Nematodes

Once a month, dig a small test hole near a mound — if you see beetles or chewed-up bits in the soil, that's a yam beetle. Dark brown patches on leaves or stems = a leaf disease (anthracnose). Always plant clean, certified seed yam pieces — buying cheap, sick ones costs you the harvest.

Once a month, check the base of each plant. Small holes with sawdust-looking dust around them = banana weevils tunnelling inside — they're the worst pest for plantain in Ghana. Always plant clean suckers from a healthy farm; don't take suckers from old or sick plants.

Every 2 weeks, look at the leaves. Yellow streaks that grow into big brown patches = a serious leaf disease called black sigatoka. Cut off infected leaves and burn them — never use them as mulch, you'll spread the disease.