Trees - Deciduous

This is a brief listing of some common problems that may affect specific species. Weather, climate, seasonal and stress related conditions will sometimes influence a plants likelihood of being affected by insects and disease, it is always good to know which insects may affect a particular plant so that timely measures can be taken to correct problems. This list covers trees that are mainly planted and used in zones 3 - 6.

Acer Species & Cultivars - Maple - Maple trees are for the most part long lived and of low susceptibility to insects and diseases. However, like most large groups of plants, there are those that are rarely troubled, those that are commonly troubled and all those in between. Despite the large list of insects and diseases that can affect maples, not all maples will develop these problems and even some of species that do, are still some of the most popular and widely used species. The insects that can sometimes affect maples are: aphids, bagworms, beetles, borers, bugs, cankerworms, caterpillars, leafhoppers, oblique-banded leaf roller, maple trumpet leaf skeletonizer, mealybugs, mites, moths, nematodes, sawflies, scale, spanworms, thrips, and white flies. Some of the diseases that can affect maples are: anthracnose, various cankers, decline, root-rots, leaf spots, powdery mildew, tar spots, verticilium wilt and leaf scorch (a physiological disease caused by stress.)

Those maples that are least affected by insects and disease are: A. campestre, A. griseum, A. japonicum, A. palmatum and A. tartaricum. Those that are commonly affected and sometimes significantly affected are the Striped Maples (A. capillipes, A. davidi, A. pensylvanicum, and A. rufinerve) A. negundo, A. pseudoplatnus and A. saccharium. I am not suggesting that these trees not be used, one must just use extra care in providing the proper location and cultural care. A. platanoides, A. rubrum and A. saccharum and their cultivars are used most often in general landscape situations and although they are not highly susceptible to insects and disease, they sometimes can become infected by any of the insects and diseases mentioned.

Aesculus species and cultivars - Buckeye/Horsechestnut - Subject to leaf blotch, leaf scorch, powdery mildew, leaf spots, wood rot, anthracnose, canker, verticillium wilt, various scales, mealybug, white-marked tussock moth, bagworm, flatheaded apple borer, omnivorous looper caterpillar, mites and Japanese beetle.

Ailanthus altissima - Tree of Heaven - Subject to Verticillium wilt, brown wood borer, cynthia moth, oystershell scale and ailanthus webworm.

Albizia - Silk Tree - One of the prettiest trees in foliage and flower, unfortunately very susceptible to mimosa webworm, a major pest that can be very destructive. Also susceptible to a vascular wilt disease, two-banded Japanese weevil, terrapin scale, twig girdler and psyllids.

Alnus glutinosa - Black Alder - Subject to borers, gypsy moth, striped alder sawfly, scales, woolly alder aphid, alder flea beetle, alder lace bug, leaf miner, tent caterpillar, canker and powdery mildew.

Amelanchier species and cultivars - Serviceberry - Subject to leaf miner, pear leaf blister mite, pear slug sawfly, various borers and scales, cedar rust, leaf blight, powdery mildew and fire blight. Fire blight being the most destructive. Many of the newer cultivars show better insect and disease resistance over the species. A member of the rosaceae family.

Asimina triloba - Pawpaw - Sometimes bothered by the stinging rose caterpillar which feeds on the leaves and the zebra swallowtail butterfly. Disease's include canker, fungus leaf spot and wood-rot.

Betula species and cultivars - Birch - The most destructive pest is the bronze birch borer. Betula nigra and Betula nigra 'Heritage' are the most resistant followed by those listed under (low susceptibility).

All birches are susceptible to a host of other insects including aphids, leaf miner, various beetles and caterpillars, including Japanese beetle and tent caterpillar, birch lace bug and various others. Disease's include canker, leaf blister, leaf rust, powdery mildew, root-rot, wet wood and wood-rot. Despite their problems, birch's remain a very popular and often used tree.

Caragana arborescens and cultivars - Weeping Pea - Occasionally bothered by leaf hoppers which can disfigure foliage and the caragana blister beetle which can defoliate the plant.

Carpinus species and cultivars - Hornbeam - Subject to the maple leafhopper & others, pitted ambrosia beetle, birch lace bug and Dicera lurida flat headed borer.

