Part 3: Improving Weed Management
in Young Trees (Spring/early summer)
In the last issue, we talked about ways to prepare your orchard
site before planting and things to do at planting time. Now that
your trees have just been planted, there are some important things
to do in their first month in the ground. Here are 4 more suggestions
to help reduce and manage weeds in young trees:
- For soils with < 2% OM: Devrinol can be applied after planting,
but requires incorporation by irrigation or rainfall (1/2")
within 5-7 days to protect it from sunlight degradation. This
is the only soil applied herbicide that is safe on low OM soils.
- For soils with > 2% OM: A residual herbicide can be applied
(if Sencor, Treflan or a tank-mix was not used PPI). In Ontario,
Casoron, Devrinol, Dual II Magnum, Princep or Sinbar are registered.
Tank-mixes of grass products like Dual II Magnum with a broadleaf
herbicide like Princep are preferred. Using a soil applied herbicide
right after planting ensures that weeds will be controlled during
the Critical Weed-free Period (see above).
- Irrigate if it doesn't rain: Soil applied herbicides require
½" of rain to be activated. In dry years, weeds may
germinate before this activation occurs - so be prepared to irrigate
in 7-10 days.
- Check for weed emergence starting 3 to 4 weeks after planting:
A glass pane laid on the ground under the tree will give you a
heads up when weeds will start to escape (usually a 3 to 5 day
advance). Identifying these weeds at the cotyledon stage will
help you decide what to do, so buy some good identification books
on seedling weeds.
Remember that reducing weeds early will result in improved growth,
early yield and better fruit size, and that makes it worth the expense
and effort. Keep up the good work targeting those weeds.
Use a pane of glass laid on the bare ground as a
first signal that weeds are ready to emerge
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