Objective 1: Develop alternative systems for the management of postharvest diseases that can be used on a variety of fruit crops and production systems, including packinghouses, urban horticulture, vertical farming, and controlled environment growing systems. [NP303, C3, PS3B] • Sub-objective 1.A. Control of strawberry diseases using UV-C/dark Period/antagonist treatment. • Sub-objective 1.B. Control of postharvest brown rot of stone fruits. Objective 2: Develop microbiome-based approaches and molecular tools to increase postharvest disease resistance and/or decrease pathogen virulence. [NP303, C3, PS3B] • Sub-objective 2.A. Identification of molecular mechanisms responsible for resistance to the postharvest pathogens Penicillium expansum and Colletotrichum acutatum to facilitate the development of markers for use in screening for resistant crosses. • Sub-objective 2.B. Characterize the microbiome on fruit crops as it relates to pre-harvest management practices and postharvest treatments.
Research is focused on reducing the need to use postharvest fungicides in fruit production. It includes developing an integrated system to enhance control of Botrytis cinerea, Colletotrichum spp., and Podoshpaera aphanis in strawberry by combining UV-C irradiation with a dark period and application of biocontrol agents. The system is designed for field use and protective culture, including high tunnels and indoor urban agricultural production. The research will also determine the effect of UV-C/dark period/antagonist treatment on the quality of strawberry fruit. Genes associated with resistance to blue mold and anthracnose disease in wild apple germplasm will be determined, including the role of constitutive phenolic compounds, to facilitate the development of markers for use in screening for resistant crosses in apple breeding programs. Integrated control of brown rot disease of plums originating in wounds and from latent infections, currently an intractable disease control problem, will be developed using Generally Regarded as Safe (GRAS) substances and heat treatments. Amplicon-based analysis of the microbial community of apple fruit and strawberry fruit and leaves, and other fruit crops will be conducted to determine the impact of pre-harvest management practices and/or postharvest treatments on bacterial and fungal communities. This research is expected to identify safe and effective strategies that reduce disease without negatively impacting fruit quality and are based on the manipulation of the natural microflora or through the purposeful design of microbial consortia. Collectively, the results of the proposed research will directly and indirectly contribute to the provision of control alternatives based on “green” technologies to combat postharvest diseases of critical importance to fruit growers and processors. The developed technology will also address consumer demands to reduce synthetic chemical residues in food.
Effectiveness of heat treatment in controlling brown rot caused by latent infection of Monilinia fructicola on plums was determined. Immersion of fruit in water at 60 degrees Celsius for 20 seconds was very effective in controlling brown rot on harvested mature plums. A study was conducted on deWit’s displacement where several mixtures of antagonists were applied to plum wounds. The yeast antagonists were more compatible with each other than with bacterial antagonists. The mutually compatible antagonists were selected for a future study. Tolerance of the selected antagonists to GRAS substances (sodium benzoate, potassium sorbate, sodium bicarbonate) was determined. Large differences between antagonists were found, which will affect their selection for the future studies. Conducted genetic and phenotypic analysis of Monilinia fructicola isolated from strawberry, peach, nectarine, plum, apple and cherry in collaboration with ARS scientists in Beltsville, Maryland. The most significant genetic and phenotypic differences were found between apple and cherry, and the rest of the isolates. There were also some differences between most strawberry isolates and other isolates. More detail genetic analysis is being conducted to characterize these differences. Genetic analysis was conducted of multiple Cladosporium spp. isolates from a culture collection and our isolate TC09 producing volatile organic compounds that promotes plant growth. Uniqueness of our isolate has been established and included in a peer-reviewed publication. Isolate TC09 was deposited in the ARS Culture Collection (NRRL) in Peoria, Illinois.
Caro, A., Gonzalez, C., Balbin-Suarez, A., Wisniewski, M.E., Berg, G., Smalla, K., Cotes, A. 2018. Microbiome studies in the biological control of plant pathogens. In: Cotes, A.M., editor. Control biologico de fitopatogenos insectos y acaros. Agrosavia, Bogata, Colombia. p. 260-292.
Zapata, Y., Cotes, A., Jijakli, H., Wisniewski, M.E. 2018. Biological control of postharvest pathogens. In: Cotes, A.M., editor. Control biologico de fitopatogenos insectos y acaros. Agrosavia, Bogata, Colombia. p. 222-259.