University of Maryland Extension

Environmental Stress and Site Problems - Trees and Shrubs

stressed azalea shrub
Stressed Azalea

Back to Common Problems - Trees and Shrubs

Stress and poor site conditions can be caused by a number of factors including environmental stress, insect damage, and disease. Environmental stresses can be caused by severe drought, poor soil aeration, reduced root growth, nutrient deficiencies, extreme temperature fluctuations, defoliation, winter damage, storm damage, chemical injury, mechanical damage, and lack of establishment due to poor site selection or transplanting practices. One or more of these conditions may cause visible symptoms, or stress may have a more subtle effect such as weakened defenses against insects or disease organisms. Plants may be predisposed to attack by pathogens or insects when they suffer stress just after planting, after storm damage or when they begin to decline in vigor. Early fall color, poor growth, and decline are symptoms displayed when shrubs are subjected to prolonged environmental stress.

poor planting site

Poor site conditions include a number of factors that relate to a plant’s health. Site conditions that need to be considered at planting include soil texture, nutrient availability and pH, proper soil drainage, and soil moisture retention. Proximity to sidewalks, roads, and buildings, as well as exposure to temperature extremes, light exposure, wind, and air pollutants, can cause significant stress on plants. Other factors that contribute to poor site conditions include construction damage, grade changes, soil compaction, and allelopathy such as proximity to black walnut trees. Select plant material adapted to the specific climatic zone or adapted to specific sites such as seashore, urban, or woodland areas. Proper site preparation and selection of high-quality plant material will help plants adapt to a difficult site. After site conditions are considered other factors such as maintenance after planting, mulching techniques, proper irrigation techniques, and weed control become important for sustained plant health. 

Attempts to remove the stress or diagnose the cause of the site problem may alleviate the symptoms and allow the plant to recover.

Photo Gallery

poor site location

poor site location and care

Junipers in a poor site next to a driveway Lack of establishment due to poor site selection, improper planting, and poor care
construction severed roots

soil compaction around tree

Severed roots at construction site Soil compaction due to heavy foot traffic





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