Management of goldenrods (Solidago spp.) in wild blueberry (Vaccinium angustifolium Ait.) fields

Abstract

Weeds are considered a major yield limiting factor in wild blueberry fields, and creeping herbaceous perennials have become common and problematic. Goldenrods are creeping herbaceous perennial weed that reproduces by seeds and extensive underground rhizomes. Current management plans do not provide adequate control of goldenrod in each production year. Therefore, it remains a serious problem in wild blueberry cropping systems. Multiple experime nts were conducted over two years to evaluate 1) summer broadcast herbicide applications, 2) summer and fall spot herbicide applications, 3) mechanical control, 4) optimum timing of mechanical and chemical control, and 5) main and interactive effects of mechanical and chemical control on goldenrods to develop an integrated management plan to control goldenrod species in wild blueberry fields. Post-emergence broadcast applications of mesotrione followed by sequentia l mesotrione application at 14, 21 and 28 days after initial application (DAIA), as well as mesotrione alone or tank mixed with bicyclopyrone, effectively controlled goldenrod shoots in the non-bearing and bearing year. Summer spot applications of glyphosate and mesotrione reduced goldenrod shoot density in both the non-bearing and bearing years. In addition, fall spot applications of glyphosate significantly reduced goldenrod shoots in the following year after application. Repeated cutting at the floral bud stage significantly reduced goldenrod shoot density in the non-bearing year, but not the bearing year. Glyphosate application at all growth stages, but particularly at flowering, caused a significant reduction in goldenrod shoot density in both the non-bearing and bearing years. In another experiment, glyphosate applied alone followed by nothing at the floral bud stage significantly decreased shoot density in both years. Based on these results, cutting twice had limited effects on goldenrod, and herbicides are recommended for goldenrod management in wild blueberries.