How to kill holly bushes?

Diseases Of Holly Bushes: Pests And Diseases Damaging Holly Bushes

While holly bushes are common additions to the landscape and generally quite hardy, these attractive shrubs occasionally suffer from their share of holly bush diseases, pests and other problems.

Common Pests and Diseases Damaging Holly Bushes

For the most part hollies are extremely hardy, suffering from few pests or diseases. In fact, most problems that do occur are usually associated with other factors, such as environmental conditions. However, pests and diseases damaging holly bushes can happen so it’s important to become familiar with the most common ones for help in prevention as well as treatment.

Holly Tree Pests

Holly tree pests such as scale, mites, and holly leaf miner are the most commonly seen affecting hollies.

  • Scale – While light infestations of scale can usually be controlled by hand, scale control for heavier infestations generally requires the use of horticultural oil. This is usually applied prior to new growth to kill both adults and their eggs.
  • Mites – Spider mites are common causes of discoloration and speckling of holly foliage. While introducing natural predators,such as ladybugs into the landscape can help minimize their numbers, a nice healthy dose of soapy water or insecticidal soap sprayed regularly on plants can also help keep these pests at bay.
  • Leaf Miner – The holly leaf miner can cause unsightly yellow to brown trails throughout the center of leaves. Infested foliage should be destroyed and treatment with a foliar insecticide is often required for leaf miner control.

Holly Tree Disease

Most diseases of holly can be attributed to fungus. The two most prevalent fungal holly tree diseases are tar spot and cankers.

  • Tar Spot – Tar spot usually occurs with moist, cool springtime temperatures. This disease begins as small yellow spots on the leaves, which eventually become reddish brown to black in color and drop out, leaving holes in the foliage. Always remove and destroy infected foliage.
  • Canker – Cankers, another holly tree disease, produce sunken areas on the stems, which eventually die out. Pruning out infected branches is usually necessary in order to save the plant.

Improving air circulation and keeping debris picked up is good for prevention in both cases.

Environmental Diseases of Holly

Sometimes a holly bush disease is due to environmental factors. Such is the case for problems like purple blotch, spine spot, holly scorch, and chlorosis.

  • Purple Blotch – With purple blotch, leaves of holly become splotched with purple-looking spots, which are usually brought on by drought, plant injury, or nutritional deficiencies.
  • Spine Spot – Spine spot is similar with gray spots edged with purple. This is most often caused by leaf punctures from other leaves.
  • Scorch – Sometimes rapid temperature fluctuations in late winter can lead to browning of the leaves, or holly scorch. It is often helpful to provide shade to plants most susceptible.
  • Chlorosis – Iron deficiency can lead to the holly bush disease, chlorosis. Symptoms include pale green to yellow leaves with dark green veins. Reducing pH levels in the soil or treating with supplemental iron-fortified fertilizer can usually alleviate the issue.

Why is my holly tree dying?

Many broadleaf evergreens — and especially hollies — suffered winter damage this year. It’s unusual, however, that the symptoms are just on one of your four hollies. Perhaps it is in a location that is dryer and more susceptible to drying winds. Winter injury can occur on dry, windy, warm or sunny winter days when the ground is frozen. Plants are unable to move water from the frozen soil to replace the water being lost from the exposed leaves. Leaves curl and droop, then brown from the tips and margins, giving them a scorched appearance. https://extension.umd.edu/hgic/winter-damage-trees-and-shrubs
We also notice in your photo that there is sapsucker damage on the trunk of the tree. This may have been a factor in weakening the health of this particular plant. Read about sapsucker damage here: https://extension.umd.edu/hgic/woodpeckers-and-sapsuckers
Wait until you see new leaves developing on the plants. If winter injury did not kill the leaf buds, you will get new growth. Where there is no new growth, you can prune out dead branches.
ckc

Ilex crenata ‘Soft Touch’

