Most lawns have a diverse population of insects present at all times. Most do not feed on turf grass plants or reach populations high enough to cause serious problems. It is only when populations reach high levels that insect activity becomes evident and control measures may be required. One of the main factors influencing the severity of insect damage to turf is the overall health of the lawn. A weak stand of grass will be damaged much faster and more severely than when turf is healthy.
Below Ground or Subsurface Insects
There are several species in this category of insects that damage lawns in our area. Unlike grubs, which live in the soil, these critters typically live in the thatch, which is a layer of living and dead roots, stems, clippings and organic matter which accumulates on the soil surface. When this layer exceeds ¾ of an inch, it becomes a perfect environment for surface insects to harbor. It also restricts the downward movement of insect controls from reaching their target area. Core aeration is a good maintenance practice to keep thatch in check before it becomes a problem.
Hairy chinch bugs are periodic surface-feeding pests that cause serious damage to lawns in our area. Infestation usually occurs in fine fescue lawns with a layer of thatch. Damage is most prone to turf that is exposed to full sunlight during periods of hot, dry weather. Injury to turf is caused by adult and nymph chinch bugs sucking sap from the crowns and stems of susceptible grasses. Extensive feeding causes grass to first turn yellow and then reddish brown. This is often mistaken by homeowners for drought stress. Left untreated, it will leave large unsightly dead areas when the rains and cooler weather of fall return. When the problem is diagnosed, insecticide treatments can provide excellent control, but do not prevent pest migration from untreated areas.
Insect infestation is no laughing matter!
Billbugs are the most common cool season pests in North America. Damage can be difficult to identify and is often mistaken for drought stress, chinch bug or white grub damage. Billbugs infest most cool weather grasses including Kentucky bluegrass or tall fescues. Adult females chew a hole in the stems of turf grasses and deposit their eggs inside. The young larvae tunnel inside feeding on the host plants stem. The larvae leave the stem and feed on the crown and roots of the plant when it gets larger. Billbug adults puncture and feed through small wounds in turf stems, but produce no noticeable damage. Billbug infestation is diagnosed by tugging out affected stems. The damaged turf should easily break off, revealing piles of sawdust like material, which is produced during feeding.
Billbug adults are located in the turf canopy but are often found walking across sidewalks and driveways during sunny weather. Chemical control is difficult because larvae spend the majority of their life inside plant stems and adults have a hard, armor-like exterior that does not easily absorb insecticides. Effective control requires precise understanding of the insect’s biology and proper application technique.
here are several diseases that can cause problems for lawns in our area. But first, it is important to understand how diseases develop. An interaction occurs among a susceptible host plant, the pathogen or disease-producing organism and environmental conditions which favor a particular disease development. Because susceptible grasses and pathogens are present in most lawns, it only requires that environmental conditions (usually weather) are favorable for a certain disease or fungus to become active. When these environmental conditions change, it usually will break this interaction and the symptoms of the disease will disappear. The adage that proper lawn maintenance reduces lawn problems is especially true concerning lawn disease. Proper mowing, watering, fertilization and thatch management all play important roles in lawn disease prevention. Fungicides are available for the prevention or control of lawn diseases. Keep in mind that fungicides are costly and may need to be reapplied to be effective. In most cases, they aren’t worth the investment because the most common lawn diseases in our area are more of a cosmetic problem than one that actually causes damage to turf grass. The following are just a few common diseases that we see in this area.
Red Thread and Pink Patch
These two diseases present similar symptoms and appear as irregular shaped patches of blighted grass ranging in size from two inches to three feet in diameter. From a distance, affected areas will have a pinkish cast. Upon closer examination, red thread disease will display a bright thread-like pink mycelium at the tips of infected leaves. In the case of pink patch, effected leaves are covered with a pink fluffy growth.
There are a number of different rust diseases that affect turf grass, but they all generally occur under the same environmental conditions. Rust is normally a late summer or early fall disease occurring during prolonged periods of overcast weather. It will first appear as a light yellow flecking on the grass leaves. Next, these spots develop into reddish-brown pustules. An affected lawn will exhibit a rust colored cast that is noticeable from a distance. When the lawn is walked upon, a red powder will collect on your shoes. In general, rust diseases do not injure turf grass, and fungicide treatments are only used as a last resort. Adequate nitrogen and irrigation to maintain growth through late summer will minimize rust infections.
Perennial weeds live for more than two years. Perennials become established by seed or by vegetative parts. Because perennial weeds live indefinitely, their persistence and spread is not as dependent upon seed germination as the other three weed groups. Seed is, however, the primary method of introducing these weeds into new areas. With regular treatments, perennials like dandelion, plantain and white clover are fairly easily controlled after they emerge with regular treatments. Some perennials like violets, wild strawberries and ground ivy are classified as hard-to-control weeds. Repeat application and changing products may be necessary to achieve adequate control.
Summer annual weeds/ Crabgrass and other annual grassy weeds
Summer annual weeds germinate, mature, produce seeds, and die in one growing season. Their seed germination period ranges from mid-spring to mid-summer, and all plants are killed by frost in the fall. Most of the non-germinated seeds lie dormant in the soil until the next spring. The most common summer annual weeds in our region are oxalis, spurge and purslane. The most common summer annual grasses in turf include crabgrass, goosegrass, foxtails, and barnyard grass. Satisfactory control of these weeds can be achieved by cultural (mowing and watering) and chemical methods, provided both are done properly.
