Optimizing tunnel systems
Fixed sprays to be tested.
The reflective Extenday material is used under this third-leaf Skeena cherry tree on Gisela 5 at the Southwest Michigan Research and Extension Center. The vertical-axis-type tree architecture helps fill the tunnel space with tall, narrow
Dr. Greg Lang continues to tweak the cherry tunnel project as he works to refine the production system. Numerous changes for the tunnel project are planned this year.
In collaboration with Dr. Art Agnello of Cornell University, Lang will be experimenting with a fixed spray system inside the tunnels that can be used for fertigation and pest management (see "Stealth Sprayer," March 1, 2008, Good Fruit Grower).
The Michigan State University horticulturist also plans to better utilize the land inside the tunnels, planting a third row of trees in the tunnels in between the tree rows. "Under our climatic conditions, I think we'd like to target yields of about 7.5 tons per acre and average fruit sizes of 11.5 to 12 grams [9-row]," he said. "If we can facilitate a third row of trees in the tunnel, we think we can get those yields higher without losing fruit size, simply by more efficient use of orchard area.
"We've eliminated the use of a tractor, so why not better utilize the space and increase yield per acre?" he asked, adding that the fixed spray system would still allow sprays to be applied.
Trees planted in the third row are being trained to high density training systems, such as Dr. Matthew Whiting's UFO (upright fruiting offshoots) training system, to learn if trees can be grown in the Midwest under a trellis system using wires. "Because of bacterial canker, the wire rub from systems that use lots of wires tends to kill cherry trees in the Midwest," Lang said.
Also, different types of plastic tunnel sheeting that allow different wavelengths of light will be compared to learn if accumulation of growing degree-days can be increased or decreased to push bloom one to two weeks earlier or later. Spore germination under the plastic with different ultraviolet transmittance also will be studied to learn if disease spores are impacted by more or less ultraviolet light.
"Just changing the type of plastic used on the tunnels could have all kinds of different impacts," he said.