To the Editor:
This letter is in response to a recent letter to the editor in opposition to Fairfax County's Fall Cankerworm (FCW) spraying program.
I am the Chairman of the Fairfax County Tree Commission, which is appointed by the Board of Supervisors to advise them on all matters relating to tree preservation in the county, including the benefits and threats to our urban forests and the potential environmental impact. The commission has positions for a representative from each county district, as well as one from the Fairfax County Park Authority, the NV Soil and Water Conservation District, the Environmental Quality Advisory Council (EQAC), the VA Dept. of Forestry, and the Virginia Cooperative Extension program.
Last year the Commission held a special meeting to hear and discuss the concerns of county citizens about the potential environmental impact of the spraying program, as well as its necessity, cost and alternative means of control. We also participated in a similar meeting held by EQAC. The spraying program is maintained by the County's Urban Forest Management Division, and it was present at both meetings to describe the program and answer questions.
After much discussion and further research, we concluded that FCW threat to our already stressed tree canopy is limited but real, and that without a carefully monitored and precisely targeted spraying program, we risk a potential outbreak of FCW that can defoliate, weaken, and ultimately kill mature trees. These includes oaks and beeches, which are favored by the FCW caterpillars. Last year, almost 57,000 acres of trees in eastern Virginia suffered light to heavy FCW defoliation, including in nearby Fauquier, Prince William and Stafford Counties. Yes, we are aware that the spraying can also kill other native butterfly and moth caterpillars that mature at the same time in the early spring, and that migratory birds, especially chickadees, feed on such all such caterpillars. But the Fairfax County spraying program is triggered only when careful monitoring of trees in areas of previous outbreaks indicate that the risk of a new outbreak is high.
The chemical used, called Btk, is derived from a naturally occurring soil bacterium and is approved by the ISDA for use in organic gardens. The spraying is done by helicopters at low altitudes over small blocks to limit drift, open areas are not sprayed, and a 200 ft buffer is maintained inside the tree line. The BTW is in low concentration, and it persists for only two weeks or less. Individual property owners can opt out of the spraying or have it done from the ground, and the Board of Supervisors must give final approval before spraying begins. Furthermore, the county has sprayed only four times in the last 15 years. In 2014, only 2,000 acres were sprayed, which is less than 1% of the county's tree canopy.
The Tree Commission has just sent a resolution to the Board of Supervisors that essentially says we wish that the already limited and carefully targeted FCW spraying program were unnecessary, but until this is so, the benefits to trees outweigh the costs and potential risks. Once mature canopy is lost, in can take decades to replace, and the environment suffers We also ask the County to reach out to volunteers and neighborhood groups to further study the longer term environmental impact of Btw spraying and to ensure that all other reasonable alternatives are used to prevent and mitigate future FCW outbreaks.
Robert Vickers, Chairman
Fairfax County Tree Commission
Great Falls