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42 WINES&VINES January 2016 I have worked with many vineyard startups during the past decade and evaluated prospective vineyard sites for count- less soon-to-be grapegrowers east of the Rocky Mountains. New growers often start growing grapes while working other jobs or after a previous career—frequently one not related to agriculture. The transition to grapegrower has a steep learning curve, and that is typically where the uni- versity or private vineyard advisor has the biggest impact on improving the success rate for vineyards. Accurately diagnos- ing vineyard problems is one of the most re- warding parts of my job. However, preventing them from occurring is the ultimate goal, and even experienced grow- ers have occasional slips. The objective of this column is to help both new and experi- enced grapegrowers avoid some of the most common and costly mistakes. This list could be extensive, but I have pared it down to the seven mistakes that occur most frequently and have the potential to cause lasting setbacks to vineyard development. 1 Using the same spray tank for herbicides and grapevine spray products No matter how well a grower rinses out the tank and nozzle of the sprayer, there will always be some herbicide residue left. Even highly diluted herbicide will in- evitably cause leaf damage or even kill young grapevines. The bigger problem occurs when residue from a systemic herbicide is left in the tank, which will kill a vine down to the roots. Young vines may have a more difficult time recovering from herbicide damage. ADVICE: If you use herbicides, designate a separate spray tank, clearly mark it "herbicides only" or draw a picture of a dying plant on the outside— whatever it takes to avoid this error. Use another tank for all other vineyard sprays such as fungicides, insecticides and fo- liar fertilizers. 2 The 'double spray' dilemma New growers often have difficulty "guessing" how much water to mix with their spray product to cover the foliage of all vines in the vineyard. In addition, the vines keep on growing, which means the volume of water needed will increase over the course of the season. The "double spray" dilemma occurs when a grower mixes more spray product than is needed to get full coverage. Not knowing what to do with the remainder, and not wanting to waste it, the grower may be tempted to go back in and "use it up" on a few rows of vines that have al- ready been sprayed. This may not cause a problem with some prod- ucts. However, many foliar fertilizers (e.g., boron) and some fungicides (e.g., phosphorous acid) can be toxic to grapes if applied at close intervals. The label rate is designed to prevent leaf burn, and spraying a second dose within hours of the first might double that concentration. ADVICE: Watch for product labels that provide a ratio of water along with the rate per acre, as these are often the products that build up in vine tissue to toxic levels. If in doubt about the n FRITZ WESTOVER Top Seven Mistakes New Grapegrowers Make If you use herbicides, designate a separate spray tank, clearly mark it 'herbicides only' or draw a picture of a dying plant on the outside. Grapegrowing A second consecutive spray of boron fertilizer causes the sub- stance to become toxic, resulting in leaf burn near bloom.