SLow Ash Mortality project (SLAM)
The SLow Ash Morality project – code named SLAM – employs a combination of strategies to reduce the population of EAB and its spread. First developed by researchers in Michigan, it is being deployed in areas with small-scale outlier EAB populations such as at Missouri’s only known infestation in Wayne County. SLAM tactics include surveys to find the population boundaries, reducing the food resource (phloem reduction), insecticide treatments (making lethal trees), sinks of attractive trees to concentrate EAB, and biological control.
Research has shown the rate at which ash tree mortality advances is related to EAB density. As outlier populations build and coalesce, the area of dead, dying and declining ash trees increases dramatically. Therefore, treatment tools and strategies that reduce EAB’s food supply should stunt population growth and slow the expansion of tree mortality.
Missouri’s SLAM project at the Greenville Recreation Area is a partnership between the U.S. Army Corps of Engineers (USACE) and Missouri Department of Agriculture (MDA), funded in part through a U.S. Forest Service grant. SLAM activities include:
- Removal of trees known to be infested
rompt removal of symptomatic ash trees in the Greenville Recreation area started in 2008. Trees were burned, which destroyed countless EAB developing inside.
- Delimit survey with girdled trees
Stressed ash trees are more attractive to adult EAB than healthy ash trees. Intentionally stressing ash trees by removing a ring of bark (girdling) is a survey tool used to detect low level EAB populations. The girdled detection trees were deployed in spring 2009 in a systematic survey grid to find the boundaries of the population. Detection tree GPS coordinates were recorded so the survey crew could easily find the trees when they returned in the fall. Trees were cut down and the bark carefully peeled with a draw knife to check for the telltale galleries left by the feeding larvae. Girdled trees are peeled prior to adult emergence. Delimit surveys with girdled trees complements the USDA-APHIS-PPQ purple sticky trap survey that was conducted on a much broader scale.
Anastasia Becker, Integrated Pest Management Program manager for MDA, uses a draw knife to strip bark from an ash tree in the Greenville Recreation Area near Lake Wappapello. Removing the bark allows researchers to find telltale s-shaped galleries left by the larvae of the emerald ash borer beetle.
The larvae of the emerald ash borer beetle tunnels under the bark of the ash tree creating S-shaped galleries in their path. The galleries destroy the phloem layer, or vascular system, killing the tree.
- Sinks made with clusters of girdled trees
In addition to the grid of girdled detection trees, clusters of girdled trees were established near the central infestation to function as “super attractors” in an effort to draw beetles back in toward the center. These trees were burned to eliminate any beetles developing inside.
- Phloem reduction
Revolves around constraining EAB density and spread by reducing the amount of food available to EAB. Less food should result in lower beetle production and fewer offspring. Two phloem reduction techniques are used: applying insecticide to make lethal trees and removing the largest trees, which is the most effective way to focus efforts to limit the food resource. Once EAB was discovered in Wayne County, initial efforts to reduce the ash resource included logging the accessible merchantable ash timber in conjunction with cutting and burning some of the ash trees surrounding the campground at Greenville Recreation area.
Steve Lawson of the U.S. Army Corps of Engineers burns ash logs gathered from the Greenville Recreation Area. Working with USDA and the Missouri Department of Agriculture, the Corps is burning ash trees in an effort to stop the spread of the emerald ash borer. The invasive pest, which made its North American debut in Michigan, is fatal to ash trees.
Continuing these efforts in 2009/2010, the USACE—with the help of funding from the American Recovery and Reinvestment Act (ARRA) — hired contract loggers and heavy equipment operators to cut down more than 1,000 ash trees in a 1,400-acre area. The cut logs were gathered into piles then burned to reduce the amount of larvae becoming reproducing adults in 2010.
Future ash reduction efforts will be guided by results from an ash inventory and SLAM computer modeling.