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Sweet potato weevil

Cylas Puncticollis, C.brunneus and C. formicarius Sweet potato weevil
  • Plant clean (insect free) vines that are deep rooted with long necks because adult weevils cannot burrow below 1cm
  • Plant new fields away from infested crops a distance away from storage facilities
  • Keep the fields weed-free
  • Ridge, mulch and routinely irrigate to prevent soil cracking
  • Rotate sweet potato with sorghum and other cereals every four years
  • Harvest when mature and avoid piecemeal harvesting
  • Plant early in the season or early-maturing varieties so that harvest can be completed before the dry season when the soil will dry and crack
  • Dip planting material in a solution of Beauveria bassiana for 10 minutes to be effective
  • Encourage generalist predators of the weevil like ants, spiders, carabids, and earwigs by planting hedgerows of target spp.
  • Additional relevant crops: morning glory, wild spinach, wild Ipomoea
  • Look out for:
    • Sweet potato larvae in the tuber and basal 10cm of the vines
    • Yellowing, cracking and wilting of vines
    • Holes in the vines and tubers early in the season
    • Storage roots that appear soft, smelling and have external scarring or small darkened holes
  • Place pheromone traps in the field at a radius of 280m to catch the weevils
  • Drench Nimbecidine at a rate of 5 ml/L
  • Remove all infested sweet potato vines and storage roots and destroy by burning or burying 2 feet deep
  • Flood infested fields for 24 hours after harvesting
  • When using a pesticide, always wear protective clothing
  • Follow the instructions on the product label, such as dosage, timing of application, pre-harvest interval, maximum number of sprays, restricted re-entry interval
  • Always consult recent list of registered pesticides (PCPB)
  • Do not empty containers into drains
  • Dip planting material in a solution of Diazinon based products (Diazol 60EC at 40-50mls/20L for 10-15 minutes, Basudin at 15ml/20L)
  • WHO Class II Moderately hazardous REI 10-14 days
  • Drench using Carbaryl based products (Sevin 80ml/20L) at planting of the crop
  • PHI 7 days WHO Class II Moderately hazardous
AUTHOR(S): Esther Macharia (KALRO), Boniface N Ndung'u (MOALF) and Miriam Otipa (KALRO) , Philip Kibet (UoN) and Benson Ngigi (MOALF)

CREATED/UPDATED: December 2014
PRODUCED BY: Plantwise

©CAB International. Published under a CC-BY-SA 4.0 licence.