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Horticulture
NORTH CENTRAL REGION
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Eric Carlson placed sticky
traps around the orchard's perimeter to help snare apple maggot
flies without insecticides.
Photo by Ken Schneider. |
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Agricultural pests and diseases ranging from apple scab to maggot
flies pose major problems for apple growers who want to reduce or eliminate
pesticides.
For Eric Carlson, who is trying to cut back his use of synthetic
chemicals to create a more sustainable orchard ecosystem, tackling those tough
pests in his Wisconsin orchard with alternative means became his top priority.
"I want to grow apples as sustainably as possible," says Carlson, who also
raises blueberries, raspberries and fresh-cut and everlasting flowers on his
10 cultivated acres. "I can usually get good quality fruit with just one or
two sprays. With some growers one or two dozen sprays isn't unheard of." Many
of those applications are tank mixes of two or more insecticides and fungicides,
he adds.
With the help of a SARE producer grant, Carlson found that some
of the popular organic fungus control practices didn't work on disease-prone
varieties in his orchard. But his research has led him to integrated pest
management (IPM) practices that provide acceptable control of insect damage
with a minimum of spray.
Carlson tested scab remedies in a planting of Cortland apples
he had managed organically for two years and under a reduced spray program
for two years before that. Cortlands are very susceptible to scab, a fungal
disease that plagues growers particularly in the Midwest and Northeast. The
fungus leaves dark blotches or lesions on leaves and fruit, making them unfit
for fresh market sales.
When Carlson applied elemental sulfur to the trees at regular
intervals or after rain, he saw very little scab. But disease pressure was
admittedly light because of dry conditions during the season of the study.
While sulfur applications are standard practice for many organic
orchardists, they concern Carlson.
"Applying sulfur may be considered organic, but I don't think
it's sustainable," he says. "Every time you spray, that's 6 pounds of sulfur
per acre that ends up in the soil, lowers the pH and affects the soil microorganisms."
Hoping for an even gentler way to tame scab, Carlson also tested
a treatment that has little or no effect on the soil. He sprayed dilute hydrogen
peroxide to sterilize plant surfaces shortly after scab infection periods
began. Unfortunately, those concentrations damaged the fruit and still did
not completely control the scab -- even with low disease pressure.
With both disease control remedies proving either ineffective
or unsustainable, Carlson decided to try varieties that are naturally resistant
to the disease.
He planted 1,000 scab-resistant trees using varieties such as
'Priscilla,' 'Liberty' and 'Sweet 16' that he expects will produce good quality
fruit with little or no fungicide in most years.
For those scab-prone varieties already in the orchard when he
moved there in 1989, Carlson now uses carefully timed applications of synthetic
fungicides. By tracking air temperature and leaf surface moisture, Carlson
is able to predict when scab infections are likely to occur and reduce his
sprays by at least 30 percent compared with conventional operations.
Carlson also found that placing sticky traps around the orchard's
perimeter helps snare apple maggot flies, one of the most pernicious insect
pests. He spaces the round red traps 15 feet apart. Females heading for Carlson's
trees mistake the traps for apples, and after landing on them, permanently
adhere to the surface.
"We don't get 100-percent control," observes Carlson, adding
that his maggot damage is usually between 3 and 5 percent, compared to about
1 percent for most conventional operations. "But by using the traps to control
maggots, there's no reason to use insecticides after June, while conventional
operations will have to keep spraying all summer."
Reducing the number of sprays may encourage populations of beneficial
insects that prey on pests.
Codling moths, however, still plague Carlson. As part of his
study, he placed lures throughout the orchard that emit very small amounts
of chemicals -- called pheromones -- that females use to attract males for
mating. The lures confuse the males, making it difficult for them to find
females, and result in fewer matings.
Carlson then charted growing degree days to carefully time a
spray of ryania, a botanical insecticide, to hit the next generation of moths
when they were most vulnerable.
But it didn't work. Carlson still registered 30- to 50-percent
fruit damage.
"At $200 per acre for the pheromone lures, I just couldn't justify
it," he says, speculating that part of the problem might have been female
moths flocking to Carlson's trees from a nearby neglected orchard that has
since been destroyed.
"But with all the wild apples growing around here, I might never
be able to control migrating codling moths without some insecticide," he says.
For now, Carlson has settled for using one or two applications
of Imidan, a relatively short-lived organo- phosphate insecticide that has
curtailed his codling moths quite successfully. As with the ryania sprays
he tried before, he times the applications based on when the pest is most
vulnerable.
"Soon my new scab-resistant varieties will start producing,"
Carlson says. "I've managed them organically so far. I'll have to wait and
see what kind of quality fruit I can get from them before I decide if I need
to spray them."
As a part of the project, Carlson has held field days and developed
posters and information packets to share his findings with other growers and
the public.
