Invasive Insect Damages US Ash Trees

A beetle invasion in the United States has killed at least twenty million ash trees. The invasion of the emerald ash borer was first discovered near Detroit, Michigan, in 2002. Experts believe the small green insects arrived in the 1990s in shipments of goods from China.

The emerald ash borer has destroyed trees in the Midwest and as far east in the United States as Maryland. The insects have also spread as far north as Ontario, Canada. Emerald ash borers are attacking tree farms and can also spread when logs and firewood are transported.

Ash trees are popular. They grow well in heavy clay soils, and they can survive ice storms well. They produce many leaves, so they provide shade protection from the sun. And in the fall the leaves turn a beautiful gold and purple.

Ash trees can resist many diseases. But they cannot resist the emerald ash borer. It lays eggs on the bark. Then the young larvae drill into and feed on the inner bark. This harms the ability of the tree to transport water and nutrients.

The United States Department of Agriculture is working to save the ash tree. So are agriculture departments and university extensions in a number of states.

In some places, farmers are using "detection trees." These have an area where bark has been cut away. The area circles the tree and is called a girdle. The girdling process weakens the trees. It makes them easier targets for borers, and shows if the insects are nearby.

Efforts to stop the spread of the emerald ash borer include cutting down affected trees. A tree farmer in Maryland, for example, recently faced the loss of hundreds of trees.

There are worries that the ash tree might disappear unless the invasion is controlled. To prepare for such a possibility, a government laboratory is collecting seeds from ash trees.

David Burgdorf works in East Lansing, Michigan, for the Natural Resources Conservation Service; the service is part of the United States Department of Agriculture. He is asking people to send in ash seeds. The laboratory examines and x-rays the seeds to make sure there are no living borer embryos.

The best seeds are then sent for storage in a seed bank in Fort Collins, Colorado. There, they are dried and frozen at the National Center for Genetic Resources Preservation. Should the seeds ever be needed, the hope is that scientists might someday develop an ash tree that could resist the little green attackers.

Source:
VOA News Service

United Nations Study Finds Improvements in the World's Forests

The Rome-based United Nations Food and Agriculture Organization (FAO) recently presented its biannual report on the State of the World's Forests, which found that most countries in Europe and North America have reversed centuries of deforestation.

In its March 2007 report, the FAO noted that economic prosperity and careful forest stewardship have had positive effects on the world's forests, with many forests showing a net increase in forest area.

But forests in poorer nations, and those embroiled in wars and internal conflicts, still face substantial threats. Around 13 million hectares of forest are still lost annually to other land uses. However, the net deforestation over the last five years has been reduced from nine to seven million hectares. This is mainly due to reforestation and preservation of existing forests.

Africa is one region that faces huge losses. The continent accounts for about 16 percent of the global forests. Between 1990 and 2005, Africa lost over nine percent of its trees.

On the positive side, forest area increased in Asia between 2000 and 2005. While severe deforestation continues in South-East Asia, especially Indonesia, Malaysia, Papua New Guinea, there were tremendous increases in forested areas in China, Vietnam and a number of smaller countries.

One of the principal causes of deforestation is the conversion of land for farming or livestock. Forests currently cover about 30 percent of the world's land area. According to the FAO the world lost three percent of its forests between 1995 and 2000.

Source:
VOA News

Treeflights Website Offers Plan to Plant Trees to Help Reduce Global Warming

A new international website is offering environmentally conscious airplane passengers a chance to plant a tree to offset the carbon dioxide damage from flying.

Fuel burned during an airplane's flight produces carbon dioxide (CO2), which scientists say contributes to global warming. Trees absorb carbon dioxide using the sun's energy.

The website, www.treeflights.com, whose slogan is "You fly - we plant," will plant one tree in a forest in Wales for each flight taken for a fee of about $19.

Treeflights founder, Ru Hartwell, says it is a simple idea that gives something back to the planet.

"Flying is a little bit hard on the planet, but planting a tree is an ecologically positive thing to kind of make amends for some of the damage that you are causing," said Hartwell.

Hartwell says because trees take a long time to mature, planting a tree does not make your flight carbon-neutral or immediately cancel out the CO2 emitted from your flight.

"We are very, very keen to stress when you plant a tree, it is not something you do for yourself. It is a long-term thing," he continued. "It is definitely not a quick fix. As humans, we are so used to thinking about this week or about next week or maybe next year. Really, to get on top of this problem, we have got to be thinking about 50 or 100 years into the future and that is what tree planting is all about. It is something you do for future generations."

Passengers can select from a variety of tree species such as birch, oak, poplar, and willow. Although Treeflights is based in Wales where Hartwell lives, he says people from around the world request to have trees planted.

"The thing to understand is that we all share the same atmosphere so it does not really matter where you are flying or where the tree is planted," noted Hartwell. "The destructive effect of the flight is the same, irrespective of where you are flying and the beneficial effect of the tree planting is the same irrespective of where the tree is planted."

Treeflights gives passengers the option of adopting a tree. Hartwell says people can visit one of the three planting sites in Wales where their tree, identified with a serial number, is planted.

Treeflights customer, Francesca Attala, says while planting a tree does not entirely negate the effects of air travel, it is better than doing nothing.

"With my work, I travel a lot. I actually use planes and trains and automobiles quite a lot and I think it is a small way of giving something back," said Attala. "I know that it is not going to make a difference tomorrow, but it will make a difference for the future generations. It is a very slow, very patient way of giving something back to the planet, but I still think it is worth it."

