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United States Department of Agriculture

Agricultural Research Service

Research Project: Chemical Alternatives to Methyl Bromide for Quarantine and Post-Harvest Pests

Location: Commodity Protection and Quality

2013 Annual Report


1a.Objectives (from AD-416):
Objective 1: Determine the efficacy of alternative chemicals to methyl bromide for post-harvest commodity fumigation and develop methods to reduce methyl bromide emission.

• Sub-objective 1A: Determine efficacy, practicality, and effects on product quality of alternative postharvest fumigants such as phosphine, sulfuryl fluoride, propylene oxide, ozone and others to control key economic pests of perishable fruits, tree nuts, and stored products. • Sub-objective 1B: Search for efficient materials to capture or destroy methyl bromide and other fumigants following postharvest commodity fumigation. • Sub-objective 1C: Develop new quarantine strategies to control regulatory pests in exported hay.

Objective 2: Develop and evaluate methods for prediction of damage to tree nuts and improve insecticide timing to control navel orangeworm.

• Sub-objective 2A: Predict navel orangeworm damage to pistachios, with an emphasis on nut factors and harvest timing. • Sub-objective 2B: Develop insecticide spray timing recommendations for Madera County, the number 2 pistachio producing county in California, with an emphasis on developing recommendations for high pressure orchards statewide. • Sub-objective 2C: Evaluate the efficacy of the newly registered softer insecticides for almonds and pistachios with a focus on adult activity, contact activity and mechanisms of detoxification. • Sub-objective 2D: Determine responses of male and female navel orangeworm to non-pheromone attractants in black and white traps. • Sub-objective 2E: Evaluate Attract & Kill technology to control navel orangeworm. • Sub-objective 2F. Determine abundance and evaluate monitoring methods for navel orangeworm in walnuts. • Sub-objective 2G: Determine the flight capacity of navel orangeworm.


1b.Approach (from AD-416):
Conduct laboratory and chamber fumigations to determine the efficacy, practicality, and effects on product quality of alternative postharvest fumigants to control key economic pests of perishable fruits, tree nuts, and stored products. Search for efficient materials to capture or destroy methyl bromide and other fumigants following postharvest commodity fumigation. Develop combinations of fumigants with other technologies to reduce the dosage of fumigant required to control or eradicate stored product and quarantine insects in durable and perishable commodities. Develop and evaluate methods to predict damage to tree nuts and improve insecticide timing to control navel orangeworm by better understanding of the ecology of the pest, use of pheromone attractants, and modeling. Develop methods to enhance or maintain quality of perishable commodities and ensure that treatments developed do not reduce quality of perishable commodities or shorten shelf-life.


3.Progress Report:
The navel orangeworm is the principal moth pest of almonds and pistachios in California. A key factor to their increased export is quality, and the challenge is to increase both crop and environmental quality by reducing insecticides input and/or increasing the use of softer insecticide chemistries. These studies now enable farmers to identify high risk orchards and high risk years so that crop protection can be maximized. Companion studies on insecticide efficacy identified new uses for current chemistries in order to maximize control of this pest.

Season-long data on navel orangeworm abundance in walnuts provided evidence of resident populations; and sampling prior to and during successive harvests showed that high navel orangeworm damage could not be explained only by re-infestation of walnuts previously infested with codling moth. Methods for attaching navel orangeworm to flight mills were developed and initial data were collected.

Last year's new volatile collection system is being employed to assess the variability in pheromone emissions from insects and the lures used in field traps in order to develop less variable trap baits. We will continue into year 2 of assessment of attract-and-kill baits. These combinations of pheromone attractants and adult-killing insecticides hold great potential for insect control, similar to mass trapping of male moths, but at a cost that growers will likely accept. The environmental impact will be greatly reduced compared to full crop spraying of insecticides.

Hay drying conditions were shown to cause high mortality of Hessian fly puparia when tested in environmental chambers that simulated harvesting conditions, or by actual open air drying on location, and in hay windrows during different harvest dates in the Kittitas Valley and East Columbia Basin of Washington, and the San Joaquin Valley and Imperial Valley of California.

Efficacy studies were conducted concomitant to quality evaluations for the following pest pairings: methyl bromide versus spotted wing drosophila on sweet cherries, blueberries, and table grapes; phosphine versus spotted wing drosophila on sweet cherries, blueberries, and table grapes; phosphine versus Fullers rose weevil on oranges; phosphine versus Oriental fruit moth on apples; propylene oxide versus microbes on almonds and walnuts.

Activated carbon sorbents were synthesized at kg-scale from almond shells, walnut shells, prune pits, and peach pits. Sorbents were tested for efficacy in removing methyl bromide and sulfuryl fluoride from aeration streams following postharvest chamber fumigations.


4.Accomplishments
1. Fumigation treatment to enable sweet cherry export. Spotted wing drosophila (Drosophila suzukii) is an emerging pest in the West Coast region that threatens exports of sweet cherries and other fruit crops grown in the region. A postharvest fumigation treatment was urgently needed to enable quarantine control of spotted wing drosophila in sweet cherries prior to export. Following requests of the Western US cherry industry, ARS researchers at Parlier, California, completed the validation of a quarantine treatment for this pest utilizing methyl bromide fumigation. This research directly enabled the retention and expansion of market access to Australia estimated at ~$55 million USD annually.

2. Navel orangeworm abundance and damage in walnuts. Insect damage to harvested walnut meats comes primarily from moth larvae. Most is believed caused by the codling moth (CM), but damage from codling moth and navel orangeworm (NOW) is sometimes poorly distinguished. An ARS researcher at Parlier, California, found NOW present year-round in walnut orchards. The progressive increase of NOW infestation during harvest was greater than could be explained only by entry of NOW into nuts previously infested by CM. Understanding the importance of NOW in walnuts will improve effectiveness of control measures, protecting a crop worth >$1 billion per year.

3. Develop new quarantine strategies to control regulatory pests in exported hay. Hessian fly is a US domestic pest but is considered an invasive species by countries such as Japan that import hay for animal feed from the western states. Hay drying tests conducted by ARS researchers at Parlier, California, showed that Hessian fly potentially contaminating export quality hay is killed in the field, before baling and processing for shipment to Asia Pacific countries. These countries include South Korea, Taiwan, China, and the United Arab Emirates. Ongoing development of new control approaches assures trade partners that the possibility of accidental introductions of regulated pests is negligible through US hay exports.

4. Navel orangeworm damage in pistachios results from a combination of nut factors and harvest timing. The navel orangeworm is the principal pest of pistachios in California, a valuable and rapidly increasing crop planted on more than 225,000 acres. An ARS researcher at Parlier, California, identified nut factors including shell defect, fungal infection, extent of shell split and harvest date that are associated with insect damage. Some of these factors can be managed by controlling irrigation and fungal diseases. Integrating management of these factors will help increase crop quality, thereby boosting profits and exports .

5. Improved insecticide spray timing will reduce navel orangeworm damage and improve crop quality. The navel orangeworm is the principal pest of California pistachios, a valuable and rapidly increasing crop planted on more than 225,000 acres. An ARS researcher at Parlier, California, developed novel spray timings to control navel orangeworm based on its rate of development, response to seasonal temperatures, and size of the existing population. This strategy emphasizes spraying before navel orangeworm becomes established in pistachios. Reduced insect damage improves crop quality which in turn supports overseas demand for pistachios. This will increase grower profits and boost trade.

6. Evaluate the efficacy of newly registered softer insecticides for almonds and pistachios with a focus on adult activity and mechanisms of detoxification. The navel orangeworm is the principal pest of California pistachios, a valuable and rapidly increasing crop planted on more than 225,000 acres. An ARS researcher at Parlier, California, demonstrated that newly registered narrow spectrum insecticides have adult and egg activity. New timing recommendations for these products based on this research will maximize insect control. Adoption of these new products decreases the use of broad spectrum insecticides, minimizing pressure on non-target species. The combination of reduced damage and minimized environmental impact results in improved quality.


Review Publications
Yokoyama, V.Y., Cambron, S.E. 2013. Survival of Hessian Fly (Diptera: Cecidomyiidae) puparia exposed to simulated hay harvest conditions, location and windrow dying in Washington and California. Journal of Economic Entomology. 106: 1164-1172.

Yokoyama, V.Y. 2012. The Japan disaster and U.S. hay exports. American Entomologist. 58:151-153.

Last Modified: 7/23/2014
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