The UVM Connection, Vermont Quarterly, Spring 2007 Alumni Publication
this article mentions the developers who isolated the fungi for use
Fungal fighter
The eastern hemlock is in trouble. From Georgia to Maine, this once-mighty conifer is now succumbing to an exotic pest, hemlock woolly adelgid. First detected in the western United States in 1924, the adelgid caused little damage. But when it was carried east and reached Virginia in the 1950s it began its destructive spread. An aphid-like insect, the adelgid kills eastern hemlocks within a few years after infestation, feeding on the sap at the base of their needles and cutting off their nutrients.
It’s a pressing problem: In Shenandoah National Park most of the famous towering hemlocks are now dead. The adelgid has ravaged parts of Kentucky, North Carolina, and the Smoky Mountains. Expanding northward, it has moved through Massachusetts into southern Maine and New Hampshire.
The only natural deterrent to the adelgid seems to be a very cold winter. With global warming, their northward spread seems inevitable. Though not officially recorded yet, “it’s probably in southern Vermont now at population levels too low to easily detect,” says Scott Costa, research assistant professor of plant and soil science, who anticipates that the adelgid will be into the Champlain Valley in not too many years.
New research in UVM’s department of plant and soil science, though, could aid the hemlock’s survival. Last December, Costa, graduate student Stacie Grassano, and two other researchers, Vladimir Gouli and Jiancai Li, submitted a provisional patent for a new method of cheaply and effectively spreading a strain of fungus called Lecanicillium muscarium, and other similar biological controls, that might beat back the adelgid without having to use expensive, toxic pesticides. They call their approach a “whey-based fungal micro-factory.”
Instead of growing fungi in a conventional factory and then transporting it out to a forest—a costly proposition—their factory will be the forest. Or, more accurately, tiny droplets of sweet whey—a cheap waste product of cheese production, inoculated with the right concentrations of the target fungus—will be their factory. By spraying the whey solution into an infected forest, they believe they can get the adelgid-killing fungi to reproduce in large numbers on its own.
Costa and Grassano’s experiments on branches taken from adelgid-infected forests in Massachusetts are proving highly successful, with rapid growth of the target fungi out-competing other fungi that live on hemlocks. If their laboratory tests continue to go well, the researchers anticipate starting field trials in 2008.
The economy and ease of the UVM team’s whey micro-factory technology might prove a critical consideration for land managers—especially in large areas with low economic value, like wild hemlock forests.
“We’re not going to eradicate the adelgid,” Costa says. “The best-case scenario for insect-killing fungi is you inoculate the environment and get disease outbreaks to start cycling. The idea is to reduce the pest population to a level that is manageable, allowing some of the trees to make seeds, grow, and survive.”
