Issue link: http://winesandvines.uberflip.com/i/643683
March 2016 WINES&VINES 41 GRAPEGROWING In our organically certified vineyards, all of the blocks are located in gravelly or cobbley clay loams along the base of the Sierra Foot- hills. While there seem to be more organically registered herbicides that are becoming avail- able to the market every year, they are all con- tact herbicides that are mostly effective only when the weeds have just emerged and are smaller than the circumference of a quarter. Berm cultivation is still required. We currently utilize a Kimco berm cultivator with rotating tines that automatically churns the soil in the berms. Its automated sensor triggers the cultivator to retract around an oncoming vine. This system can be used twice, followed by a discing to fill in the soil that has been pushed into the row. We find that it takes five to six passes to effectively control weeds in one season with cultivation. This is true CHALLENGES WITH OLD-VINE ZINFANDEL B okisch Ranches manages about 30 acres of old Zinfandel vines, and those vineyards present some viticultural challenges. "These vines pre-date the concept of vineyard mechani- zation and do not bend their will to its adoption," Markus Bokisch says. "Almost everything has to be done by hand.…Fortunately, due to a total lack of wires and a lower planting density, most labor-related tasks are cheaper than in modern, conventional vineyards." Plus, the prices paid for old-vine Zinfandel fruit are higher. In December 2013, Bokisch says, a lot of old-vine Zin- fandel in Lodi was hit by a prolonged freeze. "Due to the drought, the vines were starved for water and were not sufficiently hardened to endure the cold. Many vines died or lost many spur positions," he says. "We decided to install subsurface drip irrigation down every row to supplement the soil profile in the fall to prevent winter freeze damage. The system also served to irrigate the vines in late summer, prior to harvest. We also installed surface irrigation and placed emit- ters in the areas where vines had perished during the freeze." Spraying is also a challenge, Bokisch notes. Because Zinfandel is susceptible to mite infestations, he tries not to use sulfur dust, which can exacerbate the mite damage and use fungicide sprays. But because of the spacing of the vineyards, he's able to use only a small, 4-foot-wide sprayer. He leases a Venturi Air three-point sprayer from his neighbor and also uses it for vineyards with high-density plantings. anunci_vigas_usa.ai 1 29/09/15 15:17 "We live in a semi-arid savanna, and water efficiency should always be a top priority." —Markus Bokisch LODI WINEGRAPE COMMISSION