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Healthier crops, fewer pest problems

A focus on growing healthy crops helps keep pesticide costs in line.


November 19, 2007
By Carolyn King

Topics

Neil Boyd's approach to reducing pesticide costs sounds simple. He says, "I
try to let the crop look after itself as much as I can." To do that he
blends a variety of strategies including crop rotation, competitive crops, disease
resistant varieties, zero-tillage, shallow seeding and timing of herbicide applications,
to produce a healthy crop that can 'look after itself'. And he spices those
strategies with what he learns from many sources, ranging from research scientists
to the natural world.

On the Boyds' cattle and grain farm near Fairview, Alberta, they grow peas,
barley, oats and occasionally wheat and canola. They also grow clover and grasses
for seed and have some land in hay and pasture.

With this diversity in his cropping system, Boyd can keep pests off-balance
by "seeding at different times of the year and seeding different crops,
maybe growing some perennials instead of only annuals all the time. If you do
the same thing at the same time every year, then you encourage certain weeds
and certain insects. If we could just watch nature a whole lot more, I think
that it could teach farmers a whole lot. Plants in nature deal with diseases
and insects all the time; those plants thrive mainly because they are changing
all of the time, with different plants growing together."

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Boyd also likes to experiment with diversity by growing different crops together
in the same field. For instance, he tried growing peas with barley and oats
as feed for his cattle. He says, "I thought that if I grew enough plants
per square foot, then that would discourage weeds. And actually it did work.
I didn't put any fertilizer or herbicide on and I got a pretty good crop off
of it. The peas provided the fertility, and the barley and oats provided the
competitiveness. But after I got the crop off, I should have given it something
like a half litre of Roundup to take care of weeds like hawk's beard and thistles."

Boyd's main crop is peas, partly because he has a market for the crop at a
nearby feed mill and partly because peas improve soil health. He says legumes,
like peas and clover, not only add nitrogen to his soil; they also provide a
'biological kick' by promoting a healthy community of soil microbes.

A diverse population of soil microbes promotes crop health in many ways, like
improving the crop's access to nutrients and keeping disease-causing microbes
in check with predator microbes, explains Dr. George Clayton from the Lacombe
research centre of Agriculture and Agri-Food Canada (AAFC). For example, Dr.
Newton Lupwayi at AAFC's Beaverlodge research farm has found that growing a
pea crop in a direct seeding system reduce root disease in the following wheat
crop as compared to continuous wheat or wheat following fallow. Clayton says,
"So we know we can manipulate soil micro-organisms that will improve crop
health through such practices as crop rotation and zero-tillage."

Boyd has been following the research results of Clayton and his colleagues
on integrated crop management and the importance of growing healthy, competitive
crops. Boyd says, "I think that the best herbicide is a competitive crop.
That's one of the reasons why I like to grow barley. I find it's a competitive
crop and that it keeps ahead of the weeds. And oats will do that too."
He notes that oats, like some other plants such as fall rye, has the ability
to release substances that suppress weed growth.

When selecting crop varieties, Boyd looks for characteristics that help with
pest control. "In a barley variety, I don't want a semi-dwarf barley because
I want the height for a competitive edge over the weeds. And then I look at
the barley's disease package."

He also prefers early varieties, partly because getting his crop off in good
time helps with his herbicide strategy. "If I can spray the stubble after
combining with a generic glyphosate at about a half of a litre, I feel that
I get as good control as with a full litre of pre-harvest glyphosate. So I'm
saving the half litre plus I'm able to put it on myself. Some weeds do take
in a pre-harvest spray really well, like thistle, but a lot of weeds, like foxtail
and hawk's beard, are so far down in the canopy that I don't think they get
good coverage from the pre-harvest treatment. But a post-harvest gets them."

Boyd is always looking for new ways to reduce his herbicide costs. He says,
"For instance, if I have to spray wild oats on barley, I'll try to delay
seeding as long as I can, say to the 15th of May, and then I'll put on half
a litre of Roundup to kill any annuals. And I'll seed quite heavy and quite
shallow so I can get a really quick, competitive crop coming and then I'll only
spray a half rate of the wild oats chemical and a low rate of a broadleaf herbicide."

