Azalea Care

Parts of the information taken from-

EXPOSURE

Azaleas prefer cool, partially shaded sites, such as the filtered shade of pine trees. Azaleas planted beneath hardwoods with shallower roots must compete with these trees for nutrients and water. If placed in the right location, however, they can do well on these sites. Although some varieties tolerate sun better than others, they all prefer an area that is not exposed to long periods of hot full sun and drying winds This causes the leaves and flowers to fall off azaleas. Flowers last longer when plants are partially shaded. Azaleas exposed to full sun are more susceptible to lace bugs. Early morning sun exposure after a hard freeze may cause cold injury. Do not plant azaleas in heavy shade as poor flowering and weak growth result. Cold can blackened or severely discolored foliage.

SOIL

Azaleas are shallow-rooted plants that are easily damaged by excessive soil moisture. They grow best in acid (4.5 to 6.0 pH), well-drained, organic soils. Before planting, have the soil tested and adjust the pH according to soil test results.

Azaleas located in poorly drained sites do not receive the oxygen required for healthy growth and often develop root rot diseases. When planting in poorly drained areas,
add composted pine bark to as large an area as possible, and plant the root ball higher
than ground level.

MULCHING

A 2- to 3-inch layer of organic mulch is very important. It conserves soil moisture, maintains soil temperature and helps discourage weeds. There are many materials available suitable for mulching. Pine straw, composted pine bark and leaves work very well, enriching the soil with organic matter as they decompose. Keep the mulch a couple of inches away from the main stem to keep the bark dry and extend it beyond the outermost branches.

WATERING

Azaleas are shallow-rooted plants and require irrigation during dry periods. This is especially true of those planted in the spring. Azaleas planted in warm weather in sandy soils may require watering of the root mass twice a week during the first year.

To determine when to water, pull back a small area of mulch near the base of the plant and check the moisture level of the root ball and surrounding soil. If the top few inches of soil feels dry, wet the soil deeply, to at least a depth of 6 to 8 inches.

Use soaker hoses or drip irrigation to slowly water the base of the plants. Overhead irrigation may promote disease.

Azaleas in waterlogged soils will decline and are susceptible to root rot diseases. It is important to reach a balance of regular, deep watering and good drainage to promote a healthy plant. Too wet, hot or too dry can cause the leaves and flowers to fall off azaleas

FERTILIZING

Azaleas have low nutritional requirements compared to other shrubs. A soil amended with organic matter prior to planting followed by a mulch of compost, shredded leaves, pine straw or other organic material will usually provide sufficient nutrients for adequate growth.

Before fertilizing, have a specific reason for doing so, such as increasing growth rate or correcting a nutrient deficiency. A nutrient deficiency can be exhibited by a number of symptoms including stunted growth, smaller than normal leaves, light green to yellowish leaf color and early leaf drop. Be aware that these same symptoms can be caused by other problems such as heavily compacted soil; stresses from insects, disease organisms and weeds; and excessively wet or dry soil. Fertilization will not correct those problems, so be certain that you know the cause of the symptoms and treat them appropriately.

Having your soil tested is one way to determine if applying fertilizer will benefit your azaleas.

Most fertilizer recommendations are based on nitrogen, which is an important element in plant growth and often the one that is most likely deficient in the soil. Apply 1 pound of actual nitrogen per thousand square feet of root spread area. Up to 2 pounds can be applied with a slow-release fertilizer. In the absence of a soil test use a complete fertilizer with a ratio of 3:1:2 or 3:1:3, such as 12-4-8 or 15-5-15.

Apply fertilizer to the azalea’s root zone area (area occupied by nutrient and water-absorbing roots) which can extend beyond the drip line or outer-most branches. According to research findings, a shrub’s roots can extend three times the distance from its center to the outermost branches. So, if the distance from the center of the azalea to the outer-most branches is 2 feet, the feeder roots can extend an additional 4 feet beyond the drip line. To visualize the area to be fertilized, imagine the azalea as the center point of a circle with a 6-foot radius (the ''root radius''). Trace the outer edge of the root zone area.

