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Vine Crops

1407 - Evaluation of Potential New Organic Herbicide

Principal Investigator: Brad Hanson

Affiliation: UC Davis

Contact: bhanson@ucdavis.edu

UC Davis weed science personnel are conducting an industry-sponsored herbicide evaluation trial in a non-crop site to evaluate the weed control efficacy of a potential organic herbicide with residual activity.  Experiments are being conducted at three locations in the Central Valley, including KREC, on a range of soil types.

506 - Water Use of Thompson Seedless

Principal Investigator: Larry Williams

Affiliation: UC Davis

Contact: lewilliams@ucanr.edu

The competition between urban and agricultural entities for limited water resources is increasing in California.  This competition can be exacerbated yearly due to below average precipitation throughout the state.  The ability to determine the amount of water vineyards require to maintain productivity and maximize water use efficiency and fruit quality will allow the grape growing sector of agriculture to better utilize this natural resource.  In order for this to occur, growers need reliable estimates of grapevine water use across grape commodities and grape production areas in California.  While weighing lysimeters will provide a direct measure of grapevine water use, they are expensive to build and much time is needed to ensure their measurements are accurate.  An alternative, allowing the accurate measurement of many vines at one time and highly portable, would be useful in viticulture.  One such technique would be the use of sap flow sensors which have been used to measure transpiration of young and mature grapevines in conjunction with models of soil water evaporation to estimate crop ET.  However, the reliability of sap flow sensors, especially on large vines, has been questioned. Here we propose to further develop and implement a newly modified sap flow technique capable of precisely measuring both high and low rates of grapevine transpiration.  The output of the sensors will then be validated against transpiration of vines growing in a weighing lysimeter.