- Author: Mike Hsu
Serving Amador, Calaveras, El Dorado and Tuolumne counties, UC Cooperative Extension advisor Lynn Wunderlich was formally assigned to focus on viticulture and integrated pest management in the region. But her innate curiosity – as well as her dedication to meeting the wide-ranging needs of local communities – led her to develop expertise in a remarkable array of topics.
“That was both the challenge and the opportunity of being a foothill farm advisor – lots of small farms, lots of diverse agriculture, so I got to do some cool things,” said Wunderlich, who is set to retire on July 1. “To serve the needs of the clientele up here was very gratifying and interesting.”
Wunderlich earned her bachelor's degree in bacteriology and plant pathology from University of Wisconsin-Madison and her master's in plant protection and pest management from UC Davis. After several years as a UCCE staff research associate in Ventura and Monterey counties, Wunderlich began as a UCCE farm advisor in 2000 for El Dorado and Amador counties.
Although initially tasked with supporting tree fruit and specialty crop growers in topics such as researching alternative methods for managing codling moths, Wunderlich soon found herself studying organizational dynamics and bylaws to help the Placerville Fruit Growers Association cooperative transition to become a Limited Liability Company.
“It was really different than anything I'd been trained in before,” Wunderlich said.
That early experience set the tone for the rest of her career, as she continued to seek out – and share – knowledge across the expansive breadth of her work. In 2007, Wunderlich took on the viticulture role in Amador and El Dorado counties, where grape growers sought counsel on controlling a newly discovered pest.
“Every farm advisor has some quintessential moments of their career, and Gill's mealybug was one of mine,” Wunderlich recalled. “It's really unique; it's not found in very many places in California and it had never been described as a pest on wine grapes.”
In addition to developing effective management tactics for Gill's mealybug, Wunderlich worked with growers and the late Doug Gubler, UCCE specialist emeritus, to set up seven powdery mildew stations and rain gauges across the foothills. The stations filled a great need in the region by providing accessible, applicable pest and disease forecasting and precipitation data.
Crediting her colleagues' tutelage, Wunderlich also deepened her understanding of the diverse soils in the foothills and the latest research on evapotranspiration on wine grapes – all in the name of delivering the most current and useful information to growers.
When Christmas tree growers in the foothills found their white firs decimated by a phytophthora pathogen, Wunderlich helped them switch to Nordmann and Turkish firs, which were naturally resistant. She became one of only a few experts in the UC system on these conifers, and, in one of her last accomplishments as farm advisor, organized the International Christmas Tree Research and Extension Conference in California earlier this month.
Another late-career highlight for Wunderlich was developing training materials on the proper calibration and use of air blast sprayers. Alongside Franz Niederholzer, UCCE farm advisor for Sutter, Yuba and Colusa counties, and UC IPM colleagues Lisa Blecker, Petr Kosina and Cheryl Reynolds, Wunderlich developed, delivered and evaluated a curriculum that included both in-person classes and online components. Their efforts were recognized with an IPM Achievement Award from the California Department of Pesticide Regulation, and the online course continues to be used today.
“It's nice to be able to leave something like that behind; its principles are still valid, no matter what type of sprayer you're using,” said Wunderlich, citing it as one of her enduring legacies.
In retirement, Wunderlich plans to continue her lifelong learning and also spend more time with friends and family – especially on camping trips on the east side of the Sierra.
And, as for growers such as Chuck Mansfield, they hope Wunderlich will stay connected.
“While we are all very happy for Lynn, her presence will be sorely missed,” Mansfield said. “We hope Lynn remains a regular fixture and friend in our community.”
- Author: Emily C. Dooley
Findings could help wine industry adapt to climate change
Scientists at UC Davis have identified new root traits that help grapevines resist drought. The findings, published in the journal Annals of Botany, could speed up the development of grape rootstocks that protect vines from dry conditions, helping the grape and wine industry adapt to climate change.
The research, led by Department of Viticulture and Enology Assistant Professor Megan Bartlett, comes as 80% of California is experiencing extreme drought.
Most grapevines are not rooted directly into the ground but are instead grafted onto a rootstock, which forms the underground part of the plant and supports growth above ground.
