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Lawn Insects

Bermudagrass Mite


 

Bermuda Mites on Bermuda GrassThe bermudagrass mite Figure1 is a major problem on golf courses. It survives best on grass that is not mowed closely, such as the edge of bunkers, the lips of sand traps, and around trees. In home landscapes it is more of a problem on well fertilized lawns.

 

The first symptoms of a bermudagrass mite infestation is grass that fails to begin normal growth although it is well fertilized and properly watered. The mites feed under the leaf sheaths and suck sap from the stems. At first the leaf tips yellow slightly and the leaf tips begin to roll. As damage continues, the internode distance shortens and “witches broom” or rosetting occurs.

As the damage continues to get worse, the grass develops clumps that resemble miniature cabbage heads. The leaves eventually die back to the stem. If not controlled, the stems and stolons may die. Mite injury is much more severe during hot, dry periods.


Treatment: Chemical Insecticides controls can be used, but the spray must penetrate the leaf sheath to contact the mites. Addition of a spray adjuvant to enhance penetration may help. A second application within a week is usually needed to kill the newly hatched mites.

 

 

Chinch Bugs


Chinch Bugs on Warm Season Grass


The southern chinch bug, Blissus insularis, is a common turfgrass pest in the southeast. It is a major pest of St. Augustine grass, however, it will feed on zoysiagrass, bermudagrass, and centipedegrass.


Adult and immature chinch bugs suck sap from the host plant. As they feed a toxin is injected into the grass causing it to turn yellow and eventually die. Damage appears much quicker on grass that is under stress from drought or heat. At first infestations are very spotty. If left uncontrolled, large areas of grass will eventually die. Chinch bugs are most common on lush, heavily fertilized grass and on grass with a heavy thatch layer.


Immature chinch bugs (nymphs) are bright orange in color with a white band on the abdomen during the first two instars. The third and fourth instars are a darker red, and the fifth instar is black. Adults are black with shiny white wings. Adults may have long, fully developed wings or short wings.


St. Augustinegrass lawns should be sampled regularly for chinch bug activity. The sampling should be done on the edges of suspected areas of infestation. Floatation is a standard method of sampling for chinch bugs. A simple device is made by cutting both ends our of a one gallon can and forcing the can into the soil. Fill the can with clear water, remove the debris that floats to the top and watch for chinch bugs to float to the surface. Add water as needed to maintain an inch or two of water above the grass. Both adults and nymphs should float to the surface within five minutes. Landscape managers may want to make a more substantial device from a length of thin-wall steel tubing. Teeth can be formed on the bottom edge and handles welded near the top of the cylinder.


Treatment: A general treatment threshold for chinch bugs is 20–25 per square foot. Insecticide treatments are usually required when populations reach this level. In many areas, chinch bugs are resistant to the older organophosphate and carbamate insecticides. Many of the newer classes of insecticides are still effective. Care must be taken to follow all label directions.

 

Clover Mites



Clover Mites Clover mites, Bryobia praetiosa, are more closely related to ticks than they are to insects. They feed on grasses and on over 200 different plants in the landscape. When they occur in large numbers, they can cause parts of a lawn to take on a bronze or silvery appearance. These mites will sometimes invade homes and other structures through cracks, under doors and around windowsills. They are usually more numerous on sun-exposed surfaces.

 

The size of clover mites is smaller than a pinhead, about 1/30 inch. They are rusty red in color. If these mites are squashed, they leave a red stain that is difficult to remove from fabrics or walls. If you look closely at these mites, you will notice their long front legs, which are twice as long as their other legs. They hold these front legs out in front of the body, making them look like antennae.


Prevention: Clover mite control is usually not very difficult. If possible, remove grasses and weeds from around the foundation of the structure, leaving a bare strip about 18 inches wide. This strip can be filled with pea gravel or with plants that are not appealing to clover mites, such as marigold, zinnia, rose, chrysanthemum, petunia, or other flowering plants, or shrubs like spruce and juniper. Entry points that allow mites to come into the structure, like cracks, crevices, doorways or windowsills, should be caulked or sealed with weather-stripping. If they do come into the house, use a damp cloth to remove them, but do not crush them! Remember, clover mites can stain walls, flooring and fabrics permanently. Vacuuming is effective for removal, but the vacuum bag should be placed in the outside trash, because the mites could escape.

 

Treatment: Chemical control should only be necessary with heavy infestations. Using a labeled miticide or insecticides, spray grassy areas around the house where the mites may enter. Spray trunks of trees and shrubs that may harbor mites. More than one treatment may be necessary for effective control.


Note: Select control products that will not damage plants. Most products should be safe, but read the label before spraying. Follow all instructions carefully.


Ground Pearls


 

Ground pearls are a type of scale insect that lives on the roots of turfgrasses. The immature stages (nymphs) suck sap from the grass roots. Ground pearls are found throughout the southern United States. Warm season grasses, such as bermudagrass, St. Augustinegrass, zoysiagrass, and centipedegrass are frequently attacked. Bermudagrass and centipedegrass are the most susceptible to damage. Ground pearl problems seem to be worse in lighter soils.


