- Cultural Requirements
- Fertilization and Watering
- Pests and Diseases
- Recommended Junipers
- Juniper Diseases & Insect Pests
- Insects & Other Pests
- Other Problems
- Growing Juniper ‘Blue Star’ – Learn About Blue Star Juniper Plants
- About Blue Star Juniper
- How to Grow a Blue Star Juniper
- Address juniper problems
- Juniper tip blight
- Brown Junipers
Circular 956 View PDF picture_as_pdf
Robert R. Westerfield
Extension Consumer Horticulturist-Ornamentals
- Cultural Requirements
- Fertilization and Watering
- Pests and Diseases
- Recommended Junipers
Junipers are among one of the toughest plants for the landscape. Their hardy nature and drought tolerance make them ideal choices for many of our southern landscapes.
It is impossible to generalize about the growth habit of junipers as the species vary from low-growing ground cover types to larger conical-pyramidal forms. Foliage color varies from lustrous dark green, to light green, blue, silver-blue, yellow and many shades in between.
There is no limit to the different uses of junipers in the landscape. They make excellent screens, hedges, windbreaks, ground covers, foundation plants and specimens.
Junipers prefer open, sunny locations in well-drained soils. They will tolerate a wide range of pH levels. They are very tolerant of dry, clay soils and many varieties will grow in sand. Some types, such as Sargent juniper and Shore juniper have shown good salt tolerance.
Avoid planting junipers in shaded areas. When located in the shade, they become open, thin and are more susceptible to problems from diseases and insects. Also, avoid planting them in wet or poorly drained soils.
Be sure to properly space plants prior to planting. Junipers, particularly the horizontal types, are often planted too close together. As a result, they can form a thick layer of foliage which can lead to poor air circulation and make plants more vulnerable to insects and diseases.
After removing the plant from the container, separate the dense, root mass by loosening it with your hands or the aid of a knife. Place the top of the root ball level with the soil surface. Water thoroughly after planting and at least twice weekly for the first month to ensure establishment.
Fertilization and Watering
Once established, junipers need very little supplemental irrigation. They are one of the most drought tolerant plants in our landscape and can actually suffer from over-watering.
Junipers respond well to a balanced fertilizer at planting such as two teaspoons of 10-10-10 per 1 gallon plant. Incorporate fertilizer into the soil or spread it around the plant, but avoid directly placing fertilizer into the planting hole.
Established junipers will benefit from a complete fertilizer such as 16-4-8 or 12-4-8 applied at a rate of 1/2 lb. per 100 square feet in early spring and again in late summer. Apply prior to rainfall or irrigate immediately after application.
Junipers do not tolerate heavy pruning because of the lack of new growth on old wood. This makes it important to know the growth habit of a particular juniper prior to planting so that future pruning can be minimized. Junipers can be tip pruned and thinned, but not cut back to large limbs. Pruning out old, dead foliage underneath creeping junipers will often contribute to better air circulation and thus better health of the plant.
Pests and Diseases
Although junipers are tough, they do occasionally have some problems. Common insect pests of junipers would include bagworms, spider mites, leaf miner, webworm, scale and aphids, all of which can be controlled with an appropriate pesticide.
Several diseases can occur on junipers, but are almost always associated with poor cultural practices, such as over-watering or too much shade.
There are many cultivars of junipers available. The following are some of the most commonly available cultivars, grouped by plant size.
Low Growing (2 Feet)
Juniperus chinensis ‘Sargentii’ – Spreading green foliage, grows 18 inches to 2 feet high with a spread of 7 feet. Makes an excellent ground cover.
Juniperus horizontalis ‘Plumosa Compacta’ – Compact form of ‘Plumosa’, dense branching, flat (18 inches high) spreading to 8 feet; bronze-purple in winter, stays full in center, gray-green summer foliage
Juniperus horizontalis ‘Wiltoni’ ‘Blue Rug’ – Very flat growing form with trailing branches, 6 inches high with a spread of 6 to 8 feet, foliage-intense silver-blue, assumes light purplish tinge in winter; fairly fast growing.
Juniperus horizontalis ‘Procumbens’ – Spreading, prostrate form, 6 inches by 10 feet to 12 feet, leaves awl-shaped, soft, glaucous green, becoming bluish green with age. The cultivar ‘Greenmound’ has attractive light-green foliage that does not brown out. The cultivar ‘Nana’ is a dwarf and is similar to the species.
