Integrated Pest Management for Commercial Horticulture

Transcription

1 Scale Commonly Encountered in Maryland Landscapes and Nurseries Integrated Pest Management for Commercial Horticulture extension.umd.edu/ipm Pest Alert Introduction Scale are sucking insects that insert a needle-like mouthpart, composed of four slender stylets, into plant tissue and remove plant juices. This feeding causes stunting, reduced vigor and sometime dieback of plants. Scale were once classified in the order Homoptera, but have now been moved into the order Hemiptera. Scale insects feed on plants through a long stylet bundle (straw-like mouthparts) that is inserted into the plant. Armored scales pierce plant tissue and suck up cell contents from stems or leaves, depending on the species. They suck out cell contents from conductive tissue in the wood and the chlorophyll-containing cells of leaves. Armored scales do not produce honeydew. Early damage symptoms of armored scale feeding are chlorosis of the foliage immediately surrounding the feeding site of each scale. If many scales are present, this may be followed by browning and defoliation. Honeydew deposits are usually the first signs of feeding by soft scales and mealybugs. A black sooty mold grows on the honeydew that may cause a blackened appearance to the foliage, twigs, branches, and any other surface beneath an infested plant. They do not suck out chlorophyll, so there is no sign of chlorosis around their feeding sites. Soft scales and mealybugs generally feed on the sap in the phloem of the plant on stems and along leaf veins. Sunken areas in bark are symptoms of pit scale in the family Asterolecanidae. Lines in calendar tables for each scale indicate when crawlers are most likely to be active. Azalea Bark Scale (Acanthococcus azaleae) Family Erioccicdae Plants Damaged: This scale is a pest of azaleas and rhododendrons. This scale has been reported on hawthorn, Andromeda, poplar, willow and ornamental cherry trees. Damage Symptoms: Azalea bark scale has become recognized as a prominent pest of azaleas. Infested plants usually appear chlorotic and unthrifty. Infested plants are often covered with sooty mold, a black fungus that grows on the honeydew excreted by the azalea bark scales as they feed. Eventually twigs may die back. Life Cycle: As the female azalea bark scale matures, it secretes white, waxy threads, which become felted or matted into a thick covering over its entire body. Females lay eggs in this white wax. As the female lays eggs, its body shrivels gradually as the egg sac fills with eggs. Eggs are laid in May. They hatch in central Maryland in late May to early June. Individual crawlers are active and moving for hours. New crawlers continue to emerge over a couple of weeks. There are two generations in Maryland. This new generation matures during the

2 summer and produces eggs in September. Mature females tend to feed in crotches and on twigs. Adult males, two-winged and tiny, tend to feed on the leaves. Azalea bark scale overwinters as immatures in the forks of the twigs. Control: If the population is low and damage is minimal, look for beneficial insects which do a good job controlling this insect. If necessary, apply a dormant spray for overwintering nymphs on twigs. In summer when crawlers are active, you can use a summer rate ( %) of horticultural oil. Calico Scale (Eulecanium cerasorum), Family Coccidae Life Cycle: This scale overwinters as second instars and molts and matures to 3rd instars in early spring. The nymphs of this scale will migrate out onto the foliage in June and feed through the summer. In the fall the immatures will migrate back to the twigs where the females overwinter. Monitoring: Look for copious amounts of honeydew in late May and early June. Look for the oval-shaped, yellow-bodied crawlers in June. Control: Apply horticultural oil in March to early April to kill overwintering females. When crawlers are out, use pryriproxyfen (Distance) or buprofezin (Talus) with 0.5 1% oil. Another option for controlling soft scale is to use a soil injection, basal flare, or soil drench of a systemic insecticide, dinotefuran (Safari, Transtect). This material takes days to be taken up by the plant before it begins to control the scale. It is very effective against soft scale insects such as calico scale. European Fruit Lecanium (Parthenolecanium corni), Family Coccidae Plants Damaged: Calico scale is a general feeder and can be found on many nursery and landscape plants including dogwood, honeylocust, magnolia, maple, sweet gum, tuliptree and ornamental fruit trees. Damage Symptoms: Calico scale covers the branches and leaves of the host plant and feeds on the phloem tissue. The plant may be covered in sooty mold as a result of the large quantities of honeydew produced by the calico scale. In large numbers, feeding can result in branch dieback. Identification: This white and dark brown calico scale is about 1/4 inch in diameter and is brightest when it reaches maturity and then darkens. First instar nymphs start out pinkish and become yellowish as they enlarge. Overwintering immature females are oval, flattened, and light to dark brown and have a hard waxy coating. Just before egg hatch the covering is white with gray-blue patterns. 2 Plants Damaged: This soft scale occurs on many shade tree species including hawthorn, red maple, pyracantha, and other plants in the rose family. The European fruit lecanium is a common soft scale insect pest of shade trees and other woody ornamental plants in Maryland. This species feeds on a wide range of host plants and is considered polyphagous. Populations of this pest build up quickly so monitoring for this pest on potential host plants is important. Damage Symptoms: Feeding damage may cause curled, chlorotic foliage that may drop prematurely.

