Weed Management in Blueberry Fields
Management of weeds in blueberries is important for several reasons. First, weeds compete with plants for water, nutrients, and light. Second, some weeds can serve as alternate hosts for insects and diseases. For example, chickweed, dandelion, and red sorrel can act as hosts of the tomato ringspot virus. Weeds near the crown of blueberry plants create a condition of high relative humidity, which favors Godronia canker and growth of mummy berry apothecia. Weeds also can interfere with irrigation and harvest operations. Weeds provide habitat for vertebrate pests, such as meadow mice (voles). Finally, weeds that blossom at the same time as blueberries compete with the crop for bee pollination.
The most important weed management strategy is employed prior to planting that is, eliminating all perennial weeds. Common perennial weeds in the Pacific Northwest include common dandelion (Taraxacum officinale), Canada thistle (Cirsium arvense), stinging nettle (Urtica dioica), field bindweed (Convolvulus arvensis), field horsetail (Equisetum arvense), and quackgrass (Agro-pyron repens). Once these perennial weeds become established in a berry field, they are nearly impossible to remove.
Fields that have been in pasture often require extensive weed management prior to planting blueberries, as Canada thistle, quackgrass, and other perennials may be prevalent.
Perennial weed control should begin during the year prior to planting. A combination of several well-timed cultivations and herbicide applications will be necessary. Timing and herbicide type are dependent on the weed species present. Contact your local county Extension office for specific suggestions.
In established fields, weed management must be viewed as a continuous effort, rather than a seasonal duty. Fields should be scouted frequently to keep abreast of changing species and locations of “hot spots.” Seedlings of perennial weeds must be removed before they have a chance to establish.
Primary methods of weed management in blueberries include mulch.