San Luis Obispo County
University of California
San Luis Obispo County

2001 - 2010 Season summaries

2010 San Luis Obispo and Santa Barbara County Season Summary

The 2010 season was very challenging for San Luis Obispo and Santa Barbara County growers. Production was about average, but quality suffered in some cases due to 1) the lateness of the season and the difficulty in getting some vineyards ripe, 2) powdery mildew damage, 3) heat and sunburn damage from a very intense September heat wave, and 4) rot damage from subsequent rains. Fruit harvested before the fall heat and rain was generally of very good quality, while the fruit harvested afterwards was more compromised.

Winter had abundant rainfall, continuing into April. The cool spring led to a delayed budbreak and slower growth. The summer temperature was quite moderate until the September heat wave.

Powdery mildew pressure was unusually high for the region, and was one of the main challenges for many growers; significant infections occurred in both coastal and inland areas. The fall rains led to elevated bunch rots in the more susceptible varieties; problems noted in Pinot Noir and Chardonnay in the coastal areas, and Petite Sirah and Zinfandel in the inland areas, among others.

Yields were about average overall. Buyers were scarce for much of the season, a reflection of the overall state of the grape market in the state. Not all fruit was sold, and some vineyards that suffered the worst quality issues later in the season were left unharvested.

No European Grape Vine Moth was detected in the area in 2010; movement of grapes into the region from EGVM areas was restricted.

2009 San Luis Obispo and Santa Barbara County Season Summary

The 2009 season began with a very dry winter again; this was the third consecutive season of drought conditions in the area. The spring weather was overall relatively cool and overcast, leading to delayed bud break and increased fungal disease pressure; incidence of powdery mildew was generally more severe than in the previous two seasons.

Due to unusually cool temperatures in late spring the bloom period was extended, but fruit set was generally acceptable, and much improved over the preceding season. An unusual rain fell in early June, with between ¼” and ½” of precipitation recorded in many areas.

The summer temperatures were fairly moderate in most areas, particularly the more coastal areas, until early September when much warmer temperatures arrived. This led to accelerated ripening of early varieties and much harvest activity in September; afterwards temperatures moderated and harvest activity slowed considerably.

There was a limited amount of freeze damage in early October, mostly observed in the cool areas west of Templeton. The extended drought has exacerbated the problem of some shallower groundwater wells going dry in the Paso Robles area.

The large storm on October 13 delivered highly variable rainfall throughout the area. In San Luis Obispo County, the hills to the west of Paso Robles received nine or more inches, while Shandon to the east received less than one inch. Most areas in Santa Barbara County received between one and three inches. Emphasis was placed on harvesting the more rot-prone varieties such as Zinfandel, Chardonnay and Petite Sirah before the arrival of the storm; plantings which were not harvested in time did suffer significant rot damage in many cases. More resistant varieties such as Cabernet Sauvignon generally held up quite well through the storm.

As of the second week of November, some limited harvest of varieties such as Grenache is still occurring, as many areas still have not had a killing frost. Overall crop yields were average to slightly above; quality has been reported to be quite good. As has been observed in other areas this year, the biggest difficulty for many growers has been to find a buyer for their non-contracted fruit. A fair number of vineyards are on the market, mostly smaller operations.

2008 San Luis Obispo and Santa Barbara County Season Summary

The late fall and early winter started out with some much-needed rainfall after the extremely dry 2006/2007 winter, but the rains petered out in January, leading to another relatively dry winter overall.

The hard April freeze struck lower vineyards in the Santa Rita Hills, Santa Ynez, and Los Alamos areas in Santa Barbara County; the Santa Maria area may have been relatively less affected except in more low-lying areas. The freeze also struck vineyards in the eastern inland region of San Luis Obispo County quite heavily, with less damage heading into the hills west of Paso Robles. The coastal Edna and Arroyo Grande valleys were generally less affected.

As in other parts of the state, some long-term vineyards on sites with good air drainage which had never before suffered such freeze damage did so in April, indicating the unusual severity of the event.