A Bayfield County, Wis., agent who attended one of Carlson's
field days praised the grower for working so diligently to identify more sustainable
strategies to manage pests. Says John Markus: "We as an industry need to look
at disease and insect resistant plants to decrease our reliance on chemical
use."
Carlson hopes the work will pay off in more farmer acceptance
of alternative strategies.
"The really good growers can take this information and use it
to save considerable amounts of money," he says. "But they have to be willing
to take the time to learn about the life cycles of the insects, and go out
and walk around their orchards and see what's going on. They can't expect
to just do it on the weekend."-- Craig Cramer
NORTHEAST
REGION
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While Western New York's
climate is excellent for grape-growing, black rot and powdery
mildew remain constant disease threats.
USDA photo. |
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Grape grower James Mohart knew he had better things to spend
money on than spraying his crop. Time and expense dictated a new system.
"The sprayer is one piece of equipment that costs me $300 every
time I pull it out," he says. "I'd rather put that money in my pocket."
Trying to improve his bottom line, Mohart, a part-time Irving, N.Y., farmer,
undertook a SARE-funded producer project to test whether a weather station
in his vineyard, combined with a computer modeling program, could predict
when the grapes are most susceptible to two major diseases. After three years,
he found the $1,200 weather station and accompanying modeling saved him between
$31 and $36 per acre a year in the cost of spraying fungicides.
Mohart grows 16 acres of grapes in a vineyard first planted
by his father in 1971. The grape-growing region of western New York, which
stretches from Niagara County south to Pennsylvania along Lake Erie, encompasses
30,000 acres. The lake moderates the climate, delaying bud break in the spring,
protecting the buds from freezing and postponing the fall's first frost.
Most growers raise Concord grapes for juice; some of the largest
U.S. grape juice processors, such as Welch's Growers' Cooperative and Mogen
David Wine Co., have processing plants here.
While the region's climate is excellent for growing grapes,
black rot and powdery mildew remain the two most devastating diseases of Concord
grapes. Black rot can destroy an entire crop and powdery mildew can reduce
sugar levels, rendering grapes fit only for vinegar.
Grape growers usually protect their vineyards from those diseases
by applying fungicides at regular intervals throughout the season, usually
spraying three or four times. Encouraging growers to use weather data and
computer-generated predictions to cut down on the number of fungicide sprays,
and to spray only during the critical post-bloom period would mean big financial
savings for the farmers and much fewer pesticides being dumped into the environment.
It seemed like a winning situation to Tim Weigle, integrated
pest management specialist for Cornell Cooperative Extension, who collaborated
with Mohart on the project. Weigle reviewed research on pest biology and work
he had done using computer models to predict disease infection periods.
With Mohart, Weigle wanted to monitor for climatic conditions
most conducive to the disease spores of black rot and powdery mildew using
a weather station. Then, he wanted to test spraying only when it would be
most effective.
Ideal conditions for infection by powdery mildew spores, for
example, exist when the temperature reaches 50 degrees F and one-tenth inch
of rain falls. "By monitoring, you spray only when you need it," Weigle says.
The weather station in Mohart's vineyard registered such data
as precipitation, temperature and leaf wetness. Plugging that information
into a computer model told him when it was an ideal time to spray. "Instead
of spraying every 14 days, the weather station tells you that you may be able
to put it off for three or four days," Mohart says.
Concord grapes are susceptible to disease in the crucial weeks
before verasion, or the point at which the sugar content of the grapes is
about 5 percent and the berries change from green to purple. After that, the
fruit becomes immune from the diseases.
"As soon as you hit verasion, you're home free," Mohart says.
"If you can get away with just two sprays before that, you're golden."
The system still has some limitations. For instance, once the
ideal weather conditions are reached, a grower has just 72 hours to get the
fungicide on the grapes.
"I can spray my 16 acres in one day, but if you're a larger
operation, you may not have the manpower to do it all," Mohart says. "But
if it keeps raining or your equipment breaks down, you're in trouble."
Weigle is developing computer models that can use data from
the weather stations to predict the best time to spray for harmful insects
like grape berry moth and Eastern grape leafhopper, as well as diseases. He
is putting together an extensive network of stations throughout the grape-growing
regions so that not every grower would have to have a station in his or her
vineyard. Instead, they could tap into relevant weather data through computers.
For now, Mohart says, the results of the project are encouraging
some neighboring growers to purchase weather stations for their own vineyards.
It illustrates what Weigle knows is the surest way for an innovative practice
to catch on -- the success of a grower like Mohart.
Says Weigle: "We've found that if growers do it and go to the
coffee shop and talk about it, it gets implemented much more quickly." --
Susan Harlow
SOUTHERN REGION
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Planting a mix of rye and
hairy vetch as a windbreak attracted beneficial ladybugs to
Kenny Haines' Belvidere, N.C. farm.
