Extension Communications 3614 Administrative Services Building Ames, Iowa 50011-3614 (515) 294-9915

8/25/03

Contacts:
Paul Wray, Forestry (515) 294-1168, phw@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033, jmcguire@iastate.edu

Yard and Garden Column for the Week Beginning Aug. 25, 2003

Helping New Trees Survive Summer in Iowa

By Paul Wray
Extension Forestry Specialist
Iowa State University

Each year, homeowners and tree planters often go into the spring with high hopes and great expectations for the trees that they planted the fall before or the trees they are planting in the spring. We expect our new plantings to survive, grow fast and look beautiful. For the majority of the trees, the growing season during April, May and June is very good. Temperatures are reasonably cool and moisture is more than adequate for the new tree or shrub to grow new leaves, expand its branches and send roots into uncharted territory.

For some plantings, problems may begin earlier than later. The first stress calls to my office often occur during that first month of growth and are often the easiest diagnose. Common symptoms include failure to leaf out, part of tree died, leaves are small and stunted, leafed out but soon dried up and fell off. For most of these early problems, the reason relates to the planting stock, or in some cases, the deficiencies of the planting stock.

These early season tree failures can usually be reduced or eliminated by using quality stock. Buy from a reputable dealer that has good stock. Good stock can be defined as plants with good root systems compared to the top of the tree. Small trees with large root systems do well and suffer less transplant shock because fewer roots have been lost in the digging and planting processes. Trees with marginal root systems and those in pots that are small compared to the top of the tree may not survive the first month. During the first part of the growing season, new tree failure is almost always due to poor planting stock or planting trees with insufficient root to support the top.

As the summer progresses, getting warmer and usually drier, new tree problems become more evident and obvious to the homeowner. The weakest of the trees continue to die because the roots cannot supply the increased demand for water. Even with wet soils, the root system lacks enough surface area and feeder roots to provide the moisture to the tree or shrub. Many new plantings exhibit classic scorch symptoms—outer portion of the leaves wilt and the margins turn brown. At this stage the tree is compensating for insufficient root systems; assuming that the tree remains viable, it will do better next season because of its expanded root matrix.

Leaf loss, additional leaf scorch, slow growth and poor vigor are most common in the first one to two years of transplanting. In almost all cases, diseases are not an issue during the first two to five years after planting. Almost all tree problems can be related to transplant shock and trees with insufficient roots to supply their water needs.

Here are some guidelines to reduce the summer stress on our new planting.

Buy the best nursery stock available. Select stock that looks good above the ground, but also consider the roots and how well the balance exists between top and roots. A plant can never have too many roots.

For spring plantings, plant early. The longer the tree has to grow in the season with cool moist conditions; the more roots will become established to get it through our hot summer. Avoid summer planting because of the increased moisture stress during the hot dry months.

For fall plantings, plant conifers early and deciduous trees later. Conifers planted early will continue to grow and expand roots into the late fall. Most deciduous trees do less root growth after August 15. Planting deciduous trees that are more dormant will result in less damage to the tree. Container grown trees can be planted anytime during the fall season.

Mulch, mulch, mulch. Mulching should be considered a requirement of tree and shrub planting. Mulch with 3 to 5 inches of organic mulch well beyond the root area of the new planting, ensuring that there is no mulch next to the stem of the plant.

Don’t fertilize the first year. Fertilizer often stimulates top growth, putting additional pressure on the root system. Most soils in Iowa have more than sufficient nutrients for new tree and root development.

Water properly. Allow time between watering for the root area to dry, which promotes additional root development. When you water, water with sufficient water to soak the entire root system and beyond. Remember, you can over water with respect of frequency, but you cannot use too much water during an application. For first year conifers, continue watering until the ground is frozen.

Minimize pruning. Correct problems such as multiple leaders and rubbing branches, but leave the rest. The leaves are the source of carbohydrates for new root growth and expansion.

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ml: isugarden

Editors: Three color photos, suitable for publication, are available at right. Click on each thumbnail photo to go to the fullsized photo. The top picture's fullsize photo is 176K; the middle picture's fullsize photo is 164K; and the bottom picture's fullsize photo is 348K. Caption: A tree suffering frm leaf scorch
Caption: This leaf is exhibiting symptoms of leaf scorch
Caption: This tree did not survive being transplanted

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