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ISU Researchers Expand Study Of 'Mesotunnels' For Organic Crops

courtesy Mark Gleason
ISU professor Mark Gleason says these mesotunnels fit a sweet-spot between high and low tunnels.

By design, organic agriculture limits the products that can be applied to crops to kill pests and weeds, so farmers often look for other strategies to reduce risk.

Short, fabric-covered tunnels could be the solution for certain organic crops. Researchers at Iowa State University have developed mid-sized mesh-covered tunnels, dubbed “mesotunnels,” that let sunlight and rain in, but keep many bugs out.

“The basic idea is to try to keep pest insects out,” says Iowa State University professor of plant pathology and microbiology Mark Gleason. “And not only them, but the pathogens, the bacteria in particular, that they carry that can cause disease on these cucurbit crops.”

Cucurbit crops include squash, cucumbers, melons and gourds. Gleason and colleagues recently received a grant from the U.S. Department of Agriculture’s National Institute of Food and Agriculture to expand their trials to commercial-scale fields.

The mesotunnels are shorter than high tunnels, which can be 16 to 20 feet tall and become a nearly permanent fixture on a farm, and taller than low tunnels, which are just 18 inches high and only used during the early part of the season before the plants flower.

Mesotunnels are about 3.5 feet high and are made from bent electrical conduits covered with a nylon mesh fabric similar to a window screen. 

“It’s a sweet spot because it’s providing enough space inside that tunnel, number 1, for the plants to grow and, number 2, for bees inside the tunnel to be able to pollinate,” Gleason says.

But he says the tunnels are pricey and require a farmer to order bees and put them inside the tunnels. Typically these crops would be pollinated by naturally occurring bees.  

The next stage of the research will look at whether mesotunnels can be cost-effective and what farmers think of the system.

The $2 million grant comes through the federal farm bill, which increased research spending on organics in 2018.

“The situation for organic agriculture funding has never been better,” Gleason says. “I can’t remember a time in my 35 years here when there was this level of support for organic research. And we need it because it’s been a neglected area for many years in agriculture and there’s a great deal we need to learn.”

Gleason says even though corn and soybeans dominate the Iowa agricultural landscape, there are commercial-scale organic growers in the state who could benefit from the mesotunnels. Gleason and his Iowa State colleagues are working with researchers at Cornell University and the University of Kentucky. Farmers in New York and Kentucky also grow organic cucurbits.  

Amy Mayer is a reporter based in Ames