Juniperus squamata ‘Parsoni’ – Grey-green needles with a prostrate habit; grows 18 inches tall and 6 feet wide.
Juniperus conferta ‘Shore Juniper’ – Low growing; spreading habit; is tolerant of poor soils, especially adapted to sandy soils of the seashore. Yellowish-green in color, 12-15 inches tall, spreads to 8 feet.
Juniperus conferta ‘Blue Pacific’ – Low trailing habit and ocean blue-green foliage color; makes a good ground cover; grows to 12-15 inches tall with a spread of 5 to 7 feet.
Medium Growing (2-5 Feet)
Juniperus chinensis ‘Sea Green’ – Compact spreader with fountain-like, arching branches, dark green (mint green) foliage; 4-6 feet high, 6 to 8 feet wide; more upright than ‘Pfitzeriana’, foliage darkens in cold weather.
Juniperus virginiana ‘Grey Owl’ – Medium growing, widespread juniper with greyish green foliage. Grows to 5 feet tall with an 8 feet spread.
Juniperus chinensis ‘Saybrook Gold’ – considered one of the brightest gold foliaged J. chinensis type, primarily needle-like foliage, summer foliage is bright yellow, more bronze-yellow in winter, horizontal spreading type probably 2 to 3 feet high by 6 feet wide.
Juniperus chinensis ‘Nick’s Compact’ – A relatively flat-topped, wide-spreading form with green, slight blue overcast foliage; grows to 2 ½ feet high by 6 feet wide.
Juniperus chinensis ‘San Jose’ – Creeping form, 12 to 18 inches (24 inches) high and 6 feet to 8 feet wide, spreads irregularly; foliage sage green, young plants tend to be acicular, but with maturity there is a mixture of scale and needlelike foliage.
Juniperus chinensis ‘Holbert’ – Spreading growth habit of 3′ high and 8′ to 9′ across. Blue foliage holds color through the winter months.
Large Growing (5-12 Feet)
Juniperus chinensis ‘Aureo-Pfitzerana’ (Gold Tip Pfitzer) – Light green foliage with yellow branch tips. Grows to a height of 5 feet with a 10 foot spread.
Juniperus chinensis ‘Pfitzeriana – Probably the most widely planted juniper, wide spreading, variable form, grows about 6 feet high and 10 feet wide. Bright green foliage and is attractive as a younger plant. It can look untidy with age.
Juniperus chinensis ‘Hetzii Glauca’ – Semierect form with light blue foliage; grows 5 feet to 7 feet high, with an equal spread, a very hardy juniper.
Juniperus chinensis ‘Pfitzeriana Glauca’ (‘Blue Pfitzer’) – Possibly more dense than Pfitzer with mixed leaves, markedly blue in older plants, becoming slightly purplish blue in winter; handsome bluish foliage through the seasons in warmer climates; grows 6 feet high with a spread of 10 feet.
Juniperus chinensis ‘Blue Vase’ – Vase-shaped form with good summer and winter foliage; dense steel blue foliage; moderate growth rate, 6-10 feet high, 4-5 feet wide.
Upright Growing (Pyramidal)
Juniperus chinensis ‘Spartan’ – A fast, dense grower of tall, pyramidal or columnar habit, has a deep green color and very formal appearance, may grow to 20 feet high.
Juniperus chinensis ‘Hetzii Columnaris’ – Medium size, columnar green juniper. Dense tall growth with sharp pointed bright green needles. Grows 10-15 feet tall.
Juniperus chinensis ‘Blue Point’ – Pyramidal form with a tear drop outline, extremely dense branching, blue-green, needle and scalelike foliage; can grow 7-10 feet.
Juniperus chinensis ‘Robusta Green’ – Moderately slow grower, upright, rich green, twisted growth to 15 feet tall.
Juniperus chinensis ‘Kaizuka’ (‘Torulosa’) – Hollywood Juniper; leaves are scale-like, vivid green, branches slightly twisted; can be grown as a shrub or tree; will grow 20 to 30 feet high; excellent heat and salt tolerance.
Dirr, Michael A. Manual of Woody Landscape Plants. Stipes Publish Co., Champaign, Illinois, 1990.
Whitcomb, C.E. Know It and Grow It. Oklahoma State University Press, 1984.
