WORKING HARD TO SURVIVE
In facing hard times, the elm is not alone. Other trees have had to be scientifically altered to succeed, and new varieties developed. Here are three of them.
Crabapples are perhaps the most gorgeous of our northern flowering trees and are worth some extra energy in their preservation. Many a Palos resident has watched their crabapples slowly defoliate and die from cedar apple rust, scab, powdery mildew, fire blight, canker, scales, borers, or aphids. The trees now stand bare branched in our yards, ghosts of their old glory. Owners are reluctant to remove them in the false hope that they might revive.
Cultivars have been developed mainly for ornamental traits, size, color of flower and fruit, and disease resistance. Some of these are on the market and soon others will be: The Morton Arboretum has an on going crabapple study. In their Tree and Shrub Handbook, available at the Palos Park library, they list over one hundred crabapples which they recommend.
‘Prairie Fire’ has dark red buds, red flowers, and purplish red fruit in fall.
‘Donald Wyman’ is more typical with a rounded shape, white flowers, and orange red fruit.
‘Luwick’ is unusual with its weeping posture and pink flowers. ‘Sargentii’
is a spreading shrub tree featured in the plantings at our local hospital.
Spring Sensation, from Chicagoland Grows, has a dense, wide spreading habit, excellent disease resistance, hardy pink flowers and minimum fruit production (less cleanup).
Bradford Callery Pear
The Bradford Callery Pear has a landscape history much like the crabapple. This spring flowering darling was once the favorite of the developer and the urban forester; but, it is now out of favor because it is structurally weak and subject to breakage. Some nurserymen
are experimenting with early pruning to improve the strength of the tree. Other agriculturists are trying to breed a pear tree with all the good features: showy white spring flowers; and shiny green leaves that turn orange, crimson, yellow, and finally burgundy red over all in the Fall. And they did! The improved urban tolerant Bradford Pear is a superior flowering tree that can handle heat, pollution, salt, poor soil, pests, and fire blight.
‘Autumn Blaze’ gets the highest marks for stability of its horizontal branching. It is the most disease tolerant and cold hardy of the callery pears.
‘Autumn Blaze’ turns red early in the fall, avoiding the risk of frost spoiling the color. Researchers at the Morton Arboretum are cross-breeding callery pears to create trees that are better aligned with the Midwestern seasons.
‘Chanticleer’ is sixteen feet wide at maturity, suited to small urban spaces such as parkways and parking lots. It is disease resistant and cold hardy with good fall color. Two other narrow varieties are
‘Whitehouse’ and Capital.
Birches are the centerpiece of the garden, are adored and popular as an ornamental. Yet, almost every gardener has a sad birch story. Two characteristics attract the landscaper. The white bark and the romantic pendulous posture. The tree must not be stressed, which means it needs a cool moist, well drained setting like its native northern home. Global warming is a new threat to white birch lovers because the heat causes its growing area to shrink to the north. Cultivated birches require pampering, watering, spraying, fertilizing, and pruning, much more attention than is humanly possible. If the bronze birch borer senses a weakness, it will attack and reduce the tree to rubble. That is the bad news. The good news is that the plant industry is sincerely working on a disease resistant variety. Although they have come close, they are not there yet.
Chicagoland Grows offers ‘Betula
Madison, trademarked White Satin Birch. It possesses good borer resistance, good form, beautiful white bark, and attractive golden yellow fall foliage. At Longenecker Horticultural Garden at the University of Wisconsin, this planting in l970 produced this one survivor to borer infestation. In the thirty-three years since, this tree has remained borer resistant.
The River Birch, or Red Birch, seems much hardier in our area. It resists drought and the bronze borer. It is native to Midwestern river banks. It is resistant to wind and ice storms and is very ornamental with its shaggy peeling bark. Also, one can choose a clump specimen. The color of the bark varies according to variety--brown, orange, lavender, and
‘Heritage’ which has a pinkish white bark.