Since most azalea roots are located in the top foot of soil, surface application of the fertilizer is adequate. Evenly broadcast the fertilizer with a handheld spreader or a rotary or cyclone spreader over the root zone area. Sweep any fertilizer off the branches and water afterwards to make the nutrients available to the roots.

For azaleas growing in a bed, follow the steps below to determine how much fertilizer to apply over the bed to supply 1 pound of nitrogen per 1,000 square feet. If the shrub’s root zone area is confined by a sidewalk or driveway, reduce the area to be fertilized accordingly.

1. Measure the area of the bed, making an allowance for the roots that extend beyond the outermost branches. Let’s assume the bed is 30 feet long and 10 feet wide. The bed area (length x width) is 300 square feet.

2. Determine how much fertilizer to apply over the bed to deliver 1 pound of nitrogen per 1,000 square feet using this equation:

100 %N in bag

=

Number of pounds of fertilizer required per 1000 square feet in order to apply 1 pound of nitrogen

Assuming you have a 12-4-8 fertilizer, the equation for this example would look like this:

Since the root zone is 300 square feet, the actual amount of fertilizer to apply is calculated as follows:

Apply 2½ pounds or 5 cups of 12-4-8 evenly over the mulched bed.

Azaleas do not have to be routinely fertilized during the growing season. Any fertilizer application should be based on their appearance, such as leaf color, growth rate, soil test results and your objectives, such as encouraging growth or correcting a mineral deficiency.

The best time to apply fertilizer is when it will be readily absorbed by the roots of the plant and when the soil is moist, which can be any time from late spring (after new growth emerges) up to early fall. Avoid fertilizing plants stressed by drought during the summer months. Without water, plants are unable to absorb nutrients, so it is best not to fertilize if water is unavailable.

PRUNING

There are two pruning techniques used for azaleas: thinning and heading. Thinning refers to the removal of branches back to the main trunk or another branch. This method is used to remove leggy branches that extend beyond the canopy of the plant, remove damaged or diseased wood, or reduce the size of the plant. Thinning allows light to penetrate the shrub, encouraging growth on interior branches. You can thin at any time of the year without causing significant impact on flowering, growth or cold hardiness of the plant. How-ever, to reduce the impact on flowers the following year, prune just after flowering in the spring.

Heading refers to the cutting back of a branch, not necessarily to a side branch. This method is used to reduce the size of a plant, create a hedge or to renew old overgrown plants. Renew overgrown plants by cutting them back to within 6 to 12 inches of ground level. This practice results in abundant new growth by midsummer.

The best time to renew azaleas is before spring growth begins. This allows sufficient time for next year’s flower buds to form in midsummer, and for new growth to mature and harden off for winter. Renewal pruning before spring growth, of course, means that flowers are sacrificed for that year.

After renewal pruning, prune the tips of new shoots when they are 6 to 12 inches long, to encourage branching and a full canopy. Thin out new shoots emerging from the old stem. Keep the soil moist during the period after severe pruning.

The brown husks are natural covering for developing flowers

PROBLEMS

The most common diseases on azaleas in South Carolina include petal blight, leaf gall, leaf spots, dieback, and root and crown rot. The most common insects are lacebug and spider mites. Good cultural practices such as careful plant location, provision of good aeration and drainage, mulching and good watering habits will reduce the incidence of disease and insect damage. For more information on disease and insect problems on azaleas, refer to Azalea and Rhododendron Diseases, HGIC 2050, and Azalea and Rhododendron Insects, HGIC 2051.

Iron is essential for healthy azaleas. Iron is available for uptake by azaleas when the soil pH is low (acidic). When soil pH is too high (alkaline), iron becomes unavailable and chlorosis, or yellowing of the youngest leaves, may occur. A telltale sign of iron chlorosis is when the area between the veins is yellow or light green, while the veins are darker green. Application of iron as a foliage spray will usually give quick, temporary results when applied during the growing season.

In low pH soils, such as the clay soils in the Piedmont area, iron is readily available. In these soils, chlorosis is usually due to other causes, such as waterlogged or compacted soil, root rot, or injury caused by nematodes or too much fertilizer. The first step to determine the cause of yellowing is a soil test to determine the soil pH.

