Over the past few weeks riding down our county roads, I have noticed the Chinese privet turning green. Everyone will notice these plants because they will load the edges of the woods with large numbers of highly fragrant white flowers. In the forest, privet occupies one million acres of timberland, and is the second most invasive plant. Japanese honeysuckle wins the trophy in Alabama for being the most invasive plant in forested settings, growing on 2½ million acres. Over the last thirty years as I have watched these two plants spread, it is my opinion that privet is the worst plant. Honeysuckle is an edge plant that needs sunlight to grow. Once the forest closes the canopy, honeysuckle tends to die back if it cannot grow in the tops of the trees. Privet on the other hand will exist, as a wisp, in the understory of a forest just waiting for an opening. Once the opening occurs, the wisp will quickly grow into a thick bush. Without human intervention, that bush will grow into a fifteen-foot multi-stemmed tree. As these bush-trees grow, they shade the ground. Shade is the problem.
We have all pulled out little trees growing in our shrubs. Nicely pruned yard shrubs have sunlight reaching through them to the ground, so any seeds that land below the bush have an opportunity to germinate and grow. Whenever I trim my parents or my shrubs, I always have to check for baby trees. Cutting the top of the tree does not kill the little tree. It merely sprouts a new branch, within the bush, which turns up-ward and that branch becomes the new tree top. Sometimes the tree is cutback so often that it can develop a thumb-size or larger stem at the soil surface down below the bush. Many times this tree is impossible to pull out of the ground. When the tree is too large to pull, take a small pruning saw or loppers and cut it off and herbicide the stump. This happens in our yards, but rarely does this happen in the forest.
Shade is the issue. Yard shrubs allow sunlight to penetrate them. Privet grown in the woods does not allow sunlight to reach the forest floor. Forest trees first filter out over half of the sunlight, then the privet bush-tree filters out the remaining sunlight. Forest seeds that land on the ground under a privet bush-tree either get eaten by forest rodents, rot on the soil surface, or germinate begin to grow, then die in the shade. Our creekside hardwood bottoms are highly susceptible to privet infestations. Privet loves moist forest soils. Because of this characteristic, many of our creek bottoms are becoming overgrown with privet. Large 100’ tall oaks, yellow poplars, and cypress are being replaced with fifteen-foot tall privet forests. Not only are the trees in danger of dying out, but the critters that depend on our native trees are also in danger. If you have an established privet forest, it may take herbicides to defeat the invaders.
Contact your local Extension office for more information and help.
Garden Talk is written by Andrew J. Baril of the Alabama Cooperative Extension System, C. Beaty Hanna Horticulture & Environmental Center, which is based at the Birmingham Botanical Gardens. This column includes research-based information from land-grant universities around the country, including Alabama A&M and Auburn Universities. Email questions to firstname.lastname@example.org, or call 205 879-6964.
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