To control weeds like hawk's beard, thistles and dandelions, Boyd finds that
spraying in the fall provides better control at a lower cost. "If you try
to control dandelions in May or June, it doesn't work very well. But if you
can give them a little whiff of something around the end of September, it knocks
them for a loop. And it's the same with winter annuals."

Boyd does not use insecticides or fungicides. He says, "I'm a real believer
that if you spray insects, it's like putting gas on a fire. You may kill the
adults, but you'll have all the eggs hatching again and you wouldn't have any
predator insects. So for any kind of insect, even grasshoppers, I've just let
them go." He prefers to keep insects in check by rotating crops and by
relying on natural predators like spiders and birds. To control diseases, he
uses practices like crop rotations, resistant varieties and zero-tillage.

The Boyds began using zero-tillage in 1991. Boyd says, "Our hired man
had to go back to Poland, so we were short on help and we decided to cut out
a whole bunch of tillage." At first Boyd was not sure it was the way to
go, but the changes he has seen on their land since then have convinced him
that zero-tillage improves soil health, tilth, soil moisture and crop growth.

Boyd is a believer in looking for the causes of weeds and other problems. "Sometimes
the problems are symptoms of a bigger thing. To give you an example, if we have
certain weeds, like foxtail and thistle, if we think out why those weeds are
there, rather than just spraying them, I think we could solve our weed problem."

Clayton says, "When you ask 'why?', it complements the reactive approach
to problems. You do need to solve the problems now, but you should also ask
why that problem is there. If you look at the whole system in time and space,
and figure out what the problem is, then that takes you away from always reacting,
to solving problems over the long-term."

Putting the right pieces together
"Developing a system that promotes crop health on your own farm is partly
science and partly art," explains Clayton.

Science has helped to identify the basic pieces of a healthy cropping system.
"Tools to improve crop health include things like crop rotation, seeding
rates that achieve at least 20 cereal plants per square foot in moister areas
and 15 in drier areas, selecting competitive cultivars with resistance to diseases
in your area, early seeding and direct seeding," notes Clayton.

The art comes into the system as a grower continually adjusts and fine-tunes
the ways to use these pieces on the farm. Clayton emphasizes, "It's not
a recipe. If you find the right pieces one year, it might work for two or three
years. But then the recipe might change again because when you do the same thing
over and over again, the things that you are trying to control will adapt."

Clayton says, "Farming to me is a knowledge-based system. In a knowledge-based
system, farmers need to be intimate with their farm." So a good first step
is to scout fields as often as possible, "to know the pressure points in
each field – whether it's a nutrient problem, a weed problem, a disease
problem, or a combination – to try to understand what is going on in the
field. Once you know that, you can get information on how to deal with those
problems. You can talk to neighbours, you can talk to research scientists who
are working on those problems, you can attend field days to view results, you
can gather print information and attend meetings. You need to gather all the
information you can, distill it, and come up with some potential solutions to
the pressure points you see on your farm."

Clayton also says it is important to remember that changing one aspect of a
crop management system will affect other aspects. "Let's say the price
of seed is too high. So I decide to cut my seeding rate. I've still got enough
plants to produce a good yield. But seeding rate has an impact on weeds, maturity
and things like that, which all contribute to crop health and a farm's economics."

If a grower makes a change that increases the risk of crop problems, he could
adjust the other elements of his system to deal with that change. Clayton explains,
"If you reduce your seeding rate, you need to make sure that you take weeds
out early. Or perhaps you're growing a non-competitive crop because it's the
best variety to go into a market. Then you could boost your seeding rate so
the crop can defend itself against weeds or other problems," he says. However,
increasing the seeding rate might increase the risk of disease in some situations.
"That's when it gets difficult. You have to understand the likely impacts
– the gains from improved weed control versus the negatives from increased
disease."

The research studies by Clayton, Lupwayi, Neil Harker, Kelly Turkington, John
O'Donovan, Bob Blackshaw and other scientists on integrated crop management
provide farmers with information that can help in making those complex choices.
Clayton says, "We try to take all those difficult things and distill them
down to practical options – not easy, but practical." Even with all
the science, there are still plenty of challenges for Boyd and other producers
in practicing the art of farming. -30-