Reducing Weeds in Berry Crops:
In March, we talked about 3 things to do before planting to reduce weed
problems - site selection, crop rotation and preplant cleanup. In May,
we focused on things to do at planting time - stale seedbed, switching
to plasticulture, banding fertilizer and using trickle irrigation. In
July, we looked at things to do throughout the growing season - managing
field edges, spot treating weed patches, weed scouting, and chemical renovation.
Let's look at things we can do in the fall to reduce weeds:
Clean mulch: Avoid introducing problem weeds into your fields
with your mulch. Whether you grow your own straw or purchase it, it
is very important to use straw that is free of weed seeds and cereal
grains. Some growers have paid custom growers to apply hormone herbicides
each spring on the cereal to control broadleaf weeds like dandelions
and thistles. However, applying preharvest glyphosate on cereal where
the straw will be used for strawberry mulch is not recommended. We
have had several incidents in Ontario and Quebec where glyphosate
residues remained on the straw, and damaged strawberry plants as they
grew through the mulch the next spring.
Spot treatments: Fall is a good time to revisit the weed patches
that were spot treated through the summer. In fact, for some weeds,
fall is the best time for treatments because weeds have resumed active
growth after the summer's heat and drought. Glyphosate can be very
effective on quackgrass regrowth in the fall, even after a light frost.
Dandelion control with 2,4-D is very effective late into the fall
(again even after a light frost). Spot treatments of weeds from field
edges can be very effective at this time of year.
Weed scouting: A final assessment and mapping of weeds at
this time of year will provide you with important information to plan
your weed management strategies for next year. It may be easier to
identify weeds in the fall with flowers and seedheads present. If
you still have unknown weeds, collect several specimens (include as
much of the roots, leaves and flower structures as possible to help
identify it). Store samples in a paper bag inside a plastic bag to
preserve them for several days.
In the past 4 columns, I've talked about a dozen options to reduce weeds
in your fields, and I'm sure there are more that have been useful in your
operations. No single one of these will totally control your weed problems.
However, using all applicable options, in addition to your herbicide,
tillage or mulching treatments, will contribute to a more successful Integrated
Weed Management (IWM) system for your berry crops.
For more information:
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