The United States Bureau of Transportation Statistics reports U.S. airlines carried 746 million passengers on 11 million flights in 2005 and the number of passengers is only expected to increase.

Hartwell eventually hopes to forge partnerships with the airline industry to encourage more passengers to make theirs a treeflight.

Source:
VOA News Service
Authors: Barbara Schoetzau & Amanda Cassandra
First published: September 25, 2006

Dogwood FAQ

Should I plant flowering dogwoods? I have heard that dogwood anthracnose is devastating dogwoods and that none of them are resistant to this disease.

The native flowering dogwood is still a valuable landscape tree and is worthy of planting in the right spot. Dogwood anthracnose is caused by a fungus, Discula destructiva, that thrives in rainy, cool spring weather. A quick warmup in spring will stop the fungus in its tracks. If you plant your dogwood in a location that gets morning sun and good air circulation, it is much less likely to succumb to this disease. Dogwoods are shallow rooted and benefit greatly from some extra water in times of drought; trees stressed by drought are much more likely to be damaged by dogwood anthracnose than trees grown with ample soil moisture. It's also a good idea to remove watersprouts that grow on the trunk and large branches the fungus can use these succulent stems to travel quickly from the leaves to the inner bark, where it kills the living cambium tissue. If the fungus reaches a major branch or the trunk, it can kill the living inner bark, resulting in death of the entire tree.

I recently planted a new dogwood tree. It seemed healthy when I bought it, but the leaves soon took on a grayish white cast and puckered. What should I do?

In recent years dogwood powdery mildew has become a major threat to dogwoods. The most notable symptom of powdery mildew is a powdery white film on the leaves; usually the leaves are distorted and growth is diminished by the powdery mildew fungus. Fortunately many fungicides such as neem and horticultural oil are quite effective in controlling mildew and are not as toxic as conventional chemical fungicides. Foliage should be treated as soon as it has fully expanded to prevent the infection of powdery mildew. Repeat applications may be needed to protect the foliage from mildew through the growing season.

Don't the flowers of the native flowering dogwood, Cornus florida, grow singly?

No. The tiny yellow flowers are actually clustered tightly together in the middle of the four showy bracts. While the whole thing looks like a flower with four petals and golden stamens in the middle, it is correctly referred to as an inflorescence, which is a botanical term for a flower cluster. The bracts attract pollinating insects to the flowers that lie between them, much as petals attract pollinators to many flowers, but the bracts are modified leaves and cannot be correctly called petals. There may be as many as twenty small flowers sandwiched tightly between the four bracts.

When should I prune my dogwood?

When and how you prune your dogwood depends on what kind of dogwood you have. Shrubby dogwoods that are grown primarily for the colorful bark on the young twigs should be cut back to the ground periodically to remove less attractive older stems and promote the growth of new, colorful stems. The other dogwoods require little pruning. Dead and diseased branches should be removed as soon as they are noticed. You can the thin the branch structure of your dogwood by selectively removing crowded branches at the point where they originate from a larger branch or the trunk. You can also remove low-hanging branches. This kind of pruning, which is done to shape and thin a dogwood, is best done in late winter or early spring before new growth begins. Be very careful not to injure the bark on the trunk; it is thin and easily injured. Injured bark provides an easy entry point for dogwood borer larvae.

Can I eat the red fruits of dogwoods?

Some dogwoods produce larger fruits than others, and some are tasty and some are not. The fruits of our native flowering dogwood, Cornus florida, are not poisonous, but they do not have a very pleasing flavor. The Chinese dogwood, Cornus kousa, has spherical fruits about the size of a quarter. When ripe in midsummer, they turn coral red and develop their full flavor and sweetness, with a flavor comparable to some melons. The cornelian cherry, Cornus mas, produces a tart, elongated fruit with a hard pit in the middle and a thin layer of flesh. These bright red fruits are sometimes used to make preserves, jam, or jelly with a flavor similar to cherries.

I want to plant some dogwoods in my yard. They are common in the woodlands near my home-can't I just transplant some into my yard to save some money?

While dogwoods can be transplanted, it is difficult to transplant trees of any size from the wild. Dogwoods have shallow, far-reaching root systems, and it is difficult to get enough roots when digging a dogwood to sustain it while it is getting established in its new home. If you do get a large enough root ball, you will have disturbed a large spot in your local forest, which amounts to an invitation for woody weeds that may spread and degrade a woodland once they have gained a foothold. Another problem lies in the fact that dogwoods do not easily adapt to wide variations in light conditions. A tree that grew in the understory of the forest will most likely suffer greatly if moved into increased sunlight. Purchase a small dogwood from your favorite nursery or collect a few seeds from the dogwoods and start your own trees. Plant the seeds after removing the thin layer of pulp and place them in a pot with free-draining potting soil, water it well, and leave the seeds outdoors where they can be exposed to winter's cold. With some patience, the seeds should sprout sometime in the following growing season. They can be potted into progressively larger pots, or they can be planted directly where they are to grow.

I have some redosier dogwoods that I planted several years ago. They were beautiful for several years, but now they produce fewer red twigs. Is there anything that I can do to increase the production of red twigs?

Chop the plants back to the ground. Like most shrubby dogwoods, the redosier dogwood is perfectly adapted to severe pruning. In their native habitat, redosier is a food source for beavers and it responds to severe pruning by sending out a vigorous new flush of growth. If not pruned back every three or four years, redosier dogwood develops gray bark that is not nearly as striking as the bark on younger twigs.

Related topic: Flowering Dogwood

Source:
U.S. National Arboretum

Cultivating Conifers

What conditions do I need to grow conifers?

