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United States Department of Agriculture

Agricultural Research Service

Research Project: EMERGING TECHNOLOGIES TO MAINTAIN POSTHARVEST QUALITY AND CONTROL DECAY OF FRESH COMMODITIES

Location: Commodity Protection and Quality

2006 Annual Report


1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter?
The research is conducted under National Program 306 (Quality and Utilization of Agricultural Products) and contributes to National Program 303 (Plant Diseases). Fresh fruit are attacked by fungal diseases that rot fruit after harvest, and management of this problem is an objective in both National Programs. The fungal diseases that rot fruit after harvest cause losses of about 5% of California's $3 billion fresh fruit production. The control of the disease-causing fungi is important, and is usually accomplished using chemical fungicides and sanitizers, but issues of pest resistance to these chemicals, the dietary safety of their presence foods, and their impact on the environment has made the search for safer replacements important. Fungicides used to control these diseases interfere with the export of citrus fruit because some countries will not accept residues of the fungicides on the fruit. Three fungicides are approved for citrus fruit use in California, sodium ortho-phenyl phenate, imazalil, and thiabendazole. Sodium ortho-phenyl phenate is classified as a probable human carcinogen and imazalil as a possible human carcinogen by the U.S. Environmental Protection Agency. We propose to use combinations of 'reduced-risk' fungicides, such as lime-sulfur solution, sodium bicarbonate, or ethanol, and physical treatments such as heat, to control these fungi. These approaches minimize or eliminate the dietary risks posed by fungicides present in fruit purchased by consumers. This work benefits produce growers and distributors because chemical costs are reduced, and market opportunities are increased, because fungicide residues on products are prohibited by some importing countries and in domestic markets where organic produce is sold.


2.List by year the currently approved milestones (indicators of research progress)
Year 1 (FY 2004). Conduct laboratory trials to control postharvest green mold and sour rot on citrus fruit, and postharvest disease control trials with table grapes to control gray mold.

Develop of inoculation and culture methods for large-scale powdery mildew inoculation and disease quantification. Conduct anatomical studies of berries surfaces and skin of selections with gray mold resistance.

Initiate planned heat treatments of stone fruit and lemons; measure quality and phytotoxicity effects; extract collected samples for soluble sugars. Develop database relating fruit color, soluble solids/titratable acidity, ethanol and navel orange fruit acceptability. Assay antioxidant response to heat treatment and relate to subsequent injury.

Year 2 (FY 2005). Conduct large-scale laboratory trials to control postharvest green mold and sour rot on citrus fruit, and postharvest disease control trials with table grapes to control gray mold. Include rigorous fruit quality evaluation of effective approaches, conduct grower/processor demonstration tests, seek industry input and collaboration, inquire about registration issues with regulatory agencies, and establish the category of regulation applied to the process.

Begin large-scale powdery mildew inoculation and disease quantification, establish in which organs resistance is expressed (leaves, rachis, or fruit) and when. Determine if laboratory assessment of resistance among young vines can predict vineyard resistance to powdery mildew. Complete anatomical studies of berries surfaces and skin of selections with gray mold resistance.

Initiate planned heat treatments of stone fruit and lemons; measure quality and phytotoxicity effects; extract collected samples for soluble sugars. Develop database relating fruit color, soluble solids/titratable acidity, ethanol and navel orange fruit acceptability. Assay antioxidant response to heat treatment and relate to subsequent injury.

Year 3 (FY 2006). Conduct pilot-scale trials with naturally infected fruit in collaborator's facilities. Refine treatment protocols to maximize their effectiveness and practicality. Address patent issues. Participate in compliance of registration needs with regulatory agencies and sponsoring registrant.

Continue large-scale powdery mildew inoculation and disease quantification trials as in Year 2. Begin analysis of selections where resistance and susceptibility have been established to determine what features are associated with resistance. Prepare a manuscript on the subject of anatomical studies of berries surfaces and skin of selections with gray mold resistance.

Purify samples and determine sugars by HPLC; prepare report. Include additional variables such as waxing and handling into navel orange fruit acceptability study. Continue antioxidant assays and identify compounds present in lemon peel that are responsible for antioxidant response.

