Issue link: http://winesandvines.uberflip.com/i/365438
54 W i n e s & V i n e s s e P T e M B e R 2 0 1 4 But if glyphosate resistance is becoming an issue of greater concern, Brad Hanson, coop- erative extension weed special- ist for vineyards and orchards in the Department of Plant Sci- ences at the University of Cali- fornia, Davis, told Wines & Vines that it hasn't become one that's taking an economic toll on West Coast growers. Rather, it stands to increase management headaches and costs more than anything else. "Is this a huge problem in the vineyard system? Probably not," he said. "It's an inconve- nience—and certainly a greater expense, but for the most part it's not a crop fail- ure situation like it could be in cotton or corn or wheat." Fighting for water But with competition for water a significant issue in California right now, weed control is attracting greater interest. The herbicide Prowl performed nearly twice as well on vineyard weeds when combined with Alion or Matrix. However, the mix of Alion plus another herbicide such as Prowl (pendimethalin) and Zeus (sulfentrazone) was the most ef- fective. Zeus plus Goaltender did particularly well, too. However, the quantities obvi- ously matter. Alion, for example, was significantly more effective at 5 ounces than at 3 ounces per acre. Some materials required much larger quantities per acre than others. A note on specific weeds Panicle willowherb and horse- weed are new to the Napa area and represent some of the big- gest challenges at present. Pre-Emergent Herbicide Trial Results Ratings are the average of four replications and are based on control of four main weeds: panicle willowherb, horseweed, annual sowthis- tle and annual grasses. Source: John Roncoroni/UCCE Farm Advisor (Continued from page 53.) Herbicide Amount Applied, Mixed With 30 Gallons of Water Weed Control at 90 Days (1=No Control, 10=Total Control) Untreated control 3.50 Roundup 1 quart 4.75 Matrix 4 ounces 8.63 Chateau 12 ounces 9.00 Trellis 1 pound 8.35 Goaltender 2 quarts 9.85 Zeus 12 ounces 6.25 Prowl 6 quarts 5.50 Alion 3.5 ounces 9.25 Alion 5 ounces 10.0 Alion/Chateau 5 ounces/4 ounces 9.75 Alion/Matrix 5 ounces/2 ounces 9.75 Alion/Goaltender 5 ounces/1 quart 10.0 Alion/Zeux 5 ounces/10 ounces 10.0 Alion/Prowl 5 ounces/6 quarts 9.88 Matrix/Alion 4 ounces/2.5 ounces 10.0 Matrix/Zeux 4 ounces/10 ounces 9.60 Matrix/Goaltender 4 ounces/1 quart 9.13 Matrix/Prowl 4 ounces/6 quarts 9.88 Zeus/Alion 12 ounces/3 ounces 9.85 Zeus/Goaltender 12 ounces/2 quarts 10.0 Zeus/Chateau 12 ounces/6 ounces 8.63 Chateau/Prowl 8 ounces/6 quarts 9.13 Trellis/Surflan 1 pound/3 quarts 8.50 Trellis/Goal 2 xl/Surflan 1 pound/3 quarts/3 quarts 9.50 G R A P E G R O W I N G