Suppression of Liverwort Growth in Containers Using Irrigation, Mulches, Fertilizers, and Herbicides

Abstract

Liverwort ( Marchantia sp.) is often a serious weed in many nursery and greenhouse operations. Combinations of irrigation frequencies, surface mulches, surface fertilizers and herbicides were applied to the surface of the growing medium in 10-cm square pots planted with Rhododendron or Picea . Liverwort infestations were evaluated as the percentage of media surface covered. Mulches were placed at least 1/2-inch thick on the surface of the growing media. Five blocks of two pots per treatment were used in a completely randomized design. Oyster shell, hazelnut shell, and copper-treated geotextile mulches provided good suppression (less than 10% surface coverage) of liverwort for up to 6 weeks, while rockwool, peatmoss, coarse sand, perlite and pumice mulches required low-frequency irrigation to provide fair suppression (less than 40% surface coverage). Surface applications of oxadiazon (Ronstar), oryzalin (Surflan), iron oxide, copper sulfate, and manganese sulfate provided good suppression of liverwort for up to 4 weeks using low-frequency irrigation, but suppression was nearly eliminated if high-frequency irrigation was applied. Some combination applications of mulches and herbicides or fertilizers provided good suppression for 8 weeks (high-frequency irrigation) or 12 weeks (low-frequency irrigation). Liverwort suppression was fair when untreated geotextile mulches were used, but suppression was good (even under high-frequency irrigation) when copper-treated geotextile mulches were used.