Beat the weevil: store your maize without losing it

The maize weevil and the larger grain borer destroy a heartbreaking share of Zimbabwe’s harvest after it’s safely in from the field. The losses are avoidable. Two things do most of the work: dry it hard, then store it airtight.

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First, dry it properly

Maize comes off the field far too wet to store — often 23–28% moisture (FAO). Damp grain invites insects and mould. Dry it until the grain is hard and glassy (around 12–13% moisture — a kernel should be difficult to dent with a fingernail) before it goes into store. Dry on raised cribs or clean sheeting, never on bare ground.

Then, store it airtight

This is the game-changer. Hermetic (airtight) storage — sealed PICS triple-layer bags or metal silos — traps the grain and any insects in a sealed space. The insects use up the oxygen and the carbon dioxide builds, and they die; you don’t even need chemicals (PMC). Trials consistently show hermetic bags and metal silos far outperform ordinary woven polypropylene bags at limiting weight loss and grain damage (ScienceDirect).

What about wood ash?

Mixing wood ash through stored grain is a long-standing practice — it slows the insects by abrading and drying them. It’s genuinely useful but limited, and best kept for small amounts like seed rather than your whole harvest (FAO). Treat it as a backup, not your main defence.

Do this now

1. Dry maize hard (about 12–13% moisture) before storage.
2. Store airtight — PICS bags or a sealed metal silo.
3. Keep the store clean and off the ground.
4. Save ash for seed-sized lots, not the whole crop.

The yield you build with healthy soil only counts if it reaches the pot or the market — protect it.

PCAT BLOCK C — the locally-made, field-proven compost that rebuilds Zimbabwe’s tired, acidic soils.

Related: beat fall armyworm organically · the maize calendar