NDSU Extension - Mercer County


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dandelion control

Submitted by Craig Askim, Extension Agent, Agriculture and Natural Resources   

This spring has presented a huge population of dandelions across Mercer County. Most people dis-like this weed, but don’t have a clear understanding of how to get rid of it. Dandelions are a perennial weed that likes undisturbed sites such as lawns and no-till environments. Tilling will kill dandelions, or they can be pulled by hand, but if that doesn’t sound fun, another option for dandelion control is chemical application.

When spraying dandelions first look at the environment (lawn/field) to be sprayed. Second, consider the time of year to determine what type of herbicide will work best. If the area is not a lawn or doesn’t have anything growing, the chemical, glyphosate, will work best. Remember, any glyphosate product is a total contact herbicide, meaning it will kill everything growing in the area at the time.

When spraying dandelions in a lawn, the product 2-4-D works well. This product will kill dandelions and other small broadleaf weeds that may present themselves. However, consider the time of year. Spraying dandelions in the spring (May/June) kills the upper part of the plant but does very little to kill the root system, so the plant will continue to grow throughout the summer. An application in July/August does very little to control dandelions.

A fall application will provide the most effective kill. Again, dandelions are a perennial weed, so they harden off and grow again the following year. Therefore, spraying in the fall (September/October) allows the chemical to advance further into the plant’s roots, and since it is not actively growing and not producing an actively growing flower, it is weaker so the chemical works better on killing the stem and roots.

NDSU research has shown that a late fall application (October) of glyphosate had an 82% control rate and an application of 2-4-D had a 58% control rate the following spring compared to 58% and 30% when applied during a late spring application (May).

Proper lawn maintenance will help prevent re-invasion. Most people don’t want dandelions so they mow them which gets rid of them for a short time, but in many cases, spreads dandelion seeds, creating a bigger problem. Mow grass to a height of 2.5 - 3 inches. Leaving the grass higher will provide more competition for the dandelions to germinate. Fertilize grass when it is actively growing (June) and, if needed, after it has started to go dormant for the year (October). Water deeply but only when needed throughout the growing season.

Read and follow all label directions when making any chemical application. Also, understand the risks in making a chemical application and realize that chemicals labeled to be used to control dandelions can have negative effects on the growth and germination of trees, flowers, and gardens.

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