Volume 26 No. 5 May 31, 2019

Contents...

Scouting ReportConifers (As Christmas & Landscape

Trees): European Pine Shoot Moth, Weir’s Cushion Rust ...................17

Conifers (As Landscape Ornamentals):

Hemlock Woolly Adelgid, Juniper Scale ...........................................17

Broad-leaved: Azalea Bark Scale, Boxwood Leafminer, Boxwood Psyllid, Cottony Taxus Scale, Crape Myrtle Aphid, Euonymus Caterpillar, Kwanzan Cherry Leaf Galls, Native Holly Leafminer, Privet Rust Mite, Rose Curculio, Southern Red Mite, Sycamore Anthracnose, Two-spotted Spider Mite, Wax Scale,White Prunicola Scale ...........................18

Feature: Pest Management Tactics for Exotic Ambrosia Beetles Attacking Ornamental Trees ................. Insert

Things to Look For: Bagworms, Bronze Birch Borer, Euonymus Scale, Lophodermium Needlecast, Mountain Ash Sawfly, Pine Tortoise Scale .. 19

Phenology ....................................20

Growing Degree Days ..............20

in the center of each. The spores will be windblown to new needles. Later in the growing season, infected previous year needles are shed. The disease can infect most spruce species and poses the greatest threat to Colorado blue spruce Christmas trees. However, it will also reduce the value of landscape specimens. To treat, apply a registered fungicide when budbreak is 10 percent or more complete, and make two more applications at 7 to 10 day intervals.

Conifers(As Landscape Ornamentals Only)

Hemlock Woolly Adelgid (32)—From a submitted Long Island photo showing HWA egg masses on hemlock it appears few or no eggs have hatched, so suggest delaying treatment until they do if using foliar insecticides — be sure coverage is very thorough. For those with no HWA experience it’s important to know it does eventually kill its host and to avoid use of nitrogen fertilizers around the plant until infestations are controlled. Dormant-stage oil can work well; trunk injections, basal trunk sprays and soil insecticides are other alternatives that may be more practical for larger trees. Check Cornell Guidelines for specifics.

Juniper Scale (46)—The eggs of this scale had been laid on our last scouting trip downstate, and the yellow crawlers will soon be apparent. Light infestations cause no apparent damage, while heavy feeding causes the foliage to turn yellow. Use of a dormant spray is usually enough. In the growing season, do not spray if there is an abundance of parasites and predators. For heavy infestations only, treat crawlers in mid-June to early July (707 – 1260 GDD50).

Scouting ReportConifers (As Christmas & Landscape Trees)

European Pine Shoot Moth (17,18)—Samples of mugo pine with dead new terminal growth was found to have pupae inside, typical of European pine shoot moth. One distinguishing feature from Nantucket pine tip moth (NPTM) is the single pupa within each dead terminal; NPTM is often found in multiples in dead tips and the pupae are noticeably smaller. Diplodia tip blight results in hard, dead terminals not mined by feeding insects. An early spring application timing for this targets overwintered larvae moving to new shoots; a second application around late June or so targets newly hatching larvae. That might also be timed according to pheromone trap counts, within a few days after peak capture of males. In this case the infestation on landscape plants was light so pruning out and destroying infested terminals made the most sense.

Weir’s Cushion Rust (143)—This needle rust, caused by Chrysomyxa weirii, was sporulating on a Serbian spruce at our scouting site in Orange County last week. Infected needles have conspicuous yellow-orange spots with spore-bearing pustules

BRANCHING OUT

An Integrated Pest Management

Newsletter

For Trees and Shrubs

‘Posthorn’ crooking in mugo pine terminals from European pine shoot moth damage. © Dan Gilrein

18—Branching Out

Broad-leaved Trees and ShrubsAzalea Bark Scale (160)—Azalea bark scales were reported from rhododendron and azalea earlier this month. They typically show as small white cottony masses in bark crevices. A type of felt scale, they produce honeydew followed by sooty mold, similar to soft scales. We found Distance, TriStar 8.5SL and Sevin all worked very well applied mid-July (1424 GDD50) for settled crawlers. Distance has an approved 2(ee) label in NY for this use.

Boxwood Leafminer (94)—Boxwood leafminers were seen last week on schedule in samples at LIHREC and in landscapes. A few were even seen emerging from English box (‘Suffruticosa’), though it is resistant and infestations have not reached levels in susceptible varieties. For new plantings check the list Boxwood Leafminer-Resistant Cultivars at our Horticulture webpage: http://ccesuffolk.org/agriculture/commercial-horticulture. See the last issue, Branching Out 26(4), for management options.

