When you are busy taking care of your family and job, maybe noticing everything that's going on in your landscape is not a high priority. Months pass. Maybe years pass before you take a closer look out in back and along the edges and notice that there are some trees and shrubs growing there that you and the landscapers before you never planted. Some euphemistically call these plants volunteers. They get there because a seed sprouted, or sprouts emerged from the roots of another tree. I call them weed trees. Well, what is a weed? A weed is simply a plant growing in the wrong place. Some volunteer trees might, by chance, just happen to sprout in an advantageous spot, and with a little monitoring of its development, could grow into a suitable tree. Most, though, come up in the wrong place, and they should be eliminated before they get to be an expensive removal project. The best way is to not ignore the planter beds for too long and pull those sprouts before they get more than a few inches high. Cutting them off leaves the root, and they are not likely to give up so easily. So either get the weed tree out with its root, or dab some herbicide on the freshly cut stump with a cheap 1 inch wide paintbrush. I usually use glyphosate in its concentrated form diluted about half and half with water. If you wait more than a couple of minutes, the cells in the stump wood will seal off the vessels and the herbicide won't get into the plant's system. If that happens, just make a fresh cut.
Here are some of the common weed trees that I encounter:
Ligustrum lucidum, glossy privit—seeds, Ailanthus glandulosa, tree of heaven—seeds and root sprouts, Schinus terebinthifilius, Brazilian pepper—seeds, suckers, and root sprouts, Pyrus spp. Ornamental pear—root sprouts and suckers, Cinnamomum camphora—camphor tree—seeds, Prunus caroliniana and P. lyonii, Catalina and Carolina cherry—seeds, Olea europea, olive—seeds, Melia azederach, chinaberry—seeds, suckers, and root sprouts, Ficus carica, fruiting fig—seeds, Fraxinus uhdei, shamel ash—seeds, Ulmus parvifolia, Chinese, or lacebark, elm—seeds, Eucalyptus spp—seeds, Cupaniopsis anacardioides, carrotwood—seeds, Quercus agrifolia, coast live oak—seeds, Washingtonia, Phoenix, Syagrus, Mexican & California fan palms, date & queen palms, Ceratonia siliqua, carob—seeds, Koelreuteria spp. Goldenrain trees—seeds, and Morus alba, mulberry—seeds
A similar problem involves sports. That's when you have a variegated plant, and then it reverts back to a solid green color. Well, the variegated varieties started out as sports of the green plants, someone thought they were beautiful, and propagated them from cuttings. That's called cloning. A lot of those sports will just sport back to the solid green, and since that has more chlorophyll, it captures more sunlight energy, grows faster, and will take over if you let it. Just like weeding, you have to go through your trees and shrubbery periodically and cut out the sports. The most common ones are Pittosporum tobira, and various varieties of Euonymous, which are shrubs and ground covers. The variegated box elder tree also easily reverts back to the green, so it has to be monitored. Some dwarf varieties and varieties with compact foliage will also revert back to larger forms of the plants they originated from. You just have to be aware and prune the reversion sports out.