Depending on your soil type, available sunlight, and climate, you can choose a conifer that is very likely to succeed no matter where you live. For most conifers, slightly acid soil that is loamy and well-drained is ideal. Hemlock, dawn redwood, baldcypress, and Atlantic white cedar like soil that stays consistently moist while junipers, pines, and the true cedars are well-adapted to dry conditions. Black spruce, balsam fir, and Siberian cypress are at home where winters are bitterly cold while Arizona cypress, Japanese cedar, and deodar cedar thrive in warm temperate areas. Most conifers grow best in full sun, but a bit of afternoon shade is best for the dwarf conifers in hot southern zones. Hemlock, yew, and plumyew tolerate shade well.

When and how do I plant a conifer?

It's best to plant conifers in early autumn unless you live in an area where winters are bitterly cold. In the cool days of autumn, they have more time to make root growth in moist soil. Since good drainage through the soil and ample pore spaces for air are key to the survival of conifer roots, be careful not to plant them too deeply, especially if your soil is heavy or has a lot of clay in it. If you plant a conifer that was grown in a container, prune off any roots that encircle the outside of the root ball. If it was dug and transported with burlap and twine around the root ball, remove as much of the burlap, ties, and wire as you possibly can without injuring the roots. It's best not to amend the soil in the planting site. Compost or peat moss might pamper the roots and discourage the development of a broad, expansive root system. Stake your new tree only if it is planted in a windy location, and apply a couple of inches of shredded hardwood or pine bark mulch to the root zone to preserve soil moisture. Keep the mulch at least six inches away from the trunk. Water deeply and infrequently so the soil stays evenly moist at its depths but dries out partially at the surface between waterings. After the tree has established itself and begun to grow, remove any stakes and wires that were used to support it.

What makes a dwarf conifer dwarf?

Dwarf conifers are dwarf because of their genetics. A single bud in a normal tree may change its genetics and produce a clump of densely branched, dwarf growth. These growths are called witches brooms. Other dwarf conifers originated as slow growing individuals in a population propagated from seed. Dwarf conifers are often propagated by grafting since they are usually difficult to root and will not come true from seed.

How should I prune my conifers?

Conifers, unlike many deciduous and broad-leaved trees and shrubs, should never be pruned too drastically since most of them cannot sprout new growth from old wood. Yew and baldcypress are exceptions to this general rule and can sprout new growth even if cut back severely.

Never remove more than one third of the total growth at one time, and be sure to leave some green tissue that has potential to produce new growth. Never remove all of the green portion of conifers like juniper and arborvitae by shearing them. Removal of much of the green growth can result in a permanently misshapen plant or death of the plant. Control the size of sprawling conifers by pruning the longest branches back to where they meet with a shorter branch.

Pines can be shaped and forced to produce denser growth by a pruning technique known as candling. Candles are the elongated shoots produced at the beginning of each flush of growth. After the candles are fully grown, needles grow out of the candles. The candles can branch while they are growing if they are pruned before the needles begin to emerge. Break off about two-thirds of the candle with your fingers. Don't use pruners since you are likely to damage remaining needles, causing them to look unsightly.

Source:
U.S. National Arboretum

Trees and Shrubs

The following posts cover topics related to deciduous, evergreen, coniferous, hardwood and softwood trees and shrubs.

• 2000-Year-Old Date Palm Seed Sprouts into Sapling

• American Red Raspberry

• Balsam Fir

• Common Persimmon

• Dealing with Hazardous Defects in Trees

• Evergreen Huckleberry

• Flowering Dogwood

• Golden Currant

• Highbush Blueberry

• Scientists Discover City Tree Grows Twice as Large as Country Clone

• Sugar Maple

• Two New Lilacs Debut at the U.S. National Arboretum

• Western Redwoods Endangered by Killer Microbe

• The Wollemi Pine: Rare Conifer Dates Back to Jurassic Age

Two New Lilacs Debut at the U.S. National Arboretum

Two of the newest additions to an ever-growing list of original ornamental plants produced by breeders with the U.S. National Arboretum, Washington, D.C., are lilac cultivars named “Old Glory” and “Declaration.” They were recently released to the public by the arboretum, administered by the Agricultural Research Service (ARS), the U.S. Department of Agriculture’s chief scientific research agency.

The 446-acre arboretum maintains and displays many of the ornamentals and flowering trees, shrubs and herbaceous garden plants found in cities, towns and home landscapes throughout the United States. To these traditional favorites, researchers there and in the ARS Floral and Nursery Research Unit in Washington, have added many of the superior new floral and woody nursery plants now seen in public areas, as well as in private gardens.

Old Glory and Declaration are two new Syringa cultivars developed in the arboretum’s shrub-breeding program. Bred and initially selected by the late USNA horticulturalist Donald Egolf and released by geneticist Margaret Pooler, they follow the release of the “Betsy Ross” lilac in 2000. Old Glory and Declaration are each suited to a variety of landscape uses, including as background plantings in shrub borders, as deciduous hedges, or for mass-plantings in larger areas.

Old Glory was selected for its abundant fragrant, bluish-purple flowers, rounded growth habit and disease-tolerant foliage. In 25 years of testing in Washington, it grew nearly 11.5 feet high and a little over 13 feet wide. Compared to other Syringa x hyacinthiflora types of lilac, Old Glory has shown good field tolerance to Cercospora blight and Pseudomonas syringae in warmer climates where these diseases are a problem. It has also shown better-than-average tolerance to powdery mildew.