Carya ovata - Hickory - Subject to various aphids, beetles, borers, caterpillars, and scales, sycamore lace bug, hickory nut curculio, butternut woollyworm sawfly and fall webworm. They are also susceptible to canker, root-rot, wetwood, wood-rot and leaf spots that can occur late in the season, but result in little damage

Catalpa species and cultivars - Subject to comstock mealybug, catalpa midge, catalpa sphinx moth which can defoliate the plant, root-knot nematode, San Jose scale, canker, leaf spot, powdery mildew, sooty mold, root-rot, wood-rot and verticillium wilt, which can be the most serious of the diseases.

Celtis occidentalis and cultivars - Hackberry - Subject to various insects and disease including leaf spots, powdery mildew, ganoderma rot, eriophyes mites (which cause witches' broom), various borers, nipple gall psyllid, and several kinds of scales.

Cercidiphyllum japonicum and cultivars - Katsura- No serious insects, but susceptible to canker.

Cercis species - Redbud - Subject to leaf spots, verticillum wilt, cankers, wetwood, wood-rot, two- marked treehopper, two spotted spider mite and several kinds of scales.

Chionanthus species - Fringe Tree - Not generally troubled but occasionally there may be a problem with powdery mildew or canker.

Cladrastis lutea and cultivars - Yellowwood - Not troubled much by insects, although susceptible to such diseases as canker, powdery mildew, verticillium wilt and wood-rot.

Cornus alternifolia - Pagoda Dogwood - Similar to Cornus florida.

Cornus florida and cultivars - White Dogwood - Subject to several insects and disease including aphids, various borers, caterpillars and scales, club gall midge, rose leafhopper, leal miner, crown canker, leaf and flower blight, leaf spot, powdery mildew and more, but the most destructive disease affecting the native dogwood is anthracnose. The American native dogwood seems to be the only dogwood species affected. The disease usually starts as purple spots on the leaves and twigs, then the branches die back slowly over a period of several years until death of the entire tree occurs. Popular varieties of dogwood grafted onto Cornus florida are also susceptible to antracnose disease. It is probably best to use another species of dogwood.

Cornus controversa - Giant Dogwood - Nothing serious.

Cornus kousa - Chinese Dogwood - Nothing serious.

Cornus mas - Cornelian Cherry Dogwood - Very rarely troubled, however it is subject to canker, twig blight, leaf spots, root-rot, wood-rot and verticillium wilt.

Cornus officinalis - Japanese Cornell Dogwood - Nothing serious, but can be troubled by same problems as Cornus mas.

Corylus colurna - Turkish Filbert - Subject to the pitted ambrosia beetle, larger elm leaf beetle, eastern buck moth, juniper webworm, oblique banded leaf-roller, leaf tiers, birch case bearers, eriophyid bud mites, spider mites, striped alder sawfly, dogwood borer, alder lace bug and apple mealybug to name a few.

Cotinus obovatus - Smoketree - Nothing serious.

Crataegus species and cultivars - Hawthorn - Subject to many insects and disease including various aphids, borers, caterpillars, leaf miners and scales, beetles, hawthorn lace bug, two spotted mite, pear slug sawfly, powdery mildew, leaf rusts, leaf blight, fire blight, scab and more. Fire blight and leaf blight are the most serious problems because Crataegus is a member of the rosaceae family. Many times leaves will drop before the beginning of the fall season. Newer and more disease and insect resistant varieties should be used in place of the species.

Diospyros virginiana - Persimmon - Subject to various borers, especially the twig girdler borer common in the east, also various caterpillars and scales, canker, fruit spot, fungus leaf spot, root-rot, verticillium wilt, wood-rot.

Elaeagnus species and cultivars - Russian Olive - Subject to leaf spots, cankers, rusts, verticillium wilt, aphids and various scales.

Eucommia ulmoides - Hardy Rubber Tree - Nothing serious.

Evodia daniellii - Korean Evodia - No serious insects or disease.