Azaleas are susceptible to cold injury, especially when exposed directly to early morning sun after a hard freeze. The rapid thawing of frozen branches and twigs may result in bark splitting. Sudden early freezes in the fall and late freezes in the spring also cause bark-splitting. It may take several months before the branches die back on winter-injured azaleas with split bark. Prune out affected branches. To reduce chances of bark-splitting, plant only azalea varieties known to be hardy in your area.

Petal Blight

This fungal disease, caused by Ovulinia azaleae, primarily affects the flowers of azalea, but mountain laurel and rhododendron flowers can also be infected. Indian and kurume azaleas are especially susceptible. The disease starts on the flower petals as tiny, irregularly-shaped spots, giving a ''freckled'' appearance. On colored flowers the spots are white, and on white flowers the spots are brown. The spots quickly enlarge and become soft and watery. Flowers rot and stick to the leaves. Infection is easily spread from flower to flower by wind, rain and insects. The fungus survives the winter in the soil.

Credit: Clemson University/Photographer: James H. Blake

• Label
• MSDS

Leaf Gall

Leaf gall - Left to right shows stages of development

Credit: Clemson University/Photographer: James H. Blake

Leaf gall (Exobasidium species) is a very common fungal disease in the early spring on azaleas and occasionally on rhododendrons. Some of the native rhododendron species (azaleas) are more susceptible than hybrid rhododendrons. In April and May leaves and buds of infected plants develop distorted growth. Leaves and possibly stems become thickened, curled, fleshy and turn pale green to white. In the later stages of the disease, the galls become covered with a white powdery substance. As the galls age, they turn brown and hard.

Prevention and Treatment: This disease rarely does enough damage to require chemical control. If only a few plants are affected, pick and destroy galls. If chemical control is necessary on azaleas, mancozeb, copper salts of fatty acids or triadimefon fungicide sprays can be used according to label directions.

• Label
• MSDS

Leaf Spots

Credit: Clemson University-USDA Cooperative Extension Slide Series

Throughout the year, fungal spots (Cercospora species, Septoria species, Phyllosticta species and Colletotrichum species) of various colors appear on azalea and rhododendron leaves. The diseases caused are usually minor, only affecting the aesthetic value of the plant. Cases of severe infection may result in early leaf drop, reducing the general health of the plant.

Prevention and Treatment: Remove fallen leaves. Keep leaves dry when watering plants. Fungicide sprays during periods of high humidity will prevent serious foliage damage. Fungicide sprays recommended for azaleas include copper hydroxide, copper salts of fatty acids, thiophanate-methyl, or cholorthalonil. For Cercospora leaf spot on rhododendron use triadimefon, propiconazole, thiophanate-methyl, chlorothalonil or mancozeb. Apply these fungicides according to directions on the label.

• Label
• MSDS

Dieback

Credit: Clemson University/Photographer: James H. Blake

Dieback is an important disease of hybrid rhododendrons in the landscape and is caused by the fungus Botryosphaeria dothidea. Azaleas with similar symptoms are more likely to be infected by the fungus Phomopsis species. Typically, dying branches (stem dieback) begin to appear on an otherwise healthy plant. The leaves die and can remain attached to the plant until late summer. Usually a single branch on an established plant is affected. Scraping under the bark with a knife reveals a reddish-brown discoloration under the bark on dying branches of rhododendron. On azaleas the discolored wood under the bark appears chocolate brown.

Prevention and Treatment: Dieback is difficult to control on rhododendrons and azaleas in the landscape. The azalea varieties that are the least susceptible include: ‘Delaware Valley White,’ ‘Hershey Red,’ ‘Pink Gumpo’ and ‘Snow.’ The following rhododendron varieties are considered resistant: ‘Boursalt,’ ‘Chionoides White,’ ‘Cunningham’s White,’ ‘English Roseum, ‘Le Barr’s Red,’ ‘Roseum Two’ and ‘Wissahickon.’

