He’s testing how this and other methods of training vines affect both the sunlight environment and fruitfulness.

Difference in yields between various types of DOV systems may also be due to difference in pruning practices, Fidelibus notes. The number of buds on a cane depends on cane length and the length of the internodes. For example, the length of a 15-node cane varies from about 3.5 feet for Dovine and Thompson Seedless vines, to nearly 4 feet for Fiesta and to about 4.25 feet for Selma Pete.

 “If you cut all canes 3-feet long, regardless of variety, you’ll end up with fewer buds on the canes with the longer internodes, since those buds are farther apart than those on canes with shorter internodes,” he says. “Fewer buds means a potentially smaller crop.”

 

 

The length of the trellis cross arms can also affect DOV yields, Fidelibus notes. Shorter cross arms result in smaller canopies and lower grape production. The cross arms used in the Kearney DOV vineyards are much longer and more expansive than those used in many commercial vineyards. These longer cross arms require a much larger harvester than many growers use.

“From what growers tell me, our DOV trellis system at Kearney is at the high edge in terms of size that they can manage commercially,” Fidelibus says. “But you have to realize that when you make the cross arms narrower, yields will be somewhat lower.”

In many of the vineyards he has visited, growers have established cordons as far as 1.5 feet below the Y. Those in the Kearney vineyards are near the bottom of the Y, The lower location makes for easier pruning and other management practices, Fidelibus says. But, it also means much more shading on all the shoots below the Y.

 

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Some growers, who are familiar with the results of his DOV trials and observations, have begun making changes in the DOV trellis systems, without waiting for the findings from this season, Fidelibus reports. For these and others considering a change, he advises proceeding cautiously.

For example, he points out, lowering the cross arms to reduce the distance between the cordons and the Y of the trellis could limit cane length and reduce the size of the canopy. This would restrict yields.

“Changing a DOV system that is already established is expensive and may introduce unintended consequences,” he says. “Altering one feature can affect another, either in a good or a bad way.”