The best way to control common turfgrass diseases is to develop a healthy lawn. In this chapter, you will learn that a 100 percent weed-free lawn is not a realistic expectation. Weeds can be controlled, but your level of weed control depends on your commitment and budget.
Weed Control
Even when countless hours and dollars are spent trying to prevent them, weeds are a fact of life. A 100 percent weed-free lawn is not a realistic expectation. The best way to control weeds is to take the necessary steps, such as proper fertilizing, aerating, irrigating, and mowing, to promote the development of a thick, healthy lawn.
When turfgrass sod is installed, the weed barrier is broken. Within four weeks of the installation of your turfgrass sod, a turfgrass expert should evaluate your lawn to determine if the roots are adhering to the native soil and recommend appropriate care regiments.
Hand-Weeding
Hand-weeding can be tedious work, but it is also the most effective and environmentally friendly way to remove weeds from your lawn. There are tools available that make hand weeding easier.
Herbicides
Herbicides are chemicals that kill plants. There are both pre-emergent and post-emergent options.
Pre-emergent Herbicides are applied before weeds have germinated. A pre-emergent herbicide kills seeds as they germinate but has no effect on growing plants. Post-emergent Herbicides are applied while the plant is growing. This herbicide can kill growing plants, from seedlings to mature plants. Specific herbicides have been developed that will kill broadleaf plants like dandelions but will not affect narrow-leaf or grassy plants. Under the right circumstances, herbicides can effectively control weeds, but they should also be used sparingly. Always read and follow the label directions.
Types of Weeds
Chanshare Farms would like to extend a special thanks to Dr. Tom D. Whitson for the following compilation of the most common weeds that affect cool season turfgrass. This information comes from his book Weeds of the West (Tom D. Whitson, et al. Jackson, WY, Pioneer of Jackson Hole, 1992).
Bentgrasses
Creeping bentgrass and colonial bentgrass are perennial grassy weeds. Bentgrasses grow low to the ground, to a height of eight to 20 inches tall. They reproduce from stolons that root and creep along the soil’s surface. Pulling or digging out the weed is the best way to control bentgrasses, if at least three-quarters of the root system can be removed. Treating with a selective post-emergent herbicide may control bentgrasses, but the best solution is to consult an expert. As a weed, bentgrass is difficult to control.
Crabgrass
Large crabgrass is an annual grassy weed. It grows six inches to two feet tall. It reproduces by seed or by rooting along the stems spreading out from the plant base. Large crabgrass is a problem in lawns, gardens, and other cultivated areas. It can be controlled by applying a pre-emergent herbicide in late winter or early spring, and by developing a thick, healthy lawn. Applying a post-emergent herbicide marked specifically for crabgrass can kill established plants, or by digging the weed and soil out, and replacing the soil.
Dandelion
Dandelion is a perennial broadleaf weed. It grows with leaves clustered at the top of the root. Dandelion reproduces from seeds and from new shoots from the roots. Dandelion can be controlled by pulling, digging, spot treating, or treating the entire lawn with a selective broadleaf post-emergent herbicide in late fall or late spring. If pulling or cutting the weed out of the lawn, at least three-quarters of the long taproot must be removed, or the plant will likely return. Continued hand-weeding can weaken the plant until the bluegrass eradicates the weed.
Goosegrass
Goosegrass is an annual grassy weed. It grows in large clumps, upright, 15 to 36 inches in height. Pulling or digging out the weed is the best way to control Goosegrass, if at least 3/4 of the root system can be removed. Treating with a selective pre-emergent herbicide can also control Goosegrass.
Junglerice
Junglerice is an annual grassy weed. It grows upright, two to three feet in height. It is found in lawns, cultivated areas, and waste areas. Young plants are lime green with reddish-purple stems and have roots protruding from the base of the stem. Pulling or digging out the weed is the best way to control Junglerice, if at least three-quarters of the root system can be removed. Treating with a selective post-emergent herbicide can also control Junglerice.
