Oak Wilt 2001: Keep the momentum going

Oak wilt causes serious losses
Oak wilt disease is responsible for killing thousands of oak trees annually in residential settings, woodlots and forests. By May of 2000, surveys had identified 15,359 acres of active oak wilt in Minnesota. Most of the infection centers are concentrated in the Twin Cities, counties immediately north of the Twin Cities, and in scattered locations in the southeastern counties.

Oak wilt is a contagious disease. It spreads underground through connected root systems and overland by picnic beetles and by human transportation of fresh, infected logs. But, oak wilt is a disease that we can DO something about. Effective control programs have already been developed in Minnesota, using root system disruption by plowing, spore tree removal, and public education as the means to thwart the spread of oak wilt. The tally now stands at 6,976 acres treated and controlled.

Cost-share programs are effective
Oak wilt suppression cost-share programs have been very effective in controlling oak wilt. See table. From 1991 to 1997. the federally funded Cost-Share Program controlled nearly 60% of the identified oak wilt infection centers in selected areas of Anoka, Chisago, Dakota, Isanti, Ramsey, Sherburne, and Washington Counties. In 1998, state funding replaced federal funding and the coverage was increased to include all areas and counties with oak wilt.

During the last ten years counties and communities developed excellent programs that distributed the cost-share monies and provided oak wilt inspections, homeowner assistance, program regulation, and community education. More than 120 counties and communities have participated in this program.

Accomplishments:
* On a statewide basis, 31% of the oak wilt infection centers are controlled.
* Based on the data from several counties, the projected amount of oak wilt has been reduced by 60%. We estimate that, without control, 23,000 additional acres would be infected today.
* The spread of oak wilt into new areas has been slowed. For example, the northern "front" of the disease has only moved north 5-7 miles in the last decade. In comparison, oak wilt moved 24 miles per decade from eastern Wisconsin into the Upper Peninsula of Michigan.

Consequences of halting control
Deferring control actions to the future will ensure:
* disease intensification in nearby trees and woodlots causing needless loss of thousands of oak trees and increasing the number of oak wilt infection centers,
* the beauty and shade of your oaks will diminish as they succumb to oak wilt,
* residential property values will decline as mature oak trees die,
* new developments in infected areas will lose their oaks,
* millions of dollars will be spent taking down dead oaks on private and community lands,
* the remaining oak forest habitat will be increasingly fragmented, and,
* on all lands, fire danger will increase due to the presence of dead and fallen oaks and brushy undergrowth.

Most important, oak wilt threatens oak trees and forests in the remainder of the state. Without continuing public education, people will inadvertently carry oak wilt to recreational, suburban, and forest sites well beyond where it exists today.

If we lose momentum, it will be a daunting task to control oak wilt disease in the future.

Keep the momentum going
People are poised to continue the oak wilt cost-share program. Building on past success and the foundations laid in local programs, the state should renew its partnerships with communities and counties by continuing to provide technical assistance and cost-share monies. We need to be persistent in aggressively treating oak wilt infection centers.

We still have the momentum. Let's keep plowing.

Recommendations
A request for funding of $310K per year is made to maintain current funding levels previously provided through LCMR and general appropriations. This funding, part of the Forest Health Bill, is needed to maintain the momentum of control, Important funding requests for community forestry assessment, tree planting, and emergency storm response are parts of an overall comprehensive forestry program crucial to the health of the state's urban and rural forests.

Typical oak wilt infection center
A typical infection center is about 1 acre in size. The center is occupied by dead oak trees and the perimeter is made up of dying oaks. Next year, the circle of dead trees enlarges by about 25 feet in all directions as the fungus spread through connected roots. Old infection centers have a new "satellite" infection centers which are the result of insects carrying the fungus to nearby oaks. Insects, active in April, May, June, and early July, can spread the fungus up to 1/3 miles in a year. The satellite infection center also grow at 25 feet per year and oft3en merge with the original infection center.

Construction and storm damage increase disease spread
Insects carry the oak wilt fungus to wounded trees in spring and early summer. Unfortunately, this is the time when construction activities occur. Oak wilt gets carried to the wounded oaks and then spread to nearby oaks in the next few years.

Heavy storms break branches and damage oak trees. These wounds are liable to become infected if within 1/2 mile of an existing infection center. The damaging storms of 1997 and 1998 doubled the acreage of oak wilt in Sherburne County.

How oak wilt is controlled
Existing infection centers can be controlled by severing roots between infected and healthy trees with a vibratory plow. New infection centers can be prevented by immediately removing the dead/dying oaks, which prevents the insects from carrying the fungus to nearby wounded oaks. New infection centers can be indirectly prevented through public education about pruning, and construction damage through focused educational efforts, such as, the Best Management Practices for Conserving Wooded Areas in Developing Communities.

Community Cost-share programs
Upon successful application, the local unit of government makes a cost-share agreement with the state. The local unit of government then offers participation in the oak wilt suppression program to interested landowners. Infection centers are verified by the local forester. Sites are plowed and dying trees are removed by local vendors. The local unit of government reimburses the landowner for up to 100% of their treatment costs, depending on the local program. The state reimburses the local unit of government for up to 50% of total program costs.