September 4, 2015
Don't "Over-Care" for Landscape Trees
This summer appeared to be hard on trees as I had more questions on branch dieback and even tree death. It was not our summer that caused stress but a culmination of weather extremes over past years. We had a drought in 2012 and then the biggest problem was the extremely cold snap in mid-November last year when trees and other plants had not hardened off for the winter.
Abnormal weather leads to environmental stress because trees are best adapted to gradual changes. Sudden changes in temperature can cause direct injury to trees or set them up for attack by diseases and insects. Weather extremes have always been the norm for Nebraska. However, weather extremes are predicated to become even more extreme.
Since trees provide many benefits and increase property value, how do you guard against tree issues and tree death? You start by planting for diversity, selecting quality trees, planting correctly and following good tree care practices.
When diagnosing tree problems, it's not unusual to tell a property owner if they had NOT done this or that, the tree might not be having an issue. They usually respond "If I'd only known." Here are some tree practices to AVOID to improve your tree's health and longevity.
We need to stop overplanting single tree species, stop planting overly large trees, stop planting too deep, stop overwatering, stop overfertilizing with nitrogen, and stop mulching too heavily. Notice that most of these are examples of over doing it. The tendency to overdo shows how much we value trees and want them to do well. But too much of a good thing is rarely good for trees.
I don't know how many times I've been asked what tree is best to plant. This is impossible to answer. We've seen the problems that can happen when people thought that elm, Scotch pine and now green ash were the "perfect" trees. I encourage people to plant for diversity... plant a tree that none of your neighbors have. If three trees are to be planted, plant three different trees. If three windbreak rows are being planted, use at least three different species of trees if not six or more. Some trees have known issues. Ask about potential problems before selecting a tree.
Homeowners seem to want to spend more to plant the largest trees they can afford. However, the smaller the better from the trees standpoint IF you can keep rabbits, weed eaters and lawn mowers away... but most of people don't want to start with a seedling. You should know that research shows smaller trees catch up and surpass larger trees and often have fewer issues such as girdling roots and less transplant shock. Save some money and start with the smallest tree you are comfortable with.
Avoid planting too deep by locating the trunk taper before digging the hole. Don't plant the tree at the same depth it is in the container. Frequently, trees are planted too deep in containers. You should also cut any circling roots that can be seen when taking the tree out of the container.
Dig planting holes to the depth that allows the bottom of the root ball to be placed on solid ground, leaving the trunk taper above ground level. Be sure to dig the hole wider than the root ball to loosen the surrounding soil. Roots grow outward, not downward.
Keep the soil good and moist, especially for the first week or two. Then keep the soil moist but avoid a saturated soil or a planting hole that is full of water. Use a two to four inch layer of mulch in at least a four foot diameter ring. Avoid too deep of a layer of mulch or mulch that is piled against the trunk.
Do not fertilize at planting with nitrogen. This will increase transplant shock. And if the tree is planted in a fertilized lawn, do not add additional nitrogen to the tree. This is a waste of money; and excess nitrogen sets trees up for increased environmental stress and attack by diseases and insects.
For more information on tree care and recommended species, contact your local Nebraska Extension office.