Worm compost keeps seedlings safe

CORNELL (US) — Worm compost is not only an ideal fertilizer, it may also prove to be an organic way to protect seeds from a pathogen that has been a scourge to farmers.

By teaming up with a New York composting business, researchers believe they have found an organic way to raise healthier plants with less environmental impact.

The beneficial microbes in vermicompost—the product if composting using various species of worms—can colonize a seed’s surface and protect it from infection by releasing a substance that interferes with the chemical signaling between the host and the pathogen, says Allison Jack, a doctoral student at Cornell University, whose work builds on previous research by Eric Nelson, professor of plant pathology and plant-microbe biology.

“We know the microbes are actually adding something the zoospores don’t like,” Jack says. “Now we just have to find out what it is.”

Eric Carr, a master’s student in Nelson’s lab, is focusing on the suppressive qualities of vermicompost on a different stage of the life cycle of Pythium aphanidermatum, a pathogen whose mobile spores infect seedlings, causing them to “damp off,” or wither, shortly after germination.

The research helps contribute to opportunities to turn waste products like manure into important disease-suppressive soil amendments.

“At some point in our lives, we’re going to have to start using these types of natural resources and use them more efficiently; when that time comes, we’ll have a better idea of how it works,” Carr says.

Certain composts can suppress diseases, research has shown, but what is still unknown is which of the thousands of undescribed microbes in healthy compost are responsible for suppressing which diseases.

Another challenge in identifying suppressors and harnessing them is the variability of different composts.

To overcome this issue, Jack has teamed up with Tom Herlihy, who produces 2.5 million pounds of vermicompost a year through his Avon, NY, company, Worm Power. Because his dairy manure feedstock is regular and the process controlled, Herlihy’s end product is highly consistent, a quality that’s good for growers and for scientists.

Most seeds are treated in this country with chemicals,” Herlihy says. “If we know our vermicompost can suppress Pythium, wouldn’t it be nice if we could come up with a vermicompost-based solution, rather than a chemical one?”

There could also be economic benefit if the Environmental Protection Agency, for example, allows Herlihy to market his product as a biopesticide.

A related project focuses on vermicompost’s organic fertilizing capability. Horticulture assistant professor Neil Mattson will study how organic growers can incorporate vermicompost into their potting mixes for better nutrient management. That three-year research project, supported by the U.S. Department of Agriculture, will begin this spring

“What a lot of these growers tell us is fertility issues are the hardest to solve organically,” says Mattson. “This is a community that is doing a lot of great things. We want to make their production systems even more profitable. We want to promote production systems that promote healthy environments.”

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