Declaration was selected for its fragrant, dark-reddish-purple flowers, nearly foot-long flower clusters and open, upright growth habit. In 25 years of testing at the arboretum, it grew 8.5 feet high and about 6.5 feet wide and also is well suited to a variety of landscape uses. However, it is recommended primarily for traditional, cooler lilac-growing regions.

Both Old Glory and Declaration bloom in mid- to late April at the arboretum, which is located in Plant Hardiness Zone 7a and has an average minimum temperature range of 5 to 0 degrees Fahrenheit. Planting stock should be available from a limited number of nurseries in 2006, and should be available from retailers in 2008.

Source:
U.S. Department of Agriculture
Author: Alfredo Flores
First published: May 2, 2006

Scientists Discover City Tree Grows Twice as Large as Country Clone

This is a story about a city tree and a country tree. Each started as an identical sapling of a common cottonwood, a fast-growing poplar. Scientists wanted to analyze the impact of multiple pollutants in the two settings. And they found to their amazement that the city tree grew twice as large as its country clone.

Jillian Gregg set about to find the worst, most polluted environment in New York City. There she planted a tree. She planted another in the Hudson River Valley 80 kilometers from New York. She and a team of scientists at Cornell University and the Institute of Ecosystems Studies in New York followed the test sites over three years to understand why the city trees grew bigger.

In both locations the plants grew next to atmospheric pollutant monitoring stations. "What we did was to separate factors above ground Vs below ground. So, we went to a series of urban and rural sites and collected the soil and took them all to the same place," she says. "We could [then] ask the question within each soil type, do plants grow less in New York City?"

The answer was no. No matter what soil they were grown in, they got the same results. City trees were double the size of their country cousins. "That result was consistent for 11 different soils, 8 different sites, 2 different transects and 3 consecutive growing seasons," she says.

The scientists then set out to study above ground factors that would account for the difference. When a number of experiments ruled out warmer temperatures and higher concentration of nitrogen and carbon dioxide, scientists turned their attention to the stunted trees in the country.

Jillian Gregg says the answer is a difference in chemistry in the atmosphere that favors city trees. "We found that the cumulative ozone exposures were higher outside the city center," she says.

Rural ozone starts in the city. Automobile and industrial emissions interact with sunlight to form ozone, which the wind blows into the country.

The difference between the city and the country hinges on nitric oxide - one of the primary precursors of ozone, which was found in high concentrations in the city.

Jillian Gregg explains that it produces a chemical reaction that causes urban ozone levels to drop to nearly zero at night and in the winter. "So ozone is continually created and destroyed and created and destroyed within the city, but when that same air mass goes to the country, the high ozone concentrations remained in the atmosphere for a longer period. So you have a higher cumulative ozone exposures."

Which Jillian Gregg says translates into stunted trees. She says the work is a cautionary tale of the effects of urban pollution. "It is important for us to understand that we cannot escape the urban pollutants by going to the country, the effects can have an even greater impact there," she says. "So, if we want to get away from all of these pollutants, we need to curb them at their source."

Jillian Gregg and colleagues from Cornell University and the Institute of Ecosystem Studies write about the work in the journal Nature.

Source:
VOA News Service
Author: Rosanne Skirble
First published: August 3, 2003

2000-Year-Old Date Palm Seed Sprouts into Sapling

Israeli scientists have successfully germinated a 2000-year-old date palm seed that has now grown into a sapling. Scientists say the ancient Biblical tree has properties that could have applications in medicine.

Israeli scientists are excited about this date palm's medicinal possibilities. Researchers at the Louis Borick Natural Medicine Center in Jerusalem grew it from a 2000-year-old seed. It and other seeds were found in the desert at Masada, the archeological site famous in Jewish history.

Dr. Sara Sallon, who led the project to resurrect the seeds, describes a colleague's reaction when the plant began to grow. "She said, 'There is a little green tip coming out of the crack', and we were kind of, 'What?' So, I just said, 'Just keep doing what you are doing'."

The palm is named "Methuselah," after the Biblical figure, who was said to have lived 969 years.

Dr. Sallon said these are the oldest seeds ever germinated. ”Historically, of course, it is fascinating to wake up something that has been asleep for so long, and the whole area that this opens up, that if you can wake up a seed after 2000 years, and get it to grow, there are a lot of possibilities in that area that we can also explore."

Dr. Sallon said the ancient date palm was used to fight infection, as a fertility treatment, and even as an aphrodisiac. She and her colleagues hope the palm still retains its medicinal properties.

The plant's DNA structure is being analyzed to find out. If the plant survives, and is a female, it will take nearly 30 years before it bears any dates. If it turns out to be a male, it will not bear fruit but will still be a curiosity to scientists.

Source:
VOA News Service
Author: Kimberly Russell
First published: June 28, 2005

Western Redwoods Endangered by Killer Microbe

A microscopic pathogen, introduced to the United States about 1995, is wiping out a relative of the oak tree called the tanoak in the western states of California and Oregon. Only about ten percent of known tanoaks remain. At a slower rate, the same organism is also attacking 15 other deciduous, or leaf-bearing, trees and plants. And there is alarming evidence that the world's tallest tree, the soaring California redwood, may be next.

The awe-inspiring redwood, which can live 2,000 years and top 100 meters in height, is such a signature symbol of the northern California coast that the area is called "the Redwood Empire." Logging almost wiped out that empire until harvesting was regulated.

