MORRIS
We are talking about African sumac now. This type of pruning will not work on all large trees. If this type of pruning had been done to most ash trees, it would’ve killed them.
The acceptable method for reducing the size of larger trees is a technique called “drop crotching.” This technique identifies the tallest limbs and removes them at a crotch in the tree, using a clean cut that leaves no stubs. When cutting trees in this way, the height is reduced but strong limbs remain to support the canopy and reduce future wind damage.
Basically, drop crotching can be done to any large tree, not just African sumac. The type of pruning you saw done to your neighbor’s trees only works on trees that sucker easily from larger limbs.
Dramatically reducing the size of trees by pruning is best left to tree care professionals, certified arborists, who have passed rigorous exams demonstrating that they understand and can practice highly specialized form of pruning correctly. They are more expensive but they know how to do it correctly.
Q: I have a 12-year-old Chinaberry and I am trying to decide whether to keep it or not. I enjoy it in the spring because of its showy flowers but it has some dieback in the limbs and I fear it could be sooty canker disease. If it is sooty canker disease, is it necessary to remove immediately or could I keep it for at least one more spring? If so, should the affected limbs be removed now?
A: Sooty canker disease attacks many different types of trees and large shrubs including fruit trees. It causes limbs to die. If it spreads into the trunk, the tree should be removed. If it is only in the limbs, the infected limbs can be removed and the tree saved.
Yes, you could prune now with no problems. But you could wait a few months as it does not spread quickly.
This disease is easy to identify because dead limbs have bark that easily pulls from the wood. On the wood, under the bark, will be a black, sooty dust that looks just like soot from a chimney. It easily comes off on your fingers when you rub it, just like a sooty chimney. Spreading this soot is one way this disease can infect other trees.
Regardless, the tree needs to be pruned to remove dead limbs. Once the dead limbs are down, it may be easier to see if it is sooty canker disease. When pruning, make sure the saw is sanitized between cuts with diluted bleach or Pine Sol.
If the dead limbs are only infecting the branches, it is possible to save the tree by removing them. Be very careful to sanitize any equipment that comes in contact with infected plant parts.
Sooty canker usually attacks unhealthy trees. Make sure the tree is receiving enough water and receives a single fertilizer application each year in early spring. Bob Morris is a horticulture expert living in Las Vegas and professor emeritus at the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.