Reduce stress to the plants by planting in partial shade and watering during dry periods. Avoid wounding the plant. Prune infected branches well below all discolored wood and dispose of dead plant material. Clean pruning tools between cuts with a dilute solution of household bleach (1 part bleach to 9 parts water). For azaleas, fungicide sprays containing either thiophanate-methyl or mancozeb can be used. For rhododendrons apply a product containing Bordeaux 4-4-100, copper hydroxide, copper salts of fatty acids or chlorothalonil. Apply all chemicals according to directions on the label.

• Label
• MSDS

Root and Crown Rot.

The fungus Phytophthora species causes one of the most common disease problems in the landscape for rhododendron and azalea. This fungus is a ''water mold,'' and thrives in poorly drained or wet conditions. A wilted plant is usually the first sign of trouble. Rhododendron leaves will curl inward and droop. Drought can cause similar symptoms. Roots of affected plants appear soggy or blackened, and the outer portion of the root easily pulls away from the inner portion.

Crown rot causes the lower portions of the stem to have a brown discoloration of the wood near the soil line. This disease is favored in poorly drained areas or when plants are set too deeply. Plants may remain without symptoms until further stressed from drought or flooding.

Prevention and Treatment: Prevention of disease is important, because chemical controls are ineffective once symptoms appear in the landscape. Begin by purchasing disease-free plants from a reputable nursery. Avoid plants that lack normal green color, appear wilted in the morning, or have dark, discolored roots. Select resistant varieties for planting from the Table below.

Plant azaleas and rhododendrons in a well-drained and well-aerated soil. Heavier clay soils should be amended with organic matter before planting. Avoid planting in areas where water can collect around plant roots.

Some crown and root-rot resistant azaleas and rhododendrons

Azaleas

Resistant: R. sanctum, R. simsii (Indian azalea), R. yedoense var. poukhanense (Korean azalea), ‘Corrine,’ ‘Fakir,’ ‘Fred Cochran,’ ‘Glacier,’ ‘Hampton Beauty,’ ‘Higasa,’ ‘Merlin,’ ‘Polar Sea,’ ‘Rose Greeley’

Moderately resistant: ‘Alaska,’ ‘Chimes,’ ‘Eikan,’ ‘Jan Cochran,’ ‘Morning Glow,’ ‘New White,’ ‘Pink Gumpo,’ ‘Pink Supreme,’ ‘Rachel Cunningham,’ ‘Red Wing,’ ‘Shinkigen,’ ‘Sweetheart Supreme’

Rhododendrons

Resistant: ‘Caroline,’ ‘Martha Isaacson,’ ‘Pink Trumpet,’ ‘Prof. Hugo de Vries,’ ‘Red Head,’ R. davidsonianum, R. delavayi, R. glomerulatum, R. hyperythrum, R. lapponicum, R. occidentale, R. poukhanense, R. pseudochrysanthum, R. quinquefolium and R. websterianum

Do not set new plants any deeper than the original soil level. Planting in raised beds is suggested. Firm the soil slightly at the base of the planting hole to prevent the plant from settling into the bed. Do not plant azalea and rhododendron plants into sites where plants have previously died from root rot. Even resistant plants may succumb under these conditions. The fungus survives in the soil and cannot be eradicated once an area is infected.

Chemicals that are available will only suppress disease and not cure an infected plant. Fungicides available for use on azaleas and rhododendrons include metalaxyl and mefenoxam. Apply all chemicals according to directions on the label.

Whiteflies

R. Bessin, Univ. of Kentucky

Little white bugs that fly around the azalea or whiteflies. After blooming, spray with insecticidal soap or pyrethrins. Repeat the spray again in 3 days and again in 3 days, being sure to target the bottom of all the leaves.

Azalea Lacebug - Control

You may have seen the damage lace bugs do to azaleas without knowing who did the dirty deed. Lace bugs suck the juice out of individual leaf cells. Since they hide underneath azalea leaves, you’ll never notice the bugs but it’s easy to see their damage. Since the bugs slurp out the chlorophyl in a leaf cell, the top of the leaf has hundreds of yellow speckles. Thousands of hungry lace bugs can make an azalea appear yellow all over.

