Management of Hawkeed (Hieracium spp.) in wild blueberry fields on Prince Edward Island

Abstract

Hawkweeds (Hieracium spp.) are a persistent problem in lowbush blueberry fields on Prince Edward Island (PEI). In 2011 and 2012, experiments were conducted on PEI on the weed phenology, herbicide trials and the best time to spray to achieve maximum results. Two hawkweed species, H. pilosella and H. caespitosum were identified. H. caespitosum was the most common hawkweed species. The only herbicide which gave short term suppression on H. pilosella in 2011 was hexazinone (Velpar) applied at 1920g a.i/ha sprayed in the spring. A fall application of dicamba (Banvel) sprayed at 1104g a.i/ha or an application of clopyralid (lontrel) applied at 151.2 g a.i/ha effectively managed H. caespitosum over the season and the most effective control was obtained when applications were made in the bolting stage.