Kochia
Kochia is an annual broadleaf weed. It grows tall and narrow, to a height of one to six feet, with many branches and tiny leaves. Pulling or digging out the weed is the best way to control Kochia, if the whole root system can be removed. Spot treating with a selective herbicide specific for broadleaf weeds can control Kochia.
Longspine Sandbur
Longspine sandbur is an annual grassy weed. It sometimes grows erect, but usually spreads along the ground, eight inches to two feet in length, and forms dense mats. Longspine sandbur prefers to grow in gravely or sandy soils. Digging out or pulling the weed by hand can be very effective in controlling Longspine sandbur. It can also be controlled by spot-treating the weed with a selective herbicide labeled specifically for sandbur in early to mid-summer, or by applying a pre-emergent herbicide in early spring.
Orchardgrass
Orchardgrass is a perennial grassy weed. It grows upright in clumps up to four feet tall. It is often used in pastures, but has become a problem when it invades lawns and flower gardens. Treating with a selective post-emergent herbicide, or by digging the weed and soil out, and replacing the soil may control small patches of orchardgrass.
Quackgrass
Quackgrass is a perennial grassy weed. It grows upright in a clump to a height of 1 to 3 feet tall. Quackgrass is spread by seed or by rhizomes that are able to penetrate very hard ground and sometimes roots of other plants. Quackgrass is often a problem in lawns and home gardens. Rhizomes can produce new plants even when broken away from the original plant. Once established, quackgrass is difficult to control, often requiring that the whole area be treated and killed by a non-selective herbicide, and then the lawn in that area must be re-established. Consult an expert for this condition. The best way to prevent quackgrass is to develop a thick, healthy turfgrass lawn.
Redstem Filaree
Redstem filaree is an annual or biennial broadleaf weed. It grows along the ground, usually to a height of 1 inch with stems up to 2 feet long, green in color. Pulling or digging out the weed is the best way to control Redstem, but spot treating with a selective herbicide specific for broadleaf weeds can control Redstem.
Rust
Rust gets its name from the orange, “rusty” appearance it gives leaf blades. Rust tends to flourish in conditions of morning dew, shade, high soil compaction, and low-fertility. The best prevention for rust is to fertilize, aerate, water well in the morning hours, reduce shade, mow more frequently and bag grass clippings. If rust has been a problem in the past, mow frequently and remove clippings from the lawn. fungicides such as Triadimefon and Anilazine can be applied every 7-14 days until improvement is seen.
Tall Fescue
Tall fescue is an annual grassy weed. It grows in tufts to a height of up to four feet, green in color. Tall fescue is a deep-rooted and long-lived forage species. Pulling or digging out the weed may control tall fescue, but the roots are sufficiently sturdy that this method does not always work. A lawn-care professional can spot-treat the plants with a selective herbicide not available to homeowners that will kill tall fescue plants.
Tumble Pigweed
Tumble pigweed is an annual broadleaf weed. It grows along the ground, usually to a height of six inches tall, green in color. Tumble pigweed usually grows in cultivated or disturbed sites. Tumble pigweed can be controlled by pulling or digging the weed by hand or by spot treating with a selective herbicide specific for broadleaf weeds. A pre-emergent herbicide applied just before the last expected frost could help control the weed.
Weed Control in Newly Planted Turfgrass
Turfgrass farms are certified noxious weed free by the state of origin. Healthy turf creates a natural barrier that will not allow foreign weed seeds to germinate and sprout. This natural weed barrier is broken when turf is harvested. A newly planted lawn is susceptible to invasion from seeds in the soil under the sod. Special care should be taken to follow the watering and care instructions contained in this manual to encourage a healthy grow-in phase and minimize the possibility of weed germination. An inspection by a trained turf specialist about three weeks after installation is appropriate if you do not feel comfortable with your own diagnosis.