Photo by Andy Clark. |
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If you grow vegetables, as Kenny Haines does on 90 acres near
Belvidere, N.C., aphids are your enemy. If you're an aphid, ladybugs are your
enemy.
It stands to reason then, that Haines would want to do anything
he could to get the two insects together, especially since he's determined
to hold on to the organic certification he was granted in 1989. For organic
producers, synthetic pesticides aren't an option.
Haines had heard about businesses, most located in California,
that specialize in the rearing and delivery of beneficial insects like ladybugs,
but he'd also heard the frequent complaint that applications of bugs were
temporary solutions at best. The bugs tended to clean a crop of its pests,
then fly away in search of more. The next time a pest invasion took place,
more bugs had to be ordered, and the process would begin anew.
In 1994, Haines discovered another alternative, almost by accident, that,
nonetheless, is helping advance the science of integrated pest management
(IPM) in North Carolina. He planted rye and vetch as a cover crop and windbreak,
but soon realized an unexpected benefit.
"The following spring, I had a cover crop with a few aphids
but massive amounts of ladybugs," he recalls. He mowed most of the covers
to plant his vegetable cash crop, then found the ladybugs had migrated to
the vegetables to eat aphids.
The ladybugs nested in the windbreak, which Haines had not yet
mowed. "I'm not an entomologist, but it seemed to me those ladybugs then started
mating, and gestating, and before long there were even more ladybugs," Haines
says. "They stayed there all through the winter, too."
And that made them available, in much larger numbers, for pest
control in Haines' 1995 crops.
By then, Haines -- spurred by the excited urgings of entomologists
from North Carolina State University -- had applied for and received a producer
grant from SARE to expand his use of cover crops and windbreaks. He wanted
to see what kinds of insects various grain and leguminous cover crops would
attract. He also wanted to experiment with retaining strips of cover crop
within his fields of broccoli, cabbage, squash and cucumbers.
Haines' interest in a cover crop seeding operation isn't proprietary.
Eventually, he hopes his efforts will lead to the establishment of an operation
that can supply seeds for cover crop mixes based on the types of beneficial
insects a farmer wants, to help further sustainable agriculture in North Carolina
and beyond.
"I'm still learning every day about this," he says. "But what
I think I've learned is that so many of us, so many times, have blinders on.
For years, the entomologists only looked at bugs, while the plant biologist
only looked at the plants and the soil engineers only looked at the condition
of the soil.
"This kind of project helps emphasize how all of it works together
and how important balance is."
And that's something he said he hadn't thought of in quite the
same terms before, even though he's farmed for more than 20 years.
"The sad fact is that you're not encouraged to by the so-called
'experts.' More often than not, you get Extension people telling you how things
can't be done that way."
Haines said it takes "crazy people like me, who don't know any
better," to shake things up every now and then to prove the experts wrong.
And that's why he believes SARE grants are important. "
It gives people a chance to try out an idea. Then I can start
telling people about what I've learned, and after a while someone from the
university comes around and takes notice, and they say, 'Hey, this just may
work.'"
That, Haines adds, is when things really start happening. He
says he intends to continue his own on-farm experiments, showing his results
to as many people as possible. His latest challenge is figuring out the attractive
powers of flowering plants.
One of the cooperators in Haines' project is Michael Sligh,
with the Rural Advancement Foundation. He believes the potential impact of
Haines' work is "enormous." Sligh said that experimentation in California
already had established a fair amount of data about what types of cover crops
encourage beneficials, and how flowering and mowing patterns can encourage
an influx of beneficials at just the right times to combat and control pests
in that state's agricultural areas.
"What Kenny's doing is forming the seed of knowledge and experience
necessary for making the same determinations about what will work for farmers
in the coastal plains region," he says. "It's vital stuff. Once we learn it,
it can lead to successful farming that doesn't use any chemical pesticides."
Sligh said he expects Haines to assemble a base of knowledge
that experts can then augment. That base likely will better define the mixes
of flowering, leguminous and grain crops that attract and retain beneficial
bug populations sufficient to control pests not only on vegetables, but cotton,
peanuts and other crops grown in the South.
"We've really just touched the tip of the iceberg with this
kind of thing," adds Haines, who looks forward to the day when more integrated
field work experimentation takes place between entomology and agriculture
professionals. He hopes those professionals will view him as a resource.
Sligh says that attitude underscores for him the wisdom of SARE's
decision to fund the project. "SARE is unique in the way it supports on-farm,
farmer-led experimentation," he says. "Growers like Kenny Haines show how
that can work to benefit all of us.
"If we had to wait for the official experts to look into these
things," he adds, "we wouldn't know nearly what we know now." -- David Mudd
WESTERN REGION
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Strip-till, which works
a narrow band of soil in-between strips of residue, attracts
beneficial insects.
