Postemergence herbicides for controlling three horseweed growth stages in wine grapes

摘要

A field study was established to evaluate postemergence applications of rimsulfuron, gylphosate, paraquat, glufosinate ammonium and flumioxazin in controlling three horseweed (ERICA) growth stages in an established merlot grape vineyard. Oxyfluorfen or oryzalin were tank mixed with the above herbicides for soil residual or to burn down existing weed species. These herbicides have no postemergence activity on horseweed. No Foam A (NIS) was added to all herbicide treatments at 0.25% V/V. A single 6 by63 ft (3 ft spray swath on both sides of the vine row) area was sprayed on April 6, 2006 with 64 F air temperature and 45% relative humidity. All herbicide treatments were applied with a CO_2 pressurized backpack sprayer calibrated to deliver 40 gpa. Eight to eleven horseweed plants were flagged at each growth stage: small = 4 to 6 lf, 1 to 1.5 inch diameter, medium = 10 to 14 lf, 2 to 3 inch diameter and large = 16 to 20 lf, 3 to 5 inch height and bolting. Number of dead plants were counted and reported as percent control on April 21, April 28 and May 10, 2006 (Table).