Cashew Twig and Shoot Borer
Plocaederus ferrugineus
📖 Description
Cashew Twig and Shoot Borer is the most destructive pest of cashew across the Indian subcontinent, particularly severe in Kerala, Karnataka, Goa, Maharashtra, Andhra Pradesh, Odisha and West Bengal where cashew is grown on over 1 million hectares. The adult beetle lays eggs in bark crevices and wounds; the larva tunnels into the shoot and branches, causing wilting and die-back. A single larva can kill an entire branch within weeks. The pest is particularly damaging to young plantations (1-5 years) where infestation of the main stem can kill the entire plant. The pest also attacks mango, citrus and other fruit trees, making area-wide management essential. IPM with pruning and burning of infested branches, swabbing bore holes with insecticide and trunk painting with Bordeaux paste provides effective control. Avoidance of mechanical injury during intercultural operations is critical — wounds expose the cambium layer and attract ovipositing females. Planting resistant varieties and maintaining good garden sanitation are key preventive measures.
⚠️ Symptoms to watch for
- Yellowing and wilting of shoots, presence of bore holes at shoot base with frass and gum exudation, drying of branches, die-back of young shoots, reduced flowering and fruit set, yield loss 30-60%, plant death in severe infestation of young trees
🩹 Treatment
- Prune and burn infested shoots below bore hole, insert cotton swab soaked in monocrotophos or kerosene into bore hole and plug with mud, apply neem oil 5 ml/L on trunk and branches, use need-based insecticide
🌿 Organic treatments
- Prune infested branches 15 cm below bore hole and burn, insert cotton swab with neem oil + kerosene (1:1) into bore hole and plug with mud, apply Beauveria bassiana paste @ 5 g/L into bore hole, paint trunk with neem oil + lime mixture, install light traps @ 1/ha
🧪 Chemical treatments
- Monocrotophos 36 SL @ 5 ml/L (swab bore hole), Chlorpyriphos 20 EC @ 5 ml/L (swab bore hole), Carbaryl 50 WP @ 4 g/L (trunk and branch spray), Imidacloprid 17.8 SL @ 0.5 ml/L (soil drench for systemic action), Acephate 75 SP @ 2 g/L
🛡️ Prevention
- Maintain garden sanitation by pruning infested branches, avoid mechanical injury to bark, paint exposed wounds with Bordeaux paste, install light traps to monitor adults, plant resistant varieties (Vengurla series), avoid inter-plot movement of infested planting material
🪴 Affected plants
- Cashew, Mango, Citrus, Silk Cotton Tree, Bombax, Other Fruit Trees
🦋 Natural predators
- Woodpeckers, Predatory Bugs, Parasitic Wasps (Bracon, Metapelma), Spiders
🌱 Host plants
- Anacardium occidentale, Mangifera indica, Citrus spp., Bombax ceiba, Ceiba pentandra
🔄 Lifecycle
- Female lays 50-150 eggs in bark crevices, wounds and prune cuts.
- Eggs hatch in 7-12 days.
- Larvae tunnel into wood and feed for 60-120 days through 5-6 instars.
- Pupation inside the tunnel, lasting 15-25 days.
- Adult lifespan 30-60 days.
- Total life cycle 90-180 days; 2-3 generations per year.
📅 Season
- Year-round, peaks Mar-Jun and Sep-Nov during active growth
🔎 Appearance
- Adult is a robust longicorn (long-horned) beetle, reddish-brown to dark brown with two prominent spine-bearing antennae longer than the body.
- Larva is a creamy-white, legless grub with a brown head capsule, distinctly segmented body and powerful mandibles for tunneling wood.
- Pupates inside the tunnel.
💥 Damage level
- Severe
🔁 Reproduction rate
- Moderate
🗺️ Geographic regions
- Indian Subcontinent
- South Asia
- Southeast Asia
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