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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
For more information:
Toll Free: 1-877-424-1300
Local: (519) 826-4047
E-mail: ag.info.omafra@ontario.ca
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