While your new lawn is growing and filling in, it is important to realize that building a new lawn does take time. The first growing season will require regular maintenance; and, you should be prepared to deal with several predictable challenges, beginning with weeds.
Annual grassy weeds, like crabgrass, will be an early challenge. Assuming you seeded or sodded the new lawn in fall, open areas in the growing turf will still be plentiful, allowing weeds to invade.
There are two major groups of weeds with which you should be concerned; annual weeds, mostly grassy types, and broadleaf weeds, mostly perennial, like dandelion.
Early spring is the time to prevent crabgrass. Since this ugly invader is an annual plant, after turning an unsightly purple late summer, it dies with first frost, each fall. Unfortunately, before dying out, crabgrass and other annuals, such as goose grass, barnyard grass and foxtail, drop up to 100,000 seeds into the soil. These seeds are there the following spring, ready to germinate and grow rapidly as soil temperatures reach and maintain 55 degrees for several days. Depending on your geographical location, this can be as early as mid-April.
To prevent annual grassy weeds, apply a pre-emergent barrier prior to weed germination. When the chemical pre-emergent is applied early [March in the north], a second application is highly recommended to extend prevention through late spring. Several effective materials are available at your local nursery or garden center.
As is the case with other lawn care products, it is very important to make complete and accurate product applications. Products applied at the wrong rate and missed strips, usually due to a failure to properly overlap spreader wheel tracks, will result in weeds filling in these areas. The same is true of liquid applied pre-emergent products. Uneven application, improperly mixed materials and off-target application will have the same unwanted result. Read product directions carefully and follow application spreader settings as they appear on the package. Do not increase or decrease applications rates, as this will significantly impact results.
For best results, even when using a liquid product, at least one dry granular pre-emergent product should be applied in the early spring.
Expect approximately 80% weed prevention. Even the most accurate, properly timed product applications may not prevent all grassy weeds. Heavy spring rains, foot and equipment traffic and lawn raking can and does decrease results. When this occurs, crabgrass and other annuals can be treated with liquid spray controls once they are up and growing. Still, prevention is the recommended method of control and weed management.
Note: Always apply granular products with a properly adjusted, accurate spreader. Mis-application is a major cause of poor weed control.
Perennial broadleaf weeds. While not all broadleaf weeds are perennial [living more than two years], most troublesome lawn invaders do live for several years. This growth characteristic means that preventions is not possible. You cannot prevent what is already there, in the lawn. Often, homeowners, unaware that those frustrating dandelions that bloom in mid-spring, are well established, lying dormant until sunlight and warming soils signal the start of another growing season. Typically, while the top growth is destroyed in winter, the deep roots are alive and well.
To control perennial, broadleaf weeds [like dandelion], apply a liquid, post-emergent control when weeds begin growing actively. Treating before active growth begins is not effective.
Some broadleaf weeds are not selectively controllable. While most weeds can be managed with one or more liquid spray applications, a few simply cannot be killed without harming desirable grasses. In this case, a non-selective product, like Round Up, can be used effectively. One drawback to using a non-selective product is that, as the weeds are eliminated, large dead spots in the lawn, lead to more weeds. In addition, when used extensively, non-selective controls, while killing the weeds, leave the lawn looking less that pleasing. Most often, homeowners simply try to manage these few hard to control weeds by digging them out, using a weeding tool to remove the top growth and the root where possible.
Weeds grow all season. Because weeds sprout and invade lawns season long, whenever the lawn develops thin or damaged areas, weeds can be expected to fill in within just days. And, because weeds never stop invading, it will be necessary to continue treating as new weeds emerge. A professional service will inspect the lawn for weeds and treat as necessary on each visit. If you choose to manage weeds on your own, read the product label to be sure the control you are applying is registered for the target weeds in your lawn. Most weed controls are broad spectrum and will control all common weeds.