Hand-Weeding: Lawn Friendly Weed Eradication
Weeds are inescapable because weed seeds are inherent in native soil and topsoil. Seeds can be airborne and are carried into planting areas by a variety of sources. Lush green lawns are the key to effective weed control. It is difficult for a weed seed to take root in thick turfgrass. When weeds do sprout up, hand weeding is an effective and environmentally friendly way to remove weeds from your lawn. Weeding can be hard work. You can get your family involved or pay neighbor kids to pull weeds. Many tools, available at your local garden center, have been invented to facilitate easier weeding.
Always cut off the taproot of the plant as deep into the soil as possible. Some tougher weeds, such as dandelion, may require several cuttings to weaken the plant sufficiently for the lawn to choke out the weed. Always pull weeds prior to the plant going to seed to prevent the seeds from spreading. Boiling water is another option for killing taproot weeds. Make sure the water is boiling hot and slowly pour it over the center portion of the plant. This method will cook the root and kill the plant.
Herbicides
Expending the energy to hand-pull weeds is the ideal way to maintain a healthy, lush lawn. However, sometimes a weed infestation can be extreme and need the aid of herbicides. Most foreign plants, either broadleaf or grasses, can be controlled with herbicides. Consult your local nursery for more details if you have questions about which herbicide to purchase. Always read and follow application directions carefully. Herbicides should be used sparingly and selectively.
Insect Control
Most insects are beneficial to our lawn ecosystem; only a few are not. A newly installed lawn is a magnet for all types of insects. Insects from neighboring dry fields and vacant lots are immediately drawn to newly watered lawn areas. Generally, only two insects cause damage to cool season turfgrass lawns: billbugs and cutworms. Cutworm and Billbug can be challenging for turfgrass lawns in the arid West.
Billbug
Most of the damage inflicted by billbug is caused by the larvae. Billbug larvae are white legless grubs and are 3/8” to ½” in length. The adult billbug has a long snout used for chewing on plants and burrowing. Billbug damage appears as a small circular pattern that turns yellowish brown as billbugs feed on turfgrass roots and crowns. Attacked sections of lawn pulls easily out of the soil. White debris that looks like sawdust may be found around the area where billbugs are feeding. Adult billbugs that have survived the winter will become active in the early spring. Soon thereafter, they will lay eggs on the stems of the turfgrass plants. As the eggs hatch into grubs, the grubs move from the stems to the crowns and root of the turfgrass plants.
Cutworm
Cutworm larvae are smooth, plump and usually curl up when bothered. The larvae are most often black, brown, or gray. Some are spotted or striped and most grow to a maximum length of about 2 inches. Cutworm larvae attack both newly seeded and established turfgrass lawns at the soil level, leaving small patches of brown grass, usually 1-2 inches wide. Cutworm moths lay their eggs in late summer. The larvae hatch soon thereafter and spend the winter in clumps of grass. The larvae start feeding in the spring and mature into moths in the early summer.
Other Insects
Other insects such as white grub and sod web-worm may cause damage but are not as common. If you notice an insect infestation and you do not recognize the bug, contact the Utah State University Extension Service or a local lawn care professional for assistance.
Environmentally Friendly Insect Control
If you suspect that insects are damaging your lawn, a simple test can be used to identify the magnitude of the problem. Billbug and Cutworm do not like lemon-based dish soap solutions. Mark off one square yard of the infected area. Mix a solution of two cups of soap to one gallon of water and apply evenly over the infested area. If more than 5 worms per square yard make their way to the surface you have a problem that should be spot treated. If no more than 5 worms appear, the problem will most likely take care of itself.
Few insects negatively impact a cool season lawn. Pesticides should be used sparingly because they will not only kill the bad bugs, but the good bugs too. Both billbug and cutworm normally can be controlled with spot control methods. Pesticides for this purpose can be purchased at local garden centers. A granular grub preventor can be applied during May to prevent grub infestations.
Caution: Herbicides and pesticides are generally not very selective. In addition to killing unwanted weeds and insects, they may also kill desired plants, insects and sometimes even other animals. A lawn without insects or earthworms will not attract songbirds that are attracted to healthy lawns and gardens. Be very careful when using chemicals.
