Question
Our trees are located in the Wausau area of north central Wisconsin.  Last year a 4" diameter 25 foot Skyline Honey Locust on my property would not leaf out above the crotch of the tree.  I had planted it bare root in 2007 and it had been growing beautifully.  My thought was that since the tree had a 4 foot snow drift running through it since November, then in April we had a quick thaw followed by 2 weeks of cold (in the teens for lows), the water from the thaw could not get away from the roots (although there was no standing water) and it stressed the tree to the point that it would not leaf out.  Our soil is a pretty heavy loam and does hold water pretty well.  Our tree was turning into a locust "shrub" so we removed it.  When we removed it, we noticed the base of the trunk just below the soil line was bulged out.  Now this year a 2-1/2" Imperial Honey Locust on our lot is not leafing out above the crotch, so it appears this one is also doomed.  This one was a balled and burlapped tree also planted in 2007.  I pulled the soil away from the base and the trunk is bulged below the soil line also.  Is this what's possibly causing the problem?  I have one more 4" Skyline left that is leafing out above the crotch so I think this one is fine, so far.  We have river rock around the trees but I hold it back from the tree trunks.  This is our 4th property on which we have planted locusts and we have never had this problem.  Your insight regarding this problem is greatly appreciated.

Answer
The snow may have had an effect but I think the main problem is the rock around the trees.


The use of rock around trees should be avoided. While rock has some limited applications as a ground cover, most rock creates an alkaline environment and most trees prefer an acidic soil. Volcanic rock is particularly detrimental to trees; not only is it alkaline, but it抯 darker color causes it to hold excessive heat.

Rock over landscape fabric is a common mulching material often considered as low maintenance. It is the preferred material for non-plant areas. Rock mulch has the advantage over wood/bark chips that it does not blow, float, or require additional amounts every few years as it decomposes.

Rock mulch can become a heat sink, creating a significantly warmer afternoon, evening, and nighttime microclimate. Outdoor people space adjacent to rock mulch will be warmer and less comfortable for summertime afternoon and evening use. In planting beds, rock mulch increases temperatures and may increase water requirement.

Rock also is heavier and will compact the roots damaging them. I would recommend that you carefully remove the rock and replace it with an organic mulch.

Use organic mulch such as wood chips or compost or pinstraw. Use wood chips that have been composted for at least 3 months. A mix of fine and coarse material is best.
Apply composted material to the soil surface and top with coarser and fresher material. Incorporation into the soil is not recommended or necessary.
Mulch should be about 2-4 inches deep. Two inches for poorly drained soils. Do not exceed 6 inches in depth.
The larger the mulched area the better, but it should reach at least to the tree's drip line (the outer perimeter of the branches).
Do not use geotextile landscape fabrics beneath the mulch, as this prevents the decomposing mulch from mixing with the soil. Plus the weeds just grow on top and through the fabric.
Keep mulch at least 6 inches away from the tree trunk.
Avoid disrupting the mulch with annual flowers. If plants are desired, use perennial ground covers such as vinca or English ivy.