Arctic Fire is a compact red-twig dogwood grown for its bright red winter stems, and it is a hardy shrub that rarely has serious trouble.1Missouri Botanical Garden. Cornus sericea ‘Farrow’ ARCTIC FIRE2JNI Knowledgebase. Arctic Fire® Dogwood Most of what gardeners notice, like spotted or chewed leaves, looks worse than it is. The problems that do real harm, like dying stems, usually start when the shrub is already stressed, so how you water, site, and prune it matters more than any spray.
Spotted Leaves and Early Leaf Drop
Leaf spot is one of the two most common diseases on Arctic Fire and other red-twig dogwoods.3JNI Knowledgebase. Arctic Fire® Dogwood The spots start on the upper leaf surface as light brown to dark purple marks.4Purdue Plant Doctor. Common Problems With Arctic Fire Dogwood They grow into irregular grayish spots with dark purple or reddish borders.5Yard and Garden. The leaves on my red-twigged dogwoods are spotted and beginning to fall off. Why? The centers turn gray to tan and show tiny black bumps, which are where the fungus produces its spores.6Purdue Plant Doctor. Common Problems With Arctic Fire Dogwood
Through summer the spots can multiply enough to cause early leaf drop.7Purdue Landscape Report. Septoria Leaf Spot on Dogwood In severe cases leaves yellow and fall from the shrub.8Purdue Landscape Report. Septoria Leaf Spot on Dogwood Even so, leaf spot is cosmetic and treatment is typically not needed.9JNI Knowledgebase. Arctic Fire® Dogwood Wet weather drives it, so it comes and goes with rainy seasons.10JNI Knowledgebase. Arctic Fire® Dogwood
Sunburn or water scorch looks different from leaf spot: leaves brown from the tip and edges inward, which is covered further down. Distinct spots confined to the leaves, with stems that still look healthy and red, are a good sign you have the cosmetic problem and not canker.
In a bad leaf-spot year, rake up and discard fallen spotted leaves to cut down the spores waiting for next spring. Water at the base of the shrub in the morning instead of wetting the leaves, and thin crowded stems so foliage dries faster after rain.
Fungicide sprays rarely make sense here, because by the time spots show, the infection has already happened during wet weather.
Chewed or Stripped Leaves From Dogwood Sawfly
Dogwood sawfly larvae are quite common on red- and yellow-twig dogwood shrubs.11Purdue Plant Doctor. Common Problems With Arctic Fire Dogwood They look like caterpillars and grow up to 1.5 inches long.12Purdue Plant Doctor. Common Problems With Arctic Fire Dogwood They change look as they grow, from yellow to a white waxy coating to yellow and black in the last stage.13NC State Extension Publications. Dogwood Sawfly14Purdue Plant Doctor. Common Problems With Arctic Fire Dogwood In the white stage they can resemble bird droppings or mold at first glance, which is why they get overlooked.
Adults fly in late spring and lay eggs inside leaves, each leaving a small bump that turns brown.15NC State Extension Publications. Dogwood Sawfly16Purdue Plant Doctor. Common Problems With Arctic Fire Dogwood Eggs hatch from May to July, and young larvae eat the tissue between veins, leaving lacy leaves.17Purdue Plant Doctor. Common Problems With Arctic Fire Dogwood Larger larvae eat everything but the midrib.18NC State Extension Publications. Dogwood Sawfly In August, when big larvae are abundant, they can strip a shrub bare.19Purdue Plant Doctor. Common Problems With Arctic Fire Dogwood Losing leaves this way is unlikely to kill the plant, though it may leave it open to stem diseases.20Purdue Plant Doctor. Common Problems With Arctic Fire Dogwood
Checking early helps. Turn leaves over in June and look for small larvae and brown egg bumps.
Control is simple. Handpick larvae or knock them into soapy water, and on a small shrub prune off heavily infested leaves. Larvae overwinter in rotting wood or loose soil, so clear debris near the shrub in fall. Sawflies are relatives of wasps, not moths, so some caterpillar sprays sold for moth larvae don’t work on them.
Dying Stems and Cankers
Stem canker is the other most common disease of Arctic Fire and red-twig dogwoods.21JNI Knowledgebase. Arctic Fire® Dogwood It is caused mostly by a fungus that makes dead, sunken patches on stems, called cankers.22University of Illinois Extension. Redosier Dogwood Canker Stems beyond the canker wilt and die back.
Stress opens the door. The fungus enters through wounds, growth cracks, natural openings, and weak wood.23Horticulture For Home Gardeners. Botryosphaeria Canker of Red Twig Dogwood24University of Illinois Extension. Redosier Dogwood Canker Drought and freezing both weaken red-twig dogwoods and set them up for canker.25University of Illinois Extension. Redosier Dogwood Canker A late spring frost of around 28°F, after the shrub has started waking up, injures tissue the fungus can invade.26Extension. Dogwood leaves and branches are dying Pruning wounds, a poor site, neglect, and insect damage raise the risk too.27Horticulture For Home Gardeners. Botryosphaeria Canker of Red Twig Dogwood Canker typically doesn’t threaten the life of these hardy shrubs.28JNI Knowledgebase. Arctic Fire® Dogwood
To check a dying stem, look for a sunken, discolored or cracked patch where dead stem meets live stem. Scrape the bark: green underneath is alive, brown is dead. Dieback on one or two stems suggests canker, while wilting across the whole shrub more often points to water trouble.
After a hard winter or a late frost, stems may leaf out late or not at all, which can look just like canker. Give the shrub some weeks after it wakes up before cutting, since stems that seem dead sometimes sprout from lower buds. If the dead area has a clear sunken, discolored patch with live wood below it, canker is the more likely cause.
