- Spring 1998 "Update" Newsletter Article -
Trellis Systems Make a Difference
From CATI Publication #980401
Copyright © 1998. All rights reserved.
A viticulture research project featuring the use of experimental trellis and training systems at California State University, Fresno has shown significant yield variations in vines using the different systems.
The multi-year study is not yet concluded, but initial results showed that vines trained on an open lyre trellis produce greater yields than vines on the standard two-wire vertical trellis. In addition, vines on standard trellises but receiving minimal pruning treatments also showed higher yields.
“Currently, there are considerable changes occurring in the trellis systems used in California vineyards,” wrote research scientist Keith Striegler in a recent report to the California Agricultural Technology Institute (CATI). “Planting of new vineyards and replanting or top-grafting of existing vineyards have given growers the opportunity to install new trellis systems. The open lyre, Geneva double curtain, Scott-Henry, and vertical shoot-positioned systems are being used increasingly,” Striegler said.
In a project begun in 1995, researchers from Fresno State’s Viticulture and Enology Research Center (VERC) and Center for Irrigation Technology (CIT) joined in their effort to compare the trellis systems using surface and subsurface drip irrigation systems. Leading the effort for VERC was researcher and new director Keith Striegler. Heading up the team of irrigation specialists was CIT director David Zoldoske.
Trellising systems being compared in the project are bilateral cordon on a standard two-wire vertical trellis, open lyre, Geneva double curtain, and standard trellis with minimal pruning.
Irrigation treatments included above ground drip with water applied at 0.8 of evapotranspiration (Et); subsurface drip irrigation (SDI) with water applied at 0.8 of Et; SDI with water applied at 0.6 of Et; and SDI with water applied at 0.4 of Et.
While the effects of decreased water application were not unexpected, some results from trellis treatments were.
“Significant trellis system effects on yield and fruit composition were observed in 1996,” the researchers noted. Analysis of growth and yield data showed highest yields for the open-lyre and minimal pruning treatments. The increased yield resulted from higher numbers of clusters per vine, they said.
Also noted was delayed fruit maturation for the trellis systems which had the highest yields, and differences in soluble solids and pH levels.
In 1995 the irrigation methods had a significant effect only on berry weight, with subsurface drip irrigation (SDI) showing slightly larger berries,” the researchers reported. However, in 1996 “irrigation method also had a significant impact on yield and fruit composition.” In general, as irrigation deficit increased, yield level decreased.
Differences also were observed between the surface and subsurface irrigation treatments. For example, the use of subsurface drip irrigation allowed for reduced application of herbicides. “One application of glyphosate to perennial weeds could be avoided because berms were dry,” Zoldoske said.
On the other hand, the use of subsurface drip required increased efforts for control of gophers, he added. “For most of the season two men worked full time repairing, trapping and baiting,” the researchers noted.
Formal data from the first two years of study are expected to be released soon, through California Agricultural Technology Institute (CATI) research publications and in presentations at upcoming viticulture siminars. More data also is to be collected this coming summer as the study continues one more season.
Details will be announced through Update and the CATI web site ( cati.csufresno.edu ) as information becomes available.
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