Glyphosate application for weed control in brassica

Abstract

The disclosure provides methods of applying glyphosate to improve weed control in a field containing herbicide tolerant brassica species. More specifically, glyphosate treatments are applied to a substantial portion of herbicide tolerant brassica plants which are beyond the 2-6 leaf stage such as for example to a substantial portion of herbicide tolerant brassica plants which are at the 10% open flowers to about 10% pod stage. The disclosure provides methods that apply glyphosate at late stage brassica development.

That which is claimed: 
     
         1 . A method of applying glyphosate to improve weed control in a field containing herbicide a population of glyphosate tolerant  brassica  species, the method comprising applying a glyphosate treatment comprising an effective amount of glyphosate over the population of glyphosate tolerant  brassica  plants, wherein a substantial portion of the  brassica  plants are at reproductive stage, late inflorescence emergence stage, flowering stage, seed development and ripening stage, or the flowering stage exhibiting at least about 10% open flowers to about 10% pod stage or beyond the flowering stage and wherein a substantial portion of open flowers or pods do not show significant discoloration post-glyphosate treatment, and wherein the glyphosate tolerant  brassica  plants express a glyphosate acetyl transferase (GAT) enzyme that provides glyphosate tolerance. 
     
     
         2 . The method of  claim 1 , wherein the glyphosate tolerant  brassica  plants express a glyphosate acetyl transferase (GAT) enzyme in combination with an enzyme that provides tolerance to glufosinate herbicide. 
     
     
         3 . The method of  claim 1 , wherein the open flowers do not show significant discoloration within 5 days post-glyphosate treatment. 
     
     
         4 . The method of  claim 1 , wherein the glyphosate treatment comprises in g acid equivalent/hectare of glyphosate as the active ingredient of about 675, 1350, 2025 or 2700 in a single application 
     
     
         5 . The method of  claim 1 , wherein the glyphosate treatment comprises up to about 5400 g acid equivalent/hectare of glyphosate as the active ingredient in one or more cumulative applications 
     
     
         6 . A method of applying glyphosate to improve weed control in a field containing a population of glyphosate-tolerant  brassica  species, the method comprising:
 (a) applying one or more glyphosate treatments comprising an effective amount of glyphosate over the population of glyphosate tolerant  brassica  plants, wherein a substantial portion of the  brassica  plants are at a stage that is beyond the 6-leaf stage; and   (b) obtaining  brassica  seeds from the  brassica  plants, wherein (i) yield is not reduced by more than 5% compared to control  brassica  plants not expressing glyphosate metabolizing enzyme or (ii) a substantial portion of pods are not aborted post-glyphosate treatment and wherein the glyphosate tolerant  brassica  plants express a glyphosate acetyl transferase (GAT) enzyme that provides glyphosate tolerance.   
     
     
         7 . The method of  claim 6 , wherein the glyphosate treatment comprises 1350-2700 g ae/hectare of glyphosate and a substantial portion of the  brassica  plants are at about 10% flower stage. 
     
     
         8 . The method of  claim 6 , wherein the glyphosate application further comprises a disease control agent selected from the group consisting of insecticides, fungicides, and pesticides. 
     
     
         9 . A method of preventing yield loss or yield penalty at harvest of  brassica  plants, the method comprising:
 (a) applying one or more additional glyphosate treatments comprising an effective amount of glyphosate over a population of glyphosate tolerant  brassica  plants, wherein a substantial portion of the  brassica  plants are at a stage that is beyond the 6-leaf stage; and   (b) applying one or more additional glyphosate treatments comprising an effective amount of glyphosate over a population of glyphosate tolerant  brassica  plants, wherein a substantial portion of the  brassica  plants are at a stage that is beyond the 6-leaf stage; and   (c) obtaining  brassica  seeds from the  brassica  plants, wherein the yield loss is minimized due to a substantial reduction in discoloration or pod abortion after one or more late-stage applications of glyphosate.   
     
     
         10 . The method of  claim 9 , wherein the average  brassica  yield is reduced by no more than 5% compared to a control treatment.