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The P&PDL Picture of the Week
for 30 December 2002

Volcano mulching -- a disaster waiting to happen!

Gail Ruhl, Senior Plant Disease Diagnostician, Interim P&PDL Director, Purdue University

Applying heaping mounds of mulch right up to the tree trunk is often referred to as "volcano mulching". Having personally witnessed the decline and eventual death of young as well as established trees because of excessive mulch applications around the trunk, I cannot urge you enough to educate yourself on the proper way to mulch a tree. As mentioned by Dr.
Mike Dana, in HO-100-W Planting and Transplanting Landscape Trees and Shrubs, it is important to "keep all mulch away from the trunk of the tree or stems of shrubs". When a thick layer of mulch is placed in direct contact with a tree trunk or shrub stem, the moisture captured by the mulch will keep the bark of the tree or shrub in a continual state of wetness. Eventually, the bark will begin to decay. Insects, fungi, and bacteria will feed on the damaged tissue and the lower trunk will develop a wood rot that will most likely cause eventual death of the tree or shrub.

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Volcano mulching -- a disaster waiting to happen!

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Last updated: 30 December 2002/amd
The Plant & Pest Diagnostic Laboratory at Purdue University