Q. An olive tree on the property of our homeowner association is sending up suckers from its base and along the trunk. I am thinking it’s because the tree is not getting enough water. Our landscaper continues to remove them and thinks otherwise. Who is right?
A. Suckering from the base can be a sign of a lack of water in some trees but olive trees also sucker from the base and along the trunk easily. If you look at the base of older olive trees you will see some “knots” or swellings attached to the lower trunk, trunk limbs and root flares as they get older. There can be so many of them the tree becomes disfigured. It gives olive trees a great deal of character in their old age.
|Olives sucker easily from clusters of immature or unopened buds hidden on the trunk. You can spot them as bumps or gnarls. A limb was removed from this olive tree which encouraged the suckers to grow.|
These swellings along the trunk and limbs develop from clusters of immature buds embedded in woody growth. Suckers can originate from these “knots”. These knots or “burls” can get quite massive in older trees.
Burls are common in other trees as well particularly trees that are prone to damage from fire or animals like coastal redwoods. Burls are valued by many woodworkers but despised by the construction lumber people.
Suckering from the base of some trees, however, can be in response to drought. There may or may not be obvious swellings at the base of these trees. The tree finds it difficult to deliver water to its top when water is scarce.
|This tree rose suckered from the rootstock after the top of the tree, or scion, died back.|
These clusters of undeveloped buds, previously asleep, begin growing from the base. Some are scattered through the wood and others are in clusters. Growth from the bottom is easier to support when water is scarce then growth at the top.
Some trees like many ash trees don’t have that survival mechanism. When water is scarce, their leaves begin to scorch, push very little new growth and limbs dieback particularly during hot weather.
You could still be right. The tree may not be getting enough water and that just makes suckering even worse. It’s best to look at the tops of the trees to make a drought determination. When water is scarce, the canopy growth suffers and when water is really restricted there is leaf scorch and dieback by the tallest limbs.
If the tree is growing nicely and has lots of leaves then I would say it's getting enough water. The suckering at the base of the tree is probably normal. However, if the tree is sparse in its canopy and growth is poor and it is suckering from the base then I would worry about enough water.