Boxwood Psyllid (137)—We found a few boxwood psyllid adults on our recent scouting trip to Long Island, and we’re expecting many more to be developed by the time you get the newsletter. The adults are light green, ⅛ inch long and can be found jumping among the foliage. The adults appear by early summer and mate, and the female lays its eggs. There is one generation per year. American boxwood cultivars, except ‘Suffruticosa’, are preferred and most seriously damaged by this imported psyllid. English boxwoods rarely receive serious damage; the terminal shoots of English boxwood are infected and develop cupped leaves that are normal colored but may be stunted. See the Cornell guidelines for some specific cultivars that are noted as partially resistant. This is an aesthetic problem and treatment is not usually necessary. If damage is so severe that treatment is warranted try horticultural oil or insecticidal soap late May (290 – 440 GDD50).

Cottony Taxus Scale (164)—Cottony taxus (camellia) scales are or will soon be moving

onto foliage from twigs, producing the cottony egg masses many find objectionable. Infestations were seen on holly and also on camellia earlier this month. This scale can be also be found on Taxus, Japanese maple, euonymus, hydrangea, and Callicarpa americana. Infested plants often have noticeable black sooty mold on lower leaves. A strong spray (or wind) may knock off many, though they can continue to produce the egg masses wherever they fall. Crawlers will be active later in June and can be effectively controlled with insecticides but coverage can be tricky on evergreens. Check first for presence of natural enemies: some ladybeetle larvae resemble white mealybugs and often feed in the egg masses. Under wet conditions scales killed by fungi will have a white, powdery coating.

Crape Myrtle Aphid—Crape myrtle is now a popular landscape plant, attractive in all seasons and easily grown with varieties that do well in the warmer parts of NY. Crape myrtle aphid has become something of a plague, building very high populations quickly by summer resulting in extensive black sooty mold. A few aphids were spotted on plants by a sharp landscape professional, suggesting these are successfully overwintering (as eggs). Turn over leaves and look for the pale aphids now. Our trial last year found a single spray with TriStar, Endeavor, Aria, imidacloprid (Marathon II, Merit 2F, and generics), and a mix of SuffOil-X (2%) + M-Pede (0.5%) worked very well against a very high population (note: Aria labels exclude use in residential landscapes). We also noticed biological controls (such as multicolored Asian ladybeetles) moving in quickly to feed on the aphids. Considering the difficulty arborists are having with this insect, I suggest using any these as foliar sprays while populations are still low. These will be less deterrent to biological controls compared with residual pyrethroid sprays, from which the aphids seem to quickly rebound particularly in summer when populations are extremely high.

Euonymus Caterpillar (79)—We recently found this caterpillar on a euonymus in central New York. These young caterpillars were about ¾ inch long and found in webs near the tips of branches. Euonymus caterpillars feed gregariously and defoliate several species of euonymus, primarily Euonymus europaea (the tree form), E. kiautschovicus, and E. alatus. The colonies of larvae envelop the foliage in large silken webs. The mature larvae are about an inch long and greenish yellow. They have two rows of round black spots and black heads. If the population is low, prune out infested branches. High populations may require the use of a registered pesticide.

Kwanzan Cherry Leaf Galls—Again this year, and several years ago we received Kwanzan cherry samples from a Long Island landscape with dramatically galled (stunted, curled, red) terminal leaves caused by an aphid new to the US, Tuberocephalus sakurae. Also seen in CT and reported from tart, Yoshino and other ornamental cherries, the aphid migrates in late spring to Artemisia spp., so may not be present when galled leaves are checked. The galling doesn’t appear to be serious but in one case was extensive enough to affect the appearance of young trees and could be an issue for nursery sales. So far, the cases and severity have been quite limited.

Native Holly Leafminer (95)—We found the adults on American holly on Long Island. They are ⅛ inch long black flies and can be found around the newly expanded leaves. Although the larvae only mine the leaves of American holly (Ilex opaca) the adults do feed on English holly (Ilex aquifolium) and Japanese holly (Ilex crenata) as well, causing leaf punctures to all of them. Examine young foliage of American holly for tiny green blisters. The parasites can not be relied upon as a control because they do not reduce the area mined and the resulting aesthetic damage. Place sticky traps on the terminals of holly to detect the adults. To manage large populations, treat in mid-May (192 – 298 GDD50).

