Wednesday, September 18, 2013

Let's Get Off Our Ashes

Bald Cypress foliage

As Emerald Ash Borer steamrolls through our shade tree population we need to consider replacement choices. As one of my professors once said, "Nature abhors a monoculture." So, maybe our takeaway from the ash carnage should be about creating diversity and not overplanting any one species. A mixed forest, urban or otherwise, carries far less potential for total destruction from any insect or disease.

Let's not get caught with our plants down (literally) again. A few top-of-mind options to consider adding to your neighborhood canopy:

Autumn Blaze Maple (Acer x freemanii 'Autumn Blaze') is a great choice for those who want a fast growing tree. AB is a hybrid, resulting from a planned mating of Silver and Scarlet Maples. It was selected for possessing the best qualities of both parents. While the green leaves resemble Silver Maple, the long-lasting fall color is strong orange-red. It has a central leader, but still makes a predictable oval silhouette as it matures. The bark is gray and smooth. Matures to 50' tall, 40' wide.

Autumn Blaze Maple
Bald Cypress (Taxodium distichum) is a personal favorite. Particularly if you have a site that floods periodically, or even if you don't, this is a specimen to consider. Bald Cypress has a strong central leader like the mast of a historic "tall ship". The overall outline is a majestic pyramid. The soft green, fernlike foliage looks like it would be evergreen, but it amazingly turns rust-orange before dropping in the fall. It's a piece of cake to rake since the leaves are so lightweight. But don't let that fool you, Bald Cypress comes through gale force winds with no breakage.  No insect or disease pests. My experience with them is that they are rapid growers in about any soil, but with additional moisture stand back! Matures to 60' tall, 25-30' wide. There are now dwarf, weeping and columnar varieties to fit different situations.

Bald Cypress

Elm (Ulmus) Thanks to the hard work of hybridizers, especially at Morton Arboretum, there's a whole new world of disease resistant elms awaiting you. To highlight a couple, take a look at 'Triumph' with its broad oval/vase-shape. 'Triumph'  wears glossy, Dutch Elm disease-resistant dark green foliage. The fall color is yellow, and the arching habit desired by so many seems to develop as the tree matures to 50-60' tall, 45' wide. 'Emerald Sunshine' is more dwarf, topping out at 35', spreading to 25'. It's also DED-resistant, but is reported to have Elm leaf beetle resistance, too. Nice bonus!

Emerald Sunshine Elm foliage

Ginkgo (Ginkgo biloba), like a teenager, can sometimes be lanky until it grows and fills out. What a shame so many people overlook this amazing tree because it isn't a "perfect" shape when they first see it in the nursery. The gorgeous, fan-shaped dark green leaves are completely unique in the entire plant kingdom. In fall, they acquire a knockout bright gold fall color. While the growth rate is moderate, a Ginkgo's total indifference to insects and disease is a huge asset. But beware- buy only grafted male varieties ('Autumn Gold', 'Magyar' and 'Princeton Sentry', for example) that don't gift you with the female Ginkgo's ill-smelling fruit. A Ginkgo is a real trooper under even the most adverse conditions.

Purple Fountain Beech
Don't overlook the many regal European Beech cultivars (I obviously don't with 19 of them in my garden), our sturdy, dependable native Oaks and the beautiful Lindens. As with all portfolios, it's  smart to diversify!