Fagus species and cultivars - Beech - Subject to several insects and disease include cankers, leaf spots, powdery mildew, root-rot, wood-rot, various aphids, borers, caterpillars, moths, scales and more. Considered to be of a low susceptibility since few of these ever become a serious problem. I have found through my own experience that caterpillars and Japanese beetles are attracted to the dark red or purple leaf varieties of Fagus sylvatica.

Franklinia alatamaha - Franklin Tree - Occasionally bothered by the giant hornet wasp which tears off the bark from the twigs and branches to use in making their nests. This wasp may also injure boxwood, birch, willow, poplars and other trees and shrubs.

Fraxinus species and cultivars - Ash - Subject to many insects and disease that include anthracnose, black mildew, die back, cankers, borers, leaf rust, various leaf spots, verticillium wilt, wood-rot, bugs, caterpillars, moths, sawflies, scales, fall webworm and many others. Many new cultivars have been developed that surpass the use of the species.

Ginkgo biloba and cultivars - Seldom bothered, although they can be troubled by the grape mealybug and the American plum borer. Woodpeckers help keep this borer in check.

Gleditsia triacanthos inermis and cultivars - Honeylocust - Once considered an insect free tree, it is now highly susceptible to two very destructive insects, the mimosa webworm and the honeylocust spider mite. Also subject to bagworm, beetles, locust borers, caterpillars, leaf roller, pod gall midge, moth, and scales. Also subject to brooming disease, canker, leaf spots, powdery mildew, root-rot and wood-rot. Avoid this tree if possible.

Gymnocladus dioicus and cultivars - Kentucky Coffee Tree - Subject to verticillium wilt, wood-rot and fungus leaf spot and walnut scale.

Halesia carolina - Carolina Silverbell - Insect resistant, but susceptible to fungus leaf spot and wood-rot.

Juglans nigra - Black Walnut - Subject to anthracnose, cankers, fungus leaf spot, powdery mildew, root-rot, brooming disease, wood-rot, yellow leaf blotch, various aphids, borers, caterpillars, curculio, mites, moths, nematodes, and scales to name a few.

Kalopanax pictus - Castor Aralia - Nothing serious.

Koelreuteria paniculata and cultivars - Goldenrain Tree - No serious insect problems, although sometimes subject to canker, leaf spots, wilt disease, two-banded Japanese weevil, white peach scale, cranberry root worm (not found west of the Rocky Mountains) and the black twig borer.

Laburnum x watereri 'Vossii' - Goldenchain Tree - Subject to bean and cowpea aphids, grape mealybug depending on geographic location, locust leafminer, northern root-knot nematode, leaf spots and twig blight.

Larix species and cultivars - Larch - Subject to a variety of insects and disease. Cankers, leaf cast, needle rusts, aphids, bagworm, various beetles ( including Japanese beetle), borers, spruce budworm, various moths (including gypsy moth), caterpillar, sawflies, weevil and the larch casebearer which mines into the needles and uses them as cases.

Liquidambar styraciflua and cultivars - Sweet Gum - Subject to various caterpillars, moths including gypsy moth, scales, sweetgum webworm, sweetgum leaf tier, canker leaf spots, leader die back, root-rot and wood-rot.

Lirodendron tulipifera - Tulip Tree - Subject to several insects and diseases. Various cankers, leaf spots, powdery mildew, root and stem rot, verticillum wilt, tulip tree aphid, sapwood timber worm borer, promethea moth, various scales and sassafras weevil. Tuliptree scale which is sometimes found on linden and magnolia can be serious, but for the most part tulip trees are seldom bothered. The tulip tree aphids secrete a honeydew substance which coats the leaves, causing a black sooty mold fungus to form on them causing the tree to look ill fated and unsightly, but this will not kill or injure the trees.

Maackia amurensis - Amur Maackia - Nothing serious.

Magnolia species and cultivars - Most of the magnolias are of low susceptibility, especially Magnolia accuminata and virginiana. Magnolias are subject to leaf blight, various leaf spots, canker, mildew, verticillium wilt, wood-rot, borers, caterpillars, comstock mealybug, various scales and weevil, the most serious of these are the mealybug and the scale insects. Magnolia soulangiana is the most affected.

Malus species and cultivars - Flowering Crabapple - Flowering Crabs are subject to a host of insects including various aphids, beetles, borers, bugs, caterpillars, leaf miners, mealybug, mites, moths, scales and more. The four major diseases that affect crabapples are - scab, mildew, cedar apple rust and fire blight. Nurseries and growers who supply crabapples will often rate their susceptibility to these four problems. Some crabs are highly resistant to some or all of these insects and diseases, while others fair poorly. There are many highly resistant crabs available and new ones being developed each year. A member of the rosaceae family.

Metasequioia glyptostroboides and cultivars - Redwood - Subject to canker and occasionally Japanese beetle will feed on the foliage.

Morus species and cultivars - Mulberry - Subject to various insects and disease including leaf spots, cankers, powdery mildew, wetwood, various scales, two spotted spider mites, and mealybug.

Nyssa sylvatica - Sour/Black Gum - Subject to tupelo leaf miner, San Jose and sour-gum scales, cankers, leaf spots, cottony maple scale and although not its preferred host, it may be subject to gypsy moth and eastern and forest tent caterpillars.

Ostrya virginiana - American Hophornbeam- Subject to the pitted ambrosia beetle, trees that are heavily mulched are more subject to infestations. Also subject to the two-lined chestnut borer, basswood leaf miner, birch lace bug and the orange clumped mapleworm.

Oxydendrum arboreum - Sourwood - Subject to the rhododendron stem borer and the dogwood twig borer, as well as twig blight and leaf spots.

Parrotia persica - Persian parrotia - Insect and disease resistant.

Paulownia tomentosa - Empress Tree - Subject to the comstock mealybug and foxglove aphid, as well as powdery mildew, root-rot, twig canker and wood-rot.

Phellodendron amurense and cultivars - Insect and disease resistant.

Platanus x acerifolia cultivars - London Plane Tree - Subject to anthracnose, various cankers, powdery mildew, various borers, sycamore lace bug, caterpillars, leaf miner, mites, various moths, scales, fall webworm and more. The cultivars listed show better resistance than the species.

Populus species and cultivars - Poplar - Poplars have developed a bad name for their messiness, brittle branches and weak wood, not to mention their invasive water seeking roots. The insects and diseases seem too numerous to mention, but include various cankers, galls, leaf blister, leaf spots, leaf rusts, powdery mildew, root-rot shoot blight, wood-rot, various aphids, beetles, borers, caterpillars, leaf miners, moths, and scales to mention a few. Most of the species are subject to many of these problems, but many new cultivars have been introduced that show good resistance to them and should be used.

Prunus species and cultivars - Plum & Cherry Tree - Subject to an overwhelming number of insects and disease, including black knot, various leaf spots, cankers, twig and blossom blight, fireblight, powdery mildew, root-rot, scab, verticillium wilt, wood-rot, beetles, borers, caterpillars, mites, scales and many, many more. Japanese beetle love the dark foliage varieties, while various tent caterpillars will not pass up on a good meal when they see one. Expect to do some work in maintaining them, if you want to enjoy them. A member of the rosaceae family.

Pseudocydonia sinensis - Chinese Quince - Subject to various aphids, Japanese beetles, roundheaded apple tree borer, tent caterpillar, leaf miner, leaf roller, leaf skeletonizer, moths, pear slug sawfly, scales and fireblight. A member of the rosaceae family.

Pseudolarix kaempferi - Golden Larch - Not usually troubled by insects and disease, however can sometimes be affected by the hemlock rust mite.

Pyrus calleryana cultivars - Ornamental Pear - Although pears are considered of low susceptibility to insects and disease and are almost trouble free at this time, only time will tell if they can hold their resistance as this tree is also becoming over used and over planted. Have noticed pear blister mite damage on several trees in this area, but nothing too serious. Since pears are members of the rosaceae family, they are susceptible to fireblight disease which is very common with the common pear-Pyrus communis, the newer cultivars show good resistance to the disease, some better than others.