Thick lawns prevent weeds. One of the very best ways to manage weed populations, is to build a thick, dense lawn. When lawns are mowed tall [see “Caring for Your Lawn”], grass blades shade the soil, minimizing weed germination and growth. Most homeowners do not realize that, when they give the lawn that close mowed, crew-cut look, they are unknowingly opening up the lawn to more and more ugly weeds.
Managing lawn damaging insects
There are two basic types of turf damaging insects; surface feeding, chewing insects that feed on grass plant blades and sub-surface grubs that feed on and destroy plant roots. In addition, a few of these unwanted visitors [chinch bugs, for example], do damage by sucking plant juices, leaving behind a poisonous toxin and killing the plant.
Surface feeders. The most common chewing, surface feeding insects are the sod webworm, armyworm and cutworm. In some areas, billbugs can be extremely damaging.
These common and controllable bugs, often active during the nighttime hours, climb onto grass plant blades, chew away the tissue on either side of the mid-rib and subsequently kill the plant.
While most lawn insects are controllable, the first step in any management plan should always be to inspect the damaged areas and confirm the problem. In the case of surface feeding insects, by closely inspecting the turf at the edge of the browned out, damaged area, looking closely at the soil surface, in the thatch, you will often find a sawdust like dried material known as “frass”. This material is the remains of chewed up plant parts and a sure sign of surface feeding insects.
Taking a leisurely walk across the lawn on a summer evening can disturb small [1/2 inch in length] lawn moths, resting in the grass. Easily visible, these small, half-inch long moths flit and fly around the lawn, laying eggs. Within a few days, the eggs hatch and young insect larvae begin chewing on grass blades. With the problem identified, applying a liquid or granular insect control is the next step. Granular insecticides can be applied through your lawn fertilizer spreader. Product application settings and instructions will be supplied on the product bag. Since some insects [sod webworms, for example], have more than one summer life cycle, a repeat application may be required.
Repeating, a close inspection on your knees is the best way to spot the larvae or frass, left behind.
Sub-surface, root destroyers. White grubs can destroy an entire lawn in mere days.
Beginning in late spring, beetles, commonly known as June bugs, Japanese beetles and Chafers, spend their days eating and destroying the leaves of blooming trees and ornamentals. Within a few days, these beetles begin several weeks of laying eggs. As the beetle eggs hatch at the soil surface, they work their way to the root zone and feed on grass roots. As with surface feeding insects, most insect damage is found in sunny, therefore warm areas of the lawn.
While a few grubs per square foot should not cause serious lawn damage, as populations grow, and roots are destroyed, preventing the grass plant from taking up water and nutrients, the lawn will begin to brown out. Often, an irregular patch of browned out turf is the first sign of insect damage. To confirm grub damage, go to the browned-out area, grasp a handful of turf and attempt to lift it up. If grubs had significantly damaged roots, you will be able to raise the sod, pulling it back like a carpet.
Once grubs have killed off the turf, where damage is severe, removal of dead grass and reseeding may be necessary. Where grub populations are lower, and some green grass remains well rooted, applying a grub control and watering it in well, should stop the damage in time for the remaining healthy grass to recover.
The most sensible and effective way to avoid white grub damage is to apply a preventive control in late spring. When properly applied and watered in well, a control barrier will provide protection from newly hatched larvae for four growing months.
Managing common lawn diseases
In order for lawn disease to seriously and permanently damage a lawn, three factors known as the “disease triangle” must be present.
- The pathogen or fungus [ disease spores] must be present and active
- The host plant [susceptible grass plant] must be available
- The necessary environmental conditions [weather] must exist
When any of the above factors is NOT present, a disease epidemic cannot occur.
Lawn diseases come and go seasonally, as weather patterns change, temperatures and humidity increase and decrease, and rainfall amounts vary.
On highly maintained turf, like golf courses, where serious turf damage would limit playability, diseases are vigorously treated and controlled. In addition, the closely mowed turf on tees and putting greens, under constant and significant stress, is less likely to be able to tolerate or outgrow disease without chemical treatment.
