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United States Department of Agriculture

Agricultural Research Service

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Yield Estimation
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Accurate estimates of crop yield are important to juice processors and wineries because the processing equipment is expensive, fixed in size, and best run at optimal capacity throughout harvest. Thus juice processors and wineries want to know as far in advance as possible the amount of fruit anticipated at harvest so they can invest in new equipment when warranted, plus schedule picking, processing, fermentation, and storage. The standard method of estimating yield involves collecting grape clusters by hand, weighing the clusters, and hand counting berries, all across thousands of acres. Accurate predictions of yield are time-consuming, labor-intensive, and can be grossly miscalculated.







John (left) and Paul (right) install a monitoring system in a commercial vineyard in the YakimaValley.


Installation of monitoring system


Paul Blom, our post-doc, and John Ferguson are working on an automated system to monitor the growth of the crop throughout the season and to estimate yield in crops grown on trellises, such as grapes. The trellis wire that supports the vines is connected to a load cell, a device that detects changes in tension in the trellis wire. As the fruit gains weight during the season, more mass hangs from the trellis wire, thereby increasing tension in the wire. The load cell detects these changes, sends the signal to a microprocessor, and the data are delivered to Paul to project a yield estimate. The system is being tested in a number of commercial vineyards in Washington's YakimaValley.


Schematic diagram of a trellis

Schematic diagram of a trellis and the main forces that affect tension on the trellis wire (cordon wire in the vineyard).


Tarara, J.M., Ferguson, J.C., Blom, P.E., Pitts, M.J., and Pierce, F.J. 2004. Estimation of grapevine crop mass and yield via automated measurements of trellis tension. Transactions of the American Society of Agricultural Engineers. 47(2):647-657.


Tarara et al. Apparatus and Method for Measuring the Mass of Vegetation or Fruit Supported on a Trellils. U.S. Patent no: 6,854,337 B1. Feb. 15, 2005.


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Trellis Tension Technology Article


Scientist: Julie Tarara



Last Modified: 8/19/2016
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