Azalea bark scale on rhododendron © Dan Gilrein

Cottony taxus scales with egg masses on Ilex. Also note the sooty mold. © Dan Gilrein

Tuberocephalus sakurae galls on Kwanzan cherry © Tamson Yeh

Branching Out—19

Sycamore Anthracnose (50)—Sycamore anthracnose has caused substantial leaf and shoot blighting in the region on American sycamore as well as on London planes. The foliage of some sycamores is almost 100% infected, brown and shriveled on the branches. While trees typically recover and produce new foliage, the disease can affect the immediate appearance as well as the form, sycamores developing crooked branches and bunchy growth as a result of annual infections of the terminal buds. Resistance in London planes can vary considerably due to seedling origin, but several clones (‘Bloodgood,’ ‘Columbia,’ ‘Liberty’) are known to have resistance. London planes show less severe symptoms than American sycamore, but their level of resistance is often insufficient to maintain attractive appearance in rainier than usual springs such as this one. Control involves either trunk injection or spray applications about two weeks before budbreak, at budbreak, and a third time when leaves are fully expanded, so make plans now for next year.

Privet Rust Mite (231)—Privet rust mite injury was very apparent on a recent nursery sample, showing dramatically stunted terminals. This eriophyid mite is easily controlled now with an abamectin miticide (include 0.25 – 0.5% horticultural oil in the mix, or penetrating surfactant), or for organic situations horticultural oil alone can work if coverage is thorough. Only a few other materials are effective for eriophyid mites like PRM, including Akari, Magus/Magister, and the older carbamate carbaryl (Sevin) which oddly is ineffective against and associated with flaring twospotted spider mites. Good coverage is needed with these materials.

Rose Curculio (111)—Rose curculio is an occasional garden pest damaging flowers of roses and occasionally brambles (raspberries); it may feed on vegetative terminals where flower buds are few. Flowers may have numerous holes or fail to open and drop. A spring pest, larvae develop in buds before moving to soil to pupate. Removing infested buds and the weevils by hand may be sufficient for control.

Southern Red Mite (229)—Look now for southern red mite (SRM) adults. Injury occurs as bronze, stippled foliage. This mite is the most widespread, important, and destructive spider mite on broad-leaved evergreens such as hollies, laurel, rhododendron, camellia, and azalea. Predators are usually effective means of control except under outbreak conditions. Tap leaves over white paper — spray thoroughly if 10 mites or more per tap. Treat 246 – 366 GDD50, then again at 618 – 802 GDD50.

be the most practical solution for individual plants; larger infestations can be treated at the ‘cameo’ stage (settled crawlers). Our 2014 trial found Distance, TriStar 8.5SL and Sevin to be highly effective at this timing, around mid-July (1424 GDD50). Distance has an approved 2(ee) label in NY for this use. We also tried delaying treatment to late September (some infestations are discovered late) and found none were highly effective, though Sevin provided around 62% control.

White Prunicola Scale (188)—We found the eggs of this scale on a cherry tree during our scouting trip to Orange County. The salmon colored crawlers should be active soon. Hosts include lilac, flowering cherries, privet, willow and catalpa. Predators and parasites are numerous but are not reliable. Treatments should be made to target the crawlers in mid-June through early July (707 – 1151 GDD50). Power wash or scrub off heavy infestations on the trunk with a brush.

Things to Look For in the Upcoming WeeksBagworms (80,81)—You will soon see spindle-shaped bags that are attached to twigs and foliage of cedar, arborvitae, juniper, and other conifers. This pest is not common in the northern parts of NY. In light infestations, hand pick and destroy bags. Sex pheromone traps help in reducing the bagworm populations. With heavy infestations registered pesticides can be applied in mid-June (600 – 900 GDD50).

Bronze Birch Borer (128)—The adult bronze birch borers will soon be found crawling on the sunny sides of trees. The first symptom of infestation is the yellowing and browning of foliage in the upper branches. As the boring increases, the trunk bleeds, the tree declines, and the foliage becomes more sparse. Treat in June (440 – 880 GDD50).

Euonymus Scale (186)—Look soon for euonymus scale crawlers. They are minute, oval, and amber colored. Their hosts include euonymus, pachysandra, holly and bittersweet. The crawlers can be treated with horticultural oil, neem oil or insecticidal soap during early June (533 – 820 GDD50) and again in mid-July (1150 – 1388 GDD50).