Of these four summer annual grasses, crabgrass is by far the most prevalent. It is often said that crabgrass germinates when forsythia blooms. This holds no truth, as crabgrass germination is solely dependent on warming soil temperatures. Summer annuals generally occur most in areas where turf is somewhat thin, where sunlight is most direct, and in high-traffic areas. The pre-emergent crabgrass and summer annual weed control applied with your spring treatment gives your lawn significant protection from these weeds. This pre-emergent barrier works best where turf is thick and mowed at a taller height. Improper mowing is one of the most common causes of weed invasion. Mowing heights that are too short result in weakened turf. Direct sunlight to thin or closely cut turf speeds up the natural breaking down of this pre-emergent barrier. Heavy rains and puddles also cause it to break down. Spring aeration or dethatching following a pre-emergent application can weaken its effectiveness by disrupting the chemical barrier. Fall seeding to areas where infestations may have occurred can decrease the chances of future outbreaks.
Winter annual weeds
Winter annual weeds germinate in late summer or fall, then mature, produce seed, and then die the following spring or summer. Annual bluegrass, black medic and common chickweed are familiar winter annuals. Some winter annuals can germinate under snow cover to resume growth at the first sign of spring, then bloom and produce seed by mid-May and June. Unlike summer annuals which die from fall frost, winter annuals die from warmer weather. These weeds usually occur in areas where turf is thin and tend to reoccur annually unless the problem is corrected.
Biennial weeds grow from seed anytime during the growing season. They normally produce a rosette of leaves close to the soil surface the first year; then flower, mature, and die during the second year. A true biennial never produces flowers or seeds the first year. Biennial weeds are relatively few in number. Wild carrot and bull thistle are two of the more common biennials in our region. Growth and energy storage in the roots or crown continue until a killing frost. Unless the weed flower stalks are mowed off or killed with herbicides, they will flower and produce mature seed before the plant dies.
Yellow Nutsedge is a warm season perennial weed found in many home lawns and commercial properties. Its color and rapid growth rate make yellow nutsedge a distraction in the aesthetics of high-quality turf. Yellow nutsedge is distinctive and relatively easy to identify. The stems are erect, triangular-shaped and yellow-green in color. The shallow fibrous root system often produces many nut-like tubers, which are underground food storage organs. Each of these tubers can germinate and produce new plants. Each new plant can also produce rhizomes which can give rise to additional new plants. The above-ground foliage does not survive winters in northern areas. However, as soils warm during the late spring and early summer period, germination of tubers and seeds produced by plants from previous years are capable of producing new yellow nutsedge plants. Heavy infestation of this weed in lawns and other grass areas usually become readily apparent in July and August. Specialized products are necessary to control yellow nutsedge and can be costly.
Moles can be a considerable problem in home lawns. Their tunneling action in search for food can leave mounds of soil and uneven ground. Moles have a hairless, pointed snout extending nearly ½ inch in front of the mouth and are approximately 5 to 7 inches in body length. Moles are specialized for life underground. Their small eyes and the openings of the ears are concealed in the fur, and there are no external ears. The paddle-like forefeet are very large and broad with pronounced claws for digging. The hind feet are small and narrow, with slender, sharp claws. Mole fur is short, soft, and velvety, and when brushed offers no resistance in either direction. This adaptation allows moles to travel both forward and backward through the soil. Moles are insectivores, their diet mainly consisting of earthworms, beetles, beetle larvae and grubs where they exist.
They eat from 70 to 100 percent of their own body weight each day. They are not rodents and are related to shrews. They do not hibernate, but activity is greatest when soil remains moist for longer periods of time. A serious mole problem usually indicates that they have an abundant food supply. If grub control has been part of your maintenance program and moles still persist, it usually indicates that they are feeding on earthworms, their main food source.
It’s important to properly identify the animal causing damage before setting out to control the problem.
Shrews are much smaller than moles and are mouse-like in appearance with a long, pointed snout, a short dense coat of fur, and small eyes. Shrews do not tunnel but rather feed above ground or use the runways of other small mammals.
Voles, also called meadow mice, are about the same size as moles, with relatively large black eyes, small ears, a blunt face, and prominent orange front teeth for gnawing. Meadow voles, the most common voles in our region, are herbivores and eat a variety of grasses, seeds, and roots. Rather than digging, voles clip grass at the base to form above-ground tunnels or bare runways through the grass. These are especially noticeable in spring, when melting snow reveals the network of runways that voles used to move under the snow surface. Chipmunks may also excavate tunnels in lawns, but they do not create molehills and their deep tunnels are not visible at the surface.
Mushrooms usually occur in lawns after prolonged periods of wet weather. This often indicates the presence of decaying organic matter in the soil such as old tree roots, stumps or construction debris. Most mushrooms cause no damage to lawns and they will disappear when the weather conditions and soil dry out. If they grow in circles of dark grass called “fairy rings”, they may injure the turf by making it impervious to water. There is no effective chemical control for mushrooms. However, if you feel they are poisonous or unsightly, simply remove them with a rake.
Moss is a persistent weed that establishes itself in areas where thin and weak turf exists, as the result of environmental conditions such as shade, shallow gravelly soils, excessive moisture, low fertility, or acidic soils. Any of these conditions alone or in combination can allow for moss to establish itself. To permanently eradicate moss, one needs to first establish the cause of its presence. If it is caused by heavy shade or moist areas, removing trees or tree limbs will allow more sunlight and air circulation to stimulate better turf growth. Additional drainage may be necessary in areas that stay excessively wet. For acidic soil, lime will raise soil pH levels closer to neutral where turf grows best.
When seeding, use fine fescue in shaded areas that are well drained. Rough Kentucky bluegrass is better adapted to shaded, moist areas. Please note that all grass types need a certain amount of sunlight to survive. Chemical controls for moss exist but should only be used after all the limiting factors have been corrected. Unfortunately, controls for moss can burn surrounding desirable turf.