3 Smaller infested branches are weakened due to feeding injury or in some cases may be killed. Also, when this soft scale species is feeding on leaves and twigs, a large quantity of honeydew is secreted. Life Cycle: The 2nd instar females overwinter on the branches. The females will start to swell-up in May and crawlers emerge in late May to early June. Nymphs move out onto foliage where they feed in summer and migrate back to the stems and trunk to overwinter. Monitoring: Look for sooty mold growing on the honeydew excreted on the foliage and branches. Inspect branches using a 10-16X magnifier for crawlers Control: Using pryriproxyfen (Distance) or buprofezin (Talus) with.5 1% horticultural oil applied when crawlers are active gives good control. Another option for controlling soft scale is to use a soil injection, basal flare, or soil drench of a systemic insecticide, dinotefuran (Safari, Transtect). tan. This scale can reproduce quickly with over 1,000 eggs per female. There is one generation a year. Crawlers begin to appear in mid-june. The scale tends to accumulate on the undersides of foliage. Monitoring: Look for sooty mold and honey dew on the foliage. Examine the undersides of leaves for the white cotton-like sacs. Control: Wait for eggs to hatch and then treat with pyriproxyfen (Distance) or buprofezin (Talus) mixed with 0.5-1% horticultural oil. Another option for controlling soft scale is to use a soil injection, basal flare, or soil drench of a systemic insecticide, dinotefuran (Safari, Transtect). Cottony Cushion Scale, (Icerya purchase Maskell), Family Margarodidae Cottony Camellia/Taxus Scale (Pulvinaria floccifera), Family Coccidae Plants Damaged: This large scale attacks a wide range of woody and herbaceous plants including fir, maple, boxwood, cedar of Lebanon, citrus, cypress, elm, laurel, locust, magnolia, nandina, Boston ivy, pear, oak, rose, and willow. It also attacks the herbaceous plants sage and verbena. Plants Damaged: Taxus yews, camellia, holly, rhododendron, Japanese maple, English ivy, and mulberry. Damage Symptoms: Yellowing of foliage and dieback of plant in severe infestations. This soft scale produces large amounts of honeydew on which sooty mold will grow. Life Cycle: Adult females are oval and yellowish 3 Damage Symptoms: By removing sap from the plant this scale causes foliage to yellow and stems to die back. Large amounts of honeydew are produced with sooty mold often growing on the honeydew. Life Cycle: This scale was not believed to be winter hardy in this area, but there are indications that with the milder climate the scale is now being found on outdoor plant material in some areas. We had samples from Prince George s County and D.C. where the scale has overwintered. The large white, elongated ovisac with its distinct ridges is very noticeable.

