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The ideas and findings in this report should not be construed as an official DoD position. It is published in the interest of scientific and technical information exchange.

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The ideas and findings in this report should not be construed as an official DoD position. It is published in the interest of scientific and technical information exchange.

Allelopathy is the process whereby plants produce toxins that limit the growth of other plant species. Forest ecology and agronomy research has dealt with this phenomenon tor some time, but there is a dearth of inquiry about allelopathy in ornamental and shade trees. A review of the literature suggests that herbaceous ground-cover toxins may interfere with nutrient uptake by damaging or destroying root cells, root hairs, and mycorrhizae. Soil texture appears to be a determinant in the extent of damage. Trees on poorly drained soils may be severely damaged, whereas those on well-drained sites may be less affected. Allelopathic factors interact with competitive and environmental factors. Cultural treatments, such as mulching and herbiciding, reduce allelopathic effects as well as competition and environmental stresses. Allelopathic mitigation enhances nutrient uptake, reducing the need for tree fertilization.