Status and Revision History
Published on May 15, 2009
Published with Full Review on May 01, 2012
Published with Full Review on Mar 28, 2017
Juniper Diseases & Insect Pests
Junipers grown in South Carolina are relatively low-maintenance plants if planted in the correct location and given proper cultural care. There are several common problems that can cause browning of needles and dieback of entire shoots, especially when junipers are improperly planted or under stress from the environment. Avoid many of these problems by selecting resistant varieties, avoiding overhead watering and selecting a planting site with good drainage. More information is available in HGIC 1068, Juniper.
Twig & Tip Blight: Junipers frequently exhibit dieback of shoot tips or entire shoots and browning of needles. Needles may drop from the plant, and dark cankers may form at the junction of live and dead wood. This problem occurs typically during warm, wet weather conditions and is usually caused by one of the fungal organisms described below.
Phomopsis blight (Phomopsis juniperovora) on juniper.
Bruce Watt, University of Maine, Bugwood.org
Phomopsis Tip Blight: This disease is caused by the fungus Phomopsis juniperovora and begins by infecting the tips of branches smaller than the diameter of a pencil.
The new, immature growth becomes infected while the darker green, mature foliage remains resistant to infection. Infected twigs first become pale, then turn reddish-brown and finally become brown after death. Scraping away the bark will reveal a sharp line between discolored, dead wood and healthy wood. Watch for disease development during the spring or summer flush of new growth when warm, wet conditions are present.
Cercospora Twig Blight: This disease is caused by the fungus Cercospora sequoiae var. juniperi. It begins by infecting the oldest needles that are located on the lower branches, inside of the plant. As disease development progresses, the needle browning spreads upward and outward. Branch tips usually remain healthy and green. Needles of spur branches turn brown and die usually in the late summer, leaving a plant with an inner crown devoid of foliage. This disease is sometimes confused with mite damage.
Prevention & Treatment: Each of these diseases requires similar methods of control. First, closely inspect the entire plant, since symptoms of tip blight and twig blight can be caused by other problems, such as drought, overwatering or root injury.
Purchase disease-resistant varieties that are healthy with no evidence of dead or dying twigs. Do not stress junipers by planting them in shaded or poorly drained locations. Plant junipers in areas with good air circulation to promote rapid drying of the needles. Do not crowd plants, and avoid using sprinkler irrigation. Promptly prune and remove any diseased or browning branches as they occur. Except on highly susceptible cultivars, pruning will usually control these diseases.
If chemical control is necessary, fungicides are available to provide protection, but they must be applied before infection occurs. Select a fungicide labeled for use on junipers containing one of the following: mancozeb, thiophanate-methyl or copper salts of fatty acids. See Table 1 for examples of products. Apply all chemicals according to directions on the label.
Kabatina Twig Blight: This disease is caused by the fungus Kabatina juniperi. The symptoms are the same as described for Phomopsis tip blight, except this fungus kills older (usually 1-year-old) twigs in the spring. Damaged or stressed tissues are more susceptible to Kabatina twig blight.
Kabatina blight (Kabatina juniperi) on juniper.
Bruce Watt, University of Maine, Bugwood.org
Kabatina blight (Kabatina juniperi).
Bruce Watt, University of Maine, Bugwood.org
Cedar-apple rust (Gymnosporangium juniperi-virginianae) on Eastern red cedar.
Linda Haugen, USDA Forest Service, Bugwood.org
Cedar-Apple Rust: This fungal disease of apple, crabapple and Eastern red cedar is caused by several species of Gymnosporangium. The disease not only affects Juniperus species including Eastern red cedar (Juniperus virginiana) but requires another host plant, apple or crabapple, to complete its life cycle. This disease spreads from junipers to the apple and then back to juniper. It can be a severe problem wherever these two are grown together. Eastern red cedar is the most commonly infected juniper.
On juniper, hard, brown, up to 2-inch diameter galls form near the ends of the branches in the summer. In the spring following a rain, the galls produce large, orange, gelatin-like tendrils, full of spores, which can blow a half-mile to infect nearby apple and crabapple trees.
Symptoms that occur on the apple trees appear as yellow spots on the upper leaf surface. In the late summer, these yellow spots form spores that are spread to the leaves and twigs of nearby junipers (within 2 miles) to infect them.
Prevention & Treatment: Select resistant varieties of apple (such as ‘Enterprise’, ‘Pristine’, ‘Liberty’ or ‘Redfree’) or juniper. Prune out all galls on the juniper, if possible. Do not plant apple, crabapple and Eastern red cedar trees in the same area. If disease is severe enough to warrant control, or a particular specimen plant is affected, select a fungicide containing mancozeb or propiconazole. See Table 1 for examples of products. Do not use fruit for food if propiconazole products are used. Apply all chemicals according to directions on the label. More information is available in HGIC 2000, Apple and Crabapple Diseases.
