A number of dead trees have been submitted to the Plant Disease Clinic during the past several weeks. In most cases the trees were planted within the past few years.
What causes newly planted trees to die? As you can guess, there is not one standard answer. When trying to determine the primary cause of the problem, several factors need to be given consideration. Remember that dieback does not always occur in the first year. Some of the listed stress factors contribute to poor vigor over a period of years or cause tree death several years after planting.
Planting trees with the root collar below the soil line may cause mortality. The root collar is where the trunk meets the root and is usually indicated by a change in bark color and a flaring out or swelling at the base of the trunk. Depending on the species, problems may occur when trees are planted only a few inches too deep. Planting holes that are dug deep and filled back in with loosened soil may lead to settling of trees, in effect causing planting that is too deep.
A planting hole that is dug only large enough to insert the root system of the tree can lead to problems, especially if the soil is very compacted or high in clay content. These circumstances make it difficult for the new roots to penetrate the existing soil and grow.
Quality of stock
A tree that shows good branch and foliage growth is not a guarantee that the tree will thrive. It is important to consider the root system. Examine the roots prior to planting. An abnormally high shoot to root ratio (extensive root loss) may lead to failure. Roots that are allowed to dry out before planting may die.
Poorly drained sites and/or overwatering are common causes of tree death. Roots need oxygen. How often newly planted trees need to be watered is dependent on soil type and drainage. The soil should be saturated when watering, but allowed to dry out between waterings.
Environmental extremes, such as abnormally low winter temperatures can kill plant tissue. Warm winter sunlight can also dehydrate tender tissue.
Other factors can contribute to poor establishment and mortality of newly transplanted trees. Girdling wires, improper mulching, soil pH, improper species selection, chemical injury, and mechanical damage are a few additional examples. In many cases, several factors may be contributing to tree mortality. Pinpointing the primary factors will be helpful in taking corrective measures in future plantings.
For information on planting trees, refer to Pm-1591 "Community tree planting and care guide". This publication is available from your local county Extension office or from Extension Distribution at Iowa State University, Ames, IA 50011.
This article originally appeared in the March 21, 1997 issue, p. 27.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on March 21, 1997. The information contained within may not be the most current and accurate depending on when it is accessed.