Sweet potato weevil
Roots have small feeding holes and dark tunnels inside, smell bad and taste bitter, and the vine base is cracked and swollen.
Crops it attacks
Where the damage shows
When to act
Hang sex pheromone traps from planting and read them weekly. A rising catch means weevils are moving in. Check soil cracks over the roots in dry spells and dig a few plants each month from root set.
What to spray
Active ingredients only, never brands. The IRAC group tells how it works: switch to a different group next time, so the pest does not learn to survive it. Spray only when the damage is worth the cost, and only with products registered with the Fertilizer and Pesticide Authority for your crop. Follow the label. The Shopee and Lazada links only show who sells something with that active ingredient, not a recommendation of any seller or product.
Sprays do little: the grubs live inside vines and roots. Clean cuttings, hilling, closing soil cracks and harvest on time are the control.
On labels for it, but not advised
- Fenthion: Leaf sprays do not reach weevil grubs inside the vines and roots. Clean cuttings and hilling work better.
- Cyfluthrin: No label names it for this weevil, and a leaf spray does not reach the grubs inside the roots.
How to prevent it
- Plant clean vine tips cut from the top of healthy vines, not old stems that may hide eggs and grubs.
- Hill up soil around the plants and close soil cracks, so the weevils cannot reach the roots. Water in dry spells.
- Harvest on time. Roots left long in the ground take more damage.
- Rotate with rice or corn, and remove volunteer sweet potato and wild morning glory weeds.
- Destroy crop remains and damaged roots right after harvest, and never plant beside an old field.
- Sex pheromone traps catch many males and show when the weevils arrive.
Natural enemies and biological help
- Beauveria bassiana or Metarhizium anisopliae on the soil and in pheromone traps infect the weevils.
- Ants and earwigs eat weevil eggs and grubs in the soil.
Not sure it is this one?
Many pests look alike. Send a photo to Anee, the smart farm technician in anee.io. She reads it with your crop, its age and the weather, and tells you what it most likely is and what to do first. In Tagalog or English.