Today, more than 250,000 hectares of redwood forest remain in timber production. And safe havens for the trees were established in state and national parks. No wonder scientists and preservationists are worried about the recent discovery that the deadly Phytophthora ramorum organism has migrated from broadleaf trees to the redwoods, which are needle-bearing conifers.

Plant pathologists Matteo Garbelotto at the University of California in Berkeley, and David Rizzo at the university's branch in Davis, California, have found DNA evidence of the pathogen in dead redwood branches.

Dr. Garbelotto says Phytophthora, which is a microscopic cousin of the algae that form ocean kelp, is especially virulent because it is carried by the wind as well as moving through soil and water. So far in bushes like rhododendrons and huckleberries, it invades and kills only selected leaves and small branches. But in oaks and tanoaks, it produces enzymes that disintegrate the tree trunk's bark.

"And then once it's gone through the bark, it colonizes the cambium, which is the live part of the tree," Dr. Garbelotto said. "And by doing so, it basically kills it. It destroys the cambium, and once it's done girdling the whole circumference of the tree, the plant is dead."

Dr. Garbelotto says that while blotching has been found on redwood needles, and Phytophthora DNA has been confirmed in small, dead redwood branches, he and Dr. Rizzo have not yet confirmed that entire redwood trees have been killed by the organism.

"The branch that we're looking at is dead, but the branch could be dead for different reasons - many different reasons," he said. "What it may do - it may take out every single branch, one at a time. But that may take, you know, a long, long time. We could talk tens or even hundreds of years for a redwood."

Ken Bovero is an arborist in Mill Valley, California. He first identified Phytophthora in oaks and coined the term "sudden oak death." He says he's cut into three dead redwoods in the forest, seen other distressed redwoods, and found evidence of Phytophthora deep inside the giant trees.

"I saw dark, vertical staining between the sapwood and the heartwood. I also found a heavy odor of fermentation," he said. "It smells as if you had freshly uncorked a bottle of wine, and if you smell the cork, you smell that fermentation. That's what alarmed me. So I sent samples to a laboratory in Davis, California, and they confirmed that Phytophthora fungus was present in the samples that I sent them."

Scientists can do little to stop a blight in the areas where an outbreak has already occurred. In the late 1800s, a blight introduced to the New York Botanical Garden wiped out the entire East Coast population of chestnut trees. About the same time in Australia, a pathogen similar to Phytophthora killed a thousand native species.

Dr. Garbelotto says the spread of disease can be better controlled today than in the days of the chestnut blight. If it's confirmed that Phytophthora is threatening redwood trees, affected stands can be quarantined. Then other redwoods could be sprayed with copper sulfate, which would kill attacking spores and, hopefully, save the Redwood Empire.

Source:
VOA News Service
Author: Ted Landphair
First published: January 15, 2002

Dealing with Hazardous Defects in Trees

Trees add to our enjoyment of outdoor experiences whether in forests, parks, or urban landscapes. Too often, we are unaware of the risks associated with defective trees, which can cause personal injury and property damage. Interest in hazard tree management has increased in recent years due to safety and liability concerns resulting from preventable accidents. Recognizing hazardous trees and taking proper corrective actions can protect property and save lives.

A "hazard tree" is a tree with structural defects likely to cause failure of all or part of the tree, which could strike a "target." A target can be a vehicle, building, or a place where people gather such as a park bench, picnic table, street, or backyard. In general, it's best to consult a professional arborist when considering a major intervention with a hazardous tree.

Because of the natural variability of trees, the severity of their defects, and the different sites upon which they grow, evaluating trees for hazardous defects can be a complex process. This fact sheet presents guidelines, not absolute rules for recognizing and correcting hazardous defects. When in doubt, consult an arborist.

Inspecting Trees

Inspect trees under your responsibility every year. Tree inspections can be done at any time of year, leaf-on or leaf-off. To be thorough, inspect trees after leaf drop in fall, after leaf-out in spring, and routinely after severe storms.

Inspect trees carefully and systematically. Examine all parts of the tree, including the roots, root or trunk flare, main stem, branches, and branch unions. Be sure to examine all sides of the tree. Use a pair of binoculars to see branches high off the ground.

Consider the following factors when inspecting trees:

Tree Condition: Trees in poor condition may have many dead twigs, dead branches, or small, off-color leaves. Trees in good condition will have full crowns, vigorous branches, and healthy, full-sized leaves; however, green foliage in the crown does not ensure that a tree is safe. Tree trunks and branches can be quite defective and still support a lush green crown.

Tree Species: Certain tree species are prone to specific types of defects. For example, some species of maple and ash in the Northeast often form weak branch unions (page 5 ), and aspen is prone to breakage at a young age (50-70 years) due to a variety of factors, including decay and cankers.

Tree Age and Size: Trees are living organisms subject to constant stress. Pay particular attention to older trees, which may have accumulated multiple defects and extensive decay.

What to Look For

Hazardous defects are visible signs that the tree is failing. We recognize seven main types of tree defects: dead wood, cracks, weak branch unions, decay, cankers, root problems, and poor tree architecture. A tree with defects is not hazardous, however, unless some portion of it is within striking distance of a target.

Dead Wood

Dead wood is "not negotiable"-- dead trees and large dead branches must be removed immediately! Dead trees and branches are unpredictable and can break and fall at any time. Dead wood is often dry and brittle and cannot bend in the wind like a living tree or branch. Dead branches and tree tops that are already broken off ("hangers" or "widow makers") are especially dangerous!

Take immediate action if...

• A broken branch or top is lodged in a tree.
  
  
• A tree is dead.
  
