War of the Weeds
Some folks call them weeds, to others they’re just a plant growing where it’s not wanted. They seem to sprout overnight and can outgrow the plants you pamper in a heartbeat. Recent rains have prompted vigorous growth. Left unchecked they can steal water and nutrients from neighboring plants. Where do they come from? How can they be controlled so they don’t take over your yard? Read on for tips on controlling these pesky invaders.
Weed seeds arrive in your yard either by wind or carried in by birds. They could be brought in with yard equipment, grass seed, organic soil amendments or ‘hitch’ a ride on shoes, clothing or even on the fur of pets.
The two basic groups of weeds are grasses and broadleaf weeds. Some sprout from seeds and grow, flower, produce seed and die within one season. These are referred to as Annual weeds. Perennial weeds can live for several years. The control methods you choose will depend on what type of weed you are dealing with.
If you only have a few weeds in a relatively small area, mechanical removal is often the most desirable. This can be accomplished with sharp hoes, shovels, or hand pulling. C’mon, this is good exercise - therapeutic even. If applications of herbicides are warranted, it is important to select one that will target the weed you are dealing with and not harm surrounding vegetation. If you use grass killer on the crabgrass or nutsedge growing in your hybrid Bermuda lawn, it won’t discriminate and will kill all grass it contacts. A broad-spectrum herbicide may kill anything green it touches.
In gravel areas both annual and perennial weeds can be controlled with the application of a post-emergent herbicide. Post-emergent meaning it controls weeds that have already sprouted and are growing. The most common products for this application contain Glyphosate or Glufosinate as active ingredients listed on the label. These herbicides work by translocating the product through the leaves to the roots where they interfere with the growth process. The best control is accomplished when applied to young plants. Both these products are non-selective, meaning they will kill any growing vegetation, both grass and broadleaf plants.
In lawn areas the best weed control is a healthy lawn. Turf will out-compete most weeds and regular mowing will remove the growing tips of the weeds. Any chemical weed control should be practiced only on well established lawns as newly installed or seeded lawns are often injured by weed control agents. Spot treatment with Glyphosate is effective especially in dormant winter Bermuda lawns.
Pre-emergents work very well in preventing weed seeds from sprouting and work best in gravel areas. Do not use a pre-emergent if you plan to establish a Bermuda grass lawn by seeding. The same is true in the fall if you overseed your hybrid Bermuda or Bermuda grass lawn - it will prevent the winter rye grass seeds from sprouting! Many pre-emergents are available from your local nursery or home improvement store. For example, a common pre-emergent herbicide has a chemical name of: 3, 5-dintro-N4, N4-dipropylsulfanilamide. The chemical name is oryzalin. Ask the sales staff at your local hardware store or nursery for assistance if you are unsure which product is a pre-emergent. Brand names you might find include Weed Stopper, Weed and Grass Preventer, Weed Preventer, and Amaze. Apply twice a year in April for summer weeds and September for control of winter weeds.
Many homes in the southwest, for instance, are built on old irrigated agricultural fields where nut sedge is sometimes a problem. For control of nut sedge (nut grass) in lawns, several applications of the products that contain imazaquin (Image) or halosulfuon (Manage) in September will provide effective control. Some follow-up may be necessary. Ultimately, climate and seasonality will differ in the different regions of our country.
Caution: Some products are labeled total or complete vegetation killers. These products kill existing vegetation, but can persist in the soil for many years and leach into surrounding areas seriously affecting or killing plants there. If you have an area in your yard where nothing will grow, a total vegetation killer or soil sterilizing agent may have been applied there in the past.
Be careful when using products that contain 2-4-D. They are designed to be applied when the temperatures are below 80 degrees or so. On warm days, this product volatilizes (turns to a gas) and can cause damage to surrounding vegetation as it drifts through the air.
Remember! Always follow label directions exactly! We sometimes think if a little is good, more is a whole lot better. The average homeowner applies 9 times more chemicals to their property than a farmer does on the same size land. With herbicides and insecticides, this can be deadly - to plants, pets and humans. Wear protective clothing and avoid skin contact with the product.
By: Jo-Ann M. Greenstein CMCA, AMS, PCAM, Vice President, Phoenix, AZ