Since azalea lace bugs have an active sex life, just a few can produce thousands of offspring in the course of a summer. Dr. Kris Braman says that she has seen adult lace bugs on her research azaleas even during the winter.

Inspect your azaleas for speckled yellow leaves. Examine the backside of the leaves too. If you see tiny black spots scattered across the leaf and concentrated along the mid-vein, you will have a population explosion of the creatures before many weeks pass.

The adult lacebug is barely one fourth inch long, with transparent wings. It feeds on the underside of azalea leaves, sucking juice from the leaf cells.

Mid-spring is a great time to control the first few generations of lacebug larvae and adults. Insecticidal soap, horticultural oil, neem oil and most synthetic insecticides will kill the insects. The key to good control, though, is thorough coverage.

Use a garden sprayer and pump it up vigorously. When spraying, point the spray wand up from beneath so the undersides of the leaves are covered with spray.

Another pesticide option is to use a systemic insecticide that poisons the sap of the azalea. Imidacloprid (Bayer Tree and Shrub Insecticide) can be poured around the roots of azaleas in spring, when growth begins, to achieve season-long control.

It is easier to manage azalea lacebugs in spring or summer than it is in August!

Azalea lacebug symptoms

Again, the most important thing to remember is to READ and FOLLOW the directions on the label of the product that you purchase. Most horticultural oils will come with summer and winter directions. Don't mix stronger than the directions say. And these products don't clog up your sprayer. They are combined with emulsifiers that turn the oils into a pure solution.

Horticulture and Dormant Spray Oil

Leaf-Mining Insect

Leaves develop little white trails due to leaf mining insects.

This is best treated with malathion at half the recommended rate. Malathion should only be used outdoors. Repeat in a week. Insecticidal granules can also be used for control.

Since the flowers are so sensitive to sprays, wait until after it has finished blooming.

Parts of the information

By Michael F. Potter, Urban Extension Entomologist

Spider Mites

SPIDER MITES ON LANDSCAPE PLANTS

Spider mites are common pests in the urban landscape and can inflict serious damage to trees, shrubs and flowers. Both evergreen and deciduous plants may be attacked. Spider mites are not insects but are more closely related to ticks and spiders. Their common name is derived from their ability to produce silk, which most species spin on host plants. Mites are tiny—about the size of the period at the end of this sentence. They can also be very prolific, which is why infestations often go unnoticed until plants exhibit significant damage.

General Characteristics

Spider mites (family: Tetranychidae) have a simple, oval-shaped body and no wings or antennae. All species pass through an egg stage, a six-legged larval stage, and two eight-legged nymphal stages (protonymph and deutonymph) before transforming into an eight-legged adult. Immature stages resemble the adults except in size. An adult female may live for several weeks and lay many dozens of eggs during her lifetime. Under optimum conditions, spider mites can complete their development from egg to adult in less than one week, so there may be many overlapping generations in a single season. Therefore, populations can increase rapidly and cause extensive plant damage in a very short time. Spider mites have needle-like mouthparts and feed by piercing the leaves of host plants and sucking out the fluids from individual plant cells. This causes the leaves to have a stippled or flecked appearance, with pale dots where the cellular contents have been removed. Prolonged, heavy infestations cause yellowing or bronzing of the foliage and premature leaf drop similar to drought stress. Severely-infested plants may be stunted or even killed. Most of the mites feed from the undersides of leaves, although the damage is most evident from the upper surface.

Most spider mites have a habit of covering leaves, shoots, and flowers with very fine silken webbing, produced from a pair of glands near the mouth. The silk strands aid in dispersal by allowing the mites to spin down from infested to non-infested leaves, and to be blown by wind currents. When abundant, the silk also may shield the mites from pesticide sprays.

Damaging Species In Kentucky

Several species of spider mites live on plants. Fortunately, a rather small number routinely damage landscape plants in Kentucky. Some, such as the twospotted spider mite, have very broad host preferences, wheras with others (e.g., European red mite, spruce spider mite, southern red mite) the number of susceptible landscape plants is more limited. The twospotted spider mite and European red mite thrive under hot, dry summer conditions, whereas the spruce spider mite and southern red mite prefer cooler temperatures in the spring and fall. Being familiar with the following four mite species will help you to determine which landscape plants are most susceptible, and the time of year they are most vulnerable to attack.

