Poison ivy season is with us again. Landscape maintenance firms may be asked to control poison ivy on properties that they manage. The following is more information on the subject.
Poison ivy, Toxicodendron radicans, has fully leafed out throughout Delaware. This is a problem weed in managed woodlands, wooded properties, parklands, commercial sites, and overgrown properties. It is noted for its ability to cause allergic skin reactions. Poison ivy is woody perennial weed that can be found as an erect shrub, a trailing shrub running along the ground, or a woody vine climbing by aerial roots giving the vine a fuzzy appearance. It is identified by its leaves, newly emerged red in color then turning glossy green, consisting of 3 leaflets two to four inches long with pointed tips. Two of the leaflets are directly opposite each other and center leaflet stands out by itself, extended on a longer stalk. It spreads by rhizomes, stems rooting along the ground, and seed.
Control can be done in small areas by digging up plants making sure to get all the rhizomes. Avoid all skin contact using gloves, long sleeves, and long pants. Herbicides are best applied in early through late summer, but before leaves change color. Herbicides that are effective include glyphosate; triclopyr; 2,4-D; 2,4-D + dicamba; and fosamine. Apply as a broadcast spray to leaves. Multiple applications of these herbicides will be needed over several years for complete control. Vine and brush forms may be cut and gyphosate applied immediately to the cut stumps.
Glyphosate is recommend (as a directed or cut stump application) in landscapes and desired woodlands. Triclopyr; 2,4-D; 2,4-D + dicamba; and fosamine are most appropriate for non-landscaped areas, fencelines, and right of ways as they are general brush killers.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County