4 Inside the sac are hundreds of bright red oblong eggs. This scale is also unique in that it is a hermaphrodite. There are multiple, overlapping generations per year. After hatching the crawlers move to the foliage. This scale in mobile in all life stages and the scale will migrate back to stems and the trunk during the winter just before foliage drops in the fall. Monitoring: The large elongated, white egg sacs are the most obvious feature to monitor for this scale. Control: Soil application of imidacloprid (Merit in the landscape and Marathon in the nursery) or dinotefuran (Safari, Transtect) should give good control. Another option is to apply pyriproxyfen (Distance) or buprofezin (Talus) to mobile stages during the summer months. Control: A soil injection, basal flare, or soil drench application of dinotefuran (Safari, Transtect) should give good control. Another option is to apply pyriproxyfen (Distance) or buprofezin (Talus) to mobile stages during the summer months. Biological Control: A lady bird beetle called the Vedalia beetle (Rodolia cardinalis), has been used to control this scale. foliage. Heavy infested plants are chlorotic. Dieback occurs when populations are high. Life Cycle: This scale overwinters as second instar females. Adults occur in spring in March and April. Females lay eggs in June with crawlers appearing in June through early July. There are two generations per year. Adults of the second generation are present in July and crawlers are present in late August through September. Immatures overwinter on the needles. Monitoring: Look for chlorotic foliage with yellow spotting or banding on the needles. Look for overwintering scale on the needles. Control: A mixture of 0.5-1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) does a great job controlling this scale. Dinotefuran (Safari, Transtect) applied as a soil drench also works well. Euonymus Scale (Unaspis euonymi Comstock), Family Diaspididae Cryptomeria Scale (Aspidiotus cryptomeriae Kuwana), Family Diaspididae Plants damaged: Boxwood, camellia, and evergreen euonymus especially Euonymus japonica. Damage Symptoms: Yellowing of foliage, twig dieback and general thinning of infested plants. Plants Damaged: This scale is found on many conifer species including fir, Cedrus, Chamaecyparis, rarely this scale is found on Cryptomeria, pine, spruce, Taxus and hemlock. Damage Symptoms: As the scale draws out sap from the needles it causes a yellowing spotting of the 4 Life Cycle: This armored scale overwinters as 3rd instar females. Crawlers appear in May and continue for 4 5 weeks. Second generation adults are out in July with crawlers present from August through September. The females are dark brown, oyster shell shaped and usually found on the stems. Males are smaller, white and mostly found on the leaves.

5 Monitoring: Look for chlorotic foliage with yellowing spotting or banding on the needles. Look for overwintering scale on the needles. Control: A mixture of 1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) does a great job controlling this scale. Dinotefuran (Safari, Transtect) applied as a soil drench also works well. Winged Euonymus Scale (Lepidosaphes yanangicola (Kuwana)), Family Diaspididae Monitoring: This scale tends to blend in with the corky ridges on the winged euonymus branches making detection more challenging until your eye is trained to pick up the scale covers. Control: A mixture of 0.5-1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) does a great job controlling this scale. Dinotefuran (Safari, Transtect) applied as a soil drench also works well. European Elm Scale (Gossparia spuria) Family Coccidae Plants Damaged: Mainly found on winged euonymus (Euonymus alatus), but the scale is reported feeding on maples, ash, lilac and willow. Damage Symptoms: Yellowing of foliage and dieback of branched in heavy infestations. Heavily infested plants have been defoliated during the growing season. Life cycle: Third instar females overwinter. Eggs are produced from late May to early June and are present through July. Females (as shown in smaller photo) produce crawler flaps (white edge) 2-3 weeks before crawlers emerge. 5 Plants Damaged: Elm, mainly European and American species. Chinese elm appears to be resistant. Life Cycle: The female is oval-shaped, soft and immobile, olive-green to reddish-brown with a white waxy fringe around the edge of the body. The male is rarely seen, and looks like a yellow gnat with one pair of wings. Honeydew is produced by the scale. This scale has one generation per year. Egg laying starts in May and continues through July with each female laying up to 400 eggs. Nymphs, in summer, migrate to the foliage and establish on the undersides

6 of leaves, usually along the midrib veins. They use their stylet mouthpart to pierces into the phloem of the plant and extract plant juices. At this stage of development they look very similar to mealybugs. In the fall the nymphs will migrate back to the twigs and bark of the tree. The scale overwinter as immatures in bark cracks on elms (top photo). Monitoring: Look for the settled yellow crawlers on the undersides of the leaves in June. When examining the females squeeze the scale between your fingers and it will be blood red in color. Control: A soil injection, basal flare, or soil drench application of dinotefuran (Safari, Transtect) should give good control. Applications of oil or pyriproxyfen (Distance) or buprofezin (Talus) are not practical on large trees. for crawlers in July and August in your area. It is found mainly on the Eastern shore of Maryland where warmer winter weather allows it to overwinter. Monitoring: Females are round, brown and normally found on foliage. Control: Evaluate whether it is an occasional pest or a major threat to plant health by the population level and any dieback occurring. If control is necessary then a mixture of 0.5-1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) does a great job controlling this scale. Dinotefuran (Safari, Transtect) applied as a soil drench also works well. Felt Scale (Eriococcus quercus), Family Eriococcidae False Florida Red Scale (Chrysomphalus bifasciculatus (Ferris)), Family Diaspididae Plants Damaged: Only recorded on oaks. Damage symptoms: heavy populations can cause yellow of foliage and slow decline of trees. Plants Damaged: This armored scale feeds on a wide range of plant material and is found on Acuba, boxwood, camellia, daphne, euonymus, English ivy, holly, osmanthus, and lantana. Damage Symptoms: An occasional pest of landscape and nursery plants, it has been reported to cause yellowing and browning of foliage. Life cycle: The biology in Maryland is not well understood. Crawlers are present in May and move out onto the host foliage. It is not known if there is a second generation per season but you can examine 6 Life cycle: Life cycle is not well studied and recorded. Overwinters as immature females. Females lay dark red eggs. Crawlers hatch in May to early June. The scale feeds on new branches and in leaf axils and is rarely found on leaves. Monitoring: Examine the base of branches were populations tend to accumulate. Control: Pyriproxyfen (Distance) or buprofezin (Talus) applied at crawler period. Another control option is a soil injection, basal flare, or soil drench application of dinotefuran (Safari, Transtect).

7 Fern Scale (Pinnaspis aspidistrae (Signoret)), Family Diaspididae Damage Symptoms: Besides causing yellowing of foliage this scale will produce large amounts of honeydew in spring on which sooty mold grows. Plants Damaged: In Maryland this scale is found mainly on liriope, Rohdea and mondo (Ophiopgon) grass and ferns but it is a general feeder and has been reported on camellia, persimmon, peony, and Prunus. Damage Symptoms: When feeding on liriope and mondo grass the scale causes yellow spots on the foliage at the feeding sites. Life Cycle: On liriope the scale has been observed overwintering as late instar females in the crown of the plants. Crawler emergence coincides with new growth emerging form the liriope in May. A second generation has been observed with crawlers present in August and September. The second generation scale appear to establish in the base of the mondo grass and liriope plants. Control: Cut off infested foliage in early spring and remove it from the landscape. Treat with a systemic insecticide or apply pyriproxyfen (Distance) or buprofezin (Talus) and 0.5 1% oil when the crawlers emerge in May. Life Cycle: This scale overwinters as 2nd instar females that mature in May. The overwintering females are oval shaped and flattened in profile. In May the females will swell and become distended. The eggs will hatch into crawlers sometime in Juneabout the time when catalpa trees bloom. Monitoring: Examine stems of arborvitae and yews in winter looking for the oval shaped overwintering females. In May and June, look for honeydew and sooty mold on plants. Control: Pyriproxyfen (Distance) or buprofezin (Talus) applied when crawlers appear or a soil injection, basal flare, or soil drench application of dinotefuran (Safari, Transtect). Gloomy Scale (Melanaspis tenebricosa (Comstock)), Family Diaspididae Fletcher Scale (Parthenolecanium fletcheri (Cockerell)), Family Coccidae Plants Damaged: Arborvitae (Thuja species), and yews (Taxus) are the two plants this soft scale is commonly found on in Maryland. It has been reported on pachysandra and juniper. 7 Plants Damaged: This armored scale is commonly found on maples. It is also reported on several woody plants including dogwood, sweet gum, poplar, catalpa, black locust, willow, and grape.