Quercus species and cultivars - Oak- Subject to many insects and disease, some of which are anthracnose, various cankers, leaf spots, powdery mildew, rusts, twig blights, wilts, wood decay, various borers, caterpillars, mites, moths, scales, leaf miner, nematodes, galls, sawfly, webworm, weevil and more. Despite this long list of insects and disease, oaks are tough, durable, long lived trees. Not all oaks are subject to all of these insects and diseases, some are more susceptible than others and when grown under proper cultural conditions they will generally require a minimal amount of maintenance.

Robinia species and cultivars - Black Locust - Black locust is subject to various insects and disease, the two most common and destructive are the borer and the leaf miner. Unlike the borer that can kill the tree, the leaf miner makes the tree unsightly, leaves turn brown and prematurely drop, also subject to leaf spots, mosaic, powdery mildew, root-rot, twig canker, verticillium wilt, wetwood, brooming disease and wood-rot. It is best to use cultivars that show resistance and avoid the species. Use of the species is best used for reclamation areas, highway cut and fills, shelter plantations, etc.

Salix species and cultivars - Willow - Much like the poplars, willows have developed a bad name for their messiness and their invasive water seeking roots. Despite the fact that they are subject to many insects and disease, willows are tough and rarely killed by them. Most often they are plagued only to the extent of untidiness. Some of the insects and diseases that they can acquire are various aphids, beetles, borers, caterpillars, poplar leafhopper, grape mealybug, beaked gall midge, mites, various moths, nematodes, sawflies, scales, fall webworm, weevils, bacterial twig blight, black canker, cytospora canker, fungus canker, crown gall, leaf blight, leaf rust, powdery mildew, root-rot, sooty mold, spot anthracnose, wetwood and wood-rot.

Sassafras albidum - Common Sassafras - Subject to Japanese beetle, pitted ambrosia beetle, various caterpillars, moths including gypsy moth, scales, sassafras weevil, cankers, powdery mildew, root rot and verticillium wilt.

Sophora japonica and cultivars - Pagoda Tree - Subject to scales, leaf hoppers, locust leafminer, brooming disease, canker, powdery mildew and twig blight.

Sorbus species and cultivars - Mountain Ash - Mountain ash are beautiful trees in leaf, flower and fruit, however they are prone to various insects and disease, among them fireblight and various kinds of borers are the most destructive. Others include aphids, Japanese beetle, birch lace bug, pear leaf blister mite, moths, mountain ash sawfly, scales, crown gall, various cankers, leaf rusts, leaf spots and scab. A member of the rosaceae family.

Stewartia species - Very insect and disease resistant.

Styrax species -Snowbell - Nothing serious in the way of insects or disease, however the lace bug ( Stephanitis takeyai which is commonly found on Pieris and Leucothoe has been reported to have affected Styrax and willows from North Carolina to Maine.)

Syringa reticulata and cultivars - Lilac - Subject to many insects and disease including various blights, leaf spots, powdery mildew, caterpillars, wasps, leaf miners, scales, borers and more.

Taxodium ascendens - Pond Cypress - Nothing serious.

Taxodium distichum - bald Cypress - Subject to twig blight, cypress moth, and spider mites. Have also seen Japanese beetles feeding on the young new shoots, on trees in my nursery.

Tilia species and cultivars - Linden - Lindens are subject to many insects and disease among them anthracnose, cankers, leaf spots, powdery mildew, verticillum wilt, leaf blight, sooty mold, wetwood, wood-rot, various aphids, borers, caterpillars, scales, basswood leaf miner, elm sawfly and others. Japanese beetle seem to take a definite liking to its foliage.

Ulmus species and cultivars - Elm - Insects and disease problems are often associated with the elms, especially the dreaded Dutch elm disease and phloem necrosis (Elm yellows.) Elms are affected by other problems as well, including anthracnose, die back, wetwood disease, various cankers, leaf spots, root-rot, verticillium wilt, virus leaf scorch, wood-rot, aphids, beetles (including Japanese beetle), borers, mites, and scales to name a few. Most of the newer cultivars show good resistance to Dutch elm disease, as well as to the other problems that normally affect elms.

Zelkova serrata and cultivars - Japanese Zelkova - Subject to calico scale and elm leaf beetle. Zelkovas have no serious diseases that affect them.

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