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United States Department of Agriculture

Agricultural Research Service

Research Project: Breaking Citrus Trade Barriers using Novel Postharvest Fumigations: High-Concentration Phosphine at Low Temperature (Horn Method)

Location: Commodity Protection and Quality

2013 Annual Report


1a.Objectives (from AD-416):
The goal of this research is to develop chamber fumigations that facilitate the movement of CA citrus through trade and marketing channels. Several contemporary trade barriers restrict, or possess the potential to restrict, foreign commerce of CA citrus, including: red scale to Korea, bean thrips to Australia/New Zealand, and western flower thrips to Taiwan. An additional feature involves the determination of the insecticidal efficacy of Vaporphos to Asian citrus psyllid via collaboration with FL scientists.


1b.Approach (from AD-416):
Quarantine pests related to these trade barriers will be targeted with the Horn method of using high concentration phosphine fumigant, registered in the US as Vaporphos (Cytec), at temperatures that will not break the cold-chain of the fruit in storage (<5 C). This method is being used successfully by our Chilean reciprocal-trade counterparts, albeit on different insect pests, in citrus exports to Korea, New Zealand, Taiwan, and many other countries. Documents Trust with Citru Research Board. Log 40055.


3.Progress Report:

This Trust agreement was established to support Objective 1 of the in-house project and is related to finding postharvest methyl bromide alternatives and techniques for improving methyl bromide fumigations. The goal of this research is to develop postharvest treatments to facilitate the movement of California citrus exports, valued at 1 billion USD annually, through trade and marketing channels. Phosphine (Vaporphos) chamber fumigations were evaluated for postharvest control of California red scale (CRS), Aonidiella aurantii, in fresh citrus exports from California USA. Citrus were infested with the most phosphine-tolerant life stage of CRS (gravid females), infested fruit were buried amongst uninfested fruit, and were fumigated with 1500 ppm phosphine for 48 hr at 5.5 °C. Collectively over three independent confirmatory trials, complete mortality of approximately 1,000,000 CRS was observed. This research will be presented to trading partners that have concerns regarding the presence of CRS on California fresh citrus.


Last Modified: 4/18/2014
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