Flower and flower bud drop due to high temperatures

Flower and flower bud drop due to high temperatures is a physiological disorder rather than a biotic disease. It occurs when environmental temperatures exceed the biological tolerance threshold of the plant, causing hormonal imbalances and leading the plant to shed its reproductive structures to conserve energy for survival.

This condition frequently affects Solanaceous crops, with Sweet Pepper being one of the most susceptible species. Other crops such as tomatoes and eggplants also suffer significant reproductive failure when daytime or nighttime temperatures consistently remain outside the optimal range for successful pollination and fruit set.

The primary symptoms are the premature abscission of flower buds and fully opened flowers. Often, the flowers drop entirely with their pedicels attached. Unlike fungal diseases, there are no visible lesions, mold, or spots; the reproductive parts simply detach, leaving the plant otherwise appearing green and healthy, albeit stressed.

The development of this disorder is driven by heat-induced pollen sterility. When air temperatures rise above 32°C (90°F), pollen viability drops significantly, preventing fertilization. Furthermore, excessive heat increases the rate of transpiration, potentially leading to water stress if irrigation is insufficient to keep up with the plant's demand.

To mitigate the impact of heat stress, growers should focus on microclimate management. Protective measures include applying shade cloths, ensuring consistent and adequate soil moisture through drip irrigation, and using anti-transpirant sprays or biostimulants.

• Install shade netting in greenhouses.
• Maintain consistent watering schedules.
• Apply mulch to keep the root zone cool.
• Use seaweed extracts to boost stress resistance.