Tomato growers warned of summer stress: calcium imbalance and storm‑induced mildew

In hot summer conditions, tomatoes can develop brown, necrotic tips (apical necrosis) when calcium fails to reach the fruit. The primary trigger is irregular watering that creates hydraulic stress, causing calcium to be diverted to foliage instead of fruit. Contributing factors include excessive nitrogen, high soil salinity, pH imbalance, and aggressive pruning. The condition is reversible by maintaining consistent, deep soil moisture, applying adequate mulch, using balanced fertilizers low in ammonium, and avoiding sudden drought‑rehydration cycles.

Harvesting tomatoes immediately before a summer thunderstorm can also damage crops. Rapid soil absorption during the storm forces sap into the fruit, causing it to split, while splashing mud spreads mildew spores onto wet foliage. Picking within 12–24 hours of an approaching storm creates micro‑wounds that, when wet, become infection sites for mildew, leading to brown lesions on the plant. To prevent this, gardeners should refrain from harvesting or pruning shortly before rain, apply a thick mulch layer around plant bases, and wait until foliage is dry before handling fruits.