Question
My father is on a total crusade against the ailanthus trees- he calls them paradise trees. I've never heard them called that outside of the area where he lives. He has this stuff that costs like $250 a bottle (crossbow, i think) that you mix with diesel. I know these things are like impossible to get rid of, b/c the ones that you do are instantly replaced by other ones. I want him to stop- it's a total waste of time, energy, and money. Nothing'll ever kill those things. What can be done to maybe make them a little prettier- I've seen ones that are. But the ones he have kind of look like pencils.

Answer
Ecological Impact: Tree of Heaven grows rapidly and is a prolific seed producer. Individualtrees can produce up to 325,000 seeds per year. Seeds are wind-dispersed and seedlings rapidlyestablish by producing a well-developed tap root in less than three months. Once established,Tree of Heaven outcompetes with native vegetation for sunlight and space. It quickly takes overan area and produces a dense thicket. Trees produce a toxin in the bark and leaves. As leavesaccumulate in the soil, the toxin inhibits the growth of other species. Furthermore, the rootsystem is capable of damaging sewers and foundations.Control Methods: Tree of Heaven is very difficult to remove once established. The mosteffective control methods are to prevent establishment by annually monitoring for and removingseedlings and to treat saplings and larger trees with herbicides.Mechanical Control: Seedlings should be hand pulled after a rain when the soil is loose. Be sureto remove the entire plant including all roots, since new plants can sprout from root fragments.Root sprouts resemble seedlings, but are attached to a lateral root and are nearly impossible topull up. Saplings and larger plants can be cut using brush cutters, loppers and clippers, axes, orpower saws. Trees can also be girdled. Initially, cutting is counter-productive as it will promotelarge numbers of stump sprouts and root suckers. However, cutting will prevent seed productionand, if done repeatedly, will ultimately exhaust food reserves. If continued for several years,cutting will eventually kill the plants. The initial cut should made be in early summer when rootreserves are lowest. If only a single cut can be made, the best time is when the tree begins toflower. At this stage, the food supply in the roots is nearly exhausted and seeds have not yetbeen produced. After cutting, stems should be treated with herbicide to prevent sprouting fromroot crowns. Mature trees can be girdled with an ordinary axe in the spring when trees areactively growing. Manually cut away bark and cambial tissue in a 2-3 cm wide ring around thetrunk. To prevent sprouting, treat girdle cuts with herbicide.Chemical Control: Herbicides can be applied broad scale as a foliar spray, or to selectindividuals as injection, cut stump, or basal bark treatments. Foliar sprays are highly effective,but should be used only where contact with nearby native vegetation can be prevented. Injectiontreatment inhibits or prevents sprouting and suckering if done at the right time of year. Cutstump treatment is best in areas where trees are to be removed. Basal bark treatment is one ofthe easiest methods and does not require cutting.1) Foliar Spray: Spray plants with a systemic herbicide like glyphosate (e.g., RoundupTM orRodeoTM) when in full leaf. The leaves absorb the herbicide and transport it to the root system.If plants are in or near wetlands, only RodeoTM should be used. For backpack sprayers, use a2% solution of glyphosate and water. Another systemic herbicide known to be effective istriclopyr (Garlon 3ATM, Garlon 4TM), which is specific for broadleaf and woody plants and will notkill grasses. When using triclopyr, a small amount (0.5%, or as per label) of non-ionic surfactantshould be mixed in to help the spray spread over and penetrate the leaves. For backpacksprayers, use a 1.5% solution of a 4 lb./gallon triclopyr product (Garlon 4TM) or a 2% solution ofa 3 lb./gallon triclopyr product (Garlon 3ATM).2) Injection Treatment: This treatment is most effective if done during the summer. Control ofroot suckers decreases in the fall and is poor during winter and spring months. Using a hand axe,make downward-angled cuts into the sapwood around the tree trunk. Make one cut for each inch.