The following Juniper varieties are Generally Resistant to Phomopsis Twig Blight & Cedar Rusts:
- Juniperus chinensis – Chinese Juniper
- ‘Mint Julep™’
- var. sargentii (Sargent Juniper)
- J. communis – Common Juniper
- J. squamata – Singleseed Juniper
- var. fargesii
- J. sabina – Savin Juniper
- J. virginiana – Eastern Red Cedar
- J. horizontalis – Creeping Juniper
- ‘Wiltoni’ (‘Blue Rug’)
Phytophthora Root Rot: This root rot is one of the most serious and difficult-to-control fungal diseases that affects a wide range of plants in South Carolina. It is caused by a soil-borne fungus, Phytophthora cinnamomi, and the most common symptom is the slow decline of the plant. Leaves on the plant will become thin or sparse. Some plants may die one branch at a time, until the entire plant dies. The centers of the roots change from white to reddish-brown and the outer layer of the roots separates easily from the core. High soil moisture and warm soil temperatures favor disease development.
Prevention & Treatment: It is important to prevent this disease by cultural methods, since chemical treatment is ineffective once symptoms are noticed. Avoid planting in poorly drained areas where Phytophthora root rot thrives. Heavy clay soils, areas that flood and sites where runoff water is a problem typically create root rot problems. Plant junipers in raised beds, except in deep sandy soils. If you must plant in a site that has heavy clay or does not have good internal drainage, amend the site by thoroughly mixing a porous material, such as ground pine bark (not sawdust or peat), into the bed to a depth of 8 to 12 inches.
Avoid varieties that are the most susceptible to root rot. Some highly susceptible junipers that are likely to be killed by the root rot fungus include: ‘Andorra,’ ‘Bar Harbor,’ ‘Parsoni,’ ‘Sargents,’ ‘Shore’ and Juniperus procumbens ‘Nana.’
Fungicides can be effective on a preventative basis only, and repeat applications are required. Fungicides containing mefenoxam (Subdue GR) can be applied in the home landscape to suppress disease, but it will not cure an infected plant. Due to product cost and for accurate application, homeowners may want to hire a licensed landscaper to apply products containing these fungicides. Apply all chemicals according to directions on the label.
Insects & Other Pests
Bagworm pupae (Thyridopteryx ephemeraeformis).
Gerald J. Lenhard, Louisiana State University, Bugwood.org
Bagworm: Bagworm (Thyridopteryx ephemeraeformis) infests many shrubs and trees, but conifers (evergreens) are the preferred hosts. Damage to plants results from feeding by the caterpillar, which causes loss of leaves. Mild infestations of this pest slow the growth of junipers. Heavy infestations can kill a plant.
The adult male is a dark-colored, hairy moth with a 1-inch wingspan and clear wings. The adult female is yellow and appears almost maggot-like. The larva (immature form or caterpillar) produces a carrot-shaped bag that it carries with it as it feeds. The bag is formed from silk that the larva produces. As it feeds, the larva adds bits of plant material to the bag. The bag is about 2 inches when complete.
In South Carolina, bagworms survive the winter as eggs in a bag. The larvae hatch during May. They spin their cases and carry them along as they feed. After further development, the adult male emerges from its bag in late summer. It locates an adult female in her bag. After mating, the female lays 500 to 1,000 eggs in her bag and dies.
Prevention & Control: Several parasites and predators feed on bagworms, generally keeping their numbers under control. Removal of the egg-containing bags during winter and early spring is a very effective method for preventing problems before the next growing season. Once removed, the bags should be destroyed or placed in a deep container, which allows beneficial parasites that may also be present in the bags to escape while retaining the bagworm larvae.
If the infestation is severe or the bags are out of reach, spray with the bacterial insecticide Bt. This insecticide contains spores of the bacterium, Bacillus thuringiensis, which when eaten kill the caterpillar. Young larvae are much more susceptible to the treatment than are older larvae. As such, apply this pesticide in the spring as soon as bagworms are seen. Control is most effective when spraying is done in late afternoon or early evening. See Table 1 for examples of products containing Bt. This insecticide is very safe to use. As with any pesticide, read and follow all label directions and precautions before using.
