Issue link: http://read.dmtmag.com/i/299589
w w w. v w m m e d i a . c o m M a y - J u n e 2 014 | V I N E YA R D & W I N E RY M A N A G E M E N T 7 1 Five glyphosate-resistant weeds confirmed in California and report- ed in vineyards are: hairy fleabane (Conyza bonariensis), horseweed or mare's tail (Conyza canaden- sis), Italian ryegrass (Lolium mul- tiflorum), rigid ryegrass (Lolium rigidum) and junglerice (Echino- chloa colona). These weeds are cur- herbicides that control glyphosate- resistant weeds, including some new options: + Sulfentrazone (Zeus) from FMC Corp. was registered for grapes in California in 2013. It is a pre-emergence herbicide with residual control of some broad- leaf weeds, grasses and sedges. Trials in vineyards in the San Joaquin Valley showed good per- formance on hairy fleabane and horseweed. + Flazasulfuron (Mission), by ISK Biosciences, can provide good control on fleabane, pigweeds and other broadleaf weeds and grasses. Can be used as both a pre- and post-emergence herbicide. + Indaziflam (Alion) from Bayer CropScience was registered for grapes in California in 2012 and rently more prevalent in the Central Valley, but horseweed is now found in Sonoma County vineyards. O t h e r g l y p h o s a t e - r e s i s t a n t weeds have been identified in Cali- fornia that Hanson cautions grape- growers to be aware of: + Annual bluegrass (Poa annua): Most recently added to the resistance list. Now in almond orchards in Madera and Merced counties. + Palmer amaranth (Amaranthus palmeri): A type of pigweed that is a problem in the eastern and southern United States, and is listed as glyphosate-resistant in several states. It is now found in raisin vineyards in the southern San Joaquin Valley. + Goosegrass (Eleusine indica) and threespike goosegrass (Eleusine tristachya): Now in orchards in the northern San Joaquin Valley. NEWER HERBICIDES Hanson periodically compiles and posts an update on registered herbicides in California for trees and vines. He provided a list of + Weed resistance to glypho- sate (Roundup) herbicides continues to be an issue in vineyards. + Several glyphosate-resistant weeds are found in Califor- nia vineyards. + Newly registered herbi- cides and combinations of herbicides offer options for better control of glyphosate- resistant weeds. + Recent trials of newer spray nozzles indicate more options are available to reduce herbicide spray drift. AT A GLANCE TABLE 1: HERBICIDE USE IN CALIFORNIA WINE GRAPES IN 2011 Source: California Department of Pesticide Regulation. Active chemical ingredient listed first, followed by common brand name(s). Product Total Acres Applied Glyphosate (Roundup) 460,000 Glufosinate (Rely) 237,000 Oxyfluorfen (Goal, Goal Tender) 209,000 Flumioxazin (Chateau) 106,000 Pendamethalin (Prowl) 97,000 Simazine (Princep, Caliber 90) 84,000 Carfentrazone (Shark) 67,000 Paraquat (Gramaxone Inteon) 63,000 Rimsulfuron (Matrix, Mana) 54,000 Oryzalin (Surflan) 27,000