How to Kill Buttercups in a Flower Bed
Creeping buttercup (Ranunculus repens) is an aggressive, exotic weed that has expanded to 42 states in the U.S. One plant can spread over a 40-square-foot area per year in heavy, damp or compacted soil with low fertility. The reason for such successful colonization is its ability to adapt. In dry years, it sets seeds, while in wetter weather it increases by runners. A single plant produces more than 600 seeds that remain viable in soil for five to seven years. Its advantageous stolons root at the nodes, forming daughter plants. In open sites, the stolons are short and well branched to ensure rapid colonization. In close turf, the stolons are fewer, but longer. Does this Spark an idea?
Instructions
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Manual Removal
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Cultivate the site frequently in hot weather. Cultivate deeply and thoroughly with a tiller or pitchfork. Even buttercup buried up to 6 inches will be able to survive.
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Remove all traces of buttercup stolons and roots. Dig thoroughly through the cultivated soil to find any fragments. Even the smallest node or root piece will resprout and form a new plant. Removal is most effective when the soil is moist.
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Cultivate again each time you see a new crop of seedlings starting to germinate. Repeat until the growing season is over and again the following year beginning in February when the next year's crops begin to sprout.
Chemical Controls
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Choose a weedkiller that has the active ingredient glyphosate and double the recommended dose.
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Spray the vegetation for the most effective treatment. Glyphosate is a nonselective systemic herbicide that will move through the plant and kill the roots.
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Repeat spraying every time you see a new crop of seedlings sprout.
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Tips & Warnings
Plants damaged by a single cultivation can recover and may increase the population because it can sprout from nodes along stem and root fragments. Disturbance or clearing of the soil also increases seed germination. Completely clearing your soil, especially in spring, provides ideal conditions for rapid recolonization. After clearing, plant one or more cover crops to increase competition. Buckwheat is a good choice, for its height, dense growing habit, and fertility. Taller vegetation crowds out buttercup and a few years without mowing can dramatically reduce its population.
Chemical control of buttercup isn't the best choice, because it has developed immunity to amitrole, simazine and low rates of glyphosate. The rates necessary to kill buttercup could cause a buildup in your soil which can have strong detrimental effects on future crops.
Like most buttercups, R. repens is poisonous. It contains the toxin protoanemonin, which can cause contact dermatitis and care should be taken in handling the plants.
References
Resources
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