Spring’s Here, Get Busy!

By Jessica Cortell

While bud break might still seem distant with our cool, rainy weather, hints of spring are in the air. Before our short and frenetic season starts, it is a good time to set goals for the season, prepare fungicide spray and fertility programs, check equipment and sprayer calibration, review and develop safety programs, assess labor needs and review the requirements for third party-certified programs such as LIVE, USDA Organic, Demeter Biodynamic and Food Alliance.

With the Oregon Certified Sustainable Wine (OCSW) marketing program in place, more vineyards and wineries are becoming certified. The OCSW program requires both certification of the vineyard and winery by one of the above programs. In 2009, the USDA Oregon Vineyard and Winery Report (see page 34) showed a total of 222,803 cases of wine marketed with a sustainable label and 100,897 cases marketed with the OCSW label.

As the goals for producing high quality grapes are different from other crops, fertilizers should be applied to maintain adequate vine and canopy health to ripen the fruit but not to promote excess vegetative growth or vigor. This needs to be considered in developing a fertility plan for the coming season. It is helpful to have a recent soil test and petiole analyses (bloom and/or veraison) from the previous season.

There can be seasonal nutritional trends across the Willamette Valley related to climatic influences such as temperature and rainfall. For example, high nitrogen was common due to the high rainfall in 2010, while there were also magnesium deficiencies in many vineyards. If petiole samples are available from several years, you can observe the typical pattern in your vineyard and seasonal differences.

Most vineyards have permanent or annual cover crops. These cover crops can supply nutrients such as nitrogen to the vines particularly when nitrogen-fixing legumes are used. Due to the moderate nitrogen requirement of wine grapes, this source needs to be considered in your plan. Oregon State’s Small Farms Extension Service (http://smallfarms.oregonstate.edu) provides an online calculator that can help determine the nutritional value of your cover crop.

By having both soil fertility and petiole tests available, it is easier to determine if the nutrient is in short supply in the soil compared to an uptake issue within the vine. This could influence how and when to apply fertilizers. In addition to the use of cover crops, macronutrients (needed in large amounts) including nitrogen, phosphorus, magnesium, calcium and potassium can be applied as dry fertilizers banded under the vines or injection of liquid fertilizers banded next to the vines or through fertigation — fertilizer applied through the irrigation system. Both organic and non-organic formulations are available.

Micronutrients are required in small quantities and are often best applied as foliars added to the fungicide sprays. Boron and zinc are often low in Oregon vineyards. If boron and zinc were in the low to medium range in petiole samples, they can be applied as several foliar sprays leading up to bloom.

Each season presents varying weather conditions and levels of disease pressure. In 2010, the cool rainy spring and early fall rains promoted botrytis infections resulting in crop losses. Some organic growers also had issues with powdery mildew. If you had a breakdown in your program and had losses to diseases, analyzing what was done the previous season can help in making improvements for this season. Was it an issue related to your sprayer calibration, spray intervals, a poor choice of products or other factors?

After determining what foliar nutrient sprays are needed at key phenological stages, these can be incorporated into your fungicide spray program. While some changes will probably be made in your spray program as the season progresses, having it lined out before the growing season starts can help you stay on track, target the best products at key growth stages and help minimize disease problems. 

At this time of year, organic and Biodynamic growers need to develop and submit their annual farm plan. In this plan, all possible products that might be use during the growing season need to be included. Certified Biodynamic vineyards must meet all the National Organic Program (NOP) standards and any additional Demeter standards.

Organic growers have fewer tools to use for powdery mildew and botrytis management with programs focusing primarily on oils, sulfur, bicarbonates and biologicals. A new product of interest to organic growers is a plant extract-based product called Regalia (www.marronebioinnovations.com). This product stimulates the plant’s natural response to disease. It also has the potential to stimulate production of phenolics compounds in the fruit, which could increase tannins and anthocyanins in wine.

Growers following other programs besides organics have more options. Often growers in the LIVE program will use a mix of products allowed for organic production and also include several synthetic products at key times such as bloom, bunch closure or veraison. In order to help prevent disease resistance to these synthetic products, it is important to rotate chemical classes and consider tank mixes of different chemistries (such as sulfur with a strobilurin). Once you have your program planned, there might be benefits in buying the products before the season starts.

Now is a good time to bring out your tractor and sprayer and make sure all equipment is working after the winter. Sprayer calibration should be checked every year before the spray season starts. It is also a good time to have a safety meeting with your crew to review tractor safety and careful handling of chemicals. New OSHA requirements (www.orosha.org/standards/div_4.html) for agriculture involve having monthly safety meetings.

The final item to consider is in making sure that you are following all labor laws whether you hire your own labor or use a farm labor contractor or management company. If you have questions concerning your responsibilities as a vineyard owner, you can contact the Bureau of Labor and Industries (BOLI) at www.boli.state.or.us/BOLI/WHD/FFL/index.shtml.

Jessica Cortell received a M.S. degree in Horticulture and a Ph.D in Food Science and Technology from Oregon State University. Currently, she owns her own consulting and vineyard management company, Vitis Terra Vineyard Services, and teaches at Northwest Viticulture Center in Salem.