Feeding by the nymphs causes irregular patches of grass to appear unthrifty. Under drought conditions, the grass will become yellow and eventually turn brown and die. Weeds will rapidly invade the bare patches. Grass will rarely survive in the infested areas even when replanted.
The nymphs spend the winter in the pearl-stage. Normally, there is a single generation per year. However, under unfavorable conditions, it may take as long as three years to complete a generation.


Treatment: There are no known controls for ground pearls. The only management strategy is to try to keep the grass as healthy as possible. This includes proper fertilization, watering, and control of other pests. This usually slows the spread of the problem, but will not stop it completely. Reseeding in an infested area usually fails. The grass will most likely die in a very short time.

 

Mole Cricket Management in Home Lawns



Mole Crickets In LawnsSuccessful mole cricket management requires patience and regular monitoring of the situation. It is not a one-time, one-insecticide application. Control is dependent upon an annual, well-timed plan. Timing of controls and cultural practices are as important as the choice of insecticides.

The major effort should be directed toward young nymphs. These treatments should be applied in June, July, and early August while the nymphs are most sensitive to treatments.


Problem areas should be mapped in the spring when adults are present. These are the areas where most nymphs will be found in late June and July. These areas should be sampled carefully with a detergent flush beginning in late June. At this time, little damage is evident, but young nymphs will begin to show up following a soap flush. Mix 2 tablespoons of liquid detergent in 1 gallon of water. Pour over a 2 to 3 square feet area where damage was present in the spring. Any mole crickets present will surface in a few minutes. This should be done early in the morning or late in the afternoon. Treat if 2 to 4 mole crickets surface within three minutes


The southern mole cricket has a pronotal pattern with four distinct, white dots against a darker brown background color. The tawny mole cricket has a distinct medium brown pattern against a lighter brown to tan background color.


Treatment: Several insecticides are available for control of mole crickets. It is essential to read the label carefully to be certain you apply products at the correct rate and at the correct time of year.

 

Nematode Problems in Home Lawns



nematode damage Nematodes are major pests of lawns throughout the Southeastern United States. They are microscopic roundworms that live in the soil and on plant roots. Nematodes are particularly a problem in areas with warm temperatures and sandy soils.


Nematodes injure lawns by feeding on plant root cells with their needle-like mouth parts (stylets). The root system becomes damaged to the point where the lawn cannot properly absorb water and nutrients. The lawn becomes thin and weak, making it much more susceptible to other stresses, such as drought.


Symptoms
Nematode damage to lawns may appear very similar to symptoms caused by other stresses, so a close examination of the site and a soil test are important. Accurate diagnosis of nematode damage can be made when the following types of evidence are considered:


Above-Ground Symptoms: The lawn may appear yellow, weak and slow to grow. Areas of the lawn may begin to thin, allowing weeds to invade easily. During periods of drought or mild stress, the lawn may wilt. Affected areas may appear irregular in size and shape, since the numbers of nematodes can vary greatly within a few feet.


Below-Ground Symptoms: Grass roots that are short, stunted, or have knots and swollen areas on them may indicate a nematode problem. The root system may also appear shallow with areas that are dead or branched excessively.


Laboratory Test Results of a Soil Sample: Nematode sampling guidelines are available from any local county Extension office or Healthy Lawn Center. There is a nominal charge for each sample to help defray the costs of operating this service. Samples will be analyzed to determine the types of nematodes present and their quantities, so appropriate recommendations for control can be made.


Prevention & Treatment: Once nematodes are identified as a serious problem in your lawn, there are several things that can be done. First, there are no chemicals available to control nematodes in the home lawn, even if applied by a certified pesticide applicator. Methods that can reduce the effects of a nematode problem are:

  • Improving the Overall Health of the Lawn: Maintaining a healthy lawn is the best way to manage nematode damage in home lawns. Irrigate the lawn during periods of drought and keep fertility levels adequate. Use deep and infrequent irrigation to encourage deep root growth. Keep the lawn free from insect and disease problems. A healthy lawn with a root system slightly damaged by nematodes may be able to survive if other stresses are kept to a minimum.
  • Planting a Different Kind of Grass: Selection of a different species of turfgrass may provide a solution to certain nematode infestations. For instance, substituting St. Augustinegrass for centipedegrass in areas heavily infested with ring nematodes has been successful in some instances. Choose a substitute grass only after careful consideration of the site and maintenance requirements of the turfgrass in question.


Sod Webworms



Sod WebwormsSod webworms include at least 20 species within the family Pyralidae. Southern turfgrass may be infested by several of the temperate-region sod webworms as well as the tropical sod webworm. These pests feed almost exclusively on grasses. Newly established lawns and sod fields often suffer the worst damage. Damage is much more severe during droughts.


The adult moths are fairly distinctive. Nearly all have a distinct snout-like projection on their head. This is formed by the long labial palpi. The temperate-region sod webworms curl the wings around the body when they are at rest. The tropical sod webworm holds its wings flat. Sod webworm moths are fairly weak fliers. When they are disturbed they will fly a short distance in a zigzag pattern and then settle back into the grass. Most adults are a light brown or tan color. There may be some stripes on the wings.


