People admire sycamore trees (Platanus spp.) for their ability to thrive under difficult conditions, enjoy them for the shade they generate and appreciate their attractive bark. However, sycamores may not be desirable in certain situations. Small gardens with limited space or areas with structures that could be damaged by roots may not be ideal for sycamores. A heavily infested or diseased sycamore may be killed to prevent further spread of the problematic pathogen. Besides simple tree removal, several methods work to kill an unwanted sycamore.
Girdling is a nonchemical method used for killing standing trees. The girdling process, performed with an axe, hatchet or chainsaw, includes cutting a notch or two around the diameter of the trunk to interrupt sap flow between the roots and canopy. The proper depth and width varies depending on the tree size, ranging from 1.2 cm (1/2 inch) deep and 2.5 or 5 cm (1 or 2 inches) wide on small trees to 3.7 cm (1 1/2 inches) deep and 20 cm (8 inches) wide on very large trees.
Frilling is similar to girdling in that it is also breaks the sap flow using minimal equipment and involves no herbicides. Performed with an axe or hatchet, frilling involves making a series of downward cuts that completely encircle the tree, leaving severed bark and wood attached at the bottom if it remains.
Tree injection includes using an axe, hatchet or specialised tool to make cuts every 7.5 cm (3 inches) around the trunk of the tree followed by the placement of a small amount of herbicide in each cut. There are also commercially available, specialised "tree injectors" that expedite the process. Suitable herbicides for injection or cut surface treatment include those that contain dicamba, imazapyr, MSMA or picloram.
Basal bark spray
Basal bark herbicide applications involve spraying a lower section of the trunk with an herbicide designed to penetrate the bark, kill the tree and prevent basal buds. This application method is suitable for trees under 15 cm (6 inches) in diameter. Care must be taken to prevent herbicide runoff, as it can easily damage nearby desirable plants. Herbicides suitable for basal bark applications are 2,4-D, dicamba, imazapyr or triclopyr.
Cut stump treatment
Following the physical removal of a sycamore tree, treatment of the cut stump, particularly the sapwood and bark, will help to prevent the appearance of new sprouts. A water-soluble herbicide should be applied to the stump as quickly as possible following cutting to ensure adequate movement of the chemical into the root system. A number of herbicides are suitable for this type of application including 2,4-D, dicamba, glyphosate, triclopyr and others.