Rose curculio adult © Frank Giacalone

Privet rust mite damage © Dan Gilrein

Two-spotted Spider Mite (229)—Look now for this spider mite. It is green or greenish yellow with two dark spots that can be seen through the pale bodies. This mite causes stippling of foliage and can be a serious pest of roses, flowering fruits, azalea, and several other shrubs. In addition, it may cause damage to maple, elm, redbud, ash, black locust, and poplar. Natural predators may greatly reduce populations. Heavily infested trees may need treatment which can be applied from late May through mid-June (363 – 618 GDD50).

Wax Scale—Wax scale, an introduced pest, is common in Southeast landscapes, but appears to be making inroads north, with reports from southern NY. The overwintered females are quite obvious now, ¼" white hemispheres on twigs, recently on inkberry holly and ‘PJM’ rhododendron, but the host range includes many broadleaved woody plants. Removing the scales by hand may

Sycamore anthracnose on sycamore © Margery Daughtrey

Wax scale on Ilex glabra © Dan Gilrein

20—Branching Out Dawn Dailey O'Brien,George. Hudler & Dan Gilrein, editors

Branching OutPlant Pathology and Plant-Microbe BiologyCornell University334 Plant Science BuildingIthaca, N 14853

Lophodermium Needlecast (11)—These fruiting bodies should begin to produce infectious spores within the next few weeks. As the nature of this disease is to produce spores over a period of about four months, a simple schedule of treating once a month with a registered fungicide beginning in early July and continuing into early October has been found to be a fairly effective management strategy.

Mountain Ash Sawfly (56)—The larvae will soon begin feeding on the leaves of mountainash. Control is usually not warranted. The larvae feed in groups, so small populations can easily be pruned out or squashed. If the infestation is severe, treat in early to mid-June (448 – 707 GDD50).

Pine Tortoise Scale (41)—The crawlers will be becoming active. Treat salvageable infested trees with insecticidal soap, horticultural oil, or other registered pesticide in mid -to late June (618 – 1050 GDD50). In Christmas tree plantations cull those that can’t be restored to marketable quality immediately.

Our Financial SupportersThis issue was made possible with the generous gifts from the following:

Almstead Tree, Shrub & Lawn Care Co.Bellantoni LandscapeNortheast NurseriesThe Orentreich Family FoundationPerennial Charm NurseryPlant Care SolutionsSterling Tree and LawnWade Tree Care, IncNew York State Turfgrass Association New York State Arborists-ISA Chapter Rocco Parente Inc.Orchard Tree Care Specialists, LLCProfessional Tree Surgeons SupplyRosedale NurseriesWhitman Nurseries

As of May 28, 2019Growing Degree DaysStation GDD50

Albany ..............................366Binghamton ......................263Boston, MA ......................367Bridgeport, CT .................373Buffalo .............................211Central Park .....................569Farmingdale ....................372Hartford, CT .....................413

Station GDD50

Ithaca ................................215New Brunswick,NJ ...........575Riverhead .........................422Rochester ..........................263Syracuse ...........................299Watertown ........................127Westchester ......................387Worcester, MA .................231

PhenologyWestchester County: Flowering—Black locust, Catawba rhododendron, climbing hydrangea, cottonwood (seeds), cutleaf stephanandra, deutzia, hawthorn, Kousa dogwood, leucothoe, littleleaf lilac, multiflora rose, mock orange, royal paulownia, rugosa rose, tulip poplar, Vanhoutte spirea, white fringetree, white pineTompkins County: Flowering—Autumn olive, black cherry, deutzia, doublefile viburnum, fragrant abelia, hawthorn, horsechestnut, shrubby honeysuckles, Vanhoutte spirea

Pine tortoise scaleD. D. O’Brien

Branching Out, Volume 26 No. 5

Following are highlights from a larger article by Dr. Christopher Ranger, USDA-Agricultural Research Service and co-authors.

The full article covers aspects of the biology, behavior, ecology, and management of ambrosia beetles. The article can be found at https://academic.oup.com/jipm/article/7/1/9/2658135

Exotic Ambrosia BeetlesThe black stem borer (BSB), Xylosandrus germanus, and the granulate ambrosia beetle (GAB), Xylosandrus crassiusculus, are two of the most damaging species of exotic ambrosia beetles attacking trees in landscapes and ornamental nurseries (Fig. 1 ‒ 2). Both species are native to southeastern Asia, but are now well established in N. America. BSB was first detected in 1932 attacking grape vines in Long Island, New York, while GAB was first detected in 1974 attacking peach trees in Summerville, South Carolina. As of 2010, BSB and GAB were found in 32 and 29 of 50 U.S. states, respectively. BSB tends to be more abundant in the upper Midwestern and Northeastern U.S., while GAB tends to be more abundant in the Mid-Atlantic, Southeastern, and Southern U.S.