Disease Control
Healthy bluegrass lawns do not regularly suffer from grass diseases. Proper watering, fertilizing, mowing, dethatching and aerating will minimize the potential for lawn diseases.
Fairy Ring and Mushrooms
Poorly composted materials incorporated into native soils can encourage a fungus known as Fairy Ring. After prolonged wet weather, mushrooms may appear around the outer edge of the fungus. These are the most common diseases in the Intermountain region. Both can be controlled with adequate nitrogen application, aerating the ring to improve water penetration, and frequent mowing. There are biological aids that can help with fairy ring. Contact Chanshare Farms at 866-SOD-EASY for more information or assistance controlling Fairy Ring.
Snow Mold
Snow mold is common in cold weather climates in the early spring after prolonged snow cover. Snow mold will generally not kill bluegrass but some common-sense practices can be observed to minimize snow mold effects. In the late Fall, gradually lower the lawn blade length to approximately 1.5”. Blades laid over by heavy snowpack enhance snow mold growth in the spring. Fertilize lawns in October to ensure healthy plant life during the winter. As the snow melts in the spring, lift the lawn blades by hand raking or aerating.
Other Lawn Challenges
Sod Going to Seed
Some bluegrass cultivars have a natural tendency to produce seed in the Spring. Some Springs cause more seed production than others. To remove the seed, lower the blade on your mower by one or two spots and bag your clippings. After 3 or 4 mowings the seed pockets will be eliminated.
Summer Dormancy – Browning Out Your Lawn
Whenever an average temperature reaches over 90*, it is an acceptable practice to let rhizomatous lawn (such as bluegrass) go into dormancy. In such heat, it requires much more water to keep your lawn green. Decreasing the amount of water you apply to your lawn will force the roots to burrow deeper resulting in a heartier lawn. Once average temperatures reach below 85*, you can continue normal water practices and your lawn will return to a vibrant green color. Bluegrass lawns can survive on .5″ of water for about 4 weeks. Browning out your lawn should only be done on a healthy rhizomatous lawn. Do not let the lawn go brown for an extended period more than once in a growing season. To properly brown out your lawn use the following steps:
1. Only brown out a healthy lawn with few weeds. When you cut watering it is an opportune time for weeds to break the natural weed barrier created by a healthy lawn.
2. Do not fertilize for at least 4 weeks before.
3. Do not mow for at least 1 week before cutting water.
4. Cut all water for at least 4 weeks to get the best benefit. Try not to bring your lawn out of dormancy more than once in a season. If it starts to green up due to rain or other natural irrigation it is best to resume your regular watering schedule.
5. Resume irrigation after 4 to 6 weeks. Fertilize within 3 days of resuming irrigation.
Dog Urination Spots
Sharing your yard with your pets is one of the best parts about having a lawn- until urine spots start showing up in your landscape. Often, female dogs get blamed for urine spots, but their urine is no different than that of male dogs. The truth is, all dogs that squat to urinate, including females, puppies, small dogs, elderly dogs and even some adult males, can burn grass when they urinate in one concentrated area. Adult male dogs usually lift one leg and sprinkle urine over larger areas, which minimizes urine burns on grass. Pet urine contains urea which is made up of nitrogen and salt. While nitrogen is essential to having a healthy lawn, dog urine can bring an overdose of nitrogen and salts to your grass. The effect is not much different than fertilizer burns – damage caused by applying too much fertilizer on your lawn.
To prevent future dog urination spots, there are a couple of things you can try. If you are always with your dog in the yard on potty breaks, you can immediately spray their urination locations with a hose. This isn’t a feasible option for many pet owners. Adding one tablespoon of vinegar per gallon of drinking water will decrease the acidity of your dog’s urine. Also, there are plenty of dog chew and treat products sold online and in pet stores that claim to provide your dog with daily doses of vitamins that will neutralize their urine enough to keep your grass green.
Minor dog urine spots should fill in with the surrounding grass over time. Severe cases of dog urine damage result in areas of brown, dead grass. When these dead patches appear, a little time and effort will turn those brown spots to green in no time.
