Transplant shock is a term that refers to a number of stresses occurring in recently transplanted trees and shrubs. It involves failure of the plant to root well, consequently the plant becomes poorly established in the landscape. New transplants do not have extensive root systems, and they are frequently stressed by lack of sufficient water. Plants suffering from water stress may be more susceptible to injury from other causes such as the weather, insects, or disease. When several stresses are being experienced, the plant may no longer be able to function properly.
Leaf scorch is a common symptom of transplant shock. Leaf scorch first appears as a yellowing or bronzing of tissue between the veins or along the margins of leaves of deciduous plants (those that lose their leaves in winter). Later, the discolored tissue dries out and turns brown. Other symptoms of transplant shock appear as wilting leaves (especially on recent transplants), yellowing, and leaf rolling or curling. On needled evergreens, the first symptom of water stress is an overall grey-green coloration to the foliage; with further water stress, the ends of the needles often turn a light tan color. If stress is not alleviated, leaf death occurs and may be followed by twig and limb dieback.
Overall plant growth is greatly reduced, which is reflected in the length of the new growth. Poorly growing plants have extremely shortened internodes, resulting in shortened branch tips relative to those of an unstressed plant. New leaves or needles of a stressed plant are smaller than normal. It is not unusual for transplants to have very reduced growth the first year after planting; however, symptoms may be evident for two or more years.
Often plants do not become established because they have a poor or injured root system. Bare root trees and shrubs are most susceptible to transplant shock. Such "stressed" plants are very fragile and are more susceptible to other stress factors.
Improper planting. One of the most common causes of plant root failure is "wet feet" caused by improper soil amendments--the "bathtub effect." When planting in heavy soil, be sure to use the same heavy soil to fill the planting hole. Many gardening books suggest adding peat moss or other amendments to the back fill. This is not recommended. A light soil mix placed where it is surrounded by heavy soil too often results in trapped water, suffocated roots, and eventually a dead plant.
Planting depth is important. Deep planting results in suffocated roots while shallow planting causes root stress from the more extreme temperature and moisture fluctuations in shallow soil. Refer to Purdue publication HO-100 for recommended planting depths when planting in heavy or sandy soils.
Problems can result from failure to spread roots of container grown plants. Such plants often have roots that are coiled around the inside of the pot. Gently uncoil and spread the roots apart before planting. If this is not done, circling roots can eventually girdle or strangle the trunk as the roots increase in diameter with growth.
Always remove twine, rope, or wire from the trunk at planting time to prevent strangulation of the tree as it grows.
Improper watering. Proper watering after transplanting is especially critical in the first year; over watering is just as injurious as under watering. Soil type and amount of rainfall will determine the frequency and amount of water needed. During the growing season, landscape plants in well-drained soils should receive at least one inch of water per week. Plants in poorly drained soils will require less frequent watering. Use a garden sprinkler or soaker hose and measure the amount of water applied; use a container with straight sides.
Improper plant material. Consider the suitability of the plant to its intended site and geographic area. Select species that grow best under the prevailing conditions: wet or dry, acid or alkaline. For example, planting an acid-loving plant such as pin oak in alkaline soils is asking for trouble. Also consider the plant hardiness zone you live in and select plants adapted to that zone. Ask at the garden center or nursery if you are unsure which plants are best suited for your area.
If your plant dies, try to determine what caused the decline of the plant: Not enough water? Too much? Plant not hardy to the region? Correct the problem before replanting with the same plant in the same spot.
For additional information, refer to:
BP-2 Winter Injury of Ornamentals
BP-25 Leaf Scorch
BP-27 Iron Chlorosis of Trees and Shrubs
HO-4 Pruning Ornamental Trees and Shrubs
HO-100 Planting Landscape Trees and Shrubs.
Provides information on when to plant, how to plant, pruning, staking, trunk wrapping, and watering.
HO-123 Trees for the Landscape. Describes use, cold hardiness, size, and landscape interest for 48 trees.
HO-140 Fertilizing Woody Plants.
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