Heat hurts most at flowering and fruit or grain set.
Effects
Pollen becomes sterile, flowers and young fruit drop, grains fill poorly, fruit gets sunscald, and plants lose water faster than roots can supply.
Prevention
- Adjust sowing date so sensitive stages avoid the hottest weeks.
- Heat-tolerant varieties where available.
- Keep soil moist at critical stages; well-watered plants cool themselves by transpiration.
- Mulch to keep roots cooler.
- Shade nets for vegetables and nurseries; windbreaks help too.
Response during a heatwave
Irrigate early morning or evening, in short, frequent applications; avoid heavy fertilizer or pruning at the peak; do not spray in midday heat; and protect fruit from direct sun.
Record events and outcomes so you can plan better next season.
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