Pennywort (Dollarweed) Control (7-6-09)
Pennywort (Hydrocotyle spp.), better known locally as dollarweed, is a rhizomonous perennial with umbrella-like, long-stalked scalloped margined, waxy leaves. The petiole (stem) is found in the center of the leaf which helps define it from dichondra that has a c-shaped, smooth edged leaf with the petiole found at the edge of the c-indention. Dollarweed is most often found in moist to wet sites or anywhere moisture is in excess.
Control in Turf:
Isoxaben (Gallery) is recommended for providing effective pre-emerge control of pennywort. Post-emerge products such as atrazine or the hormonal herbicides 2,4-D and/or dicamba will provide fair control as will imazaquin. Glyphosate (Roundup, Touchdown, others) can also be used for control, but many turfgrass species can be seriously injured or killed when these products are applied to green plant parts. Manor (metsulfuron) Tranxit (rimsulfuron) and Speed-zone Southern (carfentrazone, 2,4-D ester, MCPP, and dicamba) are the newest products providing effective control. Other options include bentazon, quinclorac, fluroxypyr or other phenoxy compounds.
Tolerances of various turfgrass species differ tremendously to herbicides so it is critical that labels are read carefully for uses, rates, timing of application, etc. and strictly adhered to.
Control in Ornamentals:
Cultural practices and mulches are most likely your best defense since few effective herbicides are available in ornamentals. Coarse textured mulches like pine straw or pine mulch 2-4" deep will help smother and limit invasion. Landscape fabrics under the mulches will also help reduce emergence. Hoeing and hand pulling will also help reduce population density but regrowth will occur unless underground stems are removed.
Image (imazaquin) list dollarweed control with repeat applications and can be used around some ornamentals. Read the label carefully for specific use applications. Isoxaben (Gallery) can also be applied to many ornamentals. Glyphosate (Roundup) can be applied post-directed to dollarweed foliage, but extreme care is necessary to avoid any contact with ornamentals or severe injury can occur.
Published July 6, 2009
