissues. The larval period ranges from 36 to 78 days. Full grown grub is stout and fleshy.
The damage by Rhinoceros beetle, bud rot and leaf rot predisposes the trees to crown infestation. The eggs are laid in the exposed soft tissues of crown and the grubs on hatching enter directly into the growing point resulting in the toppling of crown.
Stem infestation
The wounds or injuries or cuts in the stem region facilitate the stem infestation. The wounds on the trunk attract the weevil for egg laying. The grubs on hatching enter through the wounds and damage the trunk by tunnelling inside.
Brownish black viscous fluid oozes out from the damage spot on the trunk. Stem infestation causes death of the trees at advanced stage of infestation if not treated properly.
Proper identification of weevil infestation in a tree is important. Weevil affected trees show oozing of brownish black viscous fluid from spots where the grubs damage the trunk. As regards the basal stem rot affected trees, the trunk shows dark brown oozing with black circular scars all round it.
Management
- Remove the fallen and dead trees and properly dispose with pesticide treatment to kill the life stages present in the trunk of the dead tree.
- Do inter culture operation in coconut garden without causing wounds or injuries to the tree trunk.
- Swab the tree trunk with lime or tar to cover the open wounds and injuries to prevent the weevils from egg laying.
- Avoid premature removal of leaves from young trees by cutting the leaves at leaf bases as this will facilitate egg laying and entry of grubs.
- Properly manage rhinoceros beetle by placing naphthalene balls in perforated sachet or Thimet granule (2gm) in perforated sachet or neem seed powder + sand mixture in the crown and 2-3 leaf axils of the crown.
D.S. SRIDHARAN
Professor of Agricultural
Entomolgy, Krishi Vigyan Kendra, TNAU, Coimbatore
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