Some additional limited freezing and cool, windy weather in May, intermixed with several multiple-day heat spikes, led to a long and erratic bloom period with very poor fruit set in many areas. High levels of shatter (coulure) and hens-and-chicks (millerandage) were prevalent in many vineyards which had escaped earlier freeze damage. Unusually severe off-shore heat in late June led to very uneven fruit development in some coastal vineyards.

The control of late-season Pacific mite continued to be a challenge in some vineyards.

To top off a tough year, an unusually early and severe mid-October freeze was a surprise in both counties, hitting many low-lying vineyards throughout the region. Temperatures reached the low-20’s in some of in the inland regions; vineyards on elevated ground were visibly less affected. This freeze caught a number of vineyards with fruit less ripe than desired, but forced growers to pick quickly nonetheless. Ripening was delayed in many areas, even with very low crop levels. Yields of some Cabernet Sauvignon and Merlot vineyards were less than 20% of normal.

Overall, a tough year for many growers.

2007 San Luis Obispo and Santa Barbara County Season Summary

The 2007 season on the Central Coast began with very cold temperatures in January; lows reach the mid-20s in the coastal areas, the low teens in inland areas, and single digits in the easternmost regions. Tender crops such as avocadoes were the most heavily impacted.

Winter rainfall levels were also unusually low throughout the area; for example the rainfall recorded at the city of Paso Robles for the winter of 2006/2007 was only 6.2 inches, which was the second driest winter on record since recordkeeping began in 1952.

Budbreak was later than normal by two to four weeks for most vineyards. Exceptionally delayed and uneven early growth was noted for vines on 110R and 101-14 rootstocks. Overall canopy growth was notably reduced in most vineyards.

The exceptionally dry conditions led to a significant number of irrigation wells going dry during the summer peak irrigation period, forcing many growers to make do with very limited irrigation. Looking forward, the potential continued lack of rainfall is one of the most significant concerns for winegrape production in the entire region.

Summer growing temperatures were fairly moderate, with the season’s peak temperatures occurring during the first week of September. This brief heat spell was followed by several weeks of unusually cool weather from mid September to mid October, delaying ripening significantly and creating a long pause in the harvest activity for many operations. Warmer weather returned later in October, leading to a resurgence of harvest. Most inland vineyards had been picked by the end of October, while some coastal vineyards were still being harvested as late as mid November.

Yields were low to average, with quality reported as being exceptionally good overall.

Considerable new hillside acreage continues to be developed in the Paso Robles Westside and the Santa Rita Hills areas.

2006 San Luis Obispo and Santa Barbara County Season Summary

Winter rainfall in San Luis Obispo and Santa Barbara Counties was average to somewhat above average for most areas; however the majority of rain fell relatively late, in March and April.

Very erratic and uneven early budbreak was observed in some coastal Chardonnay, with early shoots later damaged by cold. The cool, wet weather in March and April delayed budbreak by 3-4 weeks in most inland areas, while disease pressure was moderate to severe through the rest of the spring. Warm weather arrived by mid-May, and conditions remained good through bloom and set.

Significant heat spikes occurred in the third week of July; temperatures reached over 105 F in Santa Ynez, over 115 F in Paso Robles, and nearly 100 F in San Luis Obispo. The sudden increased demand for irrigation water caused some shallower wells to go dry during this time.

The degree-day accumulation from April 1 to September 1 was average to above average overall, but due to the late budbreak maturity was delayed. Harvest began at a moderate pace, with a pause until the sunny dry weather in mid to late October helped push ripening; most regions had finished harvest by early November.

The harvest order was unusual in many areas, i.e. Cabernet Sauvignon being picked before Merlot. Overall, initial reported yields were about average, but with high variability.

Some significant rainfall, in some locations over an inch, fell in late September and early October in Santa Barbara County; this led to some severe botrytis problems. Rainfall was less severe in San Luis Obispo County at this time, but some Zinfandel plantings were reported with significant botrytis and sour rot.

There were some reports of fruit not sugaring up adequately, including Cabernet Sauvignon, Syrah and Cabernet Franc, but not to the same degree as with the larger crops in 2005.

2005 San Luis Obispo and Santa Barbara County Season Summary

The 2005 season in San Luis Obispo and Santa Barbara Counties started with welcome relief from the previous four dry winters. In all areas, winter rainfall was well above seasonal averages. Soils in areas prone to salt accumulation benefited from the additional rainfall, with levels of soil salinity reduced.

Spring frosts hit some areas hard in April. Cold temperatures combined with strong winds frosted even some vineyards on higher elevations that had never suffered frost damage in over 20 years.

The continued rainfall in the spring also led to some occurrences of shoot botrytis in coastal areas, particularly in Pinot Grigio, less so in Pinot Noir, while Chardonnay was little affected.

With the abundant soil moisture in the early season, vineyards in all areas enjoyed some of the healthiest spring and early summer canopy growth that they had seen in a number of seasons.

Bloom and berry set progressed well, without the poor sets that were often noted in recent years with some varieties such as Merlot.

The full canopies and late rains created relatively challenging conditions for powdery mildew control; growers who in the past could rely on limited treatment regimes had to step up their efforts considerably. Likewise, weed control was much more challenging than in recent seasons.

Summer temperatures were fairly typical until mid-August, when a week-long cool spell arrived, dropping temperatures notably; for example, at one representative location near Paso Robles, the high temperature on Aug. 11 was 105 degrees F, while two days later the daily high only reached 78 degrees F. Temperatures returned to normal until the end of the first week of September, when a second period of unseasonably cool weather with daily highs in the 70’s lingered for about 10 days.

Insect pressure was moderate, with no reports of the mite outbreaks that were reported farther north.

Unexpectedly heavy crop loads were the norm in both coastal and inland areas. Even plantings that received multiple crop-thinning passes still had crop loads well above their targets. Cluster numbers were not necessarily large, but the number of berries per cluster, and/or berry size, was often unusually large. Coastal pinot noir yields of over 5 tons per acre were not uncommon, while some un-thinned inland red varieties reported crops of 10 or more tons per acre.

Isolated rain showers in September led to very limited yet occasionally severe outbreaks of botrytis in Santa Barbara County.

The long ripening season and crop load took a heavy toll on canopy health by the early fall; leaves began to senesce well before fruit had ripened in some plantings, and in severe cases sugar accumulation simply stopped when the canopies crashed. Failing canopies were most commonly seen in Syrah and Petit Sirah, but even heavily-cropped Cabernet Sauvignon had isolated problems.

Plantings with viruses that in normal seasons showed moderate symptom expression were generally much more symptomatic by late 2005, if the crop load was high; Zinfandel appeared particularly expressive.

The heavy crop loads, erratic temperatures, and variable canopy health led to varieties being harvested out of their usual sequence in many areas.

Quality has been reported as very good to excellent, in spite of the heavy crops. Spot market purchasing activity has been reported generally as being very light, with relatively few buyers for non-contracted grapes.

Renovation or removal of tired older plantings continues, following the same trend of the past several years. Moderate numbers of new areas continue to be planted as well.

2004 San Luis Obispo and Santa Barbara County Season Summary

Coming soon

2003 San Luis Obispo and Santa Barbara County Season Summary

The Central Coast experienced another dry winter; some later rainfall in April and May helped ease the pressure, but low precipitation has now been an issue for several years and is likely leading to increased salinity in many vineyard soils.

The coastal areas experienced relatively mild winter temperatures, leading to extremely early bud break for many growers; vines began growing in some Pinot Noir blocks before the first of the year, causing difficulties later with very uneven growth and fruit maturity. Warm spring and summer temperatures led to a very early start on the Pinot Noir harvest, in some areas as much as five or more weeks ahead of normal; later cooler weather stretched out the harvest period of the last Chardonnay.