Description of Life Stages Adult female BSB range 2.0 ‒ 2.4 mm in length, about 1.0 mm wide, and are dark brown to black, shiny, stout, almost cylindrical, and rounded in front and rear (Fig. 1A). Female BSB range 2.1 ‒ 2.9 mm in length, about 1.2 mm wide, and are stout and squat, cylindrical, rounded in front and rear (Fig. 1B). Adult female GAB tend to be more reddish-brown than BSB. Male BSB and GAB are flightless, rarely seen outside the gallery, and are not responsible for attacking trees. The white eggs, larvae, and pupae of BSB and GAB are found within galleries created by the adult females in stems and branches of host trees (Fig. 3).

Gallery Formation Adult female BSB and GAB tunnel deep into the stems and branches of host trees, where they create galleries for cultivating gardens of their fungal symbiont on which the larvae and adults must feed (Fig. 3, Fig. 4). Adult females carry spores of their fungal symbiont within a pouch-like structure, and the spores are then transferred from the beetles to the host tree tunnels during excavation. Ambrosiella

grosmanniae is the fungal symbiont of BSB, and Ambrosiella roeperi is the fungal symbiont of GAB. The fungal symbionts of BSB and GAB are not plant pathogens, but a variety of bacteria, yeasts, and pathogenic fungi have been detected from galleries. Adult female BSB and GAB begin laying eggs after their fungal gardens are flourishing. Like other ambrosia beetles, male BSB and GAB arise from unfertilized eggs while females arise from fertilized eggs. Thus, only one female is needed to produce offspring and colonize a host tree. Two generations per year occur in the Midwestern and Northeastern US, and three generations per year may occur within warmer US climates.

Seasonal Activity BSB and GAB overwinter as adults in their host trees galleries. Adult females generally begin to emerge from their overwintering sites when spring temperatures exceed 21°C (70°F). Peak flight activity and tree attacks are mostly associated with the overwintered adults that emerge in spring, but attacks are also associated with the first and second generations that emerge during mid and late summer months.

HostsBSB and GAB attack 100 ‒ 200 species of woody species. Deciduous, thin-barked species are preferred over coniferous species. Hosts can vary across growing regions, but trees attacked within different regions have included dogwood (Cornus spp.), honeylocust (Gleditsia triacanthos), Japanese snowbell (Styrax japonicus), magnolia (Magnolia spp.), maple (Acer spp.), oak (Quercus spp.), and redbud (Cercis spp.). Stems/trunks are preferred over branches for both BSB and GAB. Attacks tend to be most frequently reported from stems of 2.5 ‒ 7.6 cm (1 ‒ 3 in.) in diameter, but larger specimen trees are also attacked.

Pest Management Tactics for Exotic Ambrosia Beetles Attacking Ornamental TreesChristopher M. Ranger, USDA-Agricultural Research Service, Application Technology Research Unit, Horticultural Insects Research Lab, 1680 Madison Ave., Wooster OH 44691

Fig. 1. Two exotic and destructive species of ambrosia beetles that attack a wide range of trees, namely, (A) black stem borer and (B) granulate ambrosia beetle © Christopher Ranger

Fig. 2. (A) Adult female black stem borer (BSB) Xylosandrus germanus, boring into a host tree. (B) Tunnel entrance created by BSB. © Christopher Ranger

Fig. 3. Fungal gardens lining the walls of a gallery containing larvae of X. germanus. © Christopher Ranger

Fig. 4. Galleries created by ambrosia beetles.© Christopher Ranger

Branching Out, Volume 26 No. 5

Symptoms and DamageMass attacks by BSB and GAB can quickly result in rapid dieback, especially during spring months. Attacks do not always result in plant death, but growth and aesthetic value can be negatively affected. Attacks can sometimes be difficult to detect due to their small diameter, but toothpick-like extrusions of chewed wood material projecting out from the stems and sap stains on the bark are definitive symptoms (Fig. 5A-B).

