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

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

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

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