Spruce Spider Mite: Mites are not insects but are more closely related to spiders. Spruce spider mites (Oligonychus ununguis) are serious pests of juniper. They are very small and not seen easily with the naked eye. They have piercing mouthparts that they use to suck plant sap. Their feeding results in speckling (formation of tiny yellow spots) on needles. Some needles may turn brown and drop off. With heavy infestations, fine webbing may be seen on the plant. Several seasons of heavy mite feeding may kill a juniper. Although most spider mites increase in numbers during hot, dry weather, spruce spider mites are cool-weather mites. Their population peaks during spring and fall, but drops dramatically during the heat of summer when predators feed on them.
Control: Naturally occurring enemies of mites include various predator mites, ladybird beetles (ladybugs) and other insects. These predators will usually suppress mite populations. Since insecticide use kills beneficial predators as well as mites, insecticides should be avoided unless absolutely necessary. Misuse of insecticides can result in increased problems with mites by causing the death of natural predators of the mite. Miticides, labeled specifically for mite control, are less harmful to beneficial insects. Mites can be removed with a strong spray of water, if applied on a regular basis.
To determine whether insecticide use is needed, it helps to know how many mites are present. Hold a white sheet of paper under a branch and strike the branch. The mites that are knocked off will be seen crawling around on the paper. If dozens of mites are seen per whack, serious damage can result. Continue to check population numbers at seven to ten day intervals. Pesticides labeled for homeowner use against spruce spider mites include insecticidal soaps or horticulture oil sprays. See Table 1 for examples of products. As with any pesticide, read and follow all label directions and precautions before using.
Juniper Scale (Carulaspis juniperi).
Joseph La Forest, University of Georgia, Bugwood.org
Juniper Scale: Symptoms of juniper scale (Carulaspis juniperi) infestation are very similar to symptoms of spruce spider mite infestation. Initially, the juniper appears off-color and infested branches show little growth. The needles eventually turn yellow or brown. Branches may die back. If ignored, juniper scale infestation may kill the plant in two to three growing seasons. Signs of the pest include clusters of tiny bumps or scales about 1/8-inch in diameter, especially on the undersides of needles. Adult females are white at first but turn gray or black later. Adult females are mostly flat with a slight volcano appearance, if viewed through a magnifying lens. In addition, a shiny, sticky material (honeydew) is often seen on needles of junipers infested with juniper scale.
Juniper Scale (Carulaspis juniperi).
United States National Collection of Scale Insects Photograph Archive, USDA Agriculture Research Service, Bugwood.org
Adult females survive the winter on the plant. In early spring, they lay eggs under their shell. The immature forms, called crawlers, hatch and crawl around before settling on the needles to feed. They feed by sucking plant sap. As they mature, they form a crusty shell over their bodies. Their legs become useless and they remain in one location. As they feed, excess sap is excreted as a sugary material, called honeydew. The sooty mold fungus can grow on the honeydew, forming dark splotches on needles.
Control: The presence of adults or crawlers determines which treatment will be most effective. Use a 2 or 3% horticultural oil mix as a dormant spray in late winter or very early spring before new growth occurs to control adult females by suffocation. A 2% solution is made with 5 tablespoons of horticultural oil per gallon of water. See Table 1 for examples of products.
Most insecticides are effective only against the crawlers. Monitor the crawler emergence with sticky cards, double-faced tape wrapped around a branch, or by putting an infested shoot into a baggie and watching for crawler movement. Crawler activity often coincides with the flush of new plant growth in the spring. However, some scale species may have overlapping generations with an extended crawler emergence period, such as along the coast. Insecticides recommended for use against crawlers include acephate, malathion, and cyfluthrin . See Table 1 for examples of products. Read and follow all label directions and precautions before using.
Needle Browning: These symptoms appear as needles that initially turn yellow, then brown and dry, before finally dropping from the plant. These symptoms can occur inside the plant nearest the trunk, on the tips or scattered throughout the plant. The entire plant may die if the condition is severe enough. There are many conditions that will cause needles to turn brown on junipers, including many diseases already discussed. A few reasons needles may turn brown are described below.
Drought & Overwatering: These two problems cause similar symptoms on junipers. Check to see if the ground is dry or frozen. Overwatering causes the plant’s root to rot, therefore rendering it unable to take up water.
Dog Urine: Salts in the urine burn the foliage causing it to appear scorched. Rinse the foliage if you suspect this is a problem.
Note: Control of diseases and insects on large trees is usually not feasible, since adequate coverage of the foliage with a pesticide cannot be achieved.
Table 1. Insecticides & Fungicides to Control Juniper Insect Pests & Diseases.
|Insecticides & Fungicides||Examples of Brand Names & Products|
|Acephate||Bonide Systemic Insect Control Concentrate|
|Bacillus thuringiensis (Bt)||Bonide Thuricide Concentrate
Garden Safe Bt Worm & Caterpillar Killer Concentrate
Natural Guard Caterpillar Killer Spray with Bt Conc.
Safer Caterpillar Killer Concentrate
Southern Ag Thuricide Bt Caterpillar Control
Tiger Brand Worm Killer Concentrate
|Copper Fungicides||Bonide Copper Fungicide Spray or Dust
Bonide Liquid Copper Concentrate
Camelot O Fungicide/ Bactericide Concentrate
Monterey Liqui-cop Fungicide Concentrate
Natural Guard Copper Soap Liquid Fungicide Conc.
Southern Ag Liquid Copper Fungicide
|Cyfluthrin||Bayer Advanced Vegetable & Garden Insect Spray Conc.|
|Horticultural Oil||Bonide All Seasons Spray Oil Concentrate
Ferti-lome Horticultural Oil Spray Concentrate
Southern Ag ParaFine Horticultural Oil Concentrate
Monterey Horticultural Oil Concentrate
Summit Year Round Spray Oil Concentrate
|Insecticidal Soap||Bonide Insecticidal Soap Concentrate
Safer Brand Insect Killing Soap Concentrate
Natural Guard Insecticidal Soap Concentrate
Garden Safe Insecticidal Soap Insect Killer Concentrate
Espoma Earth-tone Insecticidal Soap Concentrate
|Malathion||Bonide Malathion 50% Insect Control
Gordon’s Malathion 50% Spray
Hi-Yield 55% Malathion Insect Spray
Martin’s Malathion 57% Concentrate
Ortho Max Malathion Insect Spray Concentrate
Spectracide Malathion Insect Spray Concentrate
Southern Ag Malathion 50% EC
Tiger Brand 55% Malathion
|Mancozeb||Bonide Mancozeb Flowable with Zinc Concentrate
Southern Ag Dithane M-45
|Propiconazole||Banner Maxx Fungicide
Bonide Infuse Systemic Disease Control Concentrate
Ferti-lome Liquid Systemic Fungicide II Concentrate
|Thiophanate Methyl||Cleary’s 3336-WP Turf & Ornamental Fungicide
Southern Ag Thiomyl Systemic Fungicide
Growing Juniper ‘Blue Star’ – Learn About Blue Star Juniper Plants
With a name like “Blue Star,” this juniper sounds as American as apple pie, but in fact it is native to Afghanistan, the Himalayas and western China. Gardeners love Blue Star for its thick, starry, blue-green foliage and its graceful rounded habit. Read on for more information about Blue Star juniper (Juniperus squamata ‘Blue Star’), including tips on how to grow a Blue Star juniper in your garden or backyard.
About Blue Star Juniper
Try growing juniper ‘Blue Star’ as either a shrub or a groundcover if you live in an appropriate region. It’s a lovely little mound of a plant with delightful, starry needles in a shade somewhere on the boundary between blue and green.
According to information about Blue Star juniper, these
plants thrive in U.S. Department of Agriculture plant hardiness zones 4 through 8. The foliage is evergreen and the shrubs grow into mounds some 2 to 3 feet (.6 to .9 m) high and wide.
You have to have patience when you start growing Blue Star, since the shrub doesn’t shoot up overnight. But once it gets settled in, it’s a champion garden guest. As an evergreen, it delights all year long.
How to Grow a Blue Star Juniper
Blue Star juniper care is a cinch if you plant the shrub correctly. Transplant the seedling into a sunny location in the garden.
Blue Star does best in light soil with excellent drainage but it won’t die if it doesn’t get it. It will tolerate any number of problem conditions (like pollution and dry or clay soil). But don’t make it suffer shade or wet soil.
Blue Star juniper care is a snap when it comes to pests and diseases. In short, Blue Star doesn’t have many pest or disease issues at all. Even deer leave it alone, and that is pretty rare for deer.
Gardeners and homeowners usually start growing junipers like Blue Star for the texture its evergreen foliage provides to the backyard. As it matures, it seems to undulate with every passing wind, a lovely addition to any garden.
Address juniper problems
Q. Some of the branches have turned brown on my juniper shrubs. I have had these same shrubs for years and they have been getting the same care as always but suddenly they have browning tips and branches dying. Can you tell me what is wrong?
