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United States Department of Agriculture

Agricultural Research Service

Research Project: POSTHARVEST PEST CONTROL ON PERISHABLE AGRICULTURAL COMMODITIES USING CONTROLLED ATMOSPHERES AND PURE PHOSPHINE TREATMENTS
2008 Annual Report


1a.Objectives (from AD-416)
1. Develop controlled atmosphere treatments for postharvest pest control on perishable commodities. A) Develop semi-commercial scale storage and ultralow oxygen combination treatment for control of western flower thrips on head lettuce. B) Develop semi-commercial scale storage and ultralow oxygen combination treatment for control of western flower thrips on broccoli. C) Develop controlled atmosphere treatment for control of mealybugs and black widow spiders on table grapes. D) Develop ultralow oxygen treatment for control of vine mealybug on grape rootstocks. 2. Develop pure phosphine funigant treatments for highly perishable commodities. A) Develop fumigation treatment with pure phosphine for control of western flower thrips on lettuce, broccoli, asparagus, and strawberries. B) Develop fumigation treatment with pure phosphine for control of lettuce aphid and leafminer on lettuce. C) Develop fumigation treatments with pure phosphine for control of mealybugs and spiders on table grapes.


1b.Approach (from AD-416)
The minimum duration of pre-treatment cold storage needs to be determined in order to reduce the overall duration for completing ULO treatment and make it possible for pre-export ULO treatments. Effectiveness of ULO treatments for thrips control and their effect on postharvest quality of lettuce needs to be determined in large-scale tests. Oxygen consumption rates and oxygen demands by lettuce need to be determined in large-scale trials for commercial application. Efficacy and safety of ULO treatment for control of western flower thrips on broccoli.


3.Progress Report
Laboratory studies were conducted to further modify ultralow oxygen treatments for control of western flower thrips and demonstrate efficacy of pure phosphine fumigation treatments to control insects on lettuce. A pallet-scale ULO test successfully demonstrated that pre-treatment storage of lettuce prevents heart leaf injury by ultralow oxygen treatment for control of western flower thrips, marking a significant advance in understanding effects of ultralow oxygen treatment on lettuce quality and in the development of safe and effective commercial scale, ultralow oxygen treatments for control of western flower thrips on exported lettuce. Pure phosphine was demonstrated to be safe and effective in controlling western flower thrips on lettuce and broccoli. A pure phosphine fumigation test successfully controlled western flower thrips on lettuce, broccoli, asparagus, and strawberries in commercial size, land-sea container with no negative effects on product quality.

Laboratory studies were conducted to further modify ultralow oxygen treatments for control of grape mealybug, vine mealybug, and black widow spiders on harvested table grapes. An ultralow oxygen treatment was developed for control of black widow spiders on table grapes. Complete control of the spiders was achieved in a one-day ultralow oxygen treatment at a low storage temperature. The short treatment duration and the easily attained oxygen level make the treatment promising for commercial use. Laboratory studies are continuing for determining safe and effective ultralow oxygen treatment for control of mealybugs.

This addresses NP 304, Component 5 and NP 308, Component 2.


4.Accomplishments
1. Pallet scale ultralow oxygen (ULO) treatment for control of western flower thrips on head lettuce. Western flower thrip is a quarantined pest in Taiwan. Exported lettuce to Taiwan often harbors western flower thrips and therefore requires quarantine treatments. In pallet tests conducted by ARS scientists in the Crop Inprovement and Protection Research Unit in Salinas, CA complete control of thrips was achieved and pre-treatment storage also prevented injury to lettuce heart leaves. The large scale pallet tests further demonstrated efficacy and safety of the storage-ULO treatment combination for controlling western flower thrips on head lettuce. The protocols developed for the pallet tests may also be applicable to industry development of ULO treatment and controlled atmosphere storage of fresh commodities. The ultralow oxygen treatments have good potential to be developed into a safer and effective alternative to traditional fumigation for control of quarantined pests on fresh commodities and are also compatible with organic products. The accomplishment addresses NP 308, component 2 (Postharvest Alternatives), Problem Statement 2C (Developing alternatives to methyl bromide for disinfestations of post-harvest perishable commodities).

2. Pure phosphine fumigation at low temperature for control, of western flower thrips on lettuce, broccoli, asparagus, and strawberries. Western flower thrip is a quarantined pest in Taiwan. Exported produce to Taiwan often harbors western flower thrips and therefore requires quarantine treatments. A commercial-scale fumigation trial using pure phosphine in a reefer container was conducted successfully by ARS scientists in the Postharvest Entomology Laboratory at USDA-ARS (Salinas) in collaboration with industry. Pure phosphine fumigation was demonstrated to be effective in controlling western flower thrips and safe on all of the commodities tested. This research provides an effective solution to western flower thrips control on exported fresh commodities to Taiwan and benefits U.S. agriculture. The accomplishment addresses NP 308, component 2 (Postharvest Alternatives), Problem Statement 2C (Developing alternatives to methyl bromide for disinfestations of post-harvest perishable commodities).

3. Ultralow oxygen treatment for controlling black widow spiders in table grapes. Black widow spiders have been found hitchhiking on harvested table grape clusters and pose safety hazards to workers as well as consumers, and require treatments on exported table grapes on some overseas markets. ARS scientists in the Postharvest Entomology Laboratory found that black widow spiders were very susceptible to oxygen deficiency. One-day exposure to atmosphere with 0.5% O2 or lower at low temperature was found to be adequate for successful control of the spiders. The treatment was safe for grapes and did not affect quality. Because of short treatment time, low temperature and easily attainable oxygen level, the treatment has a good potential of being used commercially. The accomplishment addresses NP 308, component 2 (Postharvest Alternatives), Problem Statement 2C (Developing alternatives to methyl bromide for disinfestations of post-harvest perishable commodities).


5.Significant Activities that Support Special Target Populations
None.


6.Technology Transfer

None

Review Publications
Hayes, R.J., Liu, Y. 2008. Genetic Variation for Shelf-life of Salad-cut Lettuce in Modified-atmosphere Environments. Journal American Society Horticultural Science. 133(2):228-233.

Last Modified: 11/26/2014
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