Two Spotted Spider Mite(Tetranychus urticae)

This is the most common and destructive mite on deciduous ornamentals. It has an extremely wide host range and will feed on many varieties of trees, shrubs, flowers, weeds, fruits, greenhouse and field crops. Immatures and adults are yellowish to greenish with two dark spots on either side of the body. Eggs are spherical and translucent. Strands of webbing are spun by the mites on the undersides of infested leaves and between branches. Twospotted spider mites overwinter as adult females in the soil or under the bark of host plants. They become active during the spring and may feed and reproduce throughout the summer and into fall provided conditions remain favorable for plant growth. It is considered a “warm season” mite which thrives under hot, dry summer conditions. Damaging populations seldom during wet, cool weather. The mites are especially destructive to winged euonymous (burning bush) in landscapes.

Another “warm season” species, this mite attacks deciduous trees and shrubs. It is especially common on flowering fruit trees such as apple/crabapple, cherry, pear, plum, hawthorn, and serviceberry. European red mites overwinter as bright red eggs laid in clusters on branches, limbs and trunk, often in such great number that the bark seems to be covered with red brick dust. Eggs of subsequent generations are laid on the foliage, usually on the lower leaf surface. Following spring egg hatch, there may be several generations per year. Development from egg to adult varies from about 3 weeks at 55 degrees F to less than 1 week at 77 degrees F. All life stages (eggs, immatures, and adults) are brick red. The presence of the overwintering eggs on the bark makes the use of dormant oils an effective control measure (see “Controlling Infestations” section below).

Despite its common name, this mite feeds on more than 40 species of conifers. Most often attacked are spruce (especially Alberta spruce), pine, juniper, fir, arborvitae, hemlock, taxus and false cypress. The mites have a similar appearance to those already discussed. Coloration varies from green to deep olive to brownish red. Close inspection of the needles will reveal tiny white flecks and speckles where the mites have fed. Prolonged feeding causes yellowing, browning, and premature needle drop, often originating from the canopy interior. Infested foliage may also display webbing, eggs and cast skins. Heavy attacks can cause branch dieback or death of the plant.

The spruce spider mite is known as a “cool season” mite and is most active in early spring and late fall. It overwinters in the egg stage attached to the base of needles or on the bark. The eggs hatch in early spring, and mature in 2 to 4 weeks. Damaging populations may be reached in April and May, before warm summer temperatures slow their activity. Spruce spider mite populations rebound in the fall with the return of cooler weather, and feeding may continue into December or beyond, if winter temperatures remain mild. Damage inflicted by mite infestations present during the fall or subsequent spring often go unnoticed until the heat and dryness of June and July.

When , what is the cause?
Spider mites are sucking insects that make the foliage look generally unhealthy (the leaves look rough and sandy). After blooming, spray with insecticidal soap or pyrethrins. Repeat if needed.

This is the most common and destructive spider mite on broad-leaved evergreens, especially Japanese and American hollies, azaleas, viburnum, roses and rhododendron. Feeding on the undersides of leaves causes stippling, browning, occasional distortion, and premature leaf drop. Southern red mites overwinter in the egg stage on the undersides of leaves. Like the spruce spider mite, its numbers are greatest during cooler periods of the spring and fall.

Diagnosing Infestations

Timely inspection of susceptible landscape plants — especially during periods favoring mite outbreaks — is key to preventing serious damage. When scouting for spider mites, pay particular attention to plants having a history of mite problems. Spider mites often re-infest the same plants year after year.

Inspect stippled and distorted leaves to determine if mites are present. Similar symptoms can be caused by pests other than mites, including thrips, leafhoppers and lace bugs. Many spider mites prefer to feed on the lower leaf surface, so examine the undersides of leaves first. A 10 - 20 power hand lens or microscope is essential for clearly seeing the mites. The tiny mites will appear yellow, green, orange, purple, black or nearly transparent. Also visible on the leaf surface may be pale-colored cast “skins” shed by developing mites, and the spherical, often translucent eggs.

