Great grandpappy knew about it and used it. Grandpappy knew
about it and used it. Pappy heard about it. Now we must learn
about it again. So, what's "it"? "It" is Integrated Weed
Management, the new buzz word in agriculture.
At our workshop in November, a number of speakers made
reference to integrated weed management strategies. Gone are the
days when we can pull the 1/2 ton up to the dealer's door and
load it up with a new herbicide. As the threat of weed resistance
to herbicides looms ever larger and as we move to less and less
tillage, new strategies must be employed if we are to fool the
weeds.
Doug Derksen with the Ag. Canada Research Station in Brandon suggests that we can manage our weeds by using a diverse rotation and alternating the timing of the herbicide. He used the following example:
Year 1 Burnoff preseeding. Seed the canola
Year 2 Burnoff preseeding. Seed the barley. Apply herbicide in-crop. Apply 2, 4-D post-harvest.
Year 3 Seed the peas. Apply herbicide in-crop. Apply Roundup, pre-harvest.
Year 4 Burn-off preseeding. Seed the wheat.
Apply herbicide in-crop. Apply granules, zero
incorporation.
By applying different herbicides at different times of the
growing season, no one group of weeds will be selected for or
against.
John O'Donovan with the Alberta Environmental Centre in
Vegreville put forward a number of cultural practises that will
give the advantage to the crop, making things rather
uncomfortable for the weeds. His first suggestion is
prevention. Using clean seed, keeping the equipment clean,
tarping grain trucks and ridding the roadsides and field margins
of weed species will help to keep the fields free from any "new"
weeds.
Management is next. He stresses that herbicides should
be used wisely. Ditches and headlands should be mowed. Crops must
be rotated. Crop competitiveness can be maximized by planting
vigorous seed and seeding competitive crops when possible. He
also suggested that biological control and intercropping might be
additional components of the management strategy.
Ensuring early crop emergence does much to increase the
competitiveness of the crop. Research has shown that it's not how
may weed plants that are present but rather, whether or not the
weeds get ahead of the crop. The old adage applies: "The first
one up, wins!"
Increasing the seeding rate ensures a healthy crop
stand.
Crop competitiveness can be enhanced when fertilizer rate
and placement are manipulated. Green foxtail decreases as N
increases, especially under Direct Seeding. Foxtail barley
numbers tend to be reduced when fertilizer is banded rather than
broadcast.
Many of the suggestions put forward by Derksen and O'Donovan
at the Conference are common sense. It seems, however, that over
the years as we have grown to rely on herbicides to take care of
our weeds, we have forgotten about these strategies. Good thing
Doug and John were there to show us how to get back to the
basics.