  • Attributes: Genus: Ilex Species: crenata Family: Aquifoliaceae Life Cycle: Woody Recommended Propagation Strategy: Stem Cutting Wildlife Value: Showy fruits are attractive to birds. Members of the genus Ilex support the following specialized bee: Colletes banksi. Play Value: Wildlife Food Source Dimensions: Height: 2 ft. 0 in. – 3 ft. 0 in. Width: 2 ft. 0 in. – 3 ft. 0 in.
  • Whole Plant Traits: Plant Type: Shrub Leaf Characteristics: Broadleaf Evergreen Habit/Form: Dense Mounding Rounded Growth Rate: Medium Maintenance: Medium Texture: Fine
  • Fruit: Fruit Color: Black Display/Harvest Time: Fall Winter Fruit Type: Berry Drupe Fruit Width: < 1 inch Fruit Description: Black ornamental berries persist throughout winter for cool season interest.
  • Leaves: Leaf Characteristics: Broadleaf Evergreen Leaf Color: Green Leaf Feel: Glossy Smooth Soft Waxy Leaf Type: Simple Leaf Arrangement: Alternate Leaf Shape: Elliptical Lanceolate Oblong Obovate Leaf Margin: Crenate Serrate Hairs Present: No Leaf Length: < 1 inch Leaf Width: < 1 inch Leaf Description: It has soft-textured, glossy green leaves that have an interesting silver mid-vein.
  • Stem: Stem Color: Brown/Copper Gray/Silver Green Stem Is Aromatic: No Stem Form: Straight Stem Surface: Smooth (glabrous)
  • Landscape: Landscape Location: Container Lawn Patio Slope/Bank Small Space Walkways Landscape Theme: Cottage Garden Design Feature: Accent Border Foundation Planting Hedge Mass Planting Small groups Specimen Attracts: Bees Pollinators Songbirds Specialized Bees

Soft Touch Hollies Slowly Declining

Japanese hollies are very popular shrubs but they can be finicky sometimes. They prefer to grow in light, moist, well-drained soil, slightly acid soils. They are sun or shade adaptable. They do not like heavy, clay soil that stays moist for prolonged periods of time. Last year we had a record-breaking amount of rainfall which really kept areas very wet. This most definitely can be a root problem as they are prone to a root rot disease. When infected shrubs experience a slow decline with sections of the shrub dying. They look like they are struggling and do not grow well. They eventually need to be replaced. If they have root rot transplanting them to another location will not save them. They might do okay initially but then will decline.
Some replacement shrubs to consider are Blue star juniper, Compacta or shamrock inkberry holly, Japanese skimmia (need a male cultivar and female shrubs for berries), sweetbox (Sarcococca) or juniper (Juniperus procumbens ‘Nana’).
You may want to consider testing the soil to check the pH.
The following is the link to our soil testing information,

By George Weigel/The Patriot-News

Q: I planted a new Ilex crenata towards the end of June. I fear I did not water it enough. The leaves are falling off, and it doesn’t seem to be taking any water. Is there anything I can do to save it?

A: Probably not. Once an evergreen like a Japanese holly drops its leaves, the root system is already dead. Lack of water is the No. 1 reason for this – especially for a new transplant planted in summer.

Sometimes transplant shock will cause a new holly to drop leaves dramatically soon after planting. But if it’s kept watered, dormant buds will pop out a new set of leaves within a few weeks.

In your case, if the plant was doing fine for weeks and then went downhill, I think it’s a goner. In my experience, Japanese hollies don’t transplant as well as most other landscape shrubs even when you do everything right. If you can get them through the first year, they can be long-lived and trouble-free plants. But they have a much higher first-year death rate than just about any shrub I’ve seen. That’s why I seldom recommend Japanese hollies. Give me dwarf boxwoods instead. They look very much the same, transplant better and take the same cultural settings as Japanese holly.

One other possible explanation for your trouble: black root rot. This is a disease caused by a fungus that attacks and kills the roots, resulting in a shutdown of the whole plant. If this disease (Thielaviopsis basicola) is in your soil, it’ll likely infect a replacement Japanese holly.

I personally would try to get my money back if the holly is guaranteed and see if I could replace it with a nice ‘Green Velvet’ or ‘Chicagoland Green’ boxwood.

Tree Diseases: Holly Leaf Spot

Introduction

Holly leaf spot, also referred to as holly tar spot, is a fungal disease that affects holly plants. Holly tar spot induces the formation of black spots on the leaves of holly. Severe infections often result in extensive defoliation of the host plant.

Hosts

Leaf spot diseases are most common on American holly, and holly bush. They may also be observed on other species of Ilex.

Disease Cycle

Holly leaf spot is likely caused by several fungi, including Phacidium curtisii, Rhytisma curtisii, Coniothyrium ilicinum, Marcpderma curtisii, and Phytophthora ilicis. Infections occur on older leaves during winter and spring. When infected, leaves will appear abnormally spotted. Infection spots are irregularly shaped, and vary in size, ranging from large to small. As the infection progresses, the spots deepen in color, eventually turning black. As the black spots develop, a cushion-shaped stroma forms beneath the leaf epidermis. The orange-red apotheical discs mature the following spring, and release ascospores, which are disseminated by air currents or rain to other host plants, where they initiate new cycles of leaf infection.

