Part 2: Improving Weed Management in Young Trees (Preplant/early spring)

Poor weed management can reduce performance of a new orchard for many years. Planning your weed management strategy for the planting year is important to maximize your investment. Here are 4 suggestions to begin reducing and managing weeds in young trees:

• Weed Reduction / Avoidance in the Preplant Year: Select fields with low weed pressure, or use a crop rotation that reduces weeds (e.g. field corn, winter cereals or green manure crops). Control perennial weeds with a 2 year strategy, targeting the most sensitive growth stage e.g. early bud in thistles, flowering in vetch. Plant a cover crop to smother weeds, especially in the fall before planting - this will prevent winter annuals from establishing. Use herbicides to control weeds in cover crops e.g. 2,4-D in wheat, or glyphosate in the spring to kill the cover crops. Mow weeds before they go to seed, especially around the field edges and in neighbouring ditches. If desired, sod can be established in the previous year and rows burnt out with glyphosate or flaming - ensure a weed-free strip at least 1.5m wide to avoid competition from the sod. Caution: Avoid herbicide residues by choosing low rates or non-residual herbicides.
  
• Before Planting Trees in the Planting Year: Choose between tilling to prepare the planting row OR using a burndown herbicide to clear early weeds. Assess your soil organic matter (OM) level - a 2% OM is required to safely use most soil applied herbicides. In Ontario, if soil OM > 2%, Sencor, Treflan or Bonanza, or a tank-mix can be incorporated before planting (PPI) to reduce weeds.
  
• Plant Trees in Straight Rows: Aside from appearances, straight rows ensure that orchard equipment like mowers, herbicide booms, flamers, or tillage tools can work close to the trunks.
  
• Mulch after planting: Mulch can be applied around each tree to suppress weeds and conserve moisture. A 10-15 cm (4-6 in) layer of settled material is required to do the job. Scout for rodents, and pull mulch back away from trunks in the fall. As well as straw, wood chips or other organic mulches, black plastic, landscape fabric, geodisks and even discarded carpet or newspapers have been used successfully. Note that where organic mulches are used, nitrogen levels in the trees need to be monitored as they break down, and extra fertilizer may be needed after a year or two.

There are many steps to a successful weed management program in new orchards, but the improved growth and early yield and fruit size makes it worth the expense and effort. Good luck with your next planting!

Related links

• Part 1: Why Improve Weed Management in Young Trees and Vines?
• Part 3: Improving Weed Management in Young Trees (Spring/early summer)
• Part 4: Improving Weed Management in Young Trees (Late summer/fall)
  

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