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United States Department of Agriculture

Agricultural Research Service

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Research Project: Chemical Alternatives to Methyl Bromide for Post-Harvest Pest Control on Perishable Commodities

Location: Crop Improvement and Protection Research

2013 Annual Report

1a. Objectives (from AD-416):
1. Develop phosphine fumigation treatment for post-harvest pest control on perishable commodities. 2. Explore new alternative treatments for post-harvest pest control.

1b. Approach (from AD-416):
Objective 1. Low temperature phosphine fumigation under the normal atmospheric oxygen and higher oxygen levels will be studied for controlling insect pests on fresh commodities. Insects that will be studied include lettuce aphid, light brown apple moth, and codling moth. The most tolerant life stage of each pest will be identified and effective phosphine fumigation treatment will be developed to control the most tolerant life stage of each pest. Effects of low temperature phosphine fumigation on postharvest quality of fresh fruits and vegetables and the treatment will be modified to achieve effective control of the pest and safety to product quality. Objective 2. Efforts will be made to evaluate potential new fumigants or non-chemical means as they become available for postharvest pest control on perish and stored products.

3. Progress Report:
This is the first report for the project 5305-43000-004-00D initiated in December 2012, for additonial information see old project 5305-43000-003-00D. Tolerance of cut flowers to phosphine fumigation for control of light brown apple moth. Nursery products including cut flowers are the primary commodities on which light brown apple moth have been found in California and therefore an effective postharvest treatment of the pest on these products is critical for nursery and horticultural industries. Research at USDA-ARS in Salinas, California, is in progress to determine tolerance of different types of cut flowers to a three day oxygenated phosphine fumigation treatment capable of controlling all light brown apple moth life stages including eggs. Close to 100% egg mortality has been achieved and the treatment is safe to most cut flowers. The research will be completed in FY2014.

4. Accomplishments
1. Development of nitric oxide fumigation for postharvest pest control. Nitric oxide is a naturally produced, small molecule that functions as a ubiquitous signal molecule in biological systems, and is not known to be insecticidal. ARS researchers in Salinas, California, discovered that under ultralow oxygen conditions nitric oxide can be a potent fumigant against insects. Nitric oxide fumigation at 0.1 to 2.0% concentrations was effective against all life stages of different types of insects from 2 to 25°C and effective controls were achieved in 2 to 48 hour depending on nitric oxide concentration, temperature, and insect species and life stage. Nitric oxide fumigation was also found to be safe to fresh products when it was terminated by reducing nitric oxide level with nitrogen flush prior to exposing contents to ambient air. Given the acute lack of safe and effective methyl bromide alternatives, high efficacy of nitric oxide fumigation, and environmental friendly nature of nitric oxide, nitric oxide fumigation has the potential to become a preferred green alternative fumigation treatment for postharvest pest control of stored and fresh agricultural products and make a significant impact on agriculture globally.

2. Improved safety of low temperature phosphine fumigation to fresh product quality. Although low temperature phosphine fumigation has been used to control some insects on fresh products, long treatment times for more tolerant insects on delicate fresh products such as lettuce cause injuries and prevent their practical uses. ARS researchers in Salinas, California, discovered that accumulation of carbon dioxide in fumigation chambers was the main cause of injuries to lettuce and demonstrated that carbon dioxide absorbent effectively prevented lettuce injuries associated with phosphine fumigation. Hermetic sealing of lettuce in fumigation chambers to simulate phosphine fumigation resulted in steady increases in carbon dioxide concentration and injuries to lettuce. Fumigation of lettuce with phosphine for three days resulted in injuries to both romaine and iceberg lettuce, but the addition of carbon dioxide absorbent in the fumigation chamber completely prevented such injuries. These results are important for the development of effective and safe low temperature phosphine fumigation treatments for lettuce and other delicate, carbon dioxide-sensitive fresh commodities.

Review Publications
Liu, Y.-B. 2013. Controlled atmosphere treatment for control of grape mealybug, Pseudococcus maritimus (Ehrhorn) (Hemiptera: Pseudococcidae), on harvested table grapes. Postharvest Biology and Technology. 86:113-117.

Last Modified: 05/24/2017
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