Conifers are among the most beautiful and versatile of all landscape plants, offering year-round variety of color, form, and texture. They remain underutilized in the South, in part because of the common misconception that they are not adaptable to the climate. Laying such claims to rest, this book introduces readers to conifers that grow successfully in southern landscapes.
Gardeners in the South traditionally have relied on the mass of spectacular spring blooms as the mainstay of their landscapes. However, with the addition of conifers or cultivars of the genus ginkgo, homeowners can enjoy twelve months of low maintenance color. Tom Cox and John Ruter present a variety of conifers that grow from Virginia to Florida to Texas. They provide tips on growing, pruning, preventing disease and pest problems, and on proper selection and cultivation requirements–all unique to the Southeast.
In short, this guide includes essential information about what to buy, where to plant it, and how to maintain it. It also offers advice on what to expect from mature conifers and ginkgo while suggesting genera and species that have proved adaptable and cultivars that have performed well in the southeastern United States. Landscaping with Conifers and Ginkgo for the Southeast is a compilation of years of research and horticulture experience that will aid anyone, whether novice or professional, in creating beautiful year-round landscapes.
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“Landscape selection of conifers and their cultivars for the Southeastern U.S. is now made easier. This is a guide every conifer-seeking gardener and landscaper in the region will want to consult. “–Ronald W. Lance, author of Woody Plants of the Southeastern United States: A Winter Guide
“Bravo! We finally have a reference suitable for conifer enthusiasts in the southern United States that explores not just the common conifers found in nurseries and landscapes but also introduces a plethora of species and varieties rarely encountered in the South and deserving greater use. “–Dave Creech, Director, Stephen F. Austin Gardens
“A good guide to what conifers may be used in the home landscape and any requirements necessary for their success.”–Don Howse, Porterhowse Farms
Tom Cox, past president of the American Conifer Society, is the founder and owner of Cox Arboretum and Gardens in Canton, Georgia.
John M. Ruter, Allan M. Armitage Endowed Professor of Horticulture at The University of Georgia, is a teacher, ornamental plant breeder, and has authored or coauthored over 400 publications and two books.
A new publication from UGA and other southeastern universities equips nursery workers (and others) to protect container and dug plants from freezing temperatures. The publication explains winter acclimatization and how cultural practices (pruning, watering, fertilization, etc.) can impact cold hardiness. The publication also discusses the types of winter injury and methods to protect plants from winter temperatures.
The following is a brief list of some of the Strategies and Techniques to Protect Plants
Push pots together in large blocks.
Wrap outside edge of plants with microfoam, spunbond nonwoven polyester material, or pine straw bales to protect from wind. No protection on inside containers.
Mulch in and around plants on the inside of the block using: i. Newspaper ii. Pine straw, hay, or some other grain iii. Leaves or other composted material
Cover blocks of plants with microfoam or spunbond nonwoven polyester fabric. i. Cover fabric with white polyethylene. ii. Use mulches under the fabric.
Overwinter plants inside a quonset-style greenhouse or similar structure.
Place single-layer white poly cover on house. i. Push plants close together with no further protection. ii. Cover plants inside structure with microfoam or spunbond nonwoven polyester. iii. Heal plants in with mulch.
Place double-layer white poly cover on house with inflator fan to create an insulating dead-air space between plastic covers. i. Also cover plants with microfoam or spunbond nonwoven polyester. ii. Provide an independent heat source inside the house:
Portable forced-air heater that runs on fuel or electricity
Permanent propane, electric, or wood-fired heater
Note: Organization of ideas based on Dunwell and McNeill, 2009.
In the fall, there are several caterpillars that feed on the leaves of trees and shrubs. Although the leaf damage may look significant, the plants may not be as damaged as one may think. You need to understand the type, size and the growth phase of the plant and the type of caterpillar you have before deciding whether to control them.
Deciduous trees will soon be losing their leaves anyway. Foliage feeding by caterpillars is likely to cause little injury. The leaves are going to fall off anyway.
For evergreen trees, foliage loss will be more likely to affect the tree and control is more likely to be needed. For evergreen trees, especially avoid defoliation of entire limbs since these often do not recover.
Bagworms are a long lasting problem since the bags contain hundreds of eggs which will hatch next year. Unfortunately, at this time of year you will need to pick off the bags and destroy them since the bags are sealed now and pesticide cannot easily get inside. Remove the bags you can see right now and plan to check these plants for small bagworms next May.
