Advertise in Print | Subscriptions
Published June 14, 2009, 12:00 AM

PRAIRIE GARDENER: The right tree: Do your homework before selecting, planting

Trees are not only a good way to improve the environment, but they also add beauty to our yards. Unlike other plantings, shade trees are a long-term investment, one that could continue for half a century or longer. So, we must choose wisely. This spring, interest in tree planting is even greater than normal as we face another possible disaster — the loss of our ash trees to the emerald ash borer.

By: Darrel Koehler, Grand Forks Herald

Trees are not only a good way to improve the environment, but they also add beauty to our yards. Unlike other plantings, shade trees are a long-term investment, one that could continue for half a century or longer. So, we must choose wisely.

This spring, interest in tree planting is even greater than normal as we face another possible disaster — the loss of our ash trees to the emerald ash borer.

If you are planning to plant shade trees this spring, here are some points to consider:

• First, you will want to make sure the tree you choose will fit in the intended space. If the area is confined, or you have overhead utility wires, you may want to pick a tree that is short in stature so it won’t have to be constantly pruned.

• Do you want an evergreen, say a pine or spruce, or do you want a deciduous tree — one that drops its leaves each fall?

• If you have a large open space, do you want to plant a tree that will become large and provide lots of shade, say a hackberry or basswood?

Other tree losses

The fate facing our ash trees (white, green and black varieties) isn’t new. In the early 1900s, the American chestnut tree was decimated by an Asian fungal blight. The chestnut at the time was the dominant forest species across much of the eastern United States, ranging from Maine to Mississippi and concentrated in the Appalachian regions. (The Prairie Gardener saw chestnut trees flourishing in Afton, Minn., 40 years ago.) Besides offering tasty nutmeats, the chestnut offered rot-resistant wood. There are hopes of breeding a disease-resistant American chestnut, but such trees aren’t likely to be available for another decade.

The story is much the same for the American elm, once the dominant shade tree here and elsewhere. They were similarly destroyed by Dutch elm disease, a malady introduced in the 1930s from the Netherlands. While Grand Forks has managed to save many of its beautiful elms, East Grand Forks hasn’t been so fortunate. Breeders are hoping to also develop a disease-resistant variety so we can once again enjoy these towering trees.

Foresters hoped the emerald ash borer wouldn’t be a problem for a decade or longer in this region. Northern Minnesota has an estimated 900 million ash trees in its forests, the most outside Maine. With the recent discovery of the ash borer in St. Paul, the timetable for the destruction of ash trees in this region has probably been speeded up. There is a root treatment for ash, similar to that for American elm, but it is pricey and must be applied annually.

Replacements

One way to get around the problem we are facing with ash is planting a variety of replacement trees. These would include the lindens, a favorite park and street tree of Europe. We can plant the native basswood or we can use the European little-leaf linden. Hackberry trees are another good choice. If you want birch trees, plant the native paper birch, which fares better than the European weeping variety. Bur oak is often overlooked, but makes for an excellent shade tree. Off-beat species would include Ohio buckeye, black walnut or silver maple hybrids such as “Autumn Blaze.”

Among evergreens, red (Norway) pine, eastern white pine and Scotch pine work. Black Hills spruce has fewer problems that the Colorado blue spruce. Tamarack or larch, a unique evergreen that drops in needles in the fall, is another choice. For medium size trees, choose from Japanese tree lilacs, hawthorns or fruiting trees. Sadly, the mountain ash is just about finished here due to fire blight woes.

Tree planting

The tree you select could be a container-grown tree or one that has balled with burlap. There may still be some bare-root trees available, but they are more readily available earlier in the spring. Bare-root stock has to be planted immediately so the roots won’t dry out.

Dig a hole that isn’t too deep. The root flare should be at slightly above the surface of the soil. Planting depth is important because if you plant too deeply, the roots will grow upward and around the tree’s trunk, causing strangulation.

You needn’t apply fertilizer when planting. You should make the application the second year. Your tree will benefit from water and mulch. Water the newly planted tree with 5 to 7 gallons of water once a week throughout the spring and summer or unless you receive sufficient rain. A layer of mulch will help retain moisture and control weeds. It should be 3 to 4 inches deep and in a doughnut shape around the trunk out about 2 feet. Leave the trunk with an inch or two of breathing room.

If you have lost a tree and had the stump ground out, don’t plant a replacement tree in the same spot. You will want to plant the tree 6 to 8 feet from the center of the previous tree’s trunk.

Myths upheld

Jeff Gillman, University of Minnesota horticulturist, writing in the May-June alumni Minnesota magazine, found three garden remedies that really work. He claims the beer trick to catch and kill slugs does what it claims. He suggests taking a pint-sized jar and placing it so that its mouth is at or slightly below the level of the soil. Fill the jar with beer (slugs prefer dark ale) up to about a half inch or slightly more from the top of the jar. The slugs will be attracted to the beer, fall in and drown.

He also found eggshells will control blossom-end rot in tomatoes. This is a major problem when the harvest first begins. Gillman suggests taking the shells of four eggs per plant and crush them into fine pieces. Mix these shells into the soil around each plant. The calcium in eggshells will dissolve slowly into the soil where it will be taken up by the plant’s roots.

To control black spot on roses, he suggests adding one cup of milk to two cups of water. Spray mixture directly onto rose leaves once a week with a handheld spray bottle to protect them from the disease.

Cold spring

While summer officially begins in a week, you’d never know it. Below normal temperatures have gripped the region for much of the past year and show no sign of relenting. The National Climatic Data Center in Asheville, N.C., predicts cooler-than-normal temperatures in the Dakotas and Minnesota for June, July and August. This means raising warm-season crops, such as tomatoes, peppers and melons, could be a real challenge. Recently, the cold, wet weather resulted in leaf drop for many of the green ash trees in Greater Grand Forks. The disease, anthracnose, is brought on by cool, wet conditions. A fungal disease, it normally doesn’t pose a problem; trees will re-leaf. The best prevention is to rake up all ash leaves and debris so they fungal spores won’t over-winter.

Garden tour

The 25th annual Grand Forks Horticulture Society garden tour should prove to be a show stopper. Promoters of the event, set for July 18-19, report special things are being planned with extra special yards. The Myra Museum on South Belmont Road will be the starting point. Tickets will be available at that site. You will also find the plant sale and garden garage sale at that site. Information: ghort&usa.net.

Koehler is the Herald’s garden columnist. His column is published every Sunday in this section during the growing season. Send garden questions to him in care of the Grand Forks Herald, Box 6008, Grand Forks ND 58206-6008. Tune in the weekly gardening show airing at 4:10 p.m. Thursdays on KNOX radio 1310 (A.M.)

Tags: