Good Fruit Grower / July 2010 / Getting it ripe

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Getting it ripe

The following viticulture strategies are recommended by Hogue Ranches and Mercer Estates’ Rick ­Hamman to help growers ripen wine grapes in eastern ­Washington Stat

• Trellis for quality sunlight and mechanization. Use modified vertical shoot position system with east canopy wires only positioned, or use three-wire fixed vertical shoot position system, with shoot tucking or sprawl. 
• Avoid direct sun exposure on west or south side of vine. Do not position westside canopy wires, allowing sprawl.
• Prune accurately. Pay attention to spur spacing, position, and renewals. For vertical shoot position trellis, leave 24 to 32 buds per vine for red varieties; in whites, leave 36 to 48 buds per vine.
• Cordon suckering. Complete by June 1 to reduce canopy congestion, removing noncount shoots.
• Remove clusters from weak shoots that are less than ten inches long after flower set (around June 15).
• Use regulated deficit irrigation to control canopy and berry size. Stop active shoot tip growth with regulated deficit irrigation by veraison, but irrigate through ­harvest to keep leaves functional.
• Improve vine uniformity through drip irrigation, using inline valves and extra emitters where needed.
• Target shoot length to be 36 to 50 inches on ­moderately vigorous sites.    
• Distance between internodes should be 2.5 to 3.5 inches as measured at the cluster.
• Irrigate to maintain growth (no stress, no vigor) once shoot length is achieved.
• Use annual cover crops on moderate to vigorous sites to compete for moisture and weed control.
• Leaf strip by July 15 when berries are no bigger than pea size—open congested canopies by leaf stripping on the east or north side.
•  Cluster thin by veraison (mid-July to August) to fine-tune crop levels. Green thin accordingly.
• Manage insects and diseases for low incidence.
• Maintain adequate bloom time nutrition. Target ranges: nitrate nitrogen (150-450 parts per million); phosphorus (0.15 to 0.30 percent); potassium (0.60 to 3.0 percent), boron (25 to 50 ppm), and zinc (25 to 50 ppm).
• Maintain good communication with winery.