Symptoms

Symptoms of holly leaf spot are easily distinguished. Most species of holly will develop tiny yellow spots on the leaves in spring. During summer, the spots gradually enlarge, turning reddish-brown. They develop into the characteristic black tar spot by early fall. Severely infected leaves drop prematurely. Defoliation generally occurs from the bottom of the plant, progressing upwards.

Management

  • Plan holly bushes in conditions suitable for the holly type.
  • Maintain plant vigor through sound cultural practices. Ensure that holly plants are sufficiently watered, especially during extended periods of drought. Apply a layer of organic mulch around the base of holly plants to improve soil quality, moderate soil temperature, and retain soil moisture.
  • Routinely prune holly plants to promote sunlight penetration, and air circulation.
  • Avoid watering holly bushes in the morning, or at night. Minimize leaf exposure to irrigation before midday. This will enable the leaves to dry rapidly during the afternoon.
  • Fungicide applications on the shoots and leaves of holly plants will mitigate the effects of holly leaf spot. Initial applications should be performed in spring, just as the buds begin to swell. Two or three subsequent applications should be made during summer.
  • Once the leaves fall, the disease cannot be treated. While this will temporarily reduce the ornamental value of the plant, the damage seldom lingers. In most instances, the host will survive, and produce a healthy flush of growth.
  • Rake and dispose of any infected leaves. This will reduce the amount of inoculum available to initiate new infections. Avoid composting infected leaves; while composting will destroy most fungi, some may survive.
  • Prune and dispose of infected leaves from holly plants. Disinfect pruning tools between each cut using a solution comprised of one part bleach and nine parts water.

If you have any questions about holly leaf spot, or you are interested in one of our tree services, contact us at 978-468-6688, or [email protected] We are available 24/7, and can accommodate any schedule. All estimates are free of charge. We look forward to hearing from you.

Photo courtesy of Gail Ruhl.

American Holly

Introduction: American holly is a broad-leaf evergreen with a beautiful shape, but with a variety of insect and disease problems. The tree offers clusters of red berries that persist throughout fall and winter. Male and female flowers are on separate trees, so trees of both sexes must be located within the same area to ensure fruit production. Culture: American holly prefers moist, acidic, loose, well-drained soil. It will grow in sun or partial shade, but berry production is best in full sun. It suffers chlorosis in high pH soils. This tree will not tolerate poorly drained areas, and will not perform well in dry, windy, unprotected sites. American holly should tolerate winter temperatures as low as 20 to 25 degrees F below zero if protected from drying winds and winter sun. It is hardy in Zones 5 to 9.

Leaf miner and scale are the worst problems for American holly, but the tree has a long list of potential problems. These include bud moth, beetles, berry midge, whitefly, southern red mite, leaf spots, cankers, tar spot, bacterial blight, spot anthracnose, leaf rot, leaf drop, powdery mildew, twig die back, spine spot and leaf scorch.

Botanical Information

  • Native habitat: Massachusetts to Florida, west to Texas and Missouri.
  • Growth habit: Densely pyramidal with branches to the ground when young; becomes open, irregular and high branching with age.
  • Tree size: 40 to 50 feet tall with a spread ranging from 18 to 40 feet.
  • Flower and fruit: Female flowers are solitary and dull white; male flowers are borne in three- to nine-flowered cymes. Male and female flowers are on separate trees. Fruit is a dull red, berry-like drupe borne on a 1/4-inch stalk. Fruit matures in October and persists into winter.
  • Leaf: Alternate, simple, evergreen, 1½ to 3½ inches long, with large, spiny teeth. Leaves are dull to dark green on top, yellowish green below.
  • Hardiness: Winter hardy to USDA Zone 5. Hardiness: Winter hardy to USDA zone 5.

Selected cultivars:

There are more than 1,000 cultivars of American holly. The best cultivars are selected for bright fruit displays, attractive leaves and a dense habit. Because American holly is dioecious, male cultivars are also available. Bernheim Forest and Arboretum in Kentucky has one of the best collections of American holly. Representative cultivars include:

  • ‘Goldie’ – A yellow-fruited cultivar. It is an extra heavy fruiter. Other yellow-fruited cultivars include: ‘Canary,’ ‘Longwood Gardens,’ ‘Oakhill Yellow,’ and ‘Morgan Gold.’
  • ‘Grace McCutchin’ – A cultivar selected for its orange-red fruit. Other cultivars with this unique color include: ‘Lake City’ and ‘Manig.’
  • ‘Jersey Knight’ – A male cultivar with dark, shiny foliage. This is one of the Jersey hollies introduced by Dr. E. Orton from Rutgers University. It is an attractive tree even though it does not fruit. ‘Gable’ is another male cultivar.
  • ‘Jersey Princess’ – An exceptional cultivar with excellent form, dark green glossy foliage and good fruit display. This is one of the Jersey hollies introduced by Dr. E. Orton from Rutgers University.
  • Other heavy-fruiting cultivars with good form include: ‘Amy,’ ‘Cheerful,’ ‘Merry Christmas,’ ‘ Miss Helen,’ ‘Old Heavy Berry,’ ‘Parkton,’ ‘Torchbearer,’ and ‘William Paca.’ ‘Judy Evans’ –
  • Good all-around American holly for its conical shape, deep green leaves and red fruit display. Selected by Theodore Klein from a plant growing in Cave Hill Cemetery in Louisville, Ky.