Monitoring TacticsEthanol is the standard attractant used in traps for BSB and GAB. Lures can be purchased or made by filling a plastic container with 70 to 95% ethanol (i.e. ethyl alcohol) and inserting a wick through the lid. Denatured ethanol can be used, but not isopropyl alcohol or other alcohols. Traps can also be purchased or inexpensively assembled. A simple trap made from a 2-liter soda bottle is an inexpensive option (Fig. 6A). Soapy water diluted with an equal part of water should be used as a killing agent and preservative in the traps. Stem sections can also be soaked in 70% ethanol for 24 hours to induce attacks for monitoring purposes (Fig. 6B). Traps or ethanol-infused bolts should be positioned low and near wooded areas.

Management TacticsMaintaining tree health is the primary foundation of an ambrosia beetle management plan, especially since insecticides do not completely prevent attacks from occurring. Since BSB and GAB are poor colonizers of vigorous trees, the significance of stress on predisposing trees to attack should not be overlooked. Risk factors potentially affecting plant health should be considered. Pyrethroid insecticides, including permethrin, cypermethrin, and bifenthrin, have been more effective than other materials, but the effects can be inconsistent. Chemical control tactics are most effective when closely timed with flight activity, particularly before spring temperatures reach 70°F. Care should be taken to minimize impacts on pollinators. Substrate drenches and trunk sprays of systemic insecticides are not effective at reducing attacks, but might reduce colonization success. Thorough coverage of the stem/trunk is important since the majority of attacks occur within this region. Trunk applications of entomopathogenic fungi have exhibited promising efficacy against BSB and GAB, for instance, Beauveria bassiana and Metarhizium anisopliae. Parasitoids and predators are not known to be effective for BSB or GAB.

Acknowledgments Much of the research mentioned in this article was supported by the Floriculture and Nursery Research Initiative (USDA-FNRI) and the Horticultural Research Institute (HRI). Mention of proprietary products or companies does not imply any endorsement or preferential treatment by the USDA-Agricultural Research Service.

Impact of Physiological Stressors on Host PreferenceDespite a broad host tree range, BSB and GAB have a strong preference for living but weakened trees. Trees subjected to stress may appear healthy, but still emit chemical indicators of stress (i.e. ethanol) that reveals their weakened state. If possible, determine what factor(s) predisposed the trees to attack to avoid the scenario in the future. Ethanol is emitted from trees in response to a variety of stressors, including flooding/poor drainage, drought, freezing/late frost, girdling, root and crown disturbance, pollutants, and pathogens. For instance, tree care professionals should avoid planting dogwood (Cornus sp.) and other thin-barked deciduous trees intolerant of flooding in poorly draining areas. Similarly, trees intolerant of freeze stress should not be planted in areas of frost pockets, or well outside of recommended growing zones. Ambrosia beetle attacks have been documented on trees subjected to late spring frosts, including, eastern redbud (Cercis canadensis), Japanese maple (Acer palmatum), Japanese snowbell (S. japonicus), Japanese zelkova (Zelkova serrata), Kentucky yellowwood (Cladrastis kentukea), kwanzan cherry (Prunus serrulata), tulip poplar (Liriodendron tulipifera), oak (Quercus rubra), sycamore (Acer pseudoplatanus), and European beech (Fagus sylvatica). Low temperature stress during winter months can also lead to bark splitting, and predispose the following trees to attack, Chinese elm (Ulmus parvifolia), Chinese fringetree (Chionanthus retusus), common hackberry (Celtis occidentalis), hardy rubber tree (Eucommia ulmoides), eastern redbud, hawthorn (Crataegus punctata), linden (Tilia sp.), oak (Quercus spp.), sweetgum (Liquidambar styraciflua), sugar maple (Acer saccharum), kwanzan cherry (Prunus serrulata), striped maple (Acer pensylvanicum), hornbeam (Carpinus betulus), paperbark maples (Acer griseum), red beech (Nothofagus fusca), Japanese snowbell, and yellowwood (Cladrastis sp.).

Fig. 5. (A) Sawdust “toothpicks” projecting out of a stem of flowering dogwood (B) Sap produced by a granulate ambrosia beetle attacking Japanese snowbell. © Christopher Ranger

Fig. 6. (A) A simple bottle trap for monitoring ambrosia beetle flight activity. (B) Stems can be soaked in ethanol for 24 hours and placed along the edge of a woodlot for monitoring attacks. © Christopher Ranger