To remove a cankered stem, cut well below the canker into healthy wood, or take the stem out at the ground. Prune in dry weather so wounds dry quickly, wipe pruners with alcohol between cuts, and discard the cut stems rather than composting them.
Prevention comes down to keeping the shrub unstressed, because no spray cures canker. Water deeply during dry spells, especially in late summer, and avoid nicking stems with mowers and string trimmers.
Drooping, Browning Leaves From Water Problems
Dogwoods have shallow, fibrous roots that spread sideways, so they dry out easily.29OSU Extension Service. What’s wrong with my droopy dogwood? Droopy, yellowing leaves with brown tips across the whole plant signal water stress.30OSU Extension Service. What’s wrong with my droopy dogwood? Leaves short on water in hot sun brown from the tip, feel thin and crispy, then fall.31Nashville Tree Conservation Corps. Water your dogwoods
Too much water causes similar symptoms. Dogwoods are also prone to root rot in poorly drained or compacted soil.32OSU Extension Service. What’s wrong with my droopy dogwood? Rotting roots can’t take up water, so a waterlogged shrub can droop just like a dry one. Adding water to a droopy shrub can make things worse if the soil is already soggy.
So check the soil before changing anything. Dig a few inches down near the roots and feel it. Dry and crumbly means the shrub needs water; wet and sour-smelling means a drainage problem.
For a shallow-rooted shrub, water deeply once or twice a week in dry spells rather than giving light daily sprinkles. A 2- to 3-inch layer of mulch keeps the roots cool and moist, as long as you keep it a few inches off the stems. New plantings need steady water through their first summer. If water pools after rain, replant on a slightly raised mound, loosen compacted soil around the root zone at planting, and redirect downspouts away from the shrub.
Scale Insects and Other Pests
Several kinds of scale infest dogwood, small oval pests that sit on stems and suck sap.33Home & Garden Information Center. Dogwood Diseases and Insect Pests in South Carolina34Plant Addicts. Dogwood Pests Some have a hard shell and others are soft-bodied.35Plant Addicts. Dogwood Pests Heavy infestations cause yellowing, stunted growth, and dying shoots or branches.36Home & Garden Information Center. Dogwood Diseases and Insect Pests in South Carolina37Plant Addicts. Dogwood Pests Still, scale is unlikely to kill a dogwood, especially a mature one.38Plant Addicts. Dogwood Pests
Scale can look like part of the bark, so try the fingernail test: a scale bump usually scrapes off and may show a soft or colored body underneath. Look along the stems in winter, when the leaves are gone. A few scale are common and harmless; trouble starts when stems are thickly crusted or the shrub is declining. Sticky leaves or a black sooty film can point to soft scale, though aphids cause the same signs.
Heavily crusted stems can be pruned out, which also renews color. Horticultural oil in late winter smothers overwintering scale.
Deer browse dogwood heavily in winter and can leave shrubs ragged.39ISU ReD: Research and eData. Browsing by White-Tailed Deer on Invasive Oriental Bittersweet Spreading into Restored Grasslands Wrap or fence small shrubs with netting in late fall. Repellent sprays need reapplying after rain and snow. Since you cut stems back anyway, light browsing is often tolerable.
Fading Red Color and Pruning Mistakes
Young stems have the brightest color, so regular pruning is recommended.40Proven Winners ColorChoice. ARCTIC FIRE Yellow Red-Twig Dogwood One method is rejuvenation pruning in late winter: removing the oldest, thickest third of stems to the ground.41Proven Winners ColorChoice. ARCTIC FIRE Yellow Red-Twig Dogwood The other is cutting the whole shrub down each spring, which removes that year’s flowers but brings vigorous new growth.42Proven Winners ColorChoice. ARCTIC FIRE Yellow Red-Twig Dogwood
Older stems develop duller, grayer or brownish bark, so a shrub left alone for years shifts from bright red to mostly muted wood. That is normal aging, not a disease.
Several pruning mistakes cause trouble. Never pruning leaves a dull, crowded shrub of old stems. Shearing the tops into a ball leaves woody stubs and hides the color. Pruning during wet weather leaves wounds open to canker fungus, and dull blades crush stems and make ragged wounds.
Pruning also helps with other problems. Removing old stems takes out cankered and scale-covered wood, and thinning improves airflow so leaf spot dries off faster.
Late winter, before buds open, is best for either method. Avoid hard pruning in late summer, which pushes tender growth before frost.
Site, Soil, and Spacing That Prevent Problems
Arctic Fire grows about 3 to 4 feet tall and as wide.43Missouri Botanical Garden. Cornus sericea ‘Farrow’ ARCTIC FIRE Unlike the full-size red-osier dogwood, it doesn’t spread by underground runners.44Missouri Botanical Garden. Cornus sericea ‘Farrow’ ARCTIC FIRE
Plant shrubs about 3 to 4 feet apart so leaves dry after rain. Crowded hedges hold humidity that favors fungal leaf disease, and you will want room to reach in for pruning.
Full sun to part shade gives the best stem color. Avoid low spots where water stands after rain, and keep the shrub away from heavy foot traffic and mower paths that wound stems. Dogwood copes with fairly high-pH soil better than many plants.45University of Alberta Scholaris. Effects of Mineral Nutrition and Iron Supply on Growth and Physiological Responses of Selected Boreal Plant Species to Root Zone pH
Lawn grass growing up to woody shrubs can slow their growth, mainly by competing for nitrogen.46Agronomy Journal. Effects of Turfgrass on the Establishment of Woody Plants Grass also competes for water. Keep a mulched ring free of grass around the shrub. The ring keeps mowers and string trimmers away from the stems, which prevents the wounds that let canker fungus in. Keep the mulch a few inches back from the stems so the bark stays dry.