“Rootstocks are an important tool to manage water stress,” Bartlett said. “Our goal was to identify traits that make rootstocks drought tolerant, so that grape breeders can amplify these traits in new varieties.”
Root cell traits
The study focused on traits measuring drought responses in living root cells.
The research specifically identified capacitance – which measures how much roots shrink as they dehydrate – as an important trait for drought tolerance.
“The water that enters the roots has to cross through a band of living cells to reach the xylem – the network of pipes that carries water up to the leaves,” said Bartlett. Most research has focused on xylem traits, but the living cells are often the first to be damaged during drought.
Water stress can shrink, deform, or even kill the living cells, causing the roots to shrivel away from the soil and lose access to the remaining soil water. Vines are then unable to replace water lost to evaporation and are forced to close the stomata – the small pores on the leaves that take in carbon dioxide for photosynthesis – to prevent severe dehydration. But closing the stomata stops photosynthesis and starves the vine of the sugars it needs to grow and ripen fruit.
This study is the first to test whether traits measuring root shrinkage and cell collapse can capture differences in rootstock drought tolerance.
Cell traits and drought tolerance
The researchers grafted Chardonnay onto eight commercial rootstocks. Half of the vines experienced drought conditions and half were kept well-watered in a greenhouse experiment.
The study found the eight rootstocks were surprisingly diverse and varied widely in their traits. The rootstocks also appeared to acclimate to drought by changing their traits in that the droughted vines were less susceptible to shrinkage and cell collapse than the well-watered vines.
Among the traits, capacitance was especially important for drought tolerance. The rootstocks with a lower capacitance (less root shrinkage) were better able to maintain photosynthesis during drought than other rootstocks.
“This research gives us a new trait to target for breeding more drought tolerant rootstocks,” study co-author and Ph.D. student Gabriela Sinclair said.
The research was supported by the American Vineyard Foundation, UC Davis, and by donations to the department from the Rossi family. Researchers at the University of British Columbia and the USDA-ARS Crops Pathology and Genetics Research Unit also contributed to the study.
/h3>/h3>/h2>- Author: Rhonda J Smith
- Contributor: Akif Eskalen
For the first time many growers are facing the dilemma of what to do with fruit that will not be sold. Although wine inventories have been slowly building over the past few years, 2019 is the first year in which a number of growers are feeling the effects of excess supply due to the large 2018 crop.
Given that yields thus far for most growers have been “average” or better and there is significant unsold inventory of bulk wines, custom crushing uncontracted grapes in 2019 may not be a viable option. Hopefully there will be buyers as the harvest continues but in this market, the prices offered are likely to be less than the cost of production.
Allowing unsold fruit to remain on the vines may seem unthinkable yet with no income from those blocks, it makes sense. This means not dropping clusters by hand and not running a harvester in the vineyard to get the berries off.
From the perspective of a plant pathologist:
clusters that decompose over the winter - either on the vine or on the ground -
are not likely to have a noticeable effect on fungal disease pressure the following year given common vineyard floor management practices.
All common grapevine fungal pathogens exist inside vineyards. For example, fallen petioles, rachises that remain on the vine after mechanical harvest, pruning debris and woody tendrils that cling to trellis wires all support the growth of fungi. These fungi act as sources of inoculum that can infect wounds caused by pruning and suckering, and infect berries at bloom and other green tissue.
The fungi that colonize decaying berries include the same fungi seen growing on damaged berries before harvest including Botrytis cinerea and Cladosporium and Aspergillus species which are associated with Botrytis bunch rot, Cladosporium rot and sour rot respectively. Fungi can infect then colonize the ripening berries when spores enter through the slightest opening in the berry cuticle caused by sunburn or the presence of diffuse, unseen powdery mildew. Berries are an overwintering structures for these fungi and others.
Botrytis cinerea spores are ubiquitous given the fungus can survive on dead tissue as well as infect living tissue. It grows on dead calyptras (flower caps) and stamens after bloom and will infect a young berry through the wounds left when the cap is shed. In various studies, Botrytis sporulation in the lab occurred on petioles and rachises collected on the ground and remnants of rachises collected from canes after pruning.
- Eliminating pruning debris will remove the inoculum formed on decomposing clusters and pieces of canes prior to bud break. Vineyard access to alternate rows is required to incorporate last year's wood and cluster remnants while maintaining resