Volume 22 No. 5 May 29, 2015

Ploioderma Needlecast (23)—Fruiting Scouting Report bodies of the that causes Ploioderma  Conifers Contents... (As Christmas & Landscape Trees) needlecast on Austrian are now readily visible on infected needles. Look for tan to Scouting Report Pine Needle Scale (47)—We recently found brown needle tips or bands on 2014 and older a few tiny red crawlers of this scale now Conifers (As Christmas & Landscape needles, especially on the lower third to half and there were still eggs under the scale of the crown. Examine these needles closely Trees): Pine Needle Scale,Weir’s covers as well. Scots, mugo and white pine for thin black lines about 1 – 5 mm long Cushion Rust, Ploioderma are common hosts. In addition, the scales and running lengthwise along any discolored Needlecast...... 17 may affect Austrian and red and portion of the needle surface. These are the less often, , Douglas- and cedar. Conifers (As Landscape Ornamentals): fruiting bodies. Do not confuse this with red- Many pesticides are band (=Dothistroma) needle blight where Elongate Hemlock Scale, registered for control Scots, mugo and short, thin dark brown bands lines may be Scale ...... 17 of this insect but white pine are common hosts. encircling portions of needles that have a most infestations can reddish-brown appearance. Broad-leaved: Apple Scab, Azalea be contained with Sporulation of Ploioderma usually begins Leaf/Flower Gall, Azalea Whitefly, applications of materials like horticultural oil within a few weeks after the appearance of Boxwood Leafminer, Four-lined Plant or insecticidal soap at 298 – 448 GDD50. Once the fruiting bodies, and with warmer and Bug, Honeylocust Plant Bug, Lilac the scales have settled and begun to form wetter weather available, they should develop Borer, Native Holly Leafminer, Privet their protective covers, they will be much quickly. Unless your area is experiencing a more difficult to eradicate and a horticultural Rust Mite, Rose Leafhopper, Two- very dry spring, you should expect oil may be your best management choice. spotted Spider Mite White Prunicola production to begin by the time the new Several treatments may be required because needles begin to emerge from the fascicle. Scale ...... 18 they hatch out over a period of time. No fungicides are currently registered in New Things to Look For—Arborvitae Weir’s Cushion Rust (143)—This needle York to manage this disease on landscape Leafminer, Bagworms, Bronze Birch rust, caused by Chrysomyxa weirii, was trees. In forest tree nurseries and plantations, apply copper hydroxide per Borer, Lophodermium Needlecast, sporulating on a Serbian spruce at our scouting site in Orange County last week. label directions. Mountain Ash Sawfly, Spider Infected needles have conspicuous yellow- Mite, Oystershell Scale, Pine Tortoise Conifers orange spots with spore-bearing pustules (As Landscape Ornamentals Only) Scale, Southern Red Mite...... 19 in the center of each. The will be windblown to new needles. Later in the Elongate Hemlock Scale (45)—We recently Feature: Matters of Scale: Wax and growing season, infected previous year found a few crawlers of elongate hemlock Azalea Bark Scales...... Insert needles are shed from the tree. The disease scale in Westchester County and Long Island. The crawlers are bright, lemon yellow and Growing Degree Days...... 20 can infect most spruce species and poses the greatest threat to Colorado blue spruce 0.1mm long. The insect is a serious pest of Phenology...... 20 Christmas trees. However, it will also hemlock and it also attacks yew, spruce, and reduce the value of landscape specimens. Douglas-fir. Feeding causes needles to turn To treat, apply a registered fungicide when yellow and drop prematurely. Treat heavily budbreak is 10 percent or more complete, infested plants in late May through mid-June and make two more applications at 7- to (360 – 700 GDD50). 10-day intervals. Juniper Scale (46)—The yellow eggs of up and destroy fallen leaves from infected damage to honeylocust. You can tap the this scale were evident at our scouting sites plants. If infestations are intolerable apply foliage over a white piece of paper and in Westchester County and Long Island. The horticultural oil, neem oil or other registered see if any plant bugs fall onto the paper. yellow crawlers will emerge soon. Light insecticide in early June to Mid-July The unfolding leaflets are very susceptible infestations cause no apparent damage, (448 – 700 GDD50) and again at 1250 – 1500 to damage. The feeding of the nymphs while heavy feeding causes the foliage GDD50 and at 2032 – 2150 GDD50. and adults causes these leaves to become to turn yellow. Use of a dormant spray is stunted, deformed, and chlorotic. With a usually enough. In the growing season, do large population of plant bugs, defoliation not spray if there is an abundance of parasites is possible. If the growing conditions are and predators. For heavy infestations only, adequate, honeylocusts will be able to treat crawlers in mid-June to early July recover from early damage and refoliate. If

(707 – 1260 GDD50). needed, treat with horticultural oil or other registered pesticide 58 – 246 GDD Broad-leaved Trees and Shrubs 50 Apple Scab (42)—The lesions of this Lilac Borer (122)—The adults of this common disease, caused by the fungus clearwing moth (Podosesia syringae) have Venturia inaequalis, are becoming quite recently been found in pheromone traps obvious now. The lesions are olive green, according to Don Gabel from New York circular with uneven margins. With time, Botanical Garden. They are ½ inch long, Azalea whiteflies on underside of leaves. Inset: Close- metallic brownish black in color. Additional the lesions enlarge, darken and turn velvety. up of an azalea whitefly. With heavy infections, the leaves may curl, hosts include privet, fringetree, and ash. cup or become dwarfed. Lesions may also Boxwood Leafminer (94)—Boxwood Look at the bark for holes (circular, clean, be seen on the fruit where they appear as leafminer adults are emerging and can easily and ¼ inch in diameter), sawdust, and cracks. rough, dark green areas. Although the first be seen flying around infested boxwood A registered pesticide should be applied cycles of the disease have already caused shrubs at various scouting sites around the in mid-May (200 – 299 GDD50), again in significant infection some protection will state. They are small orange, gnat-like flies. early June (400+ GDD50), and again two be provided by applications of appropriate Adult females lay their eggs in the tender weeks later. Spraying timing can also be fungicides starting now. leaf tissue, but the new leaves do not show determined by using pheromone traps (Make signs of mining until later in the summer an application ten days after the first male when the larvae are larger. Injury is caused moth is caught.) Prune and destroy infested when the larvae feed in the soft leaf tissue. canes. However, avoid pruning when moths Mined or blistered leaves are evident from are present. midsummer until the leaves are shed from Native Holly Leafminer (95)—We found the plant. Where allowable, soil application the adult native holly leafminers on American of imidacloprid via soil injection or drench holly on Long Island. They are ⅛ inch long is very effective. Another management black flies and can be found around the option is to spray with a registered pesticide newly expanded leaves. Although the larvae between 350 – 600 GDD . 50 only mine the leaves of American holly (Ilex Four-lined Plant Bug (190)—Four-lined opaca) the adults do feed on English holly plant bug nymphs are active and causing (Ilex aquifolium) and Japanese holly (Ilex Apple scab lesions are olive green, with uneven margins damage. The nymph’s color ranges from crenata) as well, causing leaf punctures to all Azalea Leaf/Flower Gall (124)— bright red to yellow and the forewings of them. Examine young foliage of American Symptoms caused by this fungus from the on the adult are yellow turning to green. holly for tiny green blisters. The parasites Exobasidium have begun to appear However, the four black stripes remain can not be relied upon as a control because on azalea. The size and shape of the leaf distinct. Woody ornamentals that serve as they do not reduce the area mined and the and flower galls vary with the host plant food for this insect include azalea, deutzia, resulting aesthetic damage. Place sticky and strain of fungus. Hosts include azalea, dogwood, forsythia, viburnum, weigela, rose traps on the terminals of holly to detect the mock azalea, bearberry, blueberry, cranberry, amur maple, and sumac. The plant bug also adults. To manage large populations, treat huckleberry, mountain laurel, leucothoe, and feeds on many herbaceous plants. Feeding in mid-May (192 – 298 GDD50). . We suggest that the galls be injury to upper surfaces of leaves by both picked and destroyed but there are fungicide nymphs and adults generally takes the form treatments available. of discrete circular spots that may be visible from above. Injured areas may turn black or Azalea Whitefly (151)—Adult whiteflies, become translucent, and after several weeks resembling tiny white moths, have been the remaining necrotic tissue may drop out detected on azalea on Long Island. Hosts leaving small holes. On shrubby plants the of this insect include azalea, rhododendron, topmost leaves are the first to be injured. mountain laurel, and andromeda. Predators and parasites are frequently effective in Honeylocust Plant Bug (194)—The pale keeping these pests at low levels. Rake green nymphs have emerged and are causing Native holly leafminer damage. Inset: adult.

18—Branching Out Privet Rust Mite (231)—This eriophyid White Prunicola Scale (188)—We found Bronze Birch Borer (128)—The adult mite was active at our scouting sites on Long the eggs of this scale on our scouting trip bronze birch borers will soon be found Island and in central NY. These mites are to Orange County. The salmon colored crawling on the sunny sides of trees. The white to yellow and spindle shaped with crawlers should be active soon. Hosts borers are greenish bronze in color and have four short anterior legs. Even when viewed include lilac, flowering cherries, privet, blunt heads. The body is slender, pointed, with a hand lens, they are so small that they willow and catalpa. Predators and parasites and one fourth to half an inch long. The appear as specks of dust or pollen. The are numerous but are not reliable. Treatments bronze birch borer creates D-shape holes in host plants of this pest are the amur privet should be made to target the crawlers in mid- the bark. The first symptom of infestation and the California privet and regal privet. June through early July (707 – 1151 GDD50). is the yellowing and browning of foliage in The immature mites suck leaf juices and Power wash or scrub off heavy infestations the upper branches. As the boring increases, introduce toxins that cause leaves to cup on the trunk with a brush. the trunk bleeds, the tree declines, and the downwards and turn olive green. Premature foliage becomes more sparse. Treat in June leaf drop and silvery stippling of foliage (440 – 880 GDD50). are also symptoms. Predaceous mites are Lophodermium Needlecast (11)— the most effective natural enemies to these fruiting bodies pests, but horticultural oil, neem oil or other should begin to produce infectious spores registered pesticide can be used in the last within the next few weeks. As the nature 10 days of May through Mid-June (298 – 802 of this disease is to produce spores over GDD ). 50 a period of about four months, a simple Rose Leafhopper (198)—Rose leafhopper schedule of treating once a month with a nymphs are feeding on the underside of registered fungicide beginning in early July some rose leaves and damage is becoming and continuing into early October has been apparent. These nymphs were white and found to be a fairly effective management Close-up of white prunicola scale with some covers look like tiny adult leafhoppers without removed to expose the bright orange females © Dan strategy. wings. Leafhoppers feed by sucking the Gilrein chlorophyll from leaves, resulting in minute white stippling of leaves (similar to mite Things to Look For in the damage but larger). Both the nymphs and Upcoming Weeks adults cause damage. Control is usually Arborvitae Leafminer (14)—Brush the not necessary unless a severe infestation is foliage of arborvitae to find the adult moths 1 present. of this leafminer. The adults are ⁄3 inch long and silvery gray. Lophodermium fruiting bodies Feeding by the larvae There are many Mountain Ash Sawfly (56)—The larvae will of this pest turns the effective larval soon begin feeding on the leaves of mountain tips of shoots and the parasites ash. Control is usually not warranted. The foliage brown. There larvae feed in groups, so small populations are many effective can easily be pruned out or squashed. If the larval parasites that suppress the populations infestation is severe, treat in early to mid- so chemical control may not be necessary. If June (448 – 707 GDD50). infestation is light, prune out infested tips. If control is needed, treat between Oak Spider Mite (228)—This warm season mite will be active soon. It is dark reddish 533 – 700 GDD50 for the moth stage. See Rose leafhopper damage. Inset: Nymph Cornell Guidelines for more information. brown, similar to southern red mite. They can be found on the upper leaf surfaces of Two-spotted Spider Mite (229)—This mite Bagworms (80,81)—You will soon see oak, , birch, beech, elm and hickory. is active now in southern New York. The spindle-shaped bags that are attached to If necessary treat with horticultural oil, two-spotted spider mite is green or greenish twigs and foliage of cedar, arborvitae, insecticidal soap or other registered pesticide yellow with two dark spots that can be seen juniper, and other conifers. This pest is in late June through early July (802 – 1266 through the pale bodies of these mites. This not common in the northern parts of NY GDD50). mite causes stippling of foliage and can be a State but if you live in Southeast NY they serious pest of roses, flowering fruits, azalea, can be of concern. Several parasitic insects Oystershell Scale (177)—The crawlers will and several other shrubs. In addition, it may are present in most bagworm populations, be active soon. cause damage to maple, elm, redbud, ash, yet they are rarely an acceptable mean of This pest may black locust, and poplar. Natural predators control. In light infestations, hand pick and be found on may greatly reduce populations. Heavily destroy bags. Sex pheromone traps help in apple, lilac, infested trees may need treatment with reducing the bagworm populations. With ash, willow, horticultural oil, insecticidal soap, neem oil heavy infestations registered pesticides can popular, or other registered pesticide. Treatments can be applied in mid-June (600 – 900 GDD ). maple, and 50 Oystershell scales closeup be applied from late May through mid-June Thoroughly cover the foliage. dogwood in (363 – 618 GDD50). late May. If predators are not preventing

Branching Out—19 damage to the host, treat with a registered pesticide in late May Growing Degree Days through mid-June (363 – 707 GDD50). Several sprays may be required. There is one generation per year. As of May 26, 2015 Station GDD Station GDD Pine Tortoise Scale (41)—The crawlers will be becoming active. 50 50 Treat salvageable infested trees with insecticidal soap, horticultural Albany...... 447 Ithaca...... 316 oil, or other registered pesticide in mid -to late June (618 – 1050 Binghamton...... 347 New Brunswick,NJ...... 511

GDD50). In Christmas tree plantations cull those that can’t be restored Boston, MA...... 354 Riverhead (5/27)...... 421 to marketable quality immediately. Bridgeport, CT...... 392 Rochester...... 412 Buffalo...... 362 Syracuse...... 395 Southern Red Mite (229)—The southern red mite will be active Central Park...... 629 Watertown...... 261 soon. It is the most widespread, important, and destructive spider Farmingdale (5/25) ...... 380 Westchester...... 405 mite on broad-leaved evergreens and cause bronzing and stippling Hartford, CT...... 488 Worcester, MA...... 348 of foliage. Treatment can be applied from 618 – 802 GDD50. Phenology Our Financial Supporters Long Island: Flowering—Beautybush, cotoneaster, deutzia, doublefile viburnum, dove-tree, This issue of Branching Out was made possible with the enkianthus, Kousa dogwood, Miss Kim generous gifts from the following: lilac, ruby horsechestnut, weigela, ‘Winter Jon Hickey King’ hawthorn Almstead Tree, Shrub & Lawn Care Co. Orange County: Flowering—Beautybush, burning bush, Cayuga Landscape Co., Inc. enkianthus, Kousa dogwood, white Emerald Tree Care fringetree Gary Mosca & Son Long Island Arboricultural Association Tompkins County: Flowering—Beautybush, black locust, New York State Arborists-ISA Chapter golden chain tree, horsechestnut, Miss Kim Professional Tree Surgeons Supply lilac. white fringe tree Carmine Serpe Westcheser County: Flowering—Burning bush, enkianthus, Miss Whitman Nurseries Kim lilac

20—Branching Out Dawn Dailey O'Brien and George W. Hudler, editors