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w w w. v w m m e d i a . c o m J u l y - A u g 2 014 | V I N E YA R D & W I N E RY M A N A G E M E N T 3 9 gation or rain event. However, soil moisture availability does not always equate to vine water avail- ability or vine water status, so tech- niques that measure vine water status, such as a pressure chamber that measures leaf water potential, or preferably, vine water use (tran- spiration rates), are more useful ods of high heat, which requires ensuring sufficient vine water avail- ability during these periods. M o n i t o r i n g s o i l m o i s t u r e , through devices such as the neu- tron probe, can give an indication of available soil moisture and soil moisture replenishment rates at various depths following an irri- arms, or catch wires that allow for a sprawling canopy development, allow for more shading of the clus- ters from the shoots and may be preferred in warmer climates. Another consideration for trellis design is that radiant heat can be reflected from the soil, especially bare soil, so a low fruiting-wire height can increase the tempera- ture of grape clusters. Consider a higher positioned wire in hot cli- mates to maintain lower cluster temperatures, especially if the ground will be cultivated. KEEP THE AC RUNNING Grapevine transpiration is a natu- ral cooling mechanism that involves water movement through a plant and its evaporation from leaf sto- mata, which occurs when the sto- mata open to allow the diffusion of carbon dioxide from the air in for photosynthesis, and simultaneous- ly the diffusion of water vapor out. Transpiration also enables the mass flow of mineral nutrients and water from roots to shoots. The process has a cooling effect on plants and it is the role of the viticulturist to encourage this mechanism in peri- A modified VSP trellis such as this one can provide additional shading for the grapes. Photo: Remi Cohen © 2013 StaVin Inc. StaVın Inc, P.O.Box 1693, Sausalito,CA 94966 (415) 331-7849 f (415) 331-0516 stavin.com For over twenty years we've searched the world to source the very fi nest oak known to wine. Our hikes through numerous forests in countries on two continents have yielded fi ndings some winemakers consider treasure. Such travels have shown us the rewards of perseverance, and the importance of variety. Because even the most delicious wines rarely taste the same. ® SOIL & CELLAR REMI COHEN