Answer: The lichen you describe is usually a harmless growth, but it does indicate poor growing conditions. Heavy infestations of lichens are most common on shrubs and trees in declining or poor health. Following recommended establishment, watering, and fertility practices will promote the development of a thick leaf canopy, which will inhibit lichen growth on twigs and limbs. Better growing conditions and soil fertility may stimulate new plant growth and ultimately suppress the lichens. Light pruning of affected limbs will remove some lichens and stimulate new shoot growth which may help shade out the remaining lichens. Trees and shrubs in extremely poor condition often will not respond to better care and should be replaced.
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