Young trees or trees weakened by other factors may be more likely to be damaged by loss of foliage to caterpillars than younger, healthy trees.
Evergreen shrubs retain their leaves throughout the fall and winter and into next year. Injured leaves on evergreen shrubs will be visible until they fall naturally – which could be a year or more from now. Control decisions on shrubs should be based on the level of aesthetic injury the home owner will accept.
Deciduous shrubs, like deciduous trees, will be losing their leaves soon and foliage loss to caterpillars in the fall is less likely to cause a lasting problem.
For information on control measures, see these resources:
This disease is Bot canker. Bright, rust-colored branches and yellowing or browning of shoots or branches are the first observed symptoms. Closer inspection reveals the presence of sunken, girdling cankers at the base of the dead shoot or branch. Sometimes, the main trunk shows cankers that might extend for a foot or more in length. These cankers rarely girdle the trunk, but they will kill branches that may be encompassed by the canker as it grows. Read more info in the following publication including disease management.
Authors – Alfredo Martinez, UGA Plant Pathologist, Jean Williams-Woodward, UGA Plant Pathologist and Mila Pearce, Former UGA IPM Homeowner Specialist
Leyland cypress has become one of the most widely used plants in commercial and residential landscapes across Georgia as a formal hedge, screen, buffer strip, or wind barrier. The tree is best suited for fertile, well-drained soils. However, when young, the tree will grow up to 3-4 feet per year, even in poor soils. The tree will ultimately attain a majestic height of up to 40 feet.
Leyland cypress is considered relatively pest-free. However, because of its relatively shallow root system, and because they are often planted too close together and in poorly drained soils, Leyland cypress is prone to root rot and several damaging canker diseases, especially during periods of prolonged drought. Disease management is, therefore, a consideration for Leyland cypress.
This UGA Publication discusses several Leyland Cypress diseases and their management.
Big cities with large expanses of concrete, asphalt, and buildings are usually warmer than the suburbs or countrysides that surround them, a phenomenon known as the urban heat island effect. Now new research from North Carolina State University shows that these urban heat islands increase the number of young produced by the gloomy scale insect — a significant tree pest — by 300 percent, which in turn leads to 200 times more adult gloomy scales on urban trees.
Galls are abnormal vegetative growths on trees that result from the feeding and egg laying activities of various insects and mites. Chemical secretions from the adults while laying eggs as well as the saliva from the feeding larvae cause the plant to react abnormally.
The more common gall producers on trees are aphids, beetles, jumping plant lice, midges, mites and wasps. Each species causes a swelling of plant tissue that is characteristic on specific plant parts such as the stem, twig, leaf or petiole. Most often the gall is more readily identified than the gall producer. It is convenient to identify galls and their producers simply by noting where the gall is located and also the shape of the gall. Table 2 on page 43 of the Forest Health Guide for Georgia lists some of the more common trees that are frequently attacked by gall producers along with a description and location of the gall.
Generally galls are not life threatening to trees. Oftentimes the most drastic effects are premature leaf fall and dieback of several smaller branches.
On small trees, galls should be pruned and destroyed. Leaf and twig litter that is on the ground around the base of the tree should be raked and disposed of. A few of the common species are shown in the images included here.
Merritt Melancon, news editor with the University of Georgia College of Agricultural and Environmental Sciences
Hulking above their neighbors in the Chattahoochee National Forest, Georgia’s century-old hemlocks are giants. But the relatively scarce trees are quickly being felled by the tiniest of insects — the invasive hemlock woolly adelgid.
Tiny pests, big problems
The adelgid is a tiny, fluffy aphid relative that feeds by piercing the bark of hemlock trees and draining the contents of plant cells, which contain nutrients created by the tree during photosynthesis. Millions can live on one tree, and by the time they finish feeding, the tree no longer has the strength to transport water and nutrients from its roots to its branches. The pest first arrived in Georgia 10 years ago after moving south through the forests that surround the Appalachian Mountains.
To date, the adelgid has killed millions of hemlocks on the mountainsides and stream valleys of the Appalachians, from New England south to the Smokies and the north Georgia mountains. Once infested, a centuries-old tree can die within 3 or 4 years said Will Hudson, a forest entomologist with UGA Extension.
University of Georgia researchers are racing against time looking for long-term biocontrols for the nutrient-gobbling pest.They hope by preserving specimen stands of hemlocks with insecticides now, there will be enough trees left to aid in regenerating Georgia’s hemlocks once the bio-control agents are ready.
