LSU AgCenter Horticulturist
Live oaks (Quercus virginiana) are very active this time of year — putting out pollen and shedding leaves from the canopy to produce new leaves. Many allergy sufferers, including myself, find this time of year quite difficult.
As the leaves fall, live oaks produce male flowers called catkins, producing copious amounts of pollen. It turns the tops of cars and houses and any other surface it can stick to a yellow-green color of powdery mess and creating headaches for the allergy sufferers.
The flowers then die back, turn brown and fall off, releasing yet another assault on the ground and surrounding area.
Live oaks do keep their leaves all year-round, except for the small window when flushing out new leaves in the springtime. The leaves that are dropped are a great mulch. Rake them up and place them in your compost, or recycle them and use them for mulch in landscape beds and around the base of trees.
One question I often get on live oaks is about the suckers or sprouts found at the base of some trees. You may notice these sprouts in areas where tree roots are restricted by sidewalks, parking lots or trees that have been impacted by high foot traffic and soil compaction.
These suckers are often a sign of stress from the tree. Live oaks are long-living survivors, sometimes reaching ages of hundreds of years. This adaptation has developed by live oaks to ensure succession as the mother tree ages, sending up suckers to continue the lineage. Fortunately, most live oaks do not send up suckers from their roots.
What can you do about these suckers? Removing them by hand can be tedious, but deep root pruning can reduce suckers for a few years. Unfortunately, you cannot use a herbicide on these sprouts because it can damage the mother tree. Some homeowners will plant a ground cover under the tree in an effort to cover the sprouts.
Ground covers such as Asian jasmine have a similar leaf shape to live oaks, and they can help camouflage the sprouts. However, Asian jasmine is not a native plant, and some folks find it invasive. One bonus is that it is evergreen, just as live oaks are, and the vines can be shaped, trimmed and contained to an area with a weed trimmer with little to no effort.
Unfortunately, there is no permanent solution to the sucker problem. You can easily keep the small, tender suckers cut back with a weed trimmer with your regular lawn maintenance. There are chemical products available used to suppress sucker production by applying when the suckers have been freshly cut. Look for products with the active ingredient Ethyl 1-naphthaleneacetate and names such as Sucker-Stopper.
Prune the suckers as close to the roots as possible and then spray with the product. Suckers from the oak roots will eventually begin to grow again, but it will take much longer for them to grow if you use the treatment.
Live oaks are some of the most beloved trees in the South and they have a wonderful history in Louisiana. They are native and can serve as a beautiful planting or shade tree. Be sure to provide ample room for these majestic beauties.
Live oaks under stress can send up suckers that can be controlled by trimming. Photo by Heather Kirk-Ballard/LSU AgCenter
Some live oaks can send up hundreds of tiny sprouts, often due to stress. Photo by Heather Kirk-Ballard/LSU AgCenter
Suckers from live oaks can be covered with ground covers such as Asian jasmine. Photo by Heather Kirk-Ballard/LSU AgCenter