Drought Distinction

Drought Distinction

Deficiency Diagnosis

Although scarcity of water does not appear to be an issue at this moment, sufficient precipitation and relatively mild temperatures allow for consistent, adequate soil moisture levels, however, as the growing season continues and temperatures increase drought conditions may present themselves. These conditions should be closely monitored and treated accordingly. Stress can be evaluated through visible symptoms on foliage of both broadleaf and evergreen species. But, symptom morphology can be similar for various conditions and stress factors, so it can be difficult to determine the exact source of the stress.  Discussed herein are some helpful hints in identifying stress on landscape plants due to drought, but if you notice abnormal foliage on your property consult with your arborist for a more in-depth diagnosis and possible treatments.

The physiological changes and the location of tissue damage will be indicative to what kind of stress a plant is experiencing. The distribution of symptoms can also aid in identification, consider if symptoms are apparent throughout the plant or are they concentrated in the crown, trunk, foliage or branches. Biotic stressors, such as disease or insects, will present as damage in the area of the plant first colonized. While abiotic stressors, like shading, temperature or drought, may present as overall distress. Drought stress can be a factor both airborne and soil borne stressors; leaves exposed to extended periods of sun without adequate water uptake may show leaf tissue damage as well as disfigured venation.

discoloration and drooping

Drooping foliage and leaf discoloration can be symptomatic of drought stress.

edge necrosis

Necrosis of leaf tissue at the edges is illustrative of possible stress due to water scarcity.

leaf rolling

Water stress can manifest as curling or rolling of leaves towards central vein.

Although these symptoms can be manifestations of drought stress they can also be associated with nutrient deficiencies, heavy metals, salt, frost, ozone, natural senescence or pathogens. Contextual clues will assist in diagnosis, i.e. temperature and weather patterns, but your arborist will be able to make a more definitive evaluation and develop a plan for treatment. You know your landscape better than anyone, so contact your arborist as soon as you notice any changes or possible symptoms.

(Pierre Vollenweider*, Madeleine S. Gu¨nthardt-Goerg, ‘‘Diagnosis of abiotic and biotic stress factors
using the visible symptoms in foliage’’[Environ. Pollut. 137 (2005) 455e465]*)