Answer: Controlling sandburs in the lawn requires a multi-faceted approach. One method is collecting the clippings after each mowing once the plants begin to develop burs. In this way you will be gathering up the burs which contain those seeds for next year's growth. Another way of removing those spiny seed packets is to attach an old towel or blanket to a board. Tie rope to the ends and drag it across the sandbur-infested areas of the lawn to pick up burs. Of course, this only works after the burs have formed--usually late August and beyond.
Pulling plants out by hand will work but is too tedious for most people. Stripping off or rototilling under heavily infested areas and replacing them with fresh sod is another way to take care of the problem. But the new sod will have to be maintained well to prevent burs from coming in again.
Regardless of what you attempt, complete control may be very difficult in new housing developments, especially when much of the surrounding land has been disturbed, or when sandy areas nearby are not sodded and maintained. Over the years, as turf and surrounding vegetation thickens, sandburs will have less opportunity to grow.
A strong, vigorous turf simply will not allow sandbur plants to prosper. During the dry months of the year the lawn does best with at least one inch of water per week. On sandy soil this should be applied two times weekly, using ? inch of water each time. To measure the amount that your sprinklers apply, place straight-sided cans, such as coffee cans, around the area to be watered. Keep sprinklers on until water in the can is ? inch deep.
Fertilizing is also important, particularly in sandy areas where water and nutrients leach through soil rapidly. Fertilize in late August or early September and again in late October or early November. Repeat in late May or June, if grass is not a good green color.
Pre-emergent herbicides, such as those used for crabgrass prevention, will help control sandburs. The only one specifically labeled for sandbur control in turf is trifuralin (Treflan). This is available in a mix with Balan (another pre-emergent herbicide) and lawn fertilizer. This mix of herbicide and fertilizer must be applied in late April or early May to be effective since the burs usually start to germinate during the last half of May.
Lawn chemical applicators may use other pre-emergent herbicides that are not available to the general public. Chemical controls, once sandbur plants have sprouted, are usually not effective.
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