Shrubs - Deciduous

DECIDUOUS SHRUBS Common Insects and Diseases

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 plants that are mainly planted and used in zones 3 - 6.

Abelia - Glossy Abelia - Subject to the two-banded Japanese weevil, northern root-knot nematodes, root rot, mildews and leaf spots.

Abeliophyllum distichum - Korean Abelialeaf/ White Forsythia - No serious insect or disease problems.

Acanthopanax sieboldianus - Fiveleaf Aralia - No serious insect or disease problems, but occasionally bothered by the four-lined plant bug.

Aesculus parviflora - Bottlebrush Buckeye - No serious insect or disease problems.

Aralia spinosa - Devils Walking Stick/ Hercules Club - No serious insect or disease problems.

Aronia species & cultivars - Chokeberry - Subject to chokeberry aphid, birch bark beetle, roundheaded apple tree borer, eastern tent caterpillars and various other caterpillars, leaf crumpler, leaf miners, various scales, fall webworm, leaf spots, twig and fruit blights, and powdery mildew. A member of the rosaceae family.

Azalea species - Rhododendron - Many of what we call deciduous azaleas are actually Rhododendrons and they are rarely troubled, but are susceptible to some of the same insects and disease that affect evergreen azaleas. Some of these problems include azalea petal blight, Azalea gall, powdery mildew, rust, soot blight, leaf spots, wilt, Phytophthora blight, aphids, beetles, azalea leaf miner, mealybugs, various mites, nematodes, scales and weevils.

Berberis species & cultivars - Barberry - Though rarely troubled, they are subject to anthracnose, leaf spots, root rots, rusts, barberry wilt, barberry aphids, asiatic garden beetle, eight-spotted Forester moth, northern root-knot nematode, barberry scale, barberry webworm and Japanese weevil, but rarely do barberries succumb to much.

Buddleia species & cultivars - Butterfly Bush - Although rarely troubled, they are subject to Japanese beetle, buddleia moth, root-knot nematode and white peach scale.

Callicarpa species & cultivars - Beautybush - Subject to leaf spots, black mold, various stem diseases and white peach scale.

Calycanthus floridus - Sweet Shrub/ Carolina Allspice - Generally insect and disease resistant.

Caragana species - Peashrub - Subject to leaf-hoppers and the caragana blister beetle.

Caryopteris - Bluebeard/ Blue Mist Spirea - Subject to foliage damage by the four-lined plant bug, a sucking insect that disfigures the leaves of the plant causing small, round, depressed spots, tan to brown in color. Can also be found on Acanthopanax, asters, coreopsis, forsythia, honeysuckle, shasta daisy, weigelia and other flowers and shrubs.

Ceanothus americanus - New Jersey Tea/ Redroot - Subject to ceanothus aphid and stem gall moth and crescent-marked lily aphid, grape mealy bug, ceanothus lace bug, borers, san jose, scurfy , willow scales, leaf spots and powdery mildew.

Cephalanthus occidentalis - Buttonbush - Subject to san jose, tuliptree and white peach scales.

Chaenomeles species & cultivars - Quince - Since it is a member of the rosaceae family it is subject to fireblight disease, also subject to various aphids, moths, scales, Japanese beetle, roundheaded apple tree borer, tent caterpillar, leaf miner, pear-slug sawfly and others.

Clethra alnifolia & cultivars - Summersweet - Occasionally bothered by southern red mites in dry seasons, otherwise not troubled much by insects or disease.

Comptonia peregrina - Sweet Fern - Subject to the chain-spotted geometer caterpillar, crinkled flannel moth and the cleft-headed spanworm. Although the saratoga spittlebug does not feed on Comptonia, the nymphs can be found living on them, below the surface of the ground, above the root collar of the plant.

Cornus species & cultivars - Dogwood - Subject to cankers, leaf blight, leaf spots, twig blight, root rot, powdery mildew, various borers, dogwood club gall, leaf miner, scales and others. This list applies to most shrub dogwoods, however, Cornus mas, which is sometimes grown as a tree, and Cornus racemosa are the least susceptible of the shrub dogwoods.

Corylus species & cultivars - Hazelnut -Subject to blight, leaf spots, crown gall, black knot, filbertworm caterpillar, mealybug, filbert bud mite, filbert weevil and Japanese beetle.

Cotinus coggygria & cultivars - Smoketree - Occasionally bothered by San Jose scale and oblique-banded leaf roller. Also subject to rusts, leaf spots and verticillium wilt.

Cotoneaster species - Since it is a member of the rosaceae family it is subject to fireblight disease. Cotoneasters are also troubled by hawthorn lace bug, cotoneaster webworm, sinuate pear tree borer, pear leaf blister mite, various scales and aphids.