  
• A branch is dead and of sufficient size to cause injury (this will vary with height and size of branch).
  

Cracks

A crack is a deep split through the bark, extending into the wood of the tree. Cracks are extremely dangerous because they indicate that the tree is already failing.

Take action if...

• A crack extends deeply into, or completely through the stem.
  
  
• Two or more cracks occur in the same general area of the stem.
  
  
• A crack is in contact with another defect.
  
  
• A branch of sufficient size to cause injury is cracked.
  

Weak Branch Unions

Weak branch unions are places where branches are not strongly attached to the tree. A weak union occurs when two or more similarly-sized, usually upright branches grow so closely together that bark grows between the branches, inside the union. This ingrown bark does not have the structural strength of wood, and the union is much weaker than one that does not have included bark. The included bark may also act as a wedge and force the branch union to split apart. Trees with a tendency to form upright branches, such as elm and maple, often produce weak branch unions.Weak branch unions also form after a tree or branch is tipped or topped, i.e., when the main stem or a large branch is cut at a right angle to the direction of growth leaving a large branch stub. The stub inevitably decays, providing very poor support for new branches ("epicormic" branches) that usually develop along the cut branch.

Take action if...

• A weak branch union occurs on the main stem.
  
  
• A weak branch union is cracked.
  
  
• A weak branch union is associated with a crack, cavity, or other
  defect.
  

Decay

Decaying trees can be prone to failure, but the presence of decay, by itself, does not indicate that the tree is hazardous. Advanced decay, i.e., wood that is soft, punky, or crumbly, or a cavity where the wood is missing can create a serious hazard. Evidence of fungal activity including mushrooms, conks, and brackets growing on root flares, stems, or branches are indicators of advanced decay.

A tree usually decays from the inside out, eventually forming a cavity, but sound wood is also added to the outside of the tree as it grows. Trees with sound outer wood shells may be relatively safe, but this depends upon the ratio of sound to decayed wood, and other defects that might be present. Evaluating the safety of a decaying tree is usually best left to trained arborists.

Take action if...

• Advanced decay is associated with cracks, weak branch unions, or other defects.
  
  
• A branch of sufficient size to cause injury is decayed.
  
  
• The thickness of sound wood is less than 1" for every 6" of diameter at any point on the stem.
  

Cankers

A canker is a localized area on the stem or branch of a tree, where the bark is sunken or missing. Cankers are caused by wounding or disease. The presence of a canker increases the chance of the stem breaking near the canker. A tree with a canker that encompasses more than half of the tree's circumference may be hazardous even if exposed wood appears sound.

Take action if...

• A canker or multiple cankers affect more than half of the tree's circumference.
  
  
• A canker is physically connected to a crack, weak branch union, a cavity, or other defect.
  

Root Problems

Trees with root problems may blow over in wind storms. They may even fall without warning in summer when burdened with the weight of the tree’s leaves. There are many kinds of root problems to consider, e.g., severing or paving-over roots; raising or lowering the soil grade near the tree; parking or driving vehicles over the roots; or extensive root decay.

Soil mounding, twig dieback, dead wood in the crown, and off-color or smaller than normal leaves are symptoms often associated with root problems. Because most defective roots are underground and out of sight, aboveground symptoms may serve as the best warning.

Take action if...

• A tree is leaning with recent root exposure, soil movement, or soil mounding near the base of the tree.
  
  
• More than half of the roots under the tree’s crown have been cut or crushed. These trees are dangerous because they do not have adequate structural support from the root system.
  

Source:
USDA Forest Service

The Wollemi Pine: Rare Conifer Dates Back to Jurassic Age

Inside a Plexiglas case is a small tree whose family roots date back to the age of the dinosaurs. The U.S. Botanic Garden is giving the three-year-old Wollemi Pine - which stands about half a meter high - a protected start in life.

"This exhibit is really all about the excitement about finding something brand new," says Christine Flanagan, spokeswoman for the U.S. Botanic Garden. "Suddenly we have a living fossil of which the last known living populations were 90 million years ago."

The Garden is cultivating the Wollemi under a trial program with the Royal Botanic Gardens and New South Wales National Parks and Wildlife Service in Australia.

"This tree provides us a window on all of the evolution of an entire plant family that we don't know that much about," Ms. Flanagan says. "In its genes is the story of how it survived from the Jurassic until today."

The Wollemi Pine was discovered ten years ago by a park ranger and avid bushwalker in a remote wilderness area near Sydney. John Benson, senior ecologist at the Royal Botanic Gardens in Sydney, monitors the hidden grove of about 100 Wollemi. He says the conifer-like pine is a new genus in the 200 million-year-old Araucariaceae family.

"It grows up to about 40 meters high and up to about 1 meter in diameter," he says. "It has got a very unusual bubbly chocolate colored bark that I have never seen on another tree species anywhere. It has different type of foliage from the juvenile stage to the adult stage. The juvenile stage, the leaves look a little bit ferny. As the tree grows the leaves change and become too hardened, more spiky looking leaflets."

The location among steep canyons in Wollemi National Park remains a secret. The park wants to keep curious hikers - who might trample the trees or bring in disease on their boots - away.

John Benson says the Royal Botanic Gardens and the New South Wales National Parks and Wildlife Service are behind an effort to conserve the tree through propagation. They are working with test gardens in Australia and elsewhere around the globe.

"They have found out things like they can withstand temperatures from minus 5 [degrees Celsius] to plus 45 [degrees Celsius] as long as it has got water," says John Benson. "It can withstand a little bit of frost. It certainly would be a suitable potted plant for the northern part of America and Europe and Japan, and it would grow in gardens in the mid-latitudes fairly easily. And, they have found that it grows in a wide variety of soils as well."

