Trees - Evergreen

EVERGREEN TREES 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 trees that are mainly planted and used in zones 3 - 6.

Abies - Firs - Seldom bothered by insects and disease, but are subject to needle blight, twig blight, leaf cast, rusts, cankers, root rot, wood decay, various aphids, beetles, borers, caterpillars, moths, spruce budworm, balsam gall midge, spruce spider mite, balsam fir sawfly, scales and others.

Calocedrus decurrens - Incense Cedar - Subject to heart rot, rust, leafy mistletoe, cypress tip miners, cypress bark beetle, cypress mealybug, and various scales.

Cedrus - Cedars - C. atlantica and C. libani are both subject to tip blight, cankers, various beetles, borers, mealy bugs, nematodes, sawflies, scales and the deodora weevil. C. libani seems to be the most insect and disease resistant of the two species.

Chamaecyparis - False Cypress - No serious insect or disease problems, however they can be subject to Phomopsis blight, aphids, beetles, mites, moths, scales and others. There is seldom trouble with this group of plants.

Ilex opaca - American Holly - Subject to a variety of insects and disease including leaf spots, cankers, bacterial blight, twig die back, spot anthracnose, powdery mildew, leaf miners, mealybug, mites, gypsy moth, nematodes, various scales and many others. Leaf minor can be quite common.

Juniperus - Juniper - Subject to Phomopsis blight, cedar apple rust, various aphids, beetles, borers, scales, webworm, weevil, bagworm, juniper mealybug, juniper midge, two-spotted and spruce spider mites, red cedar tortrix caterpillar, arborvitae sawfly and others. Over planted groundcover junipers, tight compact junipers, and junipers planted in too much shade or where there is poor air circulation are those most susceptible. Junipers must have full sun and good air circulation.

Larix - Larch - Subject to a variety of insects and diseases including cankers, leaf cast, needle rusts, aphids, bagworm, various beetles ( including Japanese beetle), borers, spruce budworm, various moths (including gypsy moth), caterpillar, sawflies, weevils and the larch casebearer, which mines into the needles in the spring and uses them as cases, causing them to turn brown for the rest of the season.

Metasequoia - Redwood - Generally not troubled by insects and disease but as with Taxodium distichum, I have sometimes seen Japanese beetles feeding on the young, new leaves at the tops of the trees.

Picea - Spruce - Subject to canker, rusts, needle casts, various aphids, beetles, borers, budworms, caterpillars, moths, sawflys, scales, weevils, spruce leaf miner, spruce gall midge, spruce spider mites. Despite this list of problems, spruces are popular and are excellent choices for landscape use and will rarely be affected significantly by any of these problems when grown under optimum conditions .

Pinus - Pine - Subject to a variety of insects and disease including tip blight, needle blight, twig blight, blister rust, needle rust, dieback, canker, root rot, bagworm, spruce budworm, various aphids, beetles, borers, caterpillars, leaf miners, mites, moths, nematodes, sawflys, scales, webworms and weevils. Despite this list of problems, the pines are popular and are excellent choices for landscape use and will rarely be affected significantly by any of these problems when grown under optimum conditions .

Pseudotsuga - Douglas Fir - Subject to various cankers, leaf casts, leaf blight, twig blight, needle blight, aphids, beetles borers, larch bud moth, spruce budworm, pine butterfly, caterpillars, midges, moths, nematode, scales and weevils.

Sciadopitys - Umbrella Pine - No serious insects or disease.

Thuja - Arborvitae - Subject to leaf blight, tip blight, juniper blight, arborvitae aphid, bagworm, northern cedar bark beetle, cedar tree borer, hemlock looper caterpillar, arborvitae leaf miner, spruce spider mite, arborvitae sawfly, various scales and weevils. Bagworm, mites and leaf miner are the most common problems.

Taxodium ascendens - Pond Cypress - Nothing serious.

Taxodium distichum - Bald Cypress - Subject to twig blight, cypress moth, and spider mites. Have also seen Japanese beetle feeding on the young new shoots.

Tsuga - Hemlock - Subject to cankers, leaf blights, blister rust, needle rust, sapwood rot, various beetles, borers, caterpillars, scales, spruce needle leaf miner, two-spotted and spruce spider mites, gypsy moth, nematodes, hemlock sawfly, hemlock webworm, and strawberry root weevil. Despite their susceptibility to these problems hemlocks will not often be affected significantly by any of them when grown under optimum conditions. Most problems occur when they are inappropriately planted and/or stress related factors are placed upon the tree, such as poor drainage, drought, a site that is too sunny or too windy.

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