Cytisus - Broom - Subject to leaf spot and to a leaf blight, which when left untreated, can kill the entire plant. Also subject to white peach scale.

Daphne - This plant often seems to die for no apparent reason, which may be due to its susceptibility to various viruses. Also subject to crown rot, leaf spots, twig blight, canker, several kinds of aphids and scales.

Deutzia species & cultivars - Subject to aphids, lilac leaf miner, tow-banded Japanese weevil, Fuller rose beetle, four-lined plant bug, root-knot nematode and leaf spots. Deutzia scabra is also susceptible to pittosporum scale.

Diervilla lonicera - Bush Honeysuckle - The foliage is not troubled by insects or disease as with other members of the honeysuckle family.

Dirca palustris - Leatherwood - No serious insects or disease.

Elaeagnus species & cultivars - Olive - Subject to the oleaster-thistle aphid, various scales, leaf spots, cankers, crown gall, rusts and verticillium wilt. Selected cultivars such as E. umbellata ‘Tizam’® may prove to be superior to the species.

Enkianthus campanulata - No serious insects or disease.

Euonymus alatus & cultivars - Rarely troubled but subject to the comstock mealy bug and potato aphid. Euonymous caterpillar and Euonymous alatus scale can also be found on plants, primarily in the Northeast.

Exochorda species & cultivars - Pearlbush - No serious insects or disease, however it is a member of the rosaceae family and is subject to fireblight disease. Subject also to an eriophyid mite known as Phyllocoptes sp. , (supposedly found only on Pearlbush it has recently been found on plants in New York state.) This mite causes the leaves to become deformed and dwarfed.

Forsythia species, cultivars & hybrids - Subject to the four-lined plant bug, northern root-knot nematode, Japanese weevil, crown gall, and dieback.

Fothergilla gardenii & cultivars - Virtually insect and disease resistant.

Genista species - Broom - No serious insects or disease.

Hamamelis species, hybrids & cultivars - Witch Hazel - Subject to the witch-hazel leaf gall aphid which causes conical galls to form on the upper leaf surface and the spiny witch-hazel gall aphid which forms galls on stem buds. Birch trees are alternate host plants. Also subject to the saddled prominent caterpillar, walnut scale, the yellow-necked caterpillar, eastern tent caterpillar and alder spittle bug.

Hibiscus syriacus & cultivars - Rose of Sharon - Subject to aphids, Japanese beetle, four-lined plant bug, san jose scale, leaf spots, blights, cankers and rust.

Hippophae rhamnoides & cultivars - Buckthorn - No serious insects or disease.

Hydrangea - Subject to bacterial wilt, bud blight, leaf spot, powdery mildew, aphids, rose chafer beetle, tarnished plant bug, hydrangea leaf tier, two-spotted mite, and scales. Hydrangea quercifolia seems to be the least susceptible to these problems, however I have noticed the rose chafer beetle feeding on them in landscapes that have rose bushes planted nearby.

Hypericum species & cultivars - St. Johnswort - No serious insects or disease problems.

Ilex species & cultivars - Winterberry - Subject to leaf spots, tar spots, powdery mildew, cottony taxus scale and pear plant bug.

Itea species, hybrids & cultivars - Sweetspire - No serious insects or disease.

Kerria - Subject to twig blight, leaf spot, canker, and Japanese beetle as well as fireblight, since it is a member of the rosaceae family.

Kolkwitzia amabilis & cultivars - Beautybush - No serious insects or disease.

Lespedeza species & cultivars - Bushclover - Subject to the soybean cyst nematode, lespedeza webworm and imported long-horned weevil.

Ligustrum species, hybrids & cultivars - Privet - Subject to the privet aphid, mountain-ash borer, omnivorous looper caterpillar, privet leafhopper, privet leaf miner, mealybug, privet mites, northern root-knot nematode, scales, privet thrips, weevils, anthracnose, twig blight, leaf spots, galls, powdery mildew and root rots. Despite all these problems, privet, like willows are tough and rarely killed by insects or diseases.

Lindera species - Spicebush -Subject to and occasionaly bothered by the asiatic oak weevil, found mainly east of the Mississippi River.

Lonicera - Honeysuckle - Subject to quite a few insects and disease, including various aphids, fuller rose and potato flea beetles, four-lined plant bug, omnivorous looper caterpillar, leaf rollers, mealybugs, moths, honeysuckle sawfly, various scales, fall webworm, leaf blight and powdery mildew. Aphids and powdery mildew seem to be the most troublesome and treating these problems when they first occur is the best cure.

Myrica pennsylvanica - Bayberry - Seldom troubled but subject to foxglove aphid, apple mealy bug, Japanese beetle and dogwood borer.

Perovskia atriplicifolia - Russian Sage - No serious insects or disease.

Philadelphus species, hybrids & cultivars - Mockorange - Subject to cankers, leaf spots, powdery mildew, rusts, aphids, leaf miner and nematodes.

