Xtremehorticulture

Olive Tree Suckers Easily from Many Locations

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.

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Branch Dieback in Olive Sign of Soil Disease

Q. We have a twenty year old olive tree in our front yard diagnosed with Verticillium wilt disease. The north third of the tree appears to be healthy. If we remove this tree, what distance from the old hole is needed for the new tree? We would a replacement tree to provide shade. We are looking at oak, pine, ash, spruce or fir.   Olive leaf drop and branch dieback may be a sign of verticillium wilt in olive. A. That’s unfortunate. Hopefully the diagnosis was correct and it is not something else that caused it. The information you received about the disease sounds correct. This disease is present in the soil and enters the tree via the roots.             Olive has very few pest problems and an excellent tree for the desert. Verticillium wilt disease is rare in olive here but does occur. Symptoms include the death and dieback of individual limbs for no apparent reason.             Trees resistant to Verticillium wilt disease and good choices for you in our desert include live oak such as Heritage or holly oak, ornamental pear, European pear, honeylocust, apple, crabapple and any of the conifers such as pines.             Eucalyptus is also resistant but a lot people do not like eucalyptus since it can be “messy”. I would not recommend spruce or firs since they do not grow well in our climate.             If you want warmth from the winter sun then conifers (pine) or any evergreen tree (such as our southern oaks) is not a good choice for you. I would stay with ornamental pear or honeylocust for seasonal shade, disease resistance and good looks.             If you stay with Verticillium resistant trees, planting in the same general area should not present a problem.

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