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A Tale of Two Tunnels

Pennsylvania tomato growers go undercover

The Tomato Magazine
October 2004

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. representative.

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, determinate variety.

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 into October.

"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 Midwest.

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 quality fruit."

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 Cramer.

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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