Roots

Program Contact: Tianna DuPont, Regional Specialist, Tree Fruit
(509) 663-8181 • tianna.dupont@wsu.edu

replantc

You cannot overlook the basic needs of plants when planting young trees. Plants must have soil conditions that will enable rapid, healthy root growth. Plants are relatively weak when they are young, and struggling to expand both their foliage and their roots. Top growth can’t outstrip the roots ability to support it. One of the pictures on right is from a pear tree that was growing poorly. Guess which one.

replantdYou must provide a zone around the tree where roots can expand rapidly during the first two seasons. This improved rooting zone should be at least two and one-half feet deep, and four feet in all directions from the trunk. This is vital. Research carried out in the 1960’s illustrated this when they planted trees in ever-increasing sized planting holes filled with non-orchard soil. Growth was best over an extended period when the hole was huge. (see Picture) This approach showed us something about the practicality of trying to improve tree growth by improving the very small amount of soil held within the normal sized planting hole.

The tree roots will soon have to grow outside the relatively small amended soil zone. Fiddling with planting hole soil may help the young tree grow better, but it is not the ultimate answer, at least with the soil amendments we have tried yet.

replanthWithout good root growth, top growth will suffer. Good root expansion over the first two seasons will set the tree up for good growth and production for the next 30 seasons.

Good roots provide the tree with nutrients and easy access to soil water. Trees with poor roots act water stressed, and shut down when the weather gets hot. Those with good roots grow vigorously right through the high stress portion of the season.

Trees rarely recover from a poor start, especially if they have not grown vigorously by their second year. Poor early tree growth is a symptom that important aspects of site preparation have been skipped before planting.

Sometimes the slow start is due to planting poor quality or root damaged trees. If this is the case, some of the trees may recover and grow well in the second leaf.

Without good root growth, top growth will suffer. Good root expansion over the first two seasons will set the tree up for good growth and production for the next 30 seasons.

replantiGood roots provide the tree with nutrients and easy access to soil water. Trees with poor roots act water stressed (See photo, left), and shut down when the weather gets hot. Those with good roots grow vigorously right through the high stress portion of the season.

Trees rarely recover from a poor start, especially if they have not grown vigorously by their second year. Poor early tree growth is a symptom that important aspects of site preparation have been skipped before planting.

Sometimes the slow start is due to planting poor quality or root damaged trees. If this is the case, some of the trees may recover and grow well in the second leaf.

The most promising advance relative to roots is the recent documentation of new dwarfing apple rootstocks that are somewhat resistant to replant-site related disease. These are from the Cornell-Geneva series, G41 and CG-4214 appear to be the current best combination of both horticultural qualities and disease resistance. These and other rootstocks in this series, while they are a great leap forward, respond to all of the other good management planting practices, such as soil fumigation, fertigation and drip irrigation, weed control, so they will not produce a healthy young orchard unless they receive proper care.

 

Washington State University