8 Damage Symptoms: The heaviest damage is reported on maples with dieback of terminal growth on heavily infested trees. Life Cycle: Fertilized females overwinter. Egg laying occurs in early July and continues through August. Crawlers are present a short time after egg laying. Adult males are present in August. Monitoring: Female covers are circular and brown to gray in color. Shed skins in the center appear to be shiny black. Monitoring: Examine needles on the undersides for the presence of this scale. Control: Distance can be applied to the crawlers. Horticultural oil can be used to control overwintering females. Soil applications of dinotefuran (Safari, Transtect) are effective in control of this scale. Holly Pit Scale (Aterolecanium puteanum Russell), Family Asterolecandidae Control: A mixture of 0.5-1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) could be used on small trees. Dinotefuran (Safari, Transtect) applied as a soil drench may control this pest. Elongate Hemlock Scale (Fiorinia externa Ferris), Family Diaspididae Plants Damaged: American holly, Burford holly, and Japanese holly. Most of the infestations have been found on holly growing on the Eastern shore of Maryland. Plants Damaged: Hemlock is the predominant tree we see this scale damaging n Maryland but it also attacks spruce, pine and Taxus yew. Damage Symptoms: This scale feeds on the needles and leaves of infested plants. Feeding causes chlorosis of foliage and needle drop and dieback of the plant. Life Cycle: There are two generations per season of hemlock elongate scale. Crawlers are active in May. The nymphs settle on the foliage of the plant where they spend their whole life cycle. The generations overlap for this scale which makes it somewhat challenging to control. Crawlers can be produced throughout the summer and into the fall. 8 Damage Symptoms: Pitting and distortion of woody tissue on branches and trunk of the tree. Heavy infestations cause dieback of the plant. Life Cycle: Mature females overwinter in a pit. The pit is caused by the feeding damage to the plant tissue. Crawlers emerge over a long period of time during the summer. Once nymphs have settled on a place on the plant they do not move. Monitoring: Examine twigs and trunk of tree for pit-like depressions with a scale insect in the middle of the pit. Control: A mixture of 0.5-1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) applied when crawlers are present. Photo of holly pit scale by Mike Raupp, University of Maryland

9 Indian Wax Scale (Ceroplastes ceriferus), Family Coccidae Japanese Maple Scale (Lopholeucaspis japonica (Cockerell)), Family Diaspididae Plants Damaged: This soft scale feeds on Chinese and Japanese hollies, azaleas, pyracantha, euonymus, boxwood, flowering quince, camellia, pear, azalea, persimmon, plum, barberry, and magnolia. Damage Symptoms: This scale is large enough that its mere appearance is aesthetically unpleasing. Heavy populations can cause dieback of the infested plant. Life Cycle: Females overwinter and eggs are laid in May in Maryland. Crawlers are active in early June. When crawlers emerge they will be yellow to pink in color and will excrete white wax that gives the scale a cameo appearance. Monitoring: The adult females are red and covered with bright white gummy wax. Look for the large, very noticeable females overwintering on the stems. Control: Horticultural oil does not work well on this scale. Pyriproxyfen (Distance) or buprofezin (Talus) applied when crawlers are present works well. Another option is to use a soil injection, basal flare, or soil drench of a systemic insecticide, dinotefuran (Safari, Transtect). Plants Damaged: Japanese maple scale is showing up in more landscapes and nurseries now. Look for it on Japanese maple, red maple, dogwood, lilac, zelkova, yellowwood, pyracantha, privet, holly, euonymus, redbud, stewartia, cherry, magnolia, Itea, and styrax. Damage Symptoms: This armored scale feeds directly on plant cells, not in the phloem tissue like soft scale insects. Heavy populations cause a slow decline of the tree. If high populations have resulted in dead branches on trees, prune these out before crawler hatch to reduce the number of scales potentially moving onto other branches and trees. Life Cycle: The life cycle is poorly understood. The male and females overwinters as immatures and mature in early spring. There are two generations per year. The 2 generations overlap and crawlers are present from May through October. Monitoring: Look for the white to gray, narrow oyster shell shaped female covers on twigs and main branches. Use a hand lens to look for the light purple crawlers. They should be out in late May or early June. Activity peaks in June to early July, and then we have a second crawler period in late July to mid September 9 Control: Applications of 0.5-1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) should be made when crawlers are detected. This should have about 2-3 week residual activity. At

10 that time monitor your plants again to see if crawlers are still active. The twice-stabbed lady bird beetle provides some biological control of this scale. Magnolia Scale (Neolecanium cornuparvum), Family Coccidae Maskell Scale (Lepidosaphes pallida (Maskell)), Family Diaspididae Plants Damaged: Arborvitae, junipers, Leyland cypress, Chamaecyparis, Cryptomeria, spruce, yew. Plants Damaged: This scale is found mainly on Magnolia stellata, M. acuminata, M.quimquepeta, and M. soulangeana. This scale has been reported on M. grandiflora. Damage Symptoms: Large amounts of honeydew are produced by this scale in late summer. Heavy infestations cause dieback. Life Cycle: Overwintering nymphs are oval shape, dark slate gray with a reddish brown ridge on its back. Overwintering nymphs are found on twigs. Nymphs move to foliage to feed during the summer. Adult females mature in August with crawlers present in September. There is one generation per year. Monitoring: Examine twigs for nymphs in winter. Look for honeydew and sooty mold on foliage in late summer. Control: Horticultural oil can be applied in March to control overwintering nymphs. Pyriproxyfen (Distance) or buprofezin (Talus) applied to crawlers in October. Photo by Brian Kunkel, University of Delaware, Bugwood.org Damage Symptoms: Yellowing and browning of foliage. Dieback of branches. Life Cycle: The exact number of generations per year is not clear. First instar crawlers emerge in June, and there is a second generation in August. In Maryland adult males and females are present in September through October. Eggs, crawlers and adult are all present in the early to mid fall. Monitoring: Examine foliage for elongated covers on the needles of infested plants. Control: In the dormant season a 2-4% horticultural oil can be applied to foliage and twigs. Apply pyriproxyfen (Distance) or buprofezin (Talus) and 0.5-1% oil mixture when crawlers are present. Nanokermes pubescens (gall-like scale), Family Kermesidae Plants Damaged: Oak Damage Symptoms: Heavy infestations cause twig dieback. 10

11 Life Cycle: This scale overwinters as second instar nymphs. When leaves open the scale moves to the foliage to feed on the undersides of the leaves, usually along the mid-rib veins. The eggs hatch into crawlers in June. Monitoring: Examine small twigs in winter for the presence of nymphs. They are generally found on the petioles and midribs of the leaves. Overwintering nymphs attack newly expanding leaves in April. Control: Horticultural oil applied at a 2-4% rate can be applied in March. Apply pyriproxyfen (Distance) or buprofezin (Talus) and 0.5-1% oil when crawlers emerge. Obscure Scale (Melanaspis obscura), Family Diaspididae Control: Pyriproxyfen (Distance) or buprofezin (Talus) can be applied to the crawlers. Horticultural oil can be used to control overwintering females. Soil applications of dinotefuran (Safari, Transtect) are effective in control of this scale. Minute Cypress Scale (Carulaspis minima) Family Diaspididae Plants Damaged: Obscure scale is an armored scale found on many pin oaks in the landscape, but is also found on a few other species of oak such as white oak. It has been reported on grape, dogwood, walnut, Prunus spp, pecan and hickory. Damage Symptoms: Yellowing of foliage and dieback. Plants Damaged: Arborvitae, Chamaecyparis, Cryptomeria, junipers, spruce. Damage Symptoms: Yellowing of foliage and dieback. Life Cycle: One generation per year. Fertilized females overwinter and eggs hatch in May and crawlers are present from May through early June. Adult males and females are present in early July. Monitoring: The scale are usually found on the leaf scales of small branches where they feed on the sap of the host plant. Minute cypress scale looks very similar to the Juniper scale, but the crawler period is two weeks later than Juniper scale. 11 Life Cycle: The obscure scale has one generation per year in Maryland. Second instar male and females overwinter and mature in spring in May. Eggs are laid in late June and July. Crawlers are present from July through early September. Stoetzel and Davidson (1973) found that this scale on white oak was one month behind its development on red oak. Monitoring: Adult female covers are circular and gray to black in color. The scales are usually crowded together and overlap each other on the branches and sometimes in the trunks of trees. Control: Use 0.5 1% horticultural oil or pyriproxyfen (Distance) or buprofezin (Talus) at crawler emergence. The crawlers should be active in central Maryland by the end of June. Photo: James Solomon, USDA Forest Service, Bugwood.org

12 Oystershell Scale (Lepidosaphes ulmi (Linnaeus)), Family Diaspididae Damage Symptoms: Yellowing of foliage and dieback of branches. This scale often exists in low levels on white pines but rarely reaches damaging levels. Plants Damaged: This scale is a general feeder (polyphagous) and is reported on 85 host plants in 33 families. We have observed it commonly on Acer (maples), Amelanchier (serviceberry), Cercis (redbud), Crataegus (hawthorn), Quercus (oak), and Prunus spp., but is found on many additional species. Damage Symptoms: Yellowing of foliage and dieback of branches. Life Cycle: There are univoltine and bivoltine forms found in Maryland. Bivoltine forms have crawlers present in April. Crawlers of the univoltine form are present from May through June. Monitoring: The adult females of this armored scale look like elongated oysters. Control: Use 0.5 1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) at crawler emergence. Life Cycle: This scale overwinters as females and eggs. Crawlers are present in May. The second generation occurs in mid summer with crawlers present from July through August. Monitoring: When Sargent crabapple is in full bloom we can expect to see crawlers on pine needle scale. The reddish nymphs hatch in May and there is a second generation in July. Control: Use 0.5 1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) at crawler emergence. Dinotefuran (Safari, Transtect) is reported to control this scale. Pine Tortoise Scale (Toumeyella parvicornis), Family Coccidae Pine Needle Scale (Chionaspis pinifoliae (Fitch)), Family Diaspididae Plants Damaged: Pine is the main host, but it has been observed on Abies (Spruce), Pseudotsuga, and Tsuga (hemlock). 12

13 Plants Damaged: Scots pine and Virginia pine are the two species most severely attacked by pine tortoise scale, but red, white and loblolly, Austrian pines are also affected. Damage Symptoms: These insects also produce honeydew, a substrate for the growth of a sooty mold fungus that blackens affected plants. Yellowing of foliage and dieback of branches. Life Cycle: Pine tortoise scale insects overwinter on host twigs as immature females. They are reddish brown and slightly wrinkled, but shiny, when they first begin to develop on the twigs. The females resume growth in the spring, reaching maturity in June. The, eggs are laid beneath the female s body (several hundred per female!) and the amber-colored young scale crawlers begin to emerge in June or early July. Monitoring: This scale derives its name from the characteristic appearance of the mature females. They look like tiny tortoises up to 1/4 inch in diameter and are most often found on 1- and 2-year-old shoots of hard pines. Control: A soil injection, basal flare, or soil drench of a systemic insecticide, dinotefuran (Safari, Transtect) is effective or apply 0.5 1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) when crawlers are active in June. and edible plums, peaches and pears. It will also feed on cherry laurel, cotoneaster, pyracantha, rose, and other plants in the rose family. Damage Symptoms: It feeds on the twigs and small branches and weakens the plant. Yellowing of foliage and dieback of branches Life Cycle: San Jose scale has three generations per year. The 3rd generation crawlers are still active in October. On apples the crawlers will move out onto the fruit in the first crawler emergence in May and during the second crawler emergence in July. The 3rd generation crawlers tend to be found on the twigs and branches and less on the fruit. On apples you will see round red circles on the fruit. Monitoring: The female covers are light brown and round with a raised center. Examine branches and twigs for the presence of overwintering female covers. Use a hand lens to examine foliage for presence of bright yellow crawlers which emerge in May and June. Control: Target the crawler stage for the best control. Apply 0.5 1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus). Tuliptree Scale (Toumeyella liriodendri), Family Coccidae San Jose Scale (Quadraspidiotus perniciosus), Family Diaspididae Plants Damaged: This native soft scale prefers tuliptree and magnolia. Plants Damaged: This armored scale can be found on apples, crabapples, crabapples, and ornamental 13 Damage Symptoms: Dieback of twigs and yellowing of foliage. Black sooty mold often grows on the honeydew that this scale excretes.

14 Life Cycle: They overwinter as black immatures and begin feeding around late April. The tuliptree scale females swell up in August and produce copious amounts of honeydew. The black crawlers emerge in September to October. Monitoring: Tuliptree scale tends to be found on small branches, whereas the magnolia scale is more commonly found on the main trunk. Control: When crawlers are out, pyriproxyfen (Distance) or buprofezin (Talus) mixed with 0.5-1% horticultural oil gives excellent control. White Peach Scale (Pseudaulacaspis pentagona), Family Diaspididae Control: When crawlers are out, pyriproxyfen (Distance) or buprofezin (Talus) mixed with 0.5-1% horticultural oil gives excellent control or use a soil injection, basal flare, or soil drench of a systemic insecticide, dinotefuran (Safari, Transtect). Walnut Scale (Diaspidiotus juglansregiae), Family Diaspididae Plants Damaged: This scale is a general feeder and can be found on several species of plants including holly, privet, cherry laurel, skimmia, mulberry, catalpa, and chinaberry. Damage Symptoms: Dieback of twigs, yellowing of foliage Plants Damaged: This armored scale is a general feeder and has been reported on 40 genera of plants. Walnut scale is reported to infest holly, maples, birch, redbud, crabapple, pines, poplar, Prunus species, black locust, mahonia, lilac, linden, elm, willow, and arborvitae. Life Cycle: One generation per year on holly in Maryland. Second instar males and females overwinter. Females lay eggs in June. Most crawlers are present in mid- to late-june. Though most crawlers are settled by mid-july, Stoetzel reported that she found crawlers present through September. Second instars are present sometime in September and these overwinter for the next generation. Life Cycle: First generation crawlers appears about 2 weeks later than white prunicola scale. Crawlers are out in mid-may to mid-june. Second generation crawlers are out from mid-july to mid-august. The third generation crawlers are out in September. Monitoring: Male crawlers are white and female crawlers are salmon colored. Control: When crawlers are out, pyriproxyfen (Distance) or buprofezin (Talus) mixed with 0.5-1% horticultural oil gives excellent control. 14

15 White Prunicola Scale (Pseudaulacaspis prunicola), Family Diaspididae Second generation crawlers are out from mid-july to mid-august. The third generation crawlers are out in September. Monitoring: Both male and female crawlers are salmon colored. Control: When crawlers are out, pyriproxyfen (Distance) or buprofezin (Talus) mixed with 0.5-1% horticultural oil gives excellent control. Plants Damaged: This scale is commonly found on Prunus species and also seen on magnolia, ligustrum, rhododendron, forsythia, boxwood, and lilac. Damage Symptoms: Dieback of twigs and yellowing of foliage. Life Cycle: Crawlers are present in May. A second generation occurs in July and a third in September. Crawlers appear about 2 weeks earlier than white peach scale. Crawlers are out in early May to June. Scale Commonly Encountered in Maryland Landscapes and Nurseries by Stanton Gill, Extension Specialist, IPM for Nurseries and Greenhouse, Central Maryland Research and Education Center, University of Maryland Extension, Ellicott City, MD, sgill@umd.edu Shannon Wadkins and Suzanne Klick, Technicians, Central Maryland Research and Education Center, University of Maryland Extension, Ellicott City, MD The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by University of Maryland Extension is implied. Read labels carefully before applying any pesticides. Photographs are by Suzanne Klick and Stanton Gill unless stated otherwise. University of Maryland Extension programs are open to all citizens without regard to race, color, gender, disability, religion, age, sexual orientation, marital or parental status, or national origin. Revised May 2015