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2014 Vintage Update (30 June)

**Click here for a downloadable PDF of this Vintage Update**

By Michelle Moyer, WSU Viticulture Extension Specialist

 

Growing Degree Days

The 2014 growing season is still mirroring the warm 2013 vintage, albeit we are slightly ahead of last year (Figure 1). While hot temperatures in the coming week will substantially add to the vintage GDD accumulation, remember that vines begin to shut down at temperatures above 95°F. For those doing leaf removal now, be cautious of fruit exposure during periods of high heat: sunburn is a result of both sun exposure AND high temperatures.

Figure 1- Growing Degree Day accumulation (base 50ºF) for 2014, 2013 (warm year), 2011 (cool year), and the long-term average. Charts for representative AWN stations at each AVA are updated at: http://wine.wsu.edu/research-extension/weather/growing-degree-days/ . Make your own GDD chart for the AgWeatherNet station nearest you at: http://weather.wsu.edu

Precipitation

Precipitation is still below normal for the growing season, despite several rain events in May and mid-June (Figure 2). With most vineyards past fruit set and beginning deficit irrigation practices, the lack of forecast rain bodes well for canopy management through strategic irritation implementation.  See http://wine.wsu.edu/research-extension/irrigation/ for more information on water management in vineyards.

 

Figure 2- Precipitation for 2014. While February and March rains helped replenish water reserves, the 2014 vintage is still below normal precipitation levels. Regularly updated precipitation charts are available at: http://wine.wsu.edu/research-extension/weather/precipitation/ Make your own precipitation chart for the AgWeatherNet station nearest you at: http://weather.wsu.edu

Disease Control

Early to mid-June rain events slightly increased disease pressure in Eastern WA, but overall, pressure has remained at low-to-moderate levels as we progress towards the end of the susceptible period for powdery mildew.  More information on general disease management can be found at: http://wine.wsu.edu/research-extension/plant-health/grape-diseases/ .

Nutrient Management

Many actively growing vineyards can exhibit nutrient deficiency symptoms at this time of the season. There have been several reports of nitrogen deficiency symptoms, typical in rapidly growing canopies or in vines suffering from early and severe water stress (a common problem in rain-fed vineyards where supplemental irrigation is not present during dry periods).  In addition, phosphorous deficiencies (reddening of older leaves, starting at leaf margins) can begin to show now. Phosphorous deficiency can look similar to virus symptoms; timing of symptoms is often an early distinguisher (virus symptoms begin to show later in the growing season). If your vines are exhibiting potential nutrient deficiency symptoms, consider a tissue test in a month or so, when véraison starts. See: http://wine.wsu.edu/research-extension/plant-health/nutrition-and-soils/ for more information in nutrient management.

Viticulture Extension Events:

Upcoming Viticulture Extension events are posted at: http://cahnrs.wsu.edu/events/category/grapes-wine/month/.  Save the date for the annual Washington State Viticulture Field Day co-hosted by Washington State University and the Washington State Grape Society:  15 August 2014!