Delvin Farms high tunnel berries yield better, earlier

By DOROTHY NOBLE
AFP Correspondent

LANCASTER, Pa. — Hank Delvin of Delvin Farms, College Grove, Tenn. shared his experiences with high tunnel organic strawberries at Ralph Cramer’s Haygrove owners’ conference in early December.
Delvin Farms, located just 30 miles from Nashville, grows an assortment of produce marketed to boutiques, farmers markets, grocery stores and restaurants.
Although the farm’s acreage exceeds 200, about 80 acres are devoted to certified organic fruits and vegetables.
Hank Delvin returned to his family’s farm in 2004 as more people were seeking information about where their food comes from and how it is produced. He explained that he is committed to organic production.
The farm added one acre of high tunnels in 2010. “With experience you can grow year-round,” Delvin told the group.
Delvin quickly noted the growth differences between field and tunnel production, adding, “If tomatoes are crammed in, it’s a jungle.”
Importantly, strawberries produce more and earlier in high tunnels. Delvin said each plant produced two quarts. Plus, they can be sold a month earlier when prices are typically higher.
Strawberry sales produce early cash flow. Delvin Farms commands $6 per quart from retail customers, and $3.75 from wholesale clients.
Those who enjoy the berries include 750 Community Supported Agriculture members and Whole Foods Market. Delvin says, “Our customers are loyal.” Also, they tell him that organic strawberries have better flavor.
He recommends preparing the soil in advance. Composted manure is disked in, and his soil requires lime every two years.
His cover crops include red clover, wheat and buckwheat, and are strip planted.
In addition, he practices crop rotation.
With four rows per bay in the tunnels, Delvin plans 11,520 strawberry plants this season.
From a early September waterwheel planting, a nice crown grows from the 50-cell plugs. He uses a raised bed plasticulture system.
After the initial fertilizer
application, he supplements the crop with a liquid fish product via the drip tube two or three more times.
In tunnels, he uses beneficial insects and has had relatively few pest problems.
Spider mite damage, Delvin notes, can be mistaken for fertilizer deficiency.
Stylet-oil must make contact, and predator mites have been effective.
He commented that neem oil is expensive.
He says his biggest disease threat has been Butyris gray mold, plus anthracnose in a wet year. Frequent spray application, particularly after rain events, is important for control.
Fortunately, with the dry heat conditions in the tunnels there is less disease pressure—thus less need to spray.
Delvin concluded by pointing out other advantages of high tunnel strawberries.
His strawberries are the first to appear in the markets, yield is higher, the fruit is cleaner, one can harvest in the rain, the shelf life is better and there are no deer to savor the berries.
When comparing field and high tunnel production, he said emphatically, “The tunnel wins!”