the plants and digging out the roots can be successful on newer infestations, but care must be taken to remove and dispose of all root fragments. Segments as small as 1 inch, left in or on the ground
, can grow into a new plant. Dispose of plants that have bloomed because they can continue developing and produce seeds.
several times during the growing season will prevent food production in the leaves and deplete the food reserves stored in the roots. This strategy can “starve” the plant to death, but may require several years to succeed.
Herbicides can be effective
, but should always be applied with care. Do not apply herbicides over or near water bodies. Read the label to check that you are applying an herbicide in the right place, to the right plant
, at the right time, and in the right amount. For perennial weeds
, long term control requires stopping seed production and
attacking the weed’s root system. Translocated herbicides
, (ones that move throughout a plant’s system), such as Roundup (glyphosate), Curtail (2,4-D + clopyralid), Stinger (clopyralid) and Banvel (dicamba) are recommended.
Note: Roundup is non-selective and will damage all plants. The other chemicals will target only broad-leaved plants.
Timing of application is important. Apply herbicide to actively growing plants just prior to flowering (bud stage), or early to mid-flowering, depending on the chemical (check your label). Applications to regrowth in the fall, (before freezing occurs) are very effective because the chemical is readily moved with sugars being sent to the roots for winter storage.
Cutting back the plant three to five weeks before applying herbicide will encourage active growth. Applications to active growth increase effectiveness because the herbicide moves around the plant more quickly. Also, herbicide is more easily absorbed by clean, new leaves which have not developed the thickened cuticle (waxy coating) present on mature leaves, which resists herbicide penetration.
Prepared by the Clallam County Noxious Weed Control Board; revised 11/2000
For more information call: (360) 417-2442
or see www.clallam.net/weed