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Whey to Help Hemlocks

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Photo by David A. Orwig.

Hemlock woolly adelgid, the tiny but mighty scourge of hemlocks from Tennessee to as far north as southern Maine and New Hampshire, may soon face a worthy adversary: University of Vermont researcher Scott Costa. With help from graduate student Stacie Grassano, Costa has developed a local and thrifty way of battling this pest, using a byproduct of cheese-making.

In his lab, Costa combines the cheese waste – sweet whey – with a native fungus (Lecanicillium muscarium) that has been shown to kill the adelgid by piercing its outer skeleton. The fungus thrives on the whey in the controlled environment of Costa’s lab; however, growing large batches of it inside and then applying it to stands of infested wild hemlocks would be prohibitively expensive.

That’s why Costa and his colleagues came up with a way to “seed” drops of the fungus-whey complex in the forest, where it can multiply and spread on its own. A “whey-based fungal micro-factory” is what Costa calls this application. “Essentially,” says Costa, “the micro-factories transfer a major part of fungal production for the ‘bricks and mortar’ factory out into the natural environment.”

The main costs involved are the creation of starter colonies in the lab and application of the fungus-whey complex onto affected trees. Costa’s supply of whey is currently provided free of charge from a cheese manufacturer in New York, and he is seeking funding for aerial application by helicopter, on a small scale, possibly as soon as 2008. Funding from the U.S. Department of Agriculture has thus far allowed for successful experimentation in the lab and on trees in Massachusetts.

For the adelgid, lands beyond the northern border of Massachusetts represent the next frontier. Long and cold winters have prevented the adelgid from successfully penetrating all but the mildest coastal pockets of Maine and New Hampshire so far – and there is no evidence the insect has crossed naturally into Vermont at all, though Costa and other scientists believe it has probably breached the border. Vermont, New Hampshire, and Maine have all imposed quarantines on the movement and sale of both live hemlocks and, in some cases, hemlock lumber – lumber that oftentimes comes from timber salvage cuts in places like Connecticut and southern New York, where the insect has infested many hemlocks.

Where the adelgid has gained the upper hand but not yet won the battle, Costa’s fungal factory may prove especially useful, though it won’t eradicate the insect on its own. “The idea is to reduce the pest population to a level that is manageable,” he says, “allowing some of the trees to make seeds, grow, and survive.” In conjunction with a predatory beetle that is being used in some places, including New York state, to control the adelgid, Costa’s simple and inexpensive fungal colonies may give embattled hemlocks – which are essential pieces of the Northern Forest’s ecology – a much-needed boost.

Discussion *

Oct 13, 2009

Hi Chris,

We are still moving forward. This year we conducted a test in TN and the preliminary results look promising!

Scott Costa .(JavaScript must be enabled to view this email address)

Scott Costa
Aug 23, 2009

This article is from 2007.  What is the status of this research today?  Is it possible to participate in using Lecanicillium muscarium?

Thank you.

Chris Barr

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