In 2008, a larger area was tilled, using the same sort of hand-operated machine. This time, volunteers spent a huge amount of time sifting the top layer of turned soil using a mesh frame (about 1 cm grid). By fall, the native plants they put in were doing very well and we couldn’t see any DSV.
In 2009, Agriculture and Agri-Foods Canada very kindly helped with rototilling of an area next to the birch grove. They tilled in spring and again in the fall. Volunteers also sifted part of the area, but the tilling removed a considerable amount of DSV. We planted this area with a number of wildflowers in 2010.
Mulch: We have tried a number of materials as mulch. Thick leaf cover, landscape cloth or multiple layers of newspapers are all fairly effective when used around the base of trees and shrubs – areas where DSV seems especially dense. Although some plants grow through the mulch, growth is considerably less than in un-mulched areas nearby.
Research elsewhere has shown some success with heavy plastic sheeting placed over mowed or cut plants and left in place for at least 1 year. However, if the plastic is torn allowing light to penetrate, the plants will readily grow.
At the FWG in July 2005, we placed a large tarpaulin over most of the north bank of our Amphibian Pond. This bank is quite steep, so digging out DSV plants was impractical. It has been difficult to keep the tarpaulin anchored securely. We used pieces of heavy coathanger bent into loops and pressed into the ground through the edge of the tarp. These frequently come loose and the tarp has torn in several areas. Monitoring is obviously needed.
In July 2006, although some DSV had grown through holes, no plants could be seen under intact parts of the tarpaulin. And no seedlings were visible, meaning that last year’s seeds did not germinate under the tarp.
We took advantage of the mild weather in October and November to pull back one corner of the tarp and start planting shrubs. We put in a number of dogwoods – planted about 60 cm (2 feet) apart.
In spring 2007, we removed the rest of the tarp. Only a few DSV plants were growing under it; we dug these out along with others along the edge of the cleared area and planted the slope with Wild Raisin (Viburnum cassinoides).
In 2006, we also used newspaper as mulch in some areas, especially immediately surrounding trees where there are hundreds of DSV seedlings and little or no other plant species. We place several sections of newspaper up against the tree trunk, then overlap subsequent sections working outward. The idea is to eliminate DSV near and under some trees where the seeds seem to accumulate.