Sod webworm adults are active at night. The females lay eggs at random on the grass. The eggs hatch in about 10 days and the larvae immediately begin to feed and construct silken tubes in which they live. Sod webworm larvae vary in color from gray or light green to beige or brown. Most larvae have dark spots scattered over the body.


Early detection of larval activity is very important in management of sod webworm. If large numbers of adult moths are noticed late in the day the turfgrass should be inspected carefully for larval activity in the next few days. Another indication of larval activity is large numbers of birds working the area in the early morning. A good method for detecting the larvae is to mix one or two fluid ounces of dishwashing detergent per gallon of water and pouring the solution over a 2 ft x 2 ft area. This solution is very irritating to the larvae and they will come to the surface in a short time if present in the grass. Sampling should be done on the edge of suspected damage areas.


Traditional insecticides are also available for control of sod webworms. All treatments are most effective if applied late in the day. This is because the larvae are active during the night. Always read and follow all label directions when applying any pesticide.

 

Two-Lined Spittlebug



Two Lined Spittle BugBoth the adult and the immature (nymph) stages of this insect can cause problems. The adults damage holly leaves while feeding. This can range from leaf distortion, wilting, or discoloration of young leaves to blotches on the underside of older leaves. Adult spittlebugs may feed on grasses. This results in chlorotic stippling of the blades. The nymphs suck sap from the stems of grasses. Centipedegrass and St. Augustinegrass are the preferred hosts. Heavy feeding damage makes the grass look unhealthy.

The dark brown to black adult spittlebugs are wedge-shaped with distinct red eyes and legs. Most adults have two distinct red or orange lines across the wings and a narrow band across the thorax. Unbanded adults occur as well. Adults are about 0.38 inch long. The adults spend much of the day hidden in hollies and other shrubbery. They are most active at night and may be attracted to lights.


Spittlebug nymphs have a cream-colored body and a brown head. The eyes are red. The nymphs produce a white, frothy liquid that covers them and provides protection as well as a high humidity environment, which is needed for proper development. The nymphs spend most of their life near the base of the grass plant. When they are ready to molt to the adult stage, they move to the tips of the grass. The spittle mass dries around them and the final molt takes place within the mass.

Spittlebugs spend the winter in the egg stage. The eggs are found in hollow stems, under leaf sheaths, and at the base of the plants in moist litter and debris. Most of the overwintering eggs hatch in March and April. Adults begin to appear in June. A second generation is produced and peak adult activity occurs in August and September. Damage from the second generation is usually much more serious.

Spittlebugs cause the most damage to grass when there is a thick thatch buildup.

 

Prevention: Cultural management includes dethatching and topdressing when appropriate.

 

Treatment: Insecticides treatment should be directed toward the nymphal stages. Susceptible turfgrass should be monitored closely, especially in July. Mowing and irrigating several hours before an insecticide treatment will enhance control. Treating late in the day is preferred. Use an insecticide labeled for spittlebug control on turfgrass.

 

White Grub Management In Turfgrass



White Grubs in Soil White grubs are the larval (immature) stage of several different beetles. Most of the grubs will assume a “C” shape when they are dug out of the soil (Fig. 1). They have a well–developed brownish head and three pairs of well–developed legs. With one exception, the grubs feed on the roots of warm and cool–season grasses. They show no preference for home lawns, golf courses, sports turf, or industrial landscape. All managed grass areas are potentially susceptible to grub attack. When grub numbers are high enough, the grass may be lifted like a throw rug because the grubs have eaten the roots. At lower numbers, the grass may appear unthrifty. Many times, grubs are concentrated in localized areas. For this reason, it is very important to sample several areas in the lawn or other grassy area.

Since grubs feed on the roots, this is the area that must be inspected. The simplest method of sampling is to make cuts on three sides of a 12–inch square with a stout knife or a shovel, pry this flap back, and carefully inspect the root zone and the upper 1-3 inches of soil. If grubs are present, they will be found in this area. Sample several areas and determine the average number of grubs per square foot. Most healthy turfgrasses that are not under stress can tolerate at least 5-7 grubs/square foot. Poorly managed turfgrass may show damage at lower infestation levels. These treatment thresholds can vary depending on the kind of white grub present. Treatment thresholds and identification tips will be presented during the discussion of each major type of grub.


Treatment: Control of white grubs can be difficult at times because they live in the soil. This makes it much more difficult for the insecticide to reach the grubs. Heavy thatch will bind with most insecticides and restrict downward movement. It is very important to follow label directions with respect to watering after application. Sprays should be watered in as soon as possible after application to prevent drying of the spray. When sprays dry, the insecticide sticks to the grass blades and is difficult to wash off and into the soil. Most materials for grub control should be applied after egg hatch is complete. This will be August and early September in most cases. However, some must be applied during peak adult activity before egg hatch begins. Always follow all label directions and cautions.
Note: Thatch over ½ inch should be removed.