The Norman Transcript

May 10, 2013

More of the top 10 worst trees to grow in Oklahoma


The Norman Transcript

NORMAN — Listed are the top five of the 10 worst trees to plant. If you have trouble finding the trees I recommend, don’t hesitate to ask your local greenhouse or nursery to order them for you. For a complete list of good trees for Oklahoma, visit oces.okstate.edu/cleveland/horticulture.

Although considered a native invasive, I don’t address Eastern Red Cedar in my top 10. In the right conditions, the tree can provide privacy and may grow in areas where nothing else will. If left unattended or mismanaged, Eastern Red Cedar will go nuts. Avoid it altogether and opt for one of the evergreens listed below.

5.) Green Ash: Ash trees come in white or green varieties and are readily available in the metro area.

These trees fail to grow after planting, evident by the lack of mature specimens around. Ash is very susceptible to borers like the exotic, invasive Emerald Ash Borer. Once borers are present, its days are numbered. “Urbanite” Ash is a better-performing cultivar but has an atypical form for an ash. Another alternative for fall color would be Gingko.

4.) Silver Maple: Like Pin Oak, many residential areas in central Oklahoma have old Silver Maples. They are easily recognized when the wind blows, as their leaves are silver underneath.

Silver Maples are pretty trees but are fast-growing and very weak. It’s not a matter of if one will break in severe weather but where. Silver Maple can also form unsightly abov-ground roots. Good alternatives with fall color are Chinese Pistache, Caddo Maple and Trident Maple.

3.) Austrian Pine: If you desire year-round foliage, forgo anything with needles. In our area, pines scorch, struggle with heavy clay soils and are riddled with disease. All true pines are susceptible to Pine Wilt Nematode, but non-native pines like Japanese Black, Austrian and Scotch Pines are most susceptible. Pine Wilt causes trees to brown, wilt and die in a matter of weeks. Native pines, like the commonly planted Loblolly Pine, may be able to live with disease longer.

However, Loblolly, like Pin Oak, suffers from iron chlorosis in our high pH soils. In addition, pines are chronic with fungal diseases that require yearly, foliar fungicide treatments. Better evergreen choices include Arborvitae, Nellie R. Stevens Holly or American Holly.

2.) Colorado Blue Spruce: “Out in three to five” sounds more like a prison sentence. Of spruce planted in our area, 90 percent never live to see age 3 and 95 percent are dead in five years. The operative word here is “Colorado,” meaning they like cool weather and rocky, well-drained soils uncommon in Oklahoma. Avoid all spruce and plant an Arizona Cypress, a drought-tolerant option with blue-green foliage.

1.) Bradford Pear: This selection is a no-brainer, unless you like the half-tree look. Bradford Pears are fast-growing and weak wooded. They have narrow branch angles, which cannot hold any weight or survive high wind.

These pears lose branches like crazy, break in half at the main trunk or split down the middle. The blooms of this pear can be trashy and smell like urine or dead fish to some. Bradford Pears also are spreading and naturalizing in vacant lots and native areas. This is a huge issue that could be compared to Eastern Red Cedar, if left uncontrolled.

These trees are susceptible to fire blight and cedar apple rust diseases, both of which require yearly spraying for control. Cheap, weak, stinky and invasive doesn’t describe a tree you want. Beware of the Bradford Pear.

Tracey Payton Miller is Cleveland County’s horticulture extension educator for the Oklahoma Cooperative Extension.