A. Junipers make for hardy trees and shrubs in the landscape as they withstand cold, heat and drought with ease. However, despite their resilience, junipers are prone to a couple of diseases and insect infestation that cause browning. Bagworms, spider mites, and the fungal diseases tip blight or twig blight, may cause the branches and twigs to lose their vibrant green color.
The symptoms of branches turning brown could be caused by several things. Browning and dying branch tips may indicate an insect infestation such as spider mites. You can check for this by holding a piece of white paper under a juniper branch and shaking it. Look at any small specks that fall on the paper through a magnifying glass. If you see brown, red, green or yellow eight-legged insects, your juniper has spider mites.
Twigs and branches dying back could indicate juniper tip blight. To control prune out dead tips, making sure to go into the green part of the branch at least 2 inches. Clean pruning shears with 10 percent bleach solution or rubbing alcohol between cuts.
Bad fungal infections can be controlled with copper spray. Junipers need air flow to avoid fungal disorders, so cleaning up around the shrubs and pruning out any dead wood is important. It is also important to keep branches dry during warmer weather, so avoid overhead water or watering too often during the summer.
If the drainage is poor, the plants may develop root rot, causing the whole or parts of the plant to die. I do not think this is the case with your shrubs as you said they have been growing in the same place for years.
Entire branches dying back especially on larger shrubs or juniper trees may be due to twig blight. This is caused by cankers. This disease can also cause foliage on infected branches to turn yellow or brown and wilt. According the UC, IPM site: “A canker is a localized dead (necrotic) area on branches, trunks or roots. Cankers vary greatly in appearance but are often a circular or oblong lesion that may be discolored, oozing or sunken. Cutting under cankered bark usually reveals discolored tissue, which may have a well-defined margin separating it from healthy tissue. When cankers entirely circle (girdle) stems or trunks, foliage turns yellow or brown and wilts as the plant dies outward or upward from the canker.”
Infected bark often discolors and may exude copious resin. If you think you have blight or canker, prune out infected branches, again making sure to clean pruners between cuts. For further information, go to http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/juniper.html.
The Shasta Master Gardeners Program can be reached by phone at 530 242-2219 or email [email protected] The gardener office is staffed by volunteers trained by the University of California to answer gardeners’ questions using information based on scientific research.
The popular ‘Swane’s Golden’ is a fabulous conifer for use in narrow areas, but until recently there hasn’t been a good alternative for people wanting a pencil-shaped conifer with blue foliage. In our segment Don looked at ‘Blue Arrow’, a juniper with beautiful, silvery blue foliage and a natural, pole shape.
Common name: Blue Arrow
Botanic name: Juniperus scopulorum ‘Blue Arrow’
Description: At about 5m (15′) tall ‘Blue Arrow’ is smaller than a pencil pine. It has silvery blue foliage and a neat, natural pole shape.
Best climate: Sydney to Perth and areas south, and mountains.
planting in narrow areas
silver theme garden
beautiful silvery blue foliage
natural pole shape
low maintenance – clipping is not required to keep the plant in shape
No downside really – Don thinks this juniper will become very popular for narrow areas.
Also shown in our segment:
Swane’s Golden (Cupressus sempervirens ‘Swane’s Golden’) was produced by Swane’s Nursery in Sydney. This golden form of the pencil pine has yellow and gold foliage, and maintains its colour throughout the year. It grows slowly to around 6m (20′) tall.
Conifers vary in their cultural requirements but generally they like a slightly acid, well-drained soil, enriched with organic material such as well-rotted manure or compost.
Conifers with dark green foliage will tolerate a position in semi-shade, but those with coloured or variegated foliage should be planted in full sun.
Keep plants mulched, and water well during dry spells.
Conifers are sometimes attacked by fungal diseases and insects such as borers and weevils. However, they are less susceptible to attack when grown in the climate, soil and position that suits them best, with correct fertilising and watering.
‘Blue Arrow’ is available Australia wide. Ask your local garden centre or nursery to order if they do not have one in stock. Expect to pay around $15-20 for 200mm (8″) pots.