Photinia - Christmasberry - Since it is a member of the rosaceae family it is subject to fireblight disease. Also troubled by leaf spots, powdery mildew, scales and the comstock mealybug.

Physocarpus opulifolius & cultivars - Ninebark - Subject to the dogwood borer. A member of the rosaceae family and also subject to fireblight disease.

Potentilla fruticosa & cultivars - Cinquefoil - Rarely troubled by insects, but subject to the potato and strawberry aphids and strawberry root weevils. Powdery mildew can become a problem on some cultivars. A member of the rosaceae family and also subject to fireblight disease.

Prunus - Flowering Plum, Cherry & Almond - Subject to various aphids, beetles, borers, bugs, caterpillars, mites, nematodes, scales and many others . A member of the rosaceae family and also subject to fireblight.

Rhamnus frangula & cultivars - Buckthorn - Subject to the buckthorn aphid, European red mites, oriental moth, san jose and terrapin scales, canker and wilt.

Rhododendron - See azalea in this section.

Rhodotypos scandens - Jetbead - No serious insect or disease problems., however it is a member of the rosaceae family and is subject to fireblight disease.

Rhus species & cultivars - Sumac - Subject to aphids, potato flea beetle, currant borer, caterpillars, oblique-banded leaf roller, scales, leaf spots, rust and wilt. Verticillium wilt is prevalent with staghorn sumac. Despite these problems, they are seldom troubled.

Ribes - Currant - Subject to anthracnose, cane blight, rust, leaf spots, various aphids, fuller rose beetle, currant borer, caterpillars, fruitworm, mealybug, mites, imported currant-worm sawfly, various scales, currant spanworm, currant fruit weevil and others.

Rosa - Rose - Subject to quite a few or should I say many insects and diseases, but roses still remain a favorite with many of us. The following list, is but a few of them. Black-spot leaf disease, powdery mildew, cankers, rusts, viruses, various aphids, beetles, borers, caterpillars, leafhoppers, mites, nematodes, sawflys, scales, thrips and many more. Some of the newer hybrids and cultivars show better resistance to the diseases such as with the Meidiland™ series of roses.

Salix species, hybrids & cultivars - Willow - Despite the fact that they are subject to many insects and diseases, 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.

Sambucus species & cultivars - Elder - Subject to borers, cankers, leaf spots, powdery mildew and various scales.

Shepherdia species - Buffaloberry - Subject to oleaster-thistle, russian-olive and polygonum aphids, various leaf spots, powdery mildew and rust.

Sorbaria sorbifolia - False Spirea - No serious insects or disease. However they are a member of the rosaceae family and subject to fireblight disease.

Spirea - Subject to brown and spirea aphids, oblique-banded leaf roller, northern root-knot nematode and several scales. It is a member of the rosaceae family and is therefore subject to fireblight disease but some varieties and cultivars may be affected more than others.

Stephanandra incisa 'Crispa' - Lace Shrub - A member of the rosaceae family and therefore susceptible to fireblight disease. Otherwise, seldom troubled.

Symphoricarpos - Snowberry - Subject to anthracnose, berry rot, leaf spots powdery mildew, rusts, stem gall, various aphids, flatheaded cherry tree borer, snowberry clearwing moth and various scales. Use varieties and cultivars that show better resistance than the common snowberry.

Syringa species, hybrids & cultivars - Lilac - Subject to the rhinoceros beetle, lilac borer, hickory horned devil caterpillar, lilac leaf miner, oblique-banded leaf roller, De Man's meadow and tesselate stylet nematode's, various scales, giant hornet wasp (which tears off bark around branches), weevils, bacterial blight, phytophthora blight, leaf spots, powdery mildew, wilt, ring spot virus, witches' broom, graft blight and leaf roll necrosis (caused by various air pollutants).

Tamarix ramosissima 'Summer Glow' - Subject to cottony-cushion and oystershell scales, cankers, powdery mildew, root rot and wood rot.

Vaccinium species & cultivars - Blueberry - Subject to various beetles, borers, caterpillars, plum curculio, black army cutworm, fruitworms, leafhopper, apple maggot, mites, nematodes, scales, currant spanworm, dogwood spittlebug, blueberry thrips, blueberry stem gall wasp, fall webworm and weevils. I have used many of these shrubs in the landscape and have very rarely had any problems with them.

Viburnum - Seldom bothered, but subject to leaf spots, powdery mildew, downy mildew, anthracnose, aphids, beetles, dogwood twig borer, tarnished plant bug, nematodes, scales, and others. Some varieties and cultivars show better resistance than others, while some are relatively insect and disease resistant.

Weigela florida & cultivars - Subject to the four-lined plant bug, comstock mealybug, scales and Japanese weevil.

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