Postharvest heat treatment of red ginger flowers as a possible alternative to chemical insecticidal dip.
A postharvest treatment in hot water at 49 °C for 12 to 15 min eliminated >95% of Technomyrmex albipes, Pentalonia nigronervosa and Pseudococcidae infesting red ginger flowers, Alpinia purpurata. In a 'systems-approach' to quarantine security, preharvest chlorpyrifos applications combined with either a postharvest hot-water immersion at 49 °C for 12 min or 5-min insecticidal dip in a combination of fluvalinate 2.0 flowable (F) and insecticidal soap eliminated all pest species. Phytotoxicity resulting from hot-water treatment was characterized by bract necrosis and shortened vase life. Flowers were more susceptible to heat injury if harvested during periods of high rainfall. Conditioning flowers in hot air at 39 °C for 2 h before hot-water treatment eliminated phytotoxicity.