Our segment was filmed at:
Conifer Gardens Nursery
Cnr Sherbrooke and Mt Dandenong Tourist Rds
Ferny Creek Vic 3786
Phone: (03) 9755 1793
Fax: (03) 9755 2677
Juniper tip blight
Juniper tip blight is a common disease of junipers found in most states east of the Mississippi River. There are many varieties of junipers susceptible to tip blights; however, the disease is most serious on young or newly transplanted plants. As the plant matures, disease susceptibility and severity decreases. Occasionally it can infect arborvitae, cedar, European larch, jack pine, and Douglas-fir. The two most common juniper tip blight diseases are Phomopsis juniperovora (Phomopsis tip blight) and Kabatina juniperi (Kabatina tip blight).
Phomopsis tip blight
Phomopsis tip blight, sometimes referred to as juniper twig blight, is mainly a leaf and shoot infection that affects the new, young foliage of junipers. The first symptoms, yellow spots on young needles, may occur 3-5 days after infection. (Sometimes older needles may also show spotting.) The fungus then enters young stem tissue causing dieback of the new shoot tips. Affected foliage turns dull red to brown and then ash gray. As the disease progresses, small lesions (cankers) form on the stems where infected and healthy tissue meet. Eventually the entire branch may die. Infection is spread primarily by splashing rain, wind, insects, or mechanical means. Repeated infections occur when temperatures are between 70 – 80 degrees F, during periods of high humidity, and when foliage is wet. The fungus can persist in dead parts of infected plants for as long as two years.
Kabatina tip blight
Kabatina causes symptoms very similar to Phomopsis, but usually only infects twigs a year or more old. This fungus does not infect healthy foliage, but enters through wounds caused by pruning, insects, or severe winter weather. The first symptoms, dull green then red or yellow discoloration of branch tips, appears in February and March, well before symptoms of Phomopsis tip blight appear. As the disease progresses, spores are formed in the small, ash-gray lesions (cankers) found at the junction between infected and healthy tissue. The brown, dried foliage eventually drops from the plant in late May or June. Kabatina tip blight occurs only in the early spring and does not cause extensive branch die back. The primary infection period for the Kabatina fungus is autumn, even though symptoms are not apparent until late winter or early spring.
Although Phomopsis and Kabatina blights cause almost identical symptoms, their stages of development and control differ. Therefore, it is important to distinguish between the two.
- Plant trees and shrubs that are resistant to Phomopsis and Kabatina tip blight.
- When planting, avoid heavily shaded areas and space plants to allow for good air circulation.
- Avoid wounding plants, especially in spring and fall.
- Water plants in early morning so foliage will dry during the day.
- Prune out diseased branch tips during dry summer weather and destroy.
- If the infection is severe, removal of the plant may be necessary. Replace with a resistant tree selection.
- Avoid excessive pruning or shearing.
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There are many reasons a juniper might turn brown. Fungal tip blights, cankers, mechanical damage, and salt injury are some of the most common causes.
Several juniper samples with tip blight were submitted to the Plant Disease Clinic this spring. Phomopsis and Kabatina tip blights are two common diseases of juniper. Kabatina tip blight generally appears in February and March. Phomopsis tip blight shows up later, from April through September.
Symptoms are similar for both diseases. Affected needles turn reddish-brown to gray. The fungi can girdle branches causing the tips to die. Small, black fungal fruiting structures, called pycnidia, develop on diseased leaves and branches. They often can be seen with the naked eye.
Management includes pruning out diseased branch tips when the plants are dry. This will prevent fungal spread. When creating new plantings, provide adequate space between plants to allow for good air circulation and sun exposure. Choose disease resistant varieties when possible. Fungicides are an option, but are rarely necessary in established plantings.
Junipers with fungal cankers, commonly caused by the fungus Botryosphaeria stevensii, often have entire branches that die. This symptom can look like it was caused by mechanical injury, for example if a branch breaks near the main stem. Water can’t get to the tips and the whole branch turns reddish-brown and dies. Pruning out dead branches may or may not effectively manage Botryosphaeria canker. There aren’t any fungicides labeled for Botryosphaeria canker on juniper.
Rock salt, used to melt ice, frequently causes junipers to turn brown. Salt damage usually occurs along walkways and roads. The damage typically appears uniformly on one side of the plant. Once again, it’s best to remove any brown branches to prevent the build up of fungi that like to feed on dead plant material.
The Iowa State University bulletin Pm-1702, Juniper Diseases, is available from your local county Extension office or from the Iowa State University Extension Distribution Center. Contact the Distribution Center at: 119 Printing and Publications Building Iowa State University Ames, Iowa 50011-3171 Telephone: (515) 294-5247 Fax: (515) 294-2945 https://store.extension.iastate.edu/
This article originally appeared in the May 10, 2002 issue, p. 61.