Plant Pathology Infobytes
August 21, 1996
Fall Fruit Tree Planting Season And Plant Pests
Although the planting season for fruit trees is still a couple of months off, many home fruit growers make decisions at this time of year about which trees will need replacement this fall.
Occasionally tree replant decisions are related to a desire to try new varieties, but most often it's because a dead or dying plant needs replacement. Generally, such plants are in poor condition because of disease and insect damage.
Since planting space may be limited, orchardists frequently want to know "Can I replant in the same spot or am I likely to run into the same problem again?"
One of the first things which needs to be considered is that the tree or trees scheduled for replanting probably have been in place for several years. The soil and roots most likely haven't been disturbed since the trees were planted. Over a period of time, pest populations around the root system tend to build to high levels. In many cases, the tree to be replaced may not show obvious above ground symptoms of root rot or soil-borne insect pests, so it's natural to wonder if there is any real danger in replanting in the same spot.
It's easier to understand why this practice isn't advisable if you consider that when the original tree was planted, it was likely into a spot that was "fresh", and the tree began growth with little or no hindrance from soil pests. In time, pest populations increased as the root system expanded, and over a period of several years probably reached a level which led to decline of the tree.
As these declining (or dead) fruit trees are removed and young trees planted in their place, the small trees with limited root systems must grow in soil which is contaminated with various root disease organisms and insect pests. If the young trees aren't killed immediately, they may become weakened and begin to decline gradually. They will also become more susceptible to stress from winter injury, drought, and additional pest problems.
Orchardists also want to know "How long after I remove the old fruit tree should I wait to avoid problems?" The answer to this question can only be answered once it's known which of the soil disease and insect problems are involved. A disease common on peach roots has been found in the soil thirty-five years after tree removal. Soil chemicals available to home orchardists are of limited value for use in treating the old site for this disease and other pests. So, as a general rule moving to a fresh planting site is easier than waiting out pests and a lot safer than taking a chance.
Home orchardists with limited planting space may not have much room to work with, but as another general rule, a distance of ten feet or more from the old planting site is preferred (remember, roots of the previous tree can occupy a large area of soil!). It's also important to follow other recommended planting guidelines to increase chances of long term survival of the new tree.
Infobytes newsletter was written by the late Dr. Frank Killebrew, Extension Specialist.