An efficient way to sample vegetation for mites is to hold a sheet of white paper or foam board under a branch and tap the foliage sharply. If mites are present, they will be dislodged and appear as slow- moving, dark specks on the paper.

Controlling Infestations

Spider mites are one of the more difficult groups of landscape pests to control. Infestations are easiest to control when detected early, before the mite populations have reached very high levels. Twospotted spider mite infestations can often be traced to the purchase of infested plant material, especially bedding and houseplants. When buying new plants, it pays to inspect the lower leaf surfaces for evidence of mites. Spraying plants with a strong stream of water from a garden hose or faucet can dislodge many mites from leaf surfaces. The approach is generally more effective on smaller plants (e.g., houseplants), with non-dense foliage and low mite populations. Water sprays should be directed upward against the lower leaf surfaces, and the technique will need to be repeated on regular intervals. Low populations of spider mites may be held in check by naturally occurring predatory mites which feed on both eggs and active stages.

Pesticides

Remember azaleas sprayed with leafshine or strong insecticides can causes black specks on the leaves and blooms?

Elimination of moderate to heavy infestations of spider mites usually requires the use of specific pesticides known as miticides. Some, but not all, insecticides will also control mites. Several mite-control products are listed in the table below. Some kill only active mites while others also kill eggs. Always read and follow the directions accompanying the product you are using. Some miticides may harm or discolor certain types of landscape plants.

Good spray coverage is essential when applying miticides. Thoroughly wet the foliage and try to contact as many mites as possible, paying particular attention to leaf undersides where most mites are living. In most cases, two or more applications at 5-10 day intervals will be needed for satisfactory control. Spider mite eggs that have not yet hatched are unaffected by most miticides; the same may be true of larvae and nymphs that are molting. During molting, spider mites remain inactive beneath the former skin, which serves as a barrier against insecticides. The quiescent mites also do not feed, rendering products that kill by ingestion temporarily ineffective. Consequently, if only one application is made, some of the mites may survive and the infestation will persist.

Not all products mentioned in the table are available to homeowners. Effective homeowner options include Kelthane, horticultural oils, and insecticidal/miticidal soaps. Horticultural oils and soaps can be effective alternatives to conventional miticides, but require thorough coverage so that all mite stages are contacted.

Horticultural oils can be used on landscape plants during the warmer months of the year when green foliage is present and the plants (and mites) are actively growing. Horticultural oils are applied at rates of 1.0 to 2.0 %. Dormant oils are applied in winter or early spring prior to bud break, or in the fall after the leaves have dropped and there have been several light frosts. They are useful for killing overwintering mite eggs and, therefore, can help to suppress infestations of spruce spider mites, European red mites and southern red mites which overwinter as eggs on infested plants. A dormant oil spray will not guarantee mite-free plants the following year, but will delay mite buildup the following spring. Dormant oils are either specially-formulated petroleum-based products or horticultural oils applied at higher rates (3.0 to 4.0%). When using any type of oil, be aware that these sprays will discolor many conifers that have a bluish, waxy coating on their needles. Mapes, hickories, black walnut, smoketree and azaleas also tend to be oil sensitive. (Refer to the product label for a complete list of plants which may be sensitive to these products.)

Horticulture and Dormant Spray Oil

Products Labeled for Mite Control on Landscape Plants

You can also use Generic brand Bifen and save money. It has the same ingredient as Talstar One.

Horticulture and Dormant Spray Oil

Monterey Garden Insect Spray

CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.

Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!

Check List

January

Spray azaleas, to control scale, spider mites, lace bug, leaf minor and other over-wintering insect pests. When applying the oil, the ambient temperature must be at least 40° F but 50° F is preferred.

Do NOT prune spring blooming plants such as azalea, rhododendron, and camellias because they have already set their flower buds for next spring. It is best to prune them immediately after they bloom.

For more information go to Clemson University or University of Kentucky Entomology