Year 4. (FY 2007) Conduct pilot-scale trials with naturally infected fruit in collaborator's facilities with several important cultivars. Refine treatment protocols to maximize their effectiveness and practicality. Participate in compliance of registration needs with regulatory agencies and sponsoring registrant.

Continue and confirm results from prior seasons of large-scale powdery mildew inoculation and disease quantification trials begun in Year 2. Continue analysis of selections where resistance and susceptibility have been established to determine what features are associated with resistance.

Purify samples and determine sugars by HPLC; prepare report. Include additional variables such as waxing and handling into navel orange fruit acceptability study. Continue antioxidant assays and identify compounds present in lemon peel that are responsible for antioxidant response.

Year 5. (FY 2008) Continue pilot-scale trials if necessary. Refine treatment protocols to maximize their effectiveness and practicality. Prepare manuscripts describing accomplishments.

Conclude analysis of selections where resistance and susceptibility have been established to determine what features are associated with resistance, and prepare a manuscript on this subject.

Analyze and summarize data; prepare manuscripts for review and publication.


4a.List the single most significant research accomplishment during FY 2006.
Association of Orange Fruit Maturity and Taste Panel Results. NP 303 - Component 1 - Problem 1A The California citrus industry needs to market the highest quality fruit in order to stay competitive in the marketplace. In a collaboration between ARS-Parlier and University of California, Kearney quality attributes were identified that closely relate to navel orange flavor and that change during fruit maturation and handling. New information on the relationship of these attributes and flavor is needed so that the California citrus industry can sell the highest quality fruit and stay competitive in the marketplace. Quality attributes were evaluated during fruit maturation at several locations in California and following different industry postharvest handling treatments and comparisons made to the sensory acceptability of the fruit as determined by taste panels. It was found that raising the minimum maturity requirement (sugar/acid ratio) that govern when navel oranges are harvested in California could be useful in increasing the purchase and consumption of navel oranges. This information may be used to support efforts to change the minimum maturity requirements that govern when oranges may be harvested in California.


4b.List other significant research accomplishment(s), if any.
Detection of Freeze Injury in Citrus Fruit NP 303 - Componet 1 - Problem 1A Freeze injury caused economic losses to citrus growers and packers and the industry needs a simple and inexpensive test for determining freeze injury on quality of oranges. Scientists of the Postharvest Quality and Genetics Research Unit in collaboration with support of the Citrus Research Board conducted tests of freezing temperatures on volatile emissions from navel oranges. Ethanol and three other chemical compounds were found in frozen oranges while none were detected from unfrozen fruits. The findings could provide the citrus industry a rapid method to differentiate marketable quality fruit from injured fruit.


4c.List significant activities that support special target populations.
None.


4d.Progress report.
None.


5.Describe the major accomplishments to date and their predicted or actual impact.
NP 303 - Component 1 - Problem 1A Our major accomplishments, with credit shared with collaborators, are the continued discovery, development, and transfer of technologies to detect and minimize physiological and pathological defects in citrus fruit, to replace or reduce synthetic fungicide use by the citrus industry, introduce new postharvest decay control technologies for postharvest use by the table grape industry, and to identify disease resistance in new grape selections. These accomplishments are in concordance with the objectives 1, 2 and 3 of Project 5302-43000-032-00D "Emerging Technologies to Maintain Postharvest Quality and Control Decay of Fresh Commodities", and with the Action Plans of National Programs 303 and 306. Citrus packinghouses use of aqueous, heated fungicide solutions, that enable rates to be reduced by 50% or more, is a common commercial practice now as a result of this project. Immersion of fruit in bicarbonate and carbonate solutions, which avoids fungicide use entirely, or in combination with low rates of the fungicides, has also become popular. These approaches also manage fungicide-resistant isolates of the citrus pathogens. Promising technologies that are yet to be implemented include "biofumigation" with Muscodor albus and integrated treatments incorporating biological control and thermal curing. In addition to reducing fungicide use, these techniques have improved management of postharvest citrus and table grape diseases, particularly for high value export fruit during long transit.


