The Rural Voice, 2000-06, Page 50C
somewhere in this range then identify
this as one of the first improvements
to be made. If your plant stands are
low, is it because you are not
allowing for 'a 5-10 per cent
reduction from seed drop to final
stands?
Generally you will need to plant
32,000 seeds to be assured of a final
stand of 30,000. A recent research
report published in the Agronomy
Journal (D. Bullock et. al., 1998)
indicated that the optimum final plant
population in the Midwest Corn Belt
on average is 27,160 plants per acre.
These researchers also predicted that
for every 15-bu/acre increase in
fields yield potential (or parts of
fields) that economically, optimal
populations increased by 450 plants
per acre. So in Ontario, while we
may generally shoot for slightly
higher average final stands than in
the midwest, you will also want to
ensure that your productive fields are
near the upper end of the plant
population range. Fields that are
traditionally lower yielding because
of low water holding capacity, poor
soil structure, etc., have economic
optimal populations lower in the
range.
Also keep in mind the following
points:
1) There is some evidence that
shorter season hybrids, should be
planted in the upper end of the
population range.
2) Seed companies may provide you
with additional information as to the
most suitable populations for specific
hybrids.
3) Although some corn silage
growers anticipate higher tonnage
when silage is grown at very high
populations (up to 40,000 plants per
acre), Cornell University research
indicates that silage quality generally
declines as population increases and
therefore suggests final plant stands
for silage to never exceed 35,000
ppa.
4) Researchers have shown that there
is very little hope of a net economic
return to investing in extensive site
specific soil and yield mapping and
variable rate seed technology to
adjust populations on-the-go.0
46 THE RURAL VOICE
Advice
With weed control,
timing is everything
By Hugh Martin
Time and how you manage it is
one of your best resources to control
weeds. Spray too soon, perhaps you
may miss a few but spray too late and
you may be wasting your time.
In winter wheat we often spray the
crop too late to get control of winter
annuals. Once they start to flower
they become very hard to kill. We
sometimes call spraying too late
"Revenge Spraying", we pay our
money and we feel better but it really
has very little effect on yield and it
may or may not kill the weeds.
A weed like spreading atriplex
looks like lamb's quarters in April
and you think, no problem, but if you
are in no -till and you ignore it, not
even Roundup will knock it down
when it gets bigger.
Spray pre -emergence herbicides at
planting and the herbicide may break
down a few days too early in the
summer. But, wait a week and the
crop may come up faster than you
expect;,or you may miss the rain; or
the soil can dry out so that the
herbicide does not get activated until
the weeds are too big for it to work
on them.
Spray an hour before it rains and
the rain may wash off the herbicide
before it gets into the leaves of the
weeds and your control is less than
you had hoped for. Wait a couple
hours and the field may be too wet
and you have to wait for days.
Most crops can tolerate the
herbicides when they are small but
wait until the weeds are big enough
to spray and the crop may be injured.
Some crops may also be very
sensitive when they are small —
know your herbicides.
Some products say they can be
used up to the seven or eight -leaf
stage of corn. But, if you wait that
long you will be two or three weeks
past the critical three to four leaf
stage. When weeds are allowed
compete with the corn during the
three -10 -leaf stage, yields will be
reduced.
For soybeans do not allow weeds
to compete from the first to third
trifoliate stage and for no -till
soybeans and for field beans this
period extends up to first bloom
stage. Spray to get optimum yield
protection, not to get maximum weed
control.
Another aspect of time
management is what is the
competition for your time. Manage a
livestock herd? Have hay to harvest?
Have many acres to spray or to apply
nitrogen? If you have other family
interests that are demanding, perhaps,
you need bigger spray equipment or
you need to consider a hiring crop
consultant or custom applicator to do
the things you do not have time for.
Time is a precious commodity and
you have all there is, use it wisely.0
Goatsbeard a
troublesome weed to
watch for
By John Benham
Weed Inspector
Weeds can be classified into four
groups according to their growing
habits.
An annual is a plant, which
completes its life cycle in one
growing season. An example would
be Velvetleaf.
A biennial is a plant, which
germinates in the spring, produces a
rosette of leaves and remains
vegetative during that first summer;
over winters as a rosette; then sends
up a flowering stalk during the
second summer; sets seed; and dies at
the end of the second season. An
example would be Bull Thistle.
A perennial is a plant that lives
through three or more growing
seasons. An example would be
Colt's -foot or Canada Thistle. The
fourth type is the winter annual
which is a plant that germinates in
the fall, usually over winters in the
rosette stage; flowers and sets seed
the following spring and dies in the
summer. An example would be
Shepherd's Purse.
Goat's -Beard is a biennial
reproducing only by seed. The
flowering stems are from one to three