Archive for Sunday, May 19, 2002

The weed battle begins

May 19, 2002


The signs of a well-cared-for landscape are nicely mulched weed-free flower beds. Unfortunately, these nasty invaders can grow in some pretty small areas and surprise us with their existence seemingly overnight. One of the more noxious and most difficult weeds to contend with is field bindweed. With its long runners and deep root system, once established it is next to impossible to control.

Here are some suggestions to help fight and win the battle of the weeds.

Field bindweed reproduces by both seed and underground rhizomes, making it aggressive and difficult to control. In the home vegetable garden, control requires taking the treated portion of the garden out of production for a time.

Option one is solarization, which uses the energy from the sun to produce heat that pasteurizes the soil. Follow these steps to solarize a garden area:

Select the hottest time of year to solarize, usually mid-June to mid-August.

Work the soil deeply and smooth the surface so the clear plastic will make uniform contact with the soil.

Water well. The moisture encourages seed to germinate and existing bindweed to grow so the plants can be killed by the heat. The water also helps conduct the heat deeper into the soil.

Spread clear polyethylene film over the area. Seal the edges and seams with soil to prevent air from circulating under the plastic. One mil film is most effective at creating heat, but is likely to be torn apart by Kansas winds. Film that is 4 mil thick is more likely to last.

Leave the plastic in place for 4 to 6 weeks.

Remove the plastic after 6 weeks. If you leave it in place longer, it may become brittle from exposure to ultraviolet radiation and be difficult to remove. You can plant the next day.

Option two is to use Glyphosate, which is sold under a wide variety of names, the most common name is Roundup. Take the garden out of production when treating.

Roundup will kill whatever it hits. But it is inactivated when it contacts the soil.

Apply to bindweed that is at or beyond full bloom. You can treat earlier but don't skip the late summer to fall application.

Do not apply to bindweed that is under moisture stress or not growing well.

Controlling bindweed in turf is a different story. For homeowners, use a combination herbicide that contains dicamba such as Trimec, Weed-B-Gon or Weed-Out. Though this is the best material that homeowners can use, results are often disappointing.

In shrub beds, the only option is to use a selective spray of glyphosate between plants. Use a shield if spraying near plants to keep spray from contacting green plant material.

It is possible to control field bindweed by pulling, but you must be extremely persistent.

Bruce Chladny is horticulture agent at K-State Research and Extension-Douglas County. For more information, call him at 843-7058 from 8 a.m. to 5 p.m. weekdays.

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