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GRAPE GRO WING Madera County, Calif. "Ground truthing" is another simple way to evaluate vineyards. With a de- tailed map, walk the vineyard and evalu- ate areas where vines aren't growing very well. Flag the problem spots and take some time to figure out what is going on. Backhoe pits in these areas are a quick way to figure out if there is a change in soil texture. (Remember that NRCS maps are usually done fairly quickly and in some cases are based on "best guesses" by the soil scientists look- ing at landforms and vegetation.) Evaluate the vines for diseases such as oak root fungus, which presents itself through grayish-looking dying bark and a mushroom/fungal odor just beneath the soil on the rootstock's main stem. Nema- tode sampling can also be done, but this should occur when the soil is moist and not during the hottest or coldest portions of the year. Once problem areas are as- sessed, employ techniques to address the decreased growth. The Natural Resource Conservation Service has detailed soil information for many growing areas. eas aren't growing well. In my experience, change in soil texture is the most common cause for differences in vine growth, be it too much or too little vigor. However, there may also be other problems including oak root fungus, nematodes or even phylloxera if it is an older vineyard planted on its own roots or AXR-1 rootstock. GrapeParts4Less.com Paying Too Much For Picking Rods? Now You Have A Low Cost Source! GrapeParts4Less.com supplies quality American made picking rods, closures, and parts for all major grape harvester brands. Call 559-277-7382 or visit our website. Mastercard or VISA accepted. Se habla Espaňol. GrapeParts4Less.com Your Low Cost Source For Quality Harvester Parts WINES & VINES NOVEMBER 2012 97 GP4L_W&V_April_2012.indd 1 2/27/12 11:59 AM Block for irrigation based on potential vigor If an obvious change in soil is big enough to form a farmable block, it makes sense for it to be planted and irrigated differ-