Q. We are planting a 30-gallon apricot tree. The hole is large and deep, but the bottom has lots of thin roots from nearby trees. I took out most of the bigger ones. Can I torch these small ones?
A. Roots no longer attached to the “mother” plant can be “torched”. Using fire to kill roots only kills the roots a few inches from the fire. Killing roots is due to the heat produced by the fire.
During the summer, clear plastic can be used to kill roots during the day. All roots and diseases are killed at 180F in 30 minutes and allowed to “solarize”. That’s the temperature and length of time needed to sterilize dry soil 6 to 12 inches deep. If you are still not sure, then sever the roots from the tree with a sharp shovel.
By the way, it is less of a problem if the planting hole is dug wider but not deeper. When digging a planting hole, it is recommended to dig the hole three times the width of the roots, but not any deeper than the roots or container unless, of course, there is a drainage problem. Water added to the dug hole should drain overnight.