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It’s Time to Plan Your Tree and Vine Herbicide Program for the 2013 Season
Start by making sure your sprayer is working properly and replace warn nozzles, hoses, pumps, gauges and other non-functioning components. This is also a good time to calibrate your spray rig. Also, select herbicides and rates that not only control the specific weeds in your field, but are also appropriate for the soil type. Combinations of products and/or sequential treatments will likely be needed to control the array of weeds. Refer to the herbicide labels for specific weeds controlled and the rates required.
Consider using preemergent herbicides, because they provide relatively long-term residual control and save on weed spray trips through the field. In tree nuts, apply preemergents in fall after harvest and/or during late-winter before bud swell. Regardless of timing, leaves should be mechanically blown from the tree rows to enhance herbicide-soil contact. In the fall, spray before post-harvest irrigation water is applied or within 2-3 weeks of rainfall to activate the product(s). If Goal, GoalTender, or Chateau are used, treatments should go on only after pruning and brush removal to avoid foot traffic from disturbing the soil-herbicide barrier. In grapes, apply preemergents during dormancy up to bud swell, only after pruning and cuttings have been removed or shredded.
If weeds are present at the time of preemergent treatment, add postemergent products to the tank for burn-down control. When using postemergent materials, treat small, actively growing weeds within 2-3 weeks of emergence for optimum control. Don’t wait to spray when weeds are large, dense, and stressed or herbicide performance will be poor. Use a spray volume and pressure that adequately wets the weeds. Also, be careful not to get any of the spray on tree or vine foliage or crop injury may occur. Again, select products that provide effective control of the specific weeds.
Some important questions to answer before implementing your herbicide plan:
- Is the sprayer working properly and has it been recently calibrated?
- Have herbicides and rates been selected based on your specific weed species and soil type?
- Have you read the herbicide label(s) completely?
- Will leaves and cuttings be removed from the crop rows before preemergents are applied?
- Will rainfall occur within 2-3 weeks after treating with preemergeents?
- Can you avoid physically disturbing the treated soil surface?
- Are the weeds small and actively growing when postemergents are used?
- Do you need to add surfactants or other spray additives to the tank?
- Are environmental conditions favorable for spraying to minimize risk of spray drift?
- Will follow-up treatments be needed to control weeds escaping control?
- Will you conduct an end-of-season evaluation to determine if any changes need to be made?
UC Cooperative Extension Weed Management (Fresno County)