6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
Results of this work are commercially implemented by citrus growers and packinghouses, or by table grape growers or cold storages. Many of the objectives and technologies originate from ideas suggested industry collaborators. In 2005, a new technology, first implemented in the prior year, in citrus industry packinghouses in which we participated was the use of high-volume, low-pressure overhead drench application of dilute heated fungicide solutions. More large-scale tests were conducted in 2006. In some facilities, the fungicide is combined with sodium bicarbonate, which allows an even lower rate to be used, and some control of fungicide resistant strains of the green mold pathogen was also observed. The implementation of most of the "reduced risk" and "certified organic" approaches is rapid because they may not require formal EPA registration, such as bicarbonate solutions alone or in combination with fungicides, heat treatments, or the use of generally recognized as safe buffers to optimize the pH of already approved fungicides. Other technologies that require formal regulatory approval, such as the postharvest use of ethanol on table grapes, biological control agents such as Muscodor albus or Pantoea agglomerans, have commercial advocates that are petitioners for registration and this process takes several years. The EPA classified "reduced risk" postharvest fungicide pyrimethanil for citrus was approved and entered commercial use in 2006. With collaborators, we participated in most of the tests that made the citrus registration possible. Constraints are domestic and international regulatory issues associated with residues, adequate effectiveness, costs, and worker and environmental safety.


7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below).
Smilanick, J. L. "Gray mold resistance in grapes" Seminar arranged by the Biology Department of the University of Marche, Ancona, Italy. November 2, 2005.

Smilanick, J. L. "Postharvest decay resistance in table grapes." University of California/USDA-ARS Laboratory Salinas, CA. November 18, 2005.

Smilanick, J. L. "New technologies to extend the postharvest life of table grapes." Presentation to "Grape Day" seminar sponsored by the University of California and California Table Grape Commission, February 22, 2006. Visalia CA Convention Center.

Smilanick, J. L., Mlikota Gabler, F., Mansour, M. F., Margosan, D. A. and Julien Mercier, J. 2006. New technologies to extend the postharvest life of table grapes. 9 pp article in proceedings of "Grape Day" seminar sponsored by the University of California and California Table Grape Commission, February 22, 2006. Visalia CA Convention Center.

Smilanick, J. L. "Alternatives to sulfur dioxide fumigation." Presentation within "Postharvest Table Grape Management Seminar" sponsored by the California Table Grape Commission, June 8, 2006. Tulare CA Coop Extension Center.

Smilanick, J. L., and Mlikota Gabler, F. 2006. Alternatives to sulfur dioxide fumigation. 10 pp article in proceedings of "Postharvest Table Grape Management Seminar" seminar sponsored by the California Table Grape Commission, June 8, 2006. Tulare CA Coop Extension Center.

Smilanick, J. L. "The effectiveness of pyrimethanil to inhibit germination of spores of Penicillium digitatum and to control citrus green mold after harvest." Invited participant in workshop titled "Western Tree Fruit Diseases Discussion Group" to discuss new research developments with the fungicide pyrimethanil in postharvest disease management at the Hilton Hotel, Portland Oregon. January 13, 2006.

Smilanick, J. L., Mansour, M. F., Mlikota Gabler, F., and Goodwine, W. R. 2006. The effectiveness of pyrimethanil to inhibit germination of spores of Penicillium digitatum and to control citrus green mold after harvest. Proceedings of the 80th Annual Western Orchard Pest and Disease Management Conference, Portland, Oregon, January 11-13, 2006.

Smilanick, J. L. "Drenching citrus fruit to control postharvest decay" Presented to the University of California, Plant Sciences Department, Pest Control Management Seminar at Santa Barbara, May 8, 2006. Presented twice later as a packinghouse seminar for the California Citrus Research Board on May 9 (Ventura, CA) and on May 10 (Exeter, CA).


Review Publications
Smilanick, J.L., Mansour, M., Sorenson, D. 2006. Pre- and Postharvest Treatments to Control Green Mold of Citrus Fruit During Ethylene Degreening. Plant Disease. 90:89-96.

Romanazzi, G., Gabler, M.F., Smilanick, J.L. 2006. Preharvest chitosan and postharvest uv irradiation treatments suppress gray mold of table grapes. Plant Disease. 90: 445-450.

Smilanick, J.L., Schmidt, L., Ghosph, J., Margosan, D.A. 2003. Mutation at beta-tubulin gene codon 200 of penicillium digitatum conferred thiabendazole resistance. Plant Disease. 90: 765-770.

Last Modified: 7/25/2014
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