Conversely, spring temperatures were notably cooler than normal in the inland areas of Paso Robles and Santa Ynez, leading to a late bud break and very slow early growth. Cold spells also wrought havoc with the berry set, in particular with Merlot. Harvest was spread over a long period, delayed by some unusually cool weather in August; much of the crop quickly ripened with a spell of very warm weather in late September, creating a very compressed harvest schedule.

Typical yields were somewhat lower than average, with Merlot being particularly low. Quality has been reported as fairly good in general.

Numerous growers in the warmer regions around Paso Robles and Santa Ynez have been experiencing unusually poor results with Syrah, including Syrah Noir and Shiraz, with particularly poor results this year. Symptoms include an early senescence of the canopy and very poor ripening of the fruit. Juice color is also markedly reduced. The cause of this disorder is not known; it seems to be correlated with increasing vine water stress, but nutrient (K and/or Mg) and/or pathogen interactions may also play a major role. Other varieties grown under the same conditions are not showing the same effects.

Vine mealybug continues to be the hot pest topic; increased grower awareness and use of the pheromone traps has led to the discovery of several more small-scale infestations this season, bringing the total for the two counties to 16 sites. All are being treated, and we remain optimistic.

2002 San Luis Obispo and Santa Barbara County Season Summary

Like other regions, San Luis Obispo and Santa Barbara Counties were facing the prospects of a heavy oversupply of grapes and poor spot market prices in 2002. However, for many vineyards the harvest was notably lower than their earlier crop forecasts. This provided a market for a considerable amount of fruit that otherwise may not have been sold, and kept prices from bottoming out at very low levels. Very few acres were left unharvested. Preliminary reports indicate that, on average, quality is quite good.

New plantings have been relatively few as compared to the feverish pace of planting in recent years. Many growers are taking advantage of the poor market and renovating some of their older, less-productive blocks. However, there are still a lot of young plantings, particularly Cabernet Sauvignon, which will come into full production within the next couple of years.

The current pest of concern is the vine mealybug. Many areas of the Central Coast have always had serious problems with common mealybug species, but the vine mealybug looks to be much, much worse. Three infested sites have been located so far, but unfortunately we expect to find quite a few more next season.

On a more positive note, the glassy-winged sharpshooter has not yet arrived to this area yet, thanks to the inspection efforts of the local Ag Commissioners.

2001 San Luis Obispo and Santa Barbara County Season Summary

Yields for the 2001 season were about average for most areas, depending on the particular vineyard conditions. Harvest quality has been above average to excellent, particularly for Chardonnay and Pinot Noir. This season’s grape supply situation has caused concern for many recently planted vineyards that have not yet secured contracts, particularly in San Luis Obispo County, leading to concerns about lower prices in the area.

Growing conditions during bloom time were quite erratic in many locations, due to alternating hot and cool temperatures. The summer was warm causing early ripening in some areas, followed by unusually cool weather that delayed harvest elsewhere. In the coolest areas, the latest-ripening varietals remained on the vine until mid-November.

A major expansion in local processing capacity was the opening of Courtside Cellars in San Miguel. Paso Robles continues to see the establishment of small boutique wineries and increases in planted acreage, while Santa Barbara County has been more stable.

Two introductions of the GWSS occurred in the area in 2001; both were caught in time to prevent establishment. The incidence of PD is still relatively uncommon. Grape and Obscure Mealybugs are still major problems in some vineyards, and San Luis Obispo County also experienced an isolated outbreak of Vine Mealybug. A major pest concern this season was a grasshopper infestation in the eastern areas of both counties, particularly for vineyards abutting dry rangeland.

Interest in sustainable practices is increasing and many growers are integrating alternative approaches to soil and pest management into their operations, such as winter cover crops, mechanical vine-row tillage, and the use of “softer” pesticides.

Webmaster Email: kjerdin@co.slo.ca.us