He says working with the tree is like going back to the days of the dinosaurs. "I feel that I am basically back in the Jurassic period, which ran from about 200 million years ago to 65 million years ago," he says. "I feel that I am not on this earth. It is a relic that has hung on there. It didn't want to go extinct. It somehow survived ice ages and drought and fire. And just going back and looking at what things must have been like 50 million years ago!"

On the other side of the world visitors to the U.S. Botanic Garden in Washington are getting some sense of that history as they stare at the Wollemi in the plexiglass case.

"I think that it is very cool that it is that ancient of a tree, the fact that it has been around that long," one recent visitor commented. Another added, "I was just thinking how many species are going extinct without us even knowing that they existed. And, this is obviously one that I did not know existed."

The Royal Botanic Gardens in Sydney is expected to release the propagated plants for sale in October. The money raised will be dedicated to projects that safeguard the Wollemi Pine and other rare and endangered species.

Source:
VOA News Service
First published: March 27, 2005
Author: Rosanne Skirble

Sugar Maple

Acer saccharum


Alternate common names

Hard maple, head maple, sugartree, bird’s-eye maple

Description

General: Maple Family (Aceraceae). A native tree with a dense, spreading crown, to 25-37(-40) m in height; bark light gray to gray-brown, rough, deeply furrowed, and darker with age. The leaves are deciduous, opposite, long-petioled, blades 5-11 cm long and about as wide, with 5 shallow, blunt or short-pointed lobes, edges coarsely toothed, dark green and glabrous above, whitish and more or less hairy below, turning intensely red, orange, or yellow in fall. The flowers are small, greenish-yellow, in long-stalked, drooping clusters or racemes, each cluster with 8 to 14 flowers. Most trees are either male or female (the species is essentially dioecious), but both kinds of flowers occur on some trees (technically monoecious), sometimes segregated on different branches. The fruits are winged nutlets (samaras) in a pair, 2-2.5 cm long, clustered on long stalks, red to red-brown. The common name refers to the use of the species for making sugar and syrup.

Variation within the species: Closely similar forms of sugar maple have been recognized at various taxonomic ranks – from varieties to subspecies and species. Three of them are now generally recognized as species, but the differences are technical and it is difficult to be sure of the correct identifications of trees sold as “sugar maple” in the southeastern US.

Florida maple (A. barbatum, including A. floridanum): primarily a species of the Gulf and southeast Atlantic coastal plain, from Texas to North Carolina and Virginia, and up the Mississippi valley as far as Missouri and Illinois.

chalk maple (A. leucoderme): similar in distribution to Florida maple, but not extending into Virginia or up the Mississippi valley.

black maple (A. nigrum): similar in distribution to ‘true’ sugar maple, but somewhat more restricted.

Norway maple (Acer platanoides), an introduced European species, is often planted and looks similar to sugar maple, but Norway maple has broader leaves with drooping lobes, and sap from a broken petiole is milky.

Uses

Sugar maple is the only tree today used for commercial syrup production, as its sap has twice the sugar content of other maple species. The sap, mostly collected in the spring, is concentrated by boiling or reverse osmosis, with about 35-40 liters of sap making 1 liter of syrup. A single tree may produce 5-60 liters of sap per year. Nights below freezing and days at higher than 5 degrees Celsius are needed to ensure good sap flow. Sugar maple was the premier source of sweetener, along with honey, to Native Americans and early European settlers. Native Americans also used sugar maple sap for sugar and candies, as a beverage, fresh or fermented into beer, and soured into vinegar and used to cook meat.

Sugar maple is widely planted as an ornamental or shade tree and many cultivars have been selected, based on variation in growth habit/crown shape, mature height, fall color, leaf shape, and temperature tolerance. The leaves go from green to brilliant yellow, orange, and red in autumn, although there is much variation in fall color within the species. Orange and reds seem to be more intense in New England types, while yellows are more pronounced further west. Interior leaves may be yellow, while outer exposed leaves turn orange-red. The species is best suited to larger sites where soil compaction is not a concern. It also is sometimes used in shelterbelt plantings and has potential value for rehabilitation of disturbed sites.

Sugar maple is an important timber tree valued for its hard, heavy, and strong wood, commonly used to make furniture, paneling, flooring, and veneer. It is also used for gunstocks, tool handles, plywood dies, cutting blocks, woodenware, novelty products, sporting goods, bowling pins, and musical instruments.

White-tailed deer, moose, and snowshoe hare commonly browse sugar maple. Red squirrel, gray squirrel, and flying squirrels feed on the seeds, buds, twigs, and leaves. Porcupines consume the bark and can girdle the upper stem. Songbirds, woodpeckers, and cavity nesters nest in sugar maple. Although the flowers appear to be wind-pollinated, the early-produced pollen may be important to the biology of bees and other pollen-dependent insects because many insects, especially bees, visit the flowers.

Distribution

Sugar maple is widespread in mixed hardwood forests of the eastern United States. It grows from Nova Scotia and New Brunswick westward to Ontario and Manitoba, North Dakota and South Dakota, southward into eastern Kansas into Oklahoma, and southward in the east through New England to Georgia.

