Good Fruit Grower

February 1

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Table 1 Lag phase determination Table 1 compares dates chosen as the onset of the lag phase by the two industry personnel based on the tension wire data versus dates selected by mathematical analysis of the curves. On the whole, the industry representatives selected the shoulder later than the mathematical solution, overestimating the lag phase by seven days on average. Date of onset of lag phase determined by industry representatives who visually examined daily data from measurements of cordon wire tension compared to the dates determined by analyzing mathematically the shape of the growth curve. Sensor Industry Mathematical Cultivar Year number Representative Solution Difference Date Date Days Merlot 2007 A more powerful tool would be a predictive model that could be used soon after fruit set to find where the shoulder in the growth curve is to be expected based on that season's growth. Identifying the onset of lag phase with more precision would buy the grower time for the intense sampling that is required to cover large acreages. There are practical consequences to estimating the date of the onset of lag phase later than it actually occurs. For example, a company will have less time to complete sampling before the berries start the second phase of rapid growth. Also, samples collected too late can result in yield overestimates because the lag phase multipliers then are used on larger, rapidly growing berries. Our research results on the technique are available for discussion with any sensor, equipment, or engineering firms that may be interested in commercializing a product for industry use. • June 14 +2 June 17 June 13 +4 3 June 16 June 14 +2 4 June 17 June 12 +5 5 June 22 June 15 +7 6 2009 June 16 2 Predictive tool 1 June 17 June 13 +4 June 16 +10 June 15 +11 June 22 June 13 +9 4 June 22 June 18 +4 5 June 26 June 18 +8 6 2007 June 26 June 26 3 Chardonnay 1 2 June 22 June 17 +5 For further discussion about the technology, contact Julie Tarara at: julietarara@ars.usda.gov . 1 June 22 June 14 +8 2 June 24 June 15 +9 3 +10 June 16 +5 June 22 June 15 +7 6 2009 June 12 June 21 5 Julie Tarara, U.S. Department of Agriculture, Prosser, Washington; Bernardo Chaves, Washington State University, Prosser; Luis Sanchez and Nick Dokoozlian, E & J Gallo, Modesto, California June 22 4 June 23 June 13 +10 1 June 21 June 13 +8 Further reading 2 June 7 June 12 -5 Tarara, J.M., B. Chaves, L.A. Sanchez, N.K. Dokoozlian. 2013. Analytical determination of the lag phase in grapes by remote measurement of trellis tension. HortScience 48:453-461. Tarara, J.M., J.C. Ferguson, P.E. Blom, M. Pitts, and F.J. Pierce. 2004. Estimation of grapevine crop mass and yield via automated measurements of trellis tension. Transactions of the American Society of Agricultural Engineers 47:647-657. 3 June 21 June 13 +8 4 June 27 June 12 +15 5 June 9 June 10 -1 6 June 9 June 14 -5 Source: USDA ANTONIO CARRARO Welcomes introduces the New TGF 9800 S To Our Dealership Family Low Hour Rental Returns Starting at Only $ 27,995 Priced at . . . $ 35,800 ABERDEEN CHEHALIS ELLENSBURG LYNDEN OKANOGAN POULSBO MOUNT VERNON OLYMPIA QUINCY SNOHOMISH SUMNER 509-728-3018 509-728-3016 34 FEBRUARY 1, 2014 GOOD FRUIT GROWER 75 PTO, 4WD with all the standard features YAKIMA 509-797-5806 509-322-1540 www.goodfruit.com

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