Researchers look to shrimp shell byproduct to help combat apple killer

Researchers from the University of New Hampshire (UNH) and Pennsylvania State University have joined forces to test whether chitosan, a byproduct of shrimp shells, can be used to help treat and manage apple scab, one of the fruit industry’s most devastating diseases in the U.S. Northeast.

According to a recent report from Bio Market Insights, the researchers are looking into the combination of beneficial microbes with chitosan to form a biopesticide to curb the effects of apple scab, which is caused by the fungus Venturia inaequalis. While widespread adoption of biopesticides by the tree fruit industry has yet to take hold, UNH graduate student Liza DeGenring aims to enhance the effectiveness of such treatments with chitosan.

“Because biopesticides are living products, their activity is affected by environment. Biopesticides often fail to grow and maintain high enough population levels in the orchard or do not produce antifungal compounds at levels necessary to suppress the disease. It is increasingly recognised that solving these issues is key to increasing adoption of biopesticides. I am investigating a way to enhance biopesticide effectiveness using chitosan. There is evidence that chitosan may act as a food source for the biopesticides and stimulate production of antifungal enzymes, thereby enhancing their usefulness,” DeGenring told Bio Market Insights.

There has been research into chitosan’s ability to reduce postharvest disease, with studies finding that the seafood byproduct can diminish plant disease and preserve fruits and vegetables during storage and transport, the website said. The UNH researchers are looking to take the investigation further, observing chitosan’s impact during crop production as well as alongside an application of biopesticides.

“Reduced fruit quality is a major concern for the New Hampshire tree fruit industry since NH growers primarily market retail sales of fresh apples through pick-your-own, farm stands, and direct sales to grocery stores. Apple scab lesions on the fruit can result in decreased revenue to the grower due to consumers’ low threshold for imperfections on their apples,” DeGenring said.

One of the most destructive apple diseases, apple scab is of particular concern for Northeastern U.S. growers due to warm, moist climate conditions. The disease can result in 100 percent crop loss and negatively impact fruit marketability, Bio Market Insights noted.

“UNH has a historical reputation of conducting apple scab research. Much of what we know today about the disease is based on work done by William MacHardy, professor emeritus of plant biology. New Hampshire tree fruit growers have a strong history of collaboration with UNH to develop and adopt more environmentally and economically sustainable practices. In the 1980s, MacHardy and colleagues developed disease-forecasting models that growers still use today to predict outbreaks and apply fungicides only when disease risk is high. New Hampshire growers also have adopted Integrated Pest Management, which incorporates cultural, biological, and chemical practices to suppress disease. Even with these advances, apple scab continues to be a major nemesis to tree fruit growers,” NH Agricultural Experiment Station researcher Anissa Poleatewich, an assistant professor of plant pathology and DeGenring’s faculty advisor, said.

Typically, apple scab is treated with growers using sanitation and fungicide applications in their orchards. But, increasingly consumers are demanding a decrease in the use of synthetic chemicals, and DeGenring said farmers, too, are hoping for alternatives that match the sentiments of the time while helping their profit margins.   

“Both farmers and apple consumers would like alternative options for controlling apple scab. Chitosan has shown promise in other research in reducing disease, and there is a potential to use it to suppress disease in tree fruit production,” DeGenring said to Bio Market Insights.

Apples account for a nationwide market value of USD 2.4 billion (EUR 2.02 billion), according to the USDA National Agricultural Statistics Service.

The research ongoing is supported by the NH Agricultural Experiment Station via joint funding of the National Institute of Food and Agriculture, the U.S. Department of Agriculture, and the state of New Hampshire. Funding for the project also comes from a Northeast Graduate Student USDA Sustainable Agriculture Research and Education grant and a New Hampshire Specialty Crop Block grant.

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