Issue link: http://read.dmtmag.com/i/299589
7 0 V I N E YA R D & W I N E RY M A N A G E M E N T | M a y - J u n e 2 014 w w w. v w m m e d i a . c o m eed resistance to herbicides, particularly glyphosate (Round- up), continues to be a major issue for agriculture worldwide and in vineyard weed control. New herbicides registered for use in vineyards, and combinations of herbicides with different modes of action, provide options to reduce herbicide resistance and provide better weed control. In addition, newer spray nozzles for applying herbicides can provide effective weed control and minimize unwant- ed spray drift. GLYPHOSATE-RESISTANT WEEDS AND HERBICIDE USE U C C o o p e r a t i v e E x t e n s i o n (UCCE) weed specialist Brad Han- son, based at UC Davis, has been studying and monitoring the spread of weed species and glyphosate- resistant weeds in California vine- yards and orchards. Bas ed on recent herbicide use data for wine grapes, more than 40% (by weight) of all herbicides applied in California are glyphosate (Roundup and prod- ucts with similar chemistry). The popularity of glyphosate is due to its favorable cost, safety, availability and effectiveness on a broad spectrum of weeds. Based on 2011 herbicide use data in Cali- fornia, more than 90% of vineyards received at least one application of glyphosate (see Table 1). Hanson observed, "Overusing a single her- bicide is not sustainable, even if it's a good herbicide." Managing Weeds and Herbicide Resistance in Vineyards New herbicides, combinations and spray nozzles offer control options BY TED RIEGER, SENIOR FEATURE EDITOR