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Soil additives


Mycorrhizae addition: If diagnostic tests show that mycorrhizae are lacking and soil conditions are conducive for mycorrhizae development, addition of products containing spores and other components of mycorrhizae may improve tree health. However, there are few published scientific reports showing that adding these products affects health on mature trees. Most tests with young landscape-sized trees fail to prove a benefit from adding these components. See: more on mycorrhizae.

Paclobutrazol: A growth regulator called paclobutrazol added to soil around the base of the trunk appears to shift growth from shoots to roots. This could help trees recover from construction-related injuries by slowing top growth while the root system catches up. Special training and licenses may be required to apply this material.

Humic acids: Addition of vitamins, humic acids, and other organic derivatives are sold as remedies for numerous plant maladies. Few, if any, have been shown in the scientific literature to provide benefits to trees. None appear to hurt plants when applied according to directions.