Dandelions taking over an alfalfa field near South Shore, South Dakota.
Dandelions taking over an alfalfa field near South Shore, South Dakota.

As we move into the growing season, dandelions can cause many potential headaches not just in your lawn but also in your alfalfa field. It is important to remember that dandelions establish in the fall, do not have any toxins, and provide high-quality forage. However, they can cause wet and moldy spots in hay bales when harvested and their presence is an indicator of a weak stand.

Dandelions and forage establishment

The presence of dandelions can injure alfalfa seed crops and is often the main reason for removal or rotation of these perennial stands. Dandelions are important to control during the establishment of a forage stand because their broad leaves will cover the ground and won’t let forage seedlings gain strength and good vigor during the first part of the growing season.

If producers decide to spray, this option might remove them, but at the same time will leave open spaces in the field for future regrowth of other weeds. Something else to consider is that controlling dandelions by spraying will not increase the forage yield by any significant amount.

Hay fields

The presence of dandelions can result in wet and moldy spots in hay bales decreasing the forage quality and perhaps crude protein. Producers that harvest alfalfa fields with numerous dandelions can still feed livestock with few concerns. However, have your hay bales tested for quality to get a more accurate idea of the conditions within your production fields.

What should be done?

While it may not be worthwhile to control dandelions with an herbicide, stem density should be one major aspect to determine overall alfalfa production.

  • A stem density of 50 stems of alfalfa per square foot or below indicates a low yielding field and a weaker stand. Considerations for rotation should be made.
  • A stem density of 55 stems of alfalfa per square foot or higher indicates a high yielding field with a good stand and vigor. Considerations for rotation are not needed at this time.

With dandelions, as with most other weeds, the important part of controlling them is assuring that you have a healthy field to begin with. When the stand starts to reach the end of its useful life, or in the event of a disturbance in the field, dandelions and other weeds will move in. Keeping your alfalfa stand healthy by good forage management and assuring that you have the right seed planted for the soil conditions will go a long way towards controlling weed problems.

Spring is not the time to consider control of dandelions. In the fall there are some chemicals that will give fair but not complete control. Spraying may be considered if the field is in an area where it is very tough to establish a new stand of alfalfa. It is likely that spraying will need to be repeated annually in order to get the dandelions under control. For chemical options see the 2016 Alfalfa and Oilseeds Pest Management Guide.