Archive for Thursday, November 25, 2004

Attack now to reduce weeds in spring

November 25, 2004


At a recent arborist training, 45 regional treecare professionals poked, prodded, bored into and inspected the trees at the Douglas County Fairgrounds. As they looked up, I looked down, noticing the thick mat of weeds in bare areas of the lawn and at the base of each tree, the two most prevalent weeds being henbit and chickweed.

As winter approaches, there is still time to control these winter annual weeds.

Henbit is a rather showy spring blooming weed. The violet flowers, born on stems from 8 to 12 inches tall, are quite striking on a warm March day. They are found in cultivated areas such as farmers' fields, flower beds, gardens and in the lawn. Chickweed has a lower growth habit with creamy yellow blooms.

Mix the two plants together and you can create a beautiful spring display with little effort. Keep in mind, though, as with most weeds, they can be invasive and easily take over if left unattended.

Because both weeds are self-seeding, the plants that are there this year are not the same plants that were there last year. They are, however, plants that sprouted from seeds that were dropped in April and May. The seeds have germinated and will continue to grow all winter. As the days get longer and the temperatures rise next spring, mature plants will bloom and start the process over.

If you had henbit or chickweed this past spring, now is a good time to control them for next spring. Start with mechanical controls. Hoe or lightly till bare soil in the garden and around flowers, trees and shrubs. For added control, apply a fresh layer of mulch; 2 to 3 inches should be enough.

For hard-to-reach or noncultivated areas, the broad-leaf weed killer Trimec or Weed-Free Zone by Fertilome are the two best products to use. Spray on a sunny day when the air temperatures are above 55 degrees. Avoid spraying newly sprouted grass seed as dieback may occur.

Likewise, avoid spraying desirable trees and shrubs.

Henbit is a striking spring-blooming weed, but it can be invasive.

Henbit is a striking spring-blooming weed, but it can be invasive.

On a similar note, many gardeners try to attack dandelions and clover in the spring when they are in full bloom. Unfortunately, this is not the best time of year to get either under control. Spring growth is caused by an upward flow of energy and nutrients from the roots. Sprayed herbicides do not move well from the leaves to the roots against this upward flow. In the fall, the plants are preparing for winter by moving manufactured food from the leaves to the roots. Herbicides sprayed now are taken quickly down to the roots where they can kill the plants. Use 2,4-D for dandelions and Trimec or Weed-free Zone for clover.

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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