Few herbicides are used in carrot production in the United States, and none suppress volunteer potato, a serious weed where the two crops are grown in rotation. Hand-weeding is the primary method of controlling emerged volunteer potato within carrot. The objective of this work was to evaluate carrot tolerance and volunteer potato control with single or sequential applications of prometryn, prometryn plus fluroxypyr, and ethofumesate. The treatment with fluroxypyr resulted in malformed carrots with numerous root hairs and reduced carrot yield. Treatments with prometryn, either as single or sequential POST applications at 2.23 kg ai/ha, were safe on carrot and frequently controlled volunteer potato similar to the hand-weeded treatment. Ethofumesate applied as single or sequential PRE or POST at 2.2 kg ai/ha proved safe on carrot, but higher rates reduced yield. Ethofumesate applied POST or PRE followed by POST consistently reduced volunteer potato tuber mass. If registered for use in carrot, prometryn and ethofumesate would help modernize weed management in carrot and reduce or eliminate the need for hand-weeding volunteer potato.

Nomenclature: ethofumesate; fluroxypyr; prometryn; potato, Solanum tuberosum L.; carrot, Daucus carota L.

Additional index words: Crop injury, integrated weed management, minor crop, tuber density, vegetable.

Abbreviations: EPOST, early postemergence; LPOST, late-postemergence; MPOST, midpostemergence.