A Tale of Two Tunnels
Pennsylvania tomato growers go undercover
The Tomato Magazine
By John Friel
American tomato growers are seeing the light at the end
of a British tunnel. High tunnels are somewhere between traditional row
covers, temporary protection against late frost and traditional greenhouses.
Modern tunnels are large enough to hold fruit trees and accommodate standard-size
farm machinery. Unlike row covers, high tunnels stay up all through the
growing season; unlike greenhouses, they don't stay covered in winter.
Universities in several states have experimented with single, stand-alone
structures but a British company, Haygrove Tunnels, has a more ambitious
multi-bay design capable of covering many acres.
Greenhouses can cost up to $40 per square foot, depending on design and
equipment. Haygrove, by comparison, delivers a complete tunnel system
for 50 to 80 cents per square foot. By providing protection from adverse
weather, insects and birds, Haygrove reports yield increases of 30 percent
over outdoor production. But that's in England. In the United States,
the weather mood swings are more violent and climatic extremes are more
extreme. The differences in savings can also be much more dramatic.
Steve Groff grows tomatoes for the fresh market and for processing in
southern Lancaster County, Pa. He has 30 acres each of sweet corn and
pumpkins, more of soybeans. He sells bison meat from the shaggy beasts
grazing elsewhere on the 225 acres he farms.
Completing His Second Season
Groff is now winding down his second season of growing tomatoes in Haygrove
tunnels. The summer of 2004 was extraordinarily rainy in Pennsylvania.
Tomatoes rotted in fields all over the state, succumbing to botrytis,
late blight or simply drowning. Local newspapers and television newscasts
ran ugly images of devastated crops, reporting losses of 50 to 80 percent
in Lancaster County.
"It was pretty gruesome," says Ralph Cramer, Haygrove's U.S.
Groff had no late blight (Phytophthora infestans) and his losses were
well below those atrocious numbers, but his outdoor crops suffered like
everyone else's. As of mid-August, each acre of Groff's open fields had
yielded an average of 800 thirty-pound baskets of Mountain Spring, a short,
From his one acre of tunnels, he had already reached his pre-season goal
of 2,400 baskets of the same variety - and he expected to still be picking
"It's triple the yield," Groff notes, adding that "the
Haygrove makes the difference."
And higher yields weren't the only benefit Groff realized.
"(The tunnels) will save on fungicides," he says, "because
the disease pressure is less." Groff had applied fungicides inside
five times; outside, eight. Inside, drip irrigation supplies water and
fertilizer at the root zone, so foliage stays dry. "Leaf wetness
is directly related to disease pressure," Groff adds.
Also helping to keep things dry is the weed barrier that covers the irrigation
lines and all the area around the plants. Besides almost eliminating weeding,
the fabric brought a "very significant" reduction in humidity,
Groff says. The only negative tradeoff was an increase in spider mites,
which like their foliage dry.
Last year, Groff says he planted too densely and found his plants produced
"too much foliage" with fewer and smaller fruits. This year,
he reduced the density and reaped greater yields.
Another Pennsylvania farmer also learned that lesson the hard way. Ed
Weaver runs Weaver's Orchard in Berks County. He planted double rows of
tomatoes in his Haygrove, ironically, because he had seen Groff's setup
last year, before Groff realized he had planted too closely. Groff sympathized,
and said Weaver should "go through and kill every other plant."
Also Great for Other Crops
In addition to one tunnel of tomatoes, Weaver has cherry trees, strawberries
and raspberries under cover.
We were ready to quit growing cherries. We were losing crop after crop,"
he relates. Then Cramer and John Berry of Haygrove in England persuaded
him to try tunnels. His losses in Rainier cherries outdoors that year
ran around 70 percent. Indoors, the percentage was five.
Pointing to a row of stumps, Cramer says that wherever Weaver couldn't
cover them, he had cut the trees down.
Haygrove is a large grower that developed tunnel systems to protect its
fruit crops. From that beginning, in less than a decade, the company has
covered literally thousands of acres in the U.K., U.S., Canada and Africa.
Ralph, a cut flower grower and inveterate handyman, admits his first thought
was to copy, not purchase, the system. But when he did the math, he found
buying was the better option. He now has an acre under cover.
"Everybody talks about season extension," Ralph's son, Keith,
reports. "What they don't realize until they see it is the increase
in quality they get."
Groff backs up that claim. His crops came in "a little earlier,"
he says, but the real payoff is "higher quality and `yields."
Weaver retails most of what he grows onsite. When his own strawberries
can't keep up with demand, he sources others in California. He gets $1
more per quart for his tunnel-grown, pesticide-free product. Similarly,
Groff is able to charge more for his tunnel-grown tomatoes.
As for raspberries, Cramer says, university trials have shown tunnel-grown
berries have up to twice the shelf life of those grown in the open. "They
hate rain," he points out, sampling a juicy red specimen from Weaver's
rows. "They love it in the tunnels."
Groff has a small tunnel near his house. As a trial, he grew some raspberries
in it. His eyes widen as he describes the results: "Huge, perfect
raspberries! They were pristine!"
Would he consider growing any of his other crops in tunnels? "No,"
Groff responds, but adds he is thinking about adding more bays for tomatoes.
Fertility Management Learning Curve
Tunnels require changes Groff admits he did not anticipate. "I'm
still in the learning curve in fertility management. I was really pushing
these (tomatoes) hard in mid-season, pumping extra water and fertilizer
to the crop. The result, in the unusually cool summer, was blotchy ripening."
When Groff backed off the nitrogen, his results improved. Overfertilization
has also been implicated in instances of "gray wall" in the
Are his late season tomatoes as good as his mid-summer crop? Most definitely,
Groff responds. "If the plants are good quality, you'll have good
Next year, Groff plans to replace his wooden stakes with rebar to eliminate
periodic replacement and to reduce disease. Pathogens can overwinter in
wood, he says, necessitating a yearly sterilizing drench with bleach.
Tunnels also require certain hands-on activities that open fields don't.
Pollinators, usually bumblebees, must be introduced. A late snow means
that vents have to be pushed high and wide, as open as possible, to let
the snow fall through and keep from overloading the frame, which is not
designed for the weight. "I've knocked snow off of mine," says
Groff recommends keeping gutter vents closed as much as possible early
in the season, when days and nights are both still cool. In Pennsylvania,
"early" means mid-March to mid-April, depending upon the weather's
whims in a given year and upon location: The southeast corner of the state
is much milder than the western and northern parts.
In summer, Groff removes end covers and opens gutter vents about two feet,
day and night. If strong winds are expected - Cramer's tunnels withstood
Hurricane Isabel with gusts of up to 60 mph - "make sure it's vented
properly (i.e., vents wide open to let the wind blow through) and the
ropes are tight," Ralph warns.
In fall, when the temperature stays too low too long, even without a frost,
"the plants just shut down," Weaver notes. That means it is
time to remove the poly and store it for winter.
Haygrove guarantees its plastic for three years. Many growers stretch
it a season or two longer.
Whether growing tomatoes, berries or sunflowers, "The tunnels will
help any year. In a wet year, they help more," Cramer opines.
Groff supports that view: "In a tough year, (tunnels) are going to
be better," he claims.
© 2004 Columbia Publishing
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