Photo by John Luna. |
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Oregon's normally lush Willamette Valley used to turn brown
between fall's vegetable harvest and spring planting, a result of "clean"
farming practices that left soil bare. Today, a drive through the agriculturally
productive region in winter offers a much greener look.
"Fifteen years ago, I could tell what fields had been in corn
or row crops because they were bare and brown," says Carl Hendricks, who grows
sweet corn, snap beans, broccoli and other vegetables on 2,000 acres in the
Willamette Valley. "There are still a few out there, but most fields now have
cover crops. More and more growers are using them."
Hendricks himself is a cover crops convert. For several years, he has worked
with Oregon State University's John Luna, who received a SARE grant to test
cover crop varieties and new tillage regimes to assess their potential to
improve crop yields, beat weeds, lower input costs, reduce agricultural runoff
and save farmers money.
In 1997, Hendricks measured better corn yields after planting
a winter cover of oats, vetch and Austrian winter peas, then strip-tilling
sweet corn the following spring. After killing the covers in the spring, he
planted corn into eight-inch tilled strips amid the cover crop vegetative
residue.
In the three fields enrolled in those trials, the strip-tillage
system returned $100 per acre more than the standard tillage system. The returns
resulted from increased yield as well as cost savings from reduced tillage.
"My normal practice is to plow the ground and work it all up,
but I was looking for fewer trips over the field, which saves time and money,"
Hendricks says. "Strip-tilling was positive enough this year for me to definitely
expand the trials next year."
Hendricks is one of several valley vegetable growers Luna and
collaborator Dan McGrath work with to fine-tune their use of cover crops,
typically planted to rebuild and protect the soil, not for harvest. Legumes,
such as vetch, add nitrogen to the soil; grains, such as oats, capture excess
nitrogen from a previous crop to guard against leaching into ground or surface
waters. Luna's long-term project attempts to measure those and other potential
environmental benefits against cover crop costs.
Luna collaborates with a group of farmers in the Willamette
Valley, where wet springs and a strict planting schedule dictated by vegetable
processing companies pose challenges to growers trying to incorporate a new
crop into their rotations. To meet their critical planting dates for various
vegetables between April and July, Luna has sought a combination of covers
that can fix nitrogen and add organic matter but be killed in early spring.
"Cover crops keep the soil wetter in the spring, shading the
soil so it doesn't evaporate, so it can work against farmers trying to meet
a scheduled planting date," he says. "There comes the rub -- they don't just
plant when the weather is favorable."
Some of Luna's collaborating farmers have incorporated strip-till,
which works a narrow band in between wider strips of residue-covered soil,
to help address that problem. Strip-till puts only about 20 percent of the
surface soil under tillage, helping address moisture concerns. Moreover, strip-tilling
enables growers to prepare a seedbed in just one tractor pass, compared to
five to 10 multiple passes under conventional conditions. Strip-till thus
offers a dramatic savings in soil preparation costs.
On the Hendricks farm for example, tillage savings equalled
about $30 per acre.
Luna suspects -- and wants to prove -- that increased organic
matter and minimal soil disturbance also reduces soil compaction. "Maybe we
are doing more harm by running many operations over that soil when it's not
in ideal shape," Hendricks agrees.
Cover crops also provide habitat for insects that can prey on
crop pests. Predator insects such as carabid beetles and spiders thrive in
habitat left for them on the surface. Not tilling the ground keeps that habitat
in place, a crucial consideration and an alternative to pesticides for Oregon
growers trying to combat cutworm in corn.
Sampling in Hendricks' fields in 1997 found higher numbers of
predacious carabid beetles in the strip-tillage blocks than in the conventional
tillage blocks.
Luna stresses the need for continued research. After crop yields
decreased following strip-tillage trials in 1996, Luna's experiments in 1997
incorporated at least a week-long delay between strip-tilling and planting.
That extra week allows the soil to warm and provides time for the vetch and
other legumes to begin releasing nitrogen.
Luna is encouraged by the prevalence of cover crop usage in
the valley and the strong interest in strip-tillage systems.
"Many of our farmers are encouraged enough to expand the acreage
in cover crops," he says. "They don't have much time in the spring, so if
they can make one pass over the field rather than six or 10, that saves them
time.
"We're pretty optimistic that we can really change the face
of farming in the Willamette Valley."
Hendricks hopes cover crops will help his yields while protecting
the soil from erosion. He also appreciates a more pleasing winter landscape.
"I use [covers] because I think we're doing the right thing
for the soil," he says. "We're helping catch excess nitrogen in the fall,
then putting nitrogen back into it. And I like the look of the field in the
winter when there is something green out there." -- Valerie Berton
Ten Years
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