Xiangbing Yang1, Yong-Biao Liu2. 1. Department of Plant Sciences, University of California Davis, Salinas, CA, USA. 2. Crop Improvement and Protection Unit, USDA-ARS, Salinas, CA, USA.
Abstract
BACKGROUND: The lettuce aphid, Nasonovia ribisnigri, and western flower thrips, Frankliniella occidentalis, are quarantine pests of lettuce in Asian markets and, therefore, require treatments on lettuce exported from USA to Japan and Taiwan, respectively. Nitric oxide (NO) is a newly discovered fumigant for postharvest pest control and has been demonstrated as safe to fresh fruit and vegetables. In this study, small-scale NO fumigations were conducted to determine effective treatments and large-scale confirmatory tests were conducted to determine the efficacy against N. ribisnigri and F. occidentalis on commercially packed lettuce. The safety of NO fumigation to postharvest quality of lettuce was also evaluated. RESULTS: In small-scale experiments, complete control of N. ribisnigri was achieved in 3, 8, and 16 h fumigations with 2.0%, 1.0%, and 0.5% NO, respectively, at 2 °C on both iceberg and romaine lettuce. In a large-scale experiment, complete control of both N. ribisnigri and F. occidentalis was achieved in a 16 h fumigation with 0.5% NO at 2 °C. The fumigation treatment had no effect on either external or internal postharvest quality of lettuce at 14 days after treatment. CONCLUSION: Nitric oxide fumigation was demonstrated to be effective against both N. ribisnigri and F. occidentalis and safe to lettuce quality in large-scale fumigations of commercially packed lettuce. The study suggests that NO fumigation has the potential to be an alternative treatment to methyl bromide for postharvest pest control on harvested lettuce.
BACKGROUND: The lettuce aphid, Nasonovia ribisnigri, and western flower thrips, Frankliniella occidentalis, are quarantine pests of lettuce in Asian markets and, therefore, require treatments on lettuce exported from USA to Japan and Taiwan, respectively. Nitric oxide (NO) is a newly discovered fumigant for postharvest pest control and has been demonstrated as safe to fresh fruit and vegetables. In this study, small-scale NO fumigations were conducted to determine effective treatments and large-scale confirmatory tests were conducted to determine the efficacy against N. ribisnigri and F. occidentalis on commercially packed lettuce. The safety of NO fumigation to postharvest quality of lettuce was also evaluated. RESULTS: In small-scale experiments, complete control of N. ribisnigri was achieved in 3, 8, and 16 h fumigations with 2.0%, 1.0%, and 0.5% NO, respectively, at 2 °C on both iceberg and romaine lettuce. In a large-scale experiment, complete control of both N. ribisnigri and F. occidentalis was achieved in a 16 h fumigation with 0.5% NO at 2 °C. The fumigation treatment had no effect on either external or internal postharvest quality of lettuce at 14 days after treatment. CONCLUSION:Nitric oxide fumigation was demonstrated to be effective against both N. ribisnigri and F. occidentalis and safe to lettuce quality in large-scale fumigations of commercially packed lettuce. The study suggests that NO fumigation has the potential to be an alternative treatment to methyl bromide for postharvest pest control on harvested lettuce.