Adaptation

Sugar maple most commonly occurs in rich, mesic woods but also grows in drier upland woods. It often grows in canyons, ravines, valleys, stream terraces, and streambanks, but it is occasionally found on dry rocky hillsides, at 500-1700 meters elevation. It is a dominant or codominant in many northern hardwood and mixed mesophytic forests. Common codominants include beech (Fagus grandifolia), birch (Betula spp.), American basswood (Tilia americana), northern red oak (Quercus rubra), white oak (Quercus alba), and yellow poplar (Liriodendron tulifera), but it also grows with various other hardwood species as well as conifers such as pine, spruce, fir, and eastern hemlock.

In the absence of disturbance, forests of jack pine, eastern white pine, eastern hemlock, yellow birch, or red pine are replaced by sugar maple and American basswood. Because repeated disturbance by fire was common in eastern deciduous forests in pre-settlement times, succession to sugar maple-American basswood stands may have taken as long as 650 years in some locations. Increases in sugar maple during the past 50 years in central and Great Lakes hardwood forests have been attributed to fire suppression.

This species flowers in April-June, with fruiting occurring in June-October. Fruits ripen about 12-16 weeks after flowering and begin to fall about 2 weeks after ripening. Leaves generally drop just after seeds have fallen. At the southern edge of the species' range, dead leaves tend to remain on the trees through much of the winter.

Establishment

Minimum seed-bearing age for sugar maple is 30-40 years; maximum seed production is reached after about 60 years of age. Seed is abundantly produced each year but peaks occur mostly from 2-5 years. Seeds are dispersed in fall and germinate in spring. Germination occurs on moist mineral soil or in the litter layer, at an optimal temperature of about 1 C. Seeds can remain viable for up to 5 years but few persist in the seed bank for more than one year. Sugar maple seeds require moist stratification at temperatures slightly above freezing for 35-90 days.

Sugar maple is shade-tolerant but seedlings in dense young stands may survive for only 5 years; those in older stands commonly persist for many years. Such a bank of abundant seedlings and saplings can remain suppressed until gaps are created by windfall or other disturbances, where they typically respond vigorously and rapidly to release. Sugar maples can live for up to 500 years.

Stump sprouting and root sprouting are moderately common means of vegetative reproduction after mechanical disturbance in natural conditions, especially in the northern part of its range, and layering occasionally occurs.

Management

Sugar maples are not particularly good street trees, because they are intolerant of compacted soil, high heat, air pollution, and road salt commonly found in urban environments. They are susceptible to stem and root injury, and verticillum wilt may occur when grown in heavy, poorly drained soils. “Maple decline,” periodic die-backs of relatively large trees in the Northeast, has been attributed to acid rain and other air pollutants, particularly in the last two decades, but its exact causes are not understood.

Even light ground fires may damage the thin bark of sugar maple. Hot fires can kill an entire stand and existing regeneration. The trees sprout poorly after fire. Although communities with sugar maple are relatively resistant to ground fires, a fire hazard may occur in dry years during October, after the leaves have fallen.

Seed can propagate sugar maple; early spring plantings generally produce the best results. Nurserymen usually rely on budding or grafting or sometimes use air layering or rooting of stem cuttings. Use stem tips 35-55 centimeters long taken in mid June with fully elongated bottom leaves; rooting occurs in 4-6 weeks under mist in a 2:1:1 mixture of sandy loam, vermiculite, and peat moss.

Source:
USDA, NRCS, National Plant Data Center & the Biota of North America Program

Balsam Fir

Abies balsamea


Alternate Names

Pinus balsamea

Uses

Balsam fir is used primarily for Christmas trees and pulpwood, although some lumber is produced from it in New England and the Lake States. The wood is light in weight, low in bending and compressive strength, moderately limber, soft, and low in resistance to shock.

Description

Balsam fir is a small to medium sized coniferous tree. Growth occurs in whorls of branches surrounding an upright leader or terminal, making a symmetrical tree with a broad base and narrow top. It is relatively short-lived and is considered a sub-climax type species in the New England states, but may be a climax type in the zone below timberline.

Needles are 3/4 to 1 inch long, flat, and often strongly curved. Twigs with needles have a generally flattened appearance. Both male and female flowers are found on the same branch. Cones are 2 to 4 inches long, purplish in color, and stand erect on branches (as do those of all true firs). There are about 60,000 seeds in a pound. The bark is smooth, thin, and grayish, distinguished by soft blisters containing a clear, odiferous resin known as Canadian balsam.

Adaptation and Distribution

The soils on which balsam fir grows range from silt loams developed from lake deposits to stony loams derived from glacial till. Fir will grow, but comparatively slowly, on gravelly sands and in peat bogs. It grows on soils of pH ranging from 4.0 to 6.0. It is generally found in areas with a cold moist climate and with 30 inches or more of annual precipitation. Fir is subject to windthrow, especially on shallow wet soils. Because of its thin bark, shallow root system, and flammable needles, balsam fir is easily killed by fire.

Balsam fir is distributed throughout the Northeast and upper Midwest.

Establishment

The use of natural regeneration methods for balsam fir is very effective on open and disturbed sites (heavily cut areas), but an adequate seed source must exist. This species can also be readily grown in nurseries, for transplanting to abandoned fields, Christmas tree plantations, and open areas. Use conventional tree planting techniques and equipment. Three or four year old seedling stock should be utilized.

Cultivars, Improved, and Selected Materials (and area of origin)

Although most available seedlings of balsam fir are of unknown parentage, some are produced from local selections.

Source:
USDA NRCS Northeast Plant Materials Program

Photo credit:
Robert H. Mohlenbrock
USDA NRCS 1995 Northeast Wetland Flora
@ USDA NRCS PLANTS