Additional information:
One male American holly should be planted for every three females to ensure production of berries on female trees. The fruit is an excellent food source for wildlife. Raw berries are toxic to humans. Native Americans preserved holly berries for useas decorative buttons. These were highly prized trade items.

American holly wood has been used to make furniture, canes and scroll work. The wood has also been stained black and substituted for ebony in inlay work. Holly wood is ideal for taking dyes, and is used for much of the black and white inlaid lines in musical instruments and furniture. It is also used for knife handles and black piano keys.

American holly is the state tree of Delaware. A great deal of superstition once surrounded holly. It was believed that planting hollies near buildings would provide protection from witchcraft and lightning. It was also believed that the flowers of holly could be used to turn water to ice.

Print fact sheet

American Holly Tree

(Ilex opaca)

A native broad leafed evergreen tree that does not hold up to frigid winters. Extreme low temperatures burn the leaves.

Flowers: small white blooms

Foliage: dark green dense leaves

Blooms: April to early May. American holly is dioecious, which means both a male and a female plant are needed for fruit production. Tiny creamy flowers of both sexes appear in late spring, with pollination occurring thanks to the visits of bees, wasps, ants, moths, and yellow jackets. A single male plant can pollinate up to three females.

Mature size: 20′ — 30′ tall and 10′ — 20′ wide. American holly grows somewhat slowly.

Hardy to zones: 5 — 6

Holly should be planted in fertile, moist, loose, acidic, well drained soil in partial to full sun. Ideal planting times are spring and fall up to before soil becomes frozen. Does poorly in shady conditions caused by surrounding trees. Give the holly its own root space without crowding. This holly grows in a pyramidal shape, but can be pruned.

Holly makes an excellent specimen plant or as a group planting. Typically, only female holly has the red berries.

Caring for the American Holly

American holly is prized as an easy-care tree for the home landscape. It normally doesn’t need additional watering except when first planted, in severe droughts, or late fall before the ground freezes. Even well-established trees may need watering during a severe drought.

Over-fertilization should be avoided. Only one application of a slow-release granular fertilizer designed for acid-loving plants. Once or twice a year, give your holly a treat: an inch-deep mulch layer of used coffee grounds.

Pruning the American Holly

The tree requires routine pruning to keep it in shape. The American Holly is pyramidal shaped as young trees, then become more open and irregular as they mature. Prune to maintain a tighter shape. If necessary, an American holly that has completely lost its shape can be heavily pruned, removing branches at their point of origin. Some prune grouped hollies into hedges. When shaping these shrubs, especially for hedges, do not cut lower branches shorter than the higher branches. Hollies that are narrower at the bottom than the top often lose these lower branches due to lack of sun; sometimes the whole shrub dies.

December, when the plant is dormant, is the best time to prune holly. But it can be lightly pruned any time during the year. Heavy pruning after flowering or in summer reduces berry production.

Additional care tips

Severe winter conditions, and sometimes soil deficiencies, may cause physiological problems such as sun scald and purple spot on the leaves of evergreen hollies. Winds blowing the spiny leaves together causes punctures in the foliage.

Spray holly leaves with anti-transpirant spray to protect surfaces from harsh winter sun and wind. Consider erecting a wind barrier of burlap or similar material (never use plastic!) around holly trees and shrubs exposed to prevailing winter winds. Spread winter mulch on the soil over the roots after the ground freezes.

Healthy American holly trees have few problems. If they do experience some stress, the insects that most often appear will be the leaf miner or scale. Leaf spot and mildew are two of the more common fungal diseases that will attack a stressed specimen.

History/lore/use

The American Holly tree has been popular since the beginning of American history, having served Native Americans with wood for many different applications and berries that were used for buttons and barter. It was said to be a favorite of George Washington, and more than a dozen Hollies planted by him are still in evidence today. It is also widely known as the basic raw material for Christmas wreaths. The first scientific observation of the American Holly tree was recorded in 1744. (source: The Arbor Day Foundation)

Leave a Reply

Your email address will not be published. Required fields are marked *