There’s an undeniable magic to spring. Nature reborn, vibrant growth everywhere, flowering trees and annuals in full bloom, all surrounded by lush green turf – it’s a feast for the senses. However, the explosion of the “green” also means the return of weeds, and there’s nothing magic about them. The first thing to know about weeds is that if you’ve started seeing them in your turf, the right time to get rid of them would have been weeks ago. So, let’s dig a little deeper into the topic to understand turf weeds better and explore the best ways to control them.
Turf weeds come in many shapes and forms; while that creeping, crawling, invasive crabgrass might be the most familiar turf weed across a huge portion of the country, there’s a wide variety of other grassy weeds that invade landscapes and include such descriptive names as goosegrass, foxtail and barnyard grass. Trevor Taylor, Account Manager and turf expert with Signature Landscape in Kansas City, has an interesting take on the different types of weeds, as he states that “weeds often tell us what is going on in a specific area. An area that is compact and holding moisture will commonly get nutsedge, knotweed, or goosegrass. An area that is lacking nitrogen will often have clover in it because clover produces its own nitrogen and can thrive where other weeds and grass can’t”.
You’re probably asking yourself how these weeds suddenly manage to show up on your beautifully landscaped property, right? Well, in addition to reseeding in place from last season, there are various ways they spread and arrive uninvited on your property:
- blown by the wind (dandelion seeds, for example, are carried by their own attached “parachute”);
- transported by birds that eat the seeds and later eliminate them on a lawn somewhere;
- carried by rainwater along sidewalks and driveways and sprouting up along the edges;
- brought in via different carriers, such as animals (and even humans) – seeds get attached to the coat (or to pants) for the ride and are deposited on another property where the creature passes through.
Weed seeds will somehow find a way to your property and then they lie in wait for their opportunity to sprout!
While we can’t control the birds or weather conditions, what visibly differentiates one landscape from another is the appearance of the turf. Healthy, well-managed turf will suppress weed pressure significantly. Duane Baldwin, Plant Health Care Manager at Keesen Landscape in Denver, believes that “quality turf is directly related to consistency of maintenance. Regular applications of fertilizer, pre-emergent, and weed control are the heart of good turf care. The second and very important part of quality turf care is consistency of turf moisture year-round, whether it is from Mother Nature or regular irrigation practices.”
Just like with other desirable plants or flowers, weed seed germination is favored by warm weather and sufficient soil moisture. So how do you take care of your turf grass, but at the same time prevent the weeds from growing? Here are a few best practices a landscape professional should follow:
- Pre-emergent weed control. There are effective herbicides that will kill weed seeds like crabgrass when they first sprout, but which are safe for desirable turf when properly applied. They have to be in place like an invisible soil barrier when the time is right for spring growth to emerge. A crabgrass plant can produce around 150,000 seeds, so a one-time application may not provide desired control. A split-application approach is often indicated: “Split applications are very important in our region of the country, where crabgrass has an extended germination season,” recommends Mike Hentges, COO of Columbia Landcare in Missouri. The first round should be applied between mid-March and mid-April, depending upon the spring thaw, and consist of 60% of the active ingredient; the remaining 40% is then applied mid-April to May. Depending on the region, crabgrass may start germinating between March and mid-April, when soil temperature reaches 60 degrees Fahrenheit, around the time forsythia starts blooming. In Colorado, for example, Duane Baldwin advises us that “crabgrass is a tough one to control, mostly due to microclimates on all properties. With different exposures the soil temperatures can vary dramatically, south sides can reach germination temperatures as early as late March and north side may not get there until June”.In Kansas, Mother Nature can be fickle, so Trevor Taylor’s advice is to “apply a pre-emergent such as ‘Barricade’ (Prodiamine) any time beginning in mid-February through the 1st of April to ensure the pre-emergent barrier has been established. The most important part of applying the pre-emergent is getting it watered in properly.”
- Turf mowing height. Maintaining a mowing height on the upper end of the range for each grass type provides an excellent aid in weed control, as it encourages turf density and keeps sunlight and warmth away from weed seeds at ground level, preventing germination. Crabgrass, for example, is much more frequent and more aggressive in lawns that are mowed at less than two inches.
- Proper nutrition. Turf weed control should be part of a comprehensive, multi-application program that feeds your turf and combats the weeds and pests which can attack it. A balanced approach is key, and appearance proves that all turf programs are not created equal!
- Proper irrigation. An efficient irrigation system and optimum schedule will help reduce annual weed infestation. Light and frequent irrigation will only encourage weeds to germinate. Overwatering will dilute the barrier of chemical products applied for weed control and also wash away fertilizer.
- Avoid soil disturbance. Sometimes less is more, even in weed control. Aeration, for example, should be done at the time of year when weed pressure is lower since it will break the chemical layer created by the pre-emergent products and increase your turf’s susceptibility to weeds.
- Targeted spraying or hand removal. This labor-intensive approach can be used to combat turf weeds that escaped the chemical layer created by pre-emergent materials, but it also disturbs desirable turf grass.
- Post-emergent weed control. If turf weeds have already begun growing, post-emergent herbicides can help control existing annual grasses, but you should use them with care and in cooler temperatures and when your turf is well-watered, as they can also damage your turf.
“Pre-emergent and post-emergent herbicides are meant to supplement our turf; they aren’t the answer to keeping weeds out. Regular overseeding and aeration in the fall, along with optimum doses of balanced fertilizers, help your lawn flush out in spring, thicker and fuller,” Trevor Taylor concludes.
Crabgrass and other grassy weeds are visible nuisances, but there are other pests at work which might harm your lush turf. Mites and some species of spiders are known to attack turf grass in early to mid-spring. There are also pests such as white grubs and billbugs, those annoying little insects that will feed on the roots of your plants, and can further attract animals like skunks that will damage your lawn areas further as they seek out those pests as their meal. Keys to keeping these pests away are proper soil moisture and a comprehensive turf care program.
So, don’t let crabgrass make you crabby! If you entrust your turf care to a dedicated team of landscaping professionals, they’ll worry about these details, so you don’t have to!
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