Weed Management in Highbush Blueberries: Introduction

Excerpt from 2008 Chapter 14, Publication 75, Guide to Weed Control, Order this publication

Introduction

• Cultural Weed Control - see Weed Management in Berry Crops: Introduction.
• Mulching:
  • Biodegradable mulch could be used for weed control within the plant row. Sawdust mulch will assist in weed control if it is applied early in the season before the weed seeds germinate. Apply old sawdust 5 cm thick. The mulch will not prevent the germination of weed seeds that may blow onto the surface of the mulch.
  • In subsequent years, the organic matter in the mulch may tie up and thus reduce the effectiveness of certain residual herbicides.
  • The nitrogen requirements of the crop will change as the mulch is degraded. Initially, nitrogen will be consumed by microorganisms, thus necessitating higher rates of nitrogen fertilizer. Later, as the sawdust is degrading, nitrogen will be released and the crop may require less nitrogen fertilizer than an unmulched crop. It may take 2 years or more for sawdust mulch to significantly decompose. Adjust fertilizer rates according to mulch breakdown, plant growth and leaf nutrient analysis results.
• Recommended rates /ha or /ac refer to area actually treated with herbicide.
• Site Preparation Before Planting - see Chapter 6, Special Methods of Weed Control
• Herbicide Application Timings:
  • Soil Applied Treatments include:
    • Preplant (PP) - Also see Chapter 6, Special Methods of Weed Control for details of products, rates and remarks.
    • Preemergence (PRE) - Rainfall of 15-20 mm within 7-10 days after application is necessary to activate preemergence treatments. Shallow cultivation, rotary hoeing or harrowing will control weed escapes and improves herbicide activity in the absence of rainfall.
  • Postemergence (POST) - Leaf stage of the weeds is critical for good weed control. Smaller weeds are generally easier to kill but there needs to be enough leaf surface to intercept the herbicide. Apply according to recommended leaf stages. Crop stage is important to optimize crop safety. Adjuvants will frequently improve the weed control when used as directed. Weather or other conditions may influence the optimum rate of adjuvant, see the product label for more details. Always use appropriate drift management technology.
• Caution: - Simazine, Devrinol and Sinbar residues, high enough to harm many crops, may persist for several years after removal of the planting.

Related Links

• Weeds in Ontario
• Berries in Ontario
• Problem Weed Control in Field Crops
• Integrated Pest Management (IPM)
• Pesticide Application and Safety
• Pesticide Companies and Agents
• OMAFRA Sprayer Calibration Calculator
• Search the PMRA website
• OMAFRA Publication 505: Ontario Weeds
• OMAFRA Publication 75: Guide To Weed Control

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