At his Worm Power facility 100 miles northwest of Ithaca in Avon, N.Y. Tom Herlihy feeds 20 tons of dairy cow manure to eight million earthworms each week. About 28 days after they are fed, the worms churn out “vermicompost” – a nutrient-rich organic fertilizer. Allison Jack grad, plant pathology and plant-microbe biology, has shown that vermicompost can suppress disease in crop plants.
The seeds of collaboration between Jack and Herlihy were planted at the 2003 U.S. Composting Council conference, and officially began when Herlihy, previously a consulting engineer in organic waste management, moved to N.Y. to build a business. This business, Worm Power, uses the outputs of a fourth-generation Finger Lakes dairy farm to produce vermicompost.
At the time, Jack had been making her own vermicompost with vegetable waste in the barn of the Dilmun Hill student farm. These vegetable inputs were not as consistent as the dairy cow manure.
As Herlihy stated, Worm Power’s mantra is “consistent, uniform, repeatable.” A product with these qualities is attractive to both academic researchers and to large-scale growers, such as Worm Power’s clients.
Jack’s findings show that, in a controlled research setting, Worm Power vermicompost protects plants from diseases caused by the pathogen Pythium aphanidermatum – a water mold or “oomycete.” Consequently, vermicompost can be used as an alternative to traditional pesticides.
Formerly classified as fungi, oomycetes – special types of eukaryotic cells – are only physically similar to fungi; they actually more closely related to brown algae. The Pythium genus is the culprit behind “damping off,” a disease that attacks stems at the ground level and causes young seedlings to collapse. P. aphanidermatum can cause disease in over 50 crop plants, Jack said.
The microbes present in compost are the key to suppression. These microbes colonize the seed surface within eight hours of being planted in vermicompost. The microbes chemically modify the seed as it germinates so that signaling between the seed and the motile zoospores of P. aphanidermatum is interrupted, preventing the pathogen from accessing the plant.
With vermicompost, “living microorganisms are required for the disease suppression to take place,” Jack said.
Vermicompost is probiotic, and stimulates the growth of microorganisms, unlike tranditional pesticides, which are antibiotic and inhibit such growth. It protects the plant whereas pesticides kill the pathogen. Pesticides also lose their efficacy when microbes evolve resistance, a concern that does not arise from the use of biological methods.
For this reason, among others, there is a demand for organic alternatives to pesticides in the agricultural industry.
As a businessman, Herlihy saw a missing supply line that would provide large-scale growers with vermicompost of consistent quality at sufficient quantities. As an engineer, he saw a solution both for disposing of animal waste and for suppressing disease in plants.
“We’re linking animal agriculture with plant agriculture,” he said.
Naturally, Herlihy is personally invested in Worm Power’s economic viability, but as a native of Geneseo, which is only 10 miles out of Avon, he is also aware of the rural development his company spurs.
“When we use the word ‘sustainable,’ it doesn’t just mean ‘environment;’ it also means ‘economic,’” he said.
Before partnering with Jack, Herlihy knew of the nutrient-based reason behind using compost but had only heard anecdotal evidence of disease suppression.
Even as Jack finishes her doctoral research project, she asserted that there is a great deal of research left to do because different pathogens may have unique mechanisms of suppression by composts.
“There is a lot in the popular and farming literature that [says] compost is invariably great and will invariably suppress everything, which is not the case because different pathogens work different ways,” Jack said.
Furthermore, a phenomenon – the plate count anomaly – demonstrates the void of knowledge on microbes. Given a soil sample, observation under a microscope tells scientists that there are a billion bacterial cells in the sample. And yet, if the scientists culture the sample on a petri dish, only one to ten percent of the bacteria will grow.
“Those are the bacteria that have been studied for hundreds of years … the other 90 to 99 percent … [we] cannot grow them in culture and study them,” Jack said. However, she explained that scientists can learn a lot by studying the DNA of these uncultured organisms.
Vermicompost, per gram, contains one billion bacterial cells potentially belonging to ten thousand different species, according to Jack. Currently, microbe ecologists grapple with the fact that there are thousands of “unknown bacterial species that are doing unknown things in association with the plant.”
To say there is work to be done would be an understatement.