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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

2012 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.


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. Mortality of adult Asian citrus psyllid to methyl bromide at 55°F was assessed after specimens were transferred to room temperature for 24 hour post-fumgation. Of the 331 non-fumigated controls, 258 survived (control survivability was ~77%); control mortality was a modeled-response based on probit analyses. Concentration-time cross products of 70 mg h/L were sufficient to control 99% of adult Asian citrus psyllid at the 95% level of confidence. Due to effects of commodity and packing materials on methyl bromide sorption, a 48 mg/L dose over a 2 hour fumigation period is recommended to provide control against Asian citrus psyllid in commercial scenarios. Work will continue on mapping the dose-mortality of Asian citrus psyllid to methyl bromide as we approach the commercial-scale testing scheduled for the fall of 2012 in Miami, Florida.


Last Modified: 8/30/2014
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