For The Answer
By Calvin R. Finch, PhD,
SAWS Water Resources Director, and Horticulturist
Week of April 24, 2006
Does your lawn have what looks like dying grass all over it? Your lawn may need watering because of the drought, but do not govern your irrigation by the dying weeds. Every year at this time the winter grasses – rescue grass, annual bluegrass, and rye grass decline with the heat. No amount of watering or fertilizer will restore the grassy weeds. The best control is to mow them frequently to keep the lawn attractive and to keep the weeds from forming seed heads. The seed heads, if they mature provide the seed for next year’s winter weeds.
In my opinion, the two most troublesome summer weeds are sandburs and Bermuda grass. Here are strategies that will allow you to win the war against these two pests.
Sandburs are a special problem in many landscapes. Their control is not an easy process.
· Apply a pre-emergent herbicide such as Amaze, XL, Balan, or Betasan sometime in March or April. Follow the instructions closely. If the product is applied haphazardly, you will be disappointed in the results.
· Apply a second dose two months later.
Follow this procedure for two years running, and you should win the battle with sandburs – at least until your pets track in new burs.
For individuals who want to supplement the pre-emergent herbicide strategy or missed their opportunity this spring, consider the following tactics.
Kill individual plants with a spot spray of
MSMA. Sandburs require full sun and well
drained soil so they are often in
· Organic gardeners or folks who want the exercise can also pull young sandburs by hand. This tactic is especially effective over small areas and if the pre-emergent herbicide has been relatively effective.
· Vinegar also works as a control if you can identify the sandburs at a relatively young age. Use vinegar as a spot spray.
Once the sandburs form on the plant the mission changes to one of removing the burs so they do not hurt your pets and children, or serve as seed for the next generation of plants.
· Pull the whole plant including young burs. Bury them deep in the compost pile or send them to the landfill in your garbage.
· For mature sandburs over a large area – dragging a carpet remnant can be effective at collecting a large number of burs. Enlist your half-grown children to pull it, or use your lawn tractor.
Bermuda grass is the turf we use on golf
courses and ball fields. Bermuda grass
is also a major weed. The grass is
perennial and lives with traffic and drought.
There is hope, however. There are
many herbicides that work well to kill Bermuda grass. Contact herbicides like Roundup and Finale work
very well if sprayed on