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p r a c t i c a l w i n e r y & v i n e ya r d a U G U S t 2 0 1 4 71 g r a p e g r o w i n g was a significant shift in both reduced-risk pesticide and low-risk mineral oil applica- tion. The amount of reduced-risk pesticide applied increased 315%, and acres treated increased 826%. Many reduced-risk prod- ucts have low use rates (often ounces per acre), and they replace products applied at a rate of several pounds per acre. Low-risk mineral oils have been increasing as they become incorporated into grower IPM programs. Mineral oils eradicate powdery mildew infections, one primary disease threat. Mineral oil lacks residual activity, so fungicides with 14- to 21-day residual activity are typi- cally included in the spray. Mineral oil and sulfur cannot be applied within 10 to 14 days of each other due to the risk of serious leaf burn when both products are present. Mineral oils also reduce grape leafhop- per nymph and spider mite populations. The increased application of mineral oil has decreased the need for both grape leafhopper and spider mite controls. The increased application of mineral oil as part of an IPM pest management pro- gram was a direct result of IPM Grower Appellation Meetings. These programs were launched to gen- erate data to show to those in the local community who have concerns about pesticide use in vineyards, and to elected officials and regulatory agencies. It is important that grapegrowers can demon- strate their commitment to sustainable grape production including IPM and responsible pest management. Summary Grower-to-grower education has led to significant changes in pesticide usage in Sonoma County. Sustainable winegrow- ing self-assessments have shown consis- tent increases in sustainability for pest management. Total pesticide usage has decreased, along with FQPA-targeted pes- ticide usage. Reduced-risk pesticides and low-risk mineral oil usage have increased dramatically in the 14-year period. Bevill Vineyard Management Bevill Vineyard Management farms 1,000 vineyard acres in Dry Creek Valley, Alexander Valley and Russian River Valley. Integrated pest management (IPM) is practiced in all of the vineyards Duff Bevill's team manages — this includes weekly monitoring of pests in every block during the growing season. They also monitor the Gubler Powdery Mildew Model. By June spray applica- tions tend to be on a 16- to 21-day interval. Spray applications are done with four sin- gle-row air-blast sprayers and two over- the-row two-row sprayers. (A third over-the-row two-row sprayer has been added in 2014.) Bevill believes in low-volume sprays (25 to 50 gallons per acre) and varies tractor speed, rather than water volume, to ensure good coverage. Canopy management is practiced to allow uniform spray coverage. Bevill's early spring program applies 16 ounces per acre of Sulforix (lime sulfur) plus 3 pounds per acre micronized sulfur from bud break up to 3 inches of shoot length. The use of this older technology has proven to give excellent early season control of powdery mildew before switch- ing to new, longer residual products. Min- eral oil is incorporated into the spray program once a safe interval (10 –14 days) has passed from sulfur applications. Fungicides are rotated to reduce the risk of developing powdery mildew resistance. Sulfur products and mineral oil (not mixed together) are applied every year because there are no resistance issues with them. Rotated fungicides include: Inspire Super (a DMI) and Van- guard or Mettle (a DMI), Flint or Pristine (a stobriluron), Quintec—quinoxysen; Ph-D (a group-19 cell wall biosynthesis inhibitor) and Vanguard (group-9 amino acid and protein inhibitor). The idea is to exclude one class of material in a given year. In the following year, rotate the excluded class back in and exclude another class from the rotation for one year. Bevill has experienced few mite prob- lems. Spot treatment on 20 to 40 acres may be needed in a given year, but he no longer treats an entire vineyard. One management practice change has been to have permanent cover crops in blocks prone to mite infestations. In a valley floor vineyard, Bevill often relies on natu- ral reseeding for the cover crop. Tillage is often done in every other tractor row, typically requiring two passes each year. On hillside vineyards, Zorro fescue and Brando brome are seeded to provide per- manent cover. Cover crops are mowed twice each year, with the first mowing to mulch pruned canes and the second timed after the cover crop flowers, when possible. After three years of permanent cover cropping, vines often show nitrogen defi- ciency due to competition from the cover crop. Nitrogen (20 to 30 units) is applied through the drip system at bud break. If bloom-time petiole samples show low nitrogen, an additional 10 – 20 units of nitrogen may be added through the drip system in July. In some vineyards, legumes are used for the cover crop and then either mowed or tilled to replenish soil nitrogen. Any vege- tation emerging in late spring is treated with glyphosate at a rate of 3 ounces per acre after shoot-thinning using a micro- sprayer. A selective broadleaf herbicide is added where mare's tail is a problem. Bevill has not experienced insect prob- lems using his IPM protocols. In Pierce's disease hot spots such as along Dry Creek Valley riparian zones, blue-green sharpshooters are trapped. Traps are monitored throughout the growing sea- son in order to "zero in" on the hot spot location. With this information in hand, 12 ounces per acre of Admire (imidoclo- prid) will be applied at bud break through the drip system in specific irri- gation blocks. Vegetation management is also done to reduce Pierce's disease host plants such as the invasive Himalayan blackberry. This has also been done on hillsides when Pierce's disease is observed in non-riparian areas. "Our IPM program has resulted in excel- lent powdery mildew control," says Bevill, "and greatly reduced mite and insect infes- tations that reach economic levels." Unti Vineyards Unti Vineyards, outside Healdsburg, Calif., changed from a mineral oil pro- gram to wettable sulfur for powdery mil- dew control in their organic 60-acre vineyard. Spray intervals were shortened, and spray coverage improved with a new recirculating tunnel sprayer. In three years, owner George Unti has not seen increased mite or grape leafhopper popu- lations with the switch to sulfur. The recirculating tunnel sprayer covers two vine rows. The spray that passes through the canopy is collected and recir- culated in the tunnel sprayer, thereby conserving spray material, reducing drift and non-target spray applications. Operational benefits of tunnel sprayer Labor is reduced compared to an air-blast sprayer by treating two vine rows instead of only one. Making half as many tractor passes also reduces diesel use and soil compaction in vine rows where a sprayer no longer travels. Spray applications were reduced from 56 days in 2011 to 45 days in 2012. The 250-gallon spray tank would typi- cally cover three acres, but the recirculat- ing feature covers up to 9 acres per tank in early spring, when leaf area is limited, and 4 acres when the canopy is full, thereby reducing pesticide costs. "The sprayer gives excellent coverage and allows spraying in up to 8 – 9 mph winds, compared to an air-blast sprayer that is best used with winds less than 5 mph," reports Unti.