Susceptibility of American burnweed (Erechtities hieraciifolius) to herbicides and clipping in wild blueberry (Vaccinium angustifolium Ait.)

Abstract

Wild, or lowbush, blueberry (Vaccinium augustifolium Ait.) is a perennial, deciduous shrub native to North America (Vander Kloet 1988). It is the most important fruit crop in Nova Scotia (Strik and Yarborough 2005), contributing 22 million dollars to farm gate value in 2011 (Statistics Canada 2012). Commercial fields are developed on abandoned farmland or cleared woodland where native blueberry stands already exist (AAFC 2005). Stands are managed primarily on a two-year cycle in which fields are pruned to ground level in the first year (nonbearing year) and harvested in the second year (bearing year) (AAFC 2005). Weed management options are limited due to the perennial nature of the crop, and weeds are therefore a major yield limiting factor (Jensen 1985; McCully et al. 1991). The weed flora of wild blueberry fields has traditionally been dominated by herbaceous and woody perennial species (McCully et al. 1991), but the trend since the introduction of hexazinone has been towards shorter-lived weed species that rely on reproduction by seeds for establishment and spread (Jensen and Yarborough 2004). Herbaceous annual and monocarpic perennial species, therefore, have become increasingly common in wild blueberry fields. American burnweed (Erechtites hieraciifolius) is an annual plant in the Asteraceae family (Darbyshire et al. 2012). The plant is phenotypically variable (Belcher 1956) but is generally erect (up to 300 cm tall) (Darbyshire et al. 2012) and produces abundant, wind-borne seed (Wagner 1965; Darbyshire et al. 2012). It is native to deciduous forest regions of North America and later was introduced to regions of Europe and Asia (Darbyshire et al. 2012). The distribution in Canada is from the Maritime Provinces to western Ontario (Darbyshire et al. 2012), and the plant is abundant in areas of recently cleared forest (Peterson et al. 1990; Kochenderfer and

Weed Survey of Nova Scotia Lowbush Blueberry (Vaccinium AngustifoliumAit.) Fields

“…The plant was first reported as a weed in lowbush blueberry fields in Maine, USA where it formed very dense stands that reduced yield and hindered harvest in some fields (David Yarborough, personal communication). The plant is susceptible to many currently registered herbicides in lowbush blueberry (White and Webb, 2018) but can produce up to 32,000 wind-borne seeds (Csiszár, 2006) that exhibit typical summer annual dormancy characteristics and form persistent seed banks (Baskin and Baskin, 1996). Growers should therefore begin monitoring for this weed species and implementing control measures before plants go to seed.…”

Evaluation of acetolactate synthase/acetohydroxyacid synthase – inhibiting herbicide spot applications and mesotrione tank mixtures for narrow-leaved goldenrod management in lowbush blueberry

“…ex DC.] in lowbush blueberry (White and Webb 2018). Currently registered herbicides with activity on broadleaf weeds that may exhibit sufficient crop tolerance when applied broadcast post-emergence to lowbush blueberry are limited to foramsulfuron (White and Kumar 2017), nicosulfuron + rimsulfuron (Wu and Boyd 2012), and clopyralid (Jensen 2004), but none have been evaluated for narrow-leaved goldenrod control when applied in tank mixture with mesotrione.…”