Generally speaking, however, on home lawns, where grass is mowed tall and under less stress, and in view of the fact that diseases cannot remain active when conditions change and the “disease triangle” is broken down, the most common and practical disease management strategy is to keep the lawn as healthy and strong as possible, allowing it to outgrow the disease. In addition, as a practical matter, because fungus control products are comparatively expensive and have a fairly short effective residual, using them on large home lawns is not always practical.
Below, are several turf diseases, commonly found on home lawns. Diseases are identified here using common names.
Late winter disease
Gray snow mold - Commonly found under melting snow. This disease, most often developing in a temperature range of from 28-45 degrees in the presence of excess winter moisture, does not typically kill turf. The recommended treatment for snow mold is to rake off dead area and apply a complete fertilizer. As weather warms, the lawn will grow out of the condition.
Leaf spot – Found during the cool, damp spring season on most cool season turf grasses [Kentucky bluegrass, fine fescue, perennial ryegrass], leaf spot is easily identified by its “cigarette burn” lesion on grass blades. As the disease progresses, the lesions coalesce to form larger damaged areas at the crown of the plant. When this occurs, now referred to as crown rot, significant plant damage and death is possible.
Leaf spot is treatable with readably available fungus controls. If conditions, however, do not change in 10-14 days, the disease will again become active and re-treatment necessary.
Recommended cultural controls include adequate [1.0 pound/1000 sq. ft.] but not excessive nitrogen fertilizer and watering in lieu of rainfall. Mow tall to reduce stress.
Damaged area should be reseeded with resistant cultivars, now available. Consult local extension service for specific, local recommendations.
Red Thread – Active on perennial ryegrass and other cool season turf, this disease is first seen as yellowish colored areas across the lawn. These irregular patches become pink to red, over time. Limited to plant leaves and stems, drying plants turn a straw-colored tan but most often are not killed off. Culturally treating red thread calls for the application of a complete fertilizer with repeat application in four weeks.
Summer / Fall diseases
Rust – Found on cool season turf, rust forms most often in late summer and early fall. Yellowish spots appear on grass blades. As the disease progresses, the outer layer of the grass blade ruptures and millions of disease spores ooze onto the surface of the blade. Soon, the spores form a rust colored coating which easily rubs off on shoes and equipment on the lawn. As temperatures continue to drop, this condition typically subsides without significant plant damage.
Brown patch – During the hot, summer months, most turf varieties, north and south, are impacted by large, irregular brown patches of diseased turf, commonly referred to as brown patch. This is a soil active pathogen, attacking plant roots under stress. Preventive chemical applications are recommended to avoid this predictable problem. When lawns, especially in the mid to deep south are not treated in advance of the diseases development, entire lawns can be and are killed annually. Recommendations are for the application of only a low amount of nitrogen fertilizer during active disease periods.
Summer patch [necrotic ring spot and other summer patch syndromes] – Summer patch diseases are caused by soil active pathogens. These pathogens, active during the hottest, most stressful times of the growing season, attack and destroy plant roots on cool season turf grass. Attacking mostly mature lawns, leaves turn from tan to a reddish color, then die. Often, during the diseases development, a “frog eye” type damaged spot can be seen; browned turf with a tuft of green grass in the center. Culturally, recommendations include mowing tall and possibly providing a core aeration to improve drainage. Dead areas should be replanted with perennial rye grass, which is resistant to most patch diseases.
Fairy ring – Appearing as dark green circles in the lawn, fairy ring is the product of dead and decaying tree roots and stumps under the ground. As decay takes place, the rotting material sends up nitrogen, which leads to the dark green color seen in the lawn. Since the rotting material can be several feet deep, digging it out can be difficult. In addition, the darkened green turf can be literally fill of mushrooms. The good news is, as the decaying plant decomposes and disappears, the condition should end. There is no treatment for his condition. Turf grass will not be damaged.