“We can’t just let a bug loose in the forest and hope it works. The requirements for testing and screening of a new biocontrol agent are — and rightfully so — really, really stringent, and it takes time. The hemlocks don’t have that time,” said Hudson.
Enter the Legacy Tree Project — a public-private partnership between UGA researchers, Valent USA, private tree care companies and several municipalities. The project’s goal is to preserve stands of hemlocks so they can regenerate once the woolly adelgid is under control.
While hemlocks make up a small percentage of the forest canopy in Georgia, they are vitally important to the forest ecosystem — especially around streams. The giant trees shade streams and stream banks and provide the cool waters that Georgia’s trout populations need to survive while sustaining the tourist economy that surrounds the trout.
In addition to the aesthetic impact of the loss of the largest trees in mountain forests, dead trees pose a threat of falling, making camping, hiking and even driving, risky.
Two solutions, one goal
The woolly adelgids can be controlled two ways. One way is through the development or discovery of biocontrol agents — predatory insects that eat adelgids, but leave the rest of the ecosystem intact. This is a painstaking process of trial and error, but will offer low-cost, long-term control.
The other method is to treat every hemlock in the forest to prevent or cure adelgid infestation. This would be prohibitively expensive, time-consuming, logistically implausible and possibly ecologically damaging.
Entomologists at UGA and the U.S. Forest Service, including recently retired UGA forest entomologist Mark Dalusky, have identified and released two predatory beetles. They hope these insects will be effectively control the adelgid without harming the forest, but neither beetle has reached the numbers needed to control the pest.
Saving trees now, so that they can be preserved later
UGA entomologists, north Georgia arborist and hemlock enthusiast Jann George and Legacy Tree Project founder Joe Chamberlin have teamed up for the effort.
Chamberlin’s company, Valent, helped launch the Legacy Tree Project in 2010 in a handful of Midwestern towns with the goal of saving ash trees from emerald ash borers. Thousands of trees were saved, and a framework for battling other invasive tree pests was developed.
Valent donates insecticide where landmark hemlocks are dying – like the Chattahoochee National Forest.
The insecticide, a dry powder mixed with water, is injected into the ground around the hemlock’s root ball and the tree slowly absorbs the material, which kills the adelgids and prevents new infestations.
“Nearly 100 percent of the chemical is absorbed by the tree, which means there is very little chance any will move into nearby streams or groundwater,” George said. “There is hope for biological controls coming down the line. But the only way to get your hemlock tree back to health, at this point, is to use chemicals.”
This is the first time that the Legacy Tree Project has worked on public land. George has worked with Young Harris, Clarkesville, Dillard and Sky Valley and saved between 10 and 15,000 hemlocks on private land.
“The problem of global trade and invasive species are here to stay,” Chamberlain said. “We only have so many well adapted native species of trees that we can rely on, and we need to maintain them. What we’re trying to do is build awareness about invasives and stimulate action to help protect native tree populations.”
For more information about the hemlock infestation in north Georgia and UGA’s research into stopping the pest, visit www.forestpests.org/.
Jean Williams-Woodward, UGA Extension Plant Pathologist
I’ve been getting some calls and emails about “orange goo” growing on cut hardwood stumps. It is weird, interesting and looks like an attack of ‘the blob” (see the image to the right). So, what causes the orange goo?
It’s the yeast, Cryptococcus macerans, growing on the sugary sap flowing from the cut branches or trunk. A few other fungi can also be found mixed in, including some species of Fusarium and Acremonium. The yeast is harmless to the plant; it is just growing on the sap.
The orange color comes from the pigment carotene, which is the same pigment that colors carrots orange. Some strains of Cryptococcus macerans could cause disease in humans, so if you can’t resist touching it, wash your hands! Generally though, it is harmless and just another interesting oddity in the fungal world.
Spot anthracnose of dogwood, not to be confused with the lethal canker disease, dogwood anthracnose, is common on flowering dogwoods in the Spring. Spot anthracnose, caused by the fungus, Elsinoe corni, causes small, circular, reddish spots on the bracts and leaves. Severe infection can cause leaf and bract distortion.
Spot anthracnose is mostly an aesthetic disease. It will not kill the trees or significantly affect tree growth. Once spots are seen, it is too late to manage the disease with fungicides. Fungicides are generally not needed nor recommended unless in nurseries where tree’s aesthetics can affect sales. Fungicides needed to be applied at bud break to reduce infection and disease development.