Effect of Postharvest Naled and Sulfotep Fumigation on Western Flower Thrips Infesting Carnation

Abstract

Carnation (Dianthus caryophyllus) infested with western flower thrips (WFT) were harvested from a commercial greenhouse and prepared for shipment. The cut flowers were placed in water buckets and fumigated at ≈23°C in a 33-m³ ocean cargo container (a small fan circulated the fumigant). Naled (Dibrom 8EC) was applied at 4.49, 8.98 and 17.96 g (AI)/100 m³ for 1 h and 35.92 and 89.80 g (AI)/100 m³ for 2 h. Naled reduced thrips in flowers by 78.4 to 89.2%. Sulfotep (Plantfume 103) was applied at 13.77 g (AI)/100 m³ for 2 h and 15 h, and reduced thrips in flowers 52.4 and 64.3%, respectively. Naled was phytotoxic to the cultivar ‘Chianti’, which exhibited blackened petal tips at 8.98 g (AI)/100 m³ or higher. Sulfotep was also phytotoxic on ‘Chianti’. Naled at 4.49 g (AI)/10 m³ applied for 1 h resulted in significant reduction of thrips without phytotoxic effects. Increased fumigant rates and fumigation time did not eliminate WFT completely.