Primetime Newspapers
By Calvin R. Finch, PhD,
SAWS Water Resources Director, and Horticulturist
Week of April 24, 2006
 “Summer Weeds”  

            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

 

            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 Bermuda lawns on sandy soils.  In such a situation an MSMA product can be sprayed over the whole lawn.  MSMA does not hurt Bermuda, zoysia, or buffalo grass; however, MSMA kills St. Augustine grass and broadleaf weeds.

 

 

 

 

 

·      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 Bermuda when it is growing vigorously.  Use these products to spray the weed when it is isolated.  Both products will kill other plants if it gets on their foliage or green stems.  The grass specific contact herbicides, however, can be sprayed on Bermuda grass that is growing in your flower gardens, ornamentals, and groundcovers.  Spray on the Bermuda foliage, and within a few weeks the grass will die, roots and all.  You can make straight lines between garden borders and lawn with the sprays and used every month they will keep Bermuda grass completely in check.  The grass specific sprays will not hurt your roses, zinnias, Asiatic jasmine or other broadleaf plants even if the spray wets the leaves.  Grass specific sprays include Over the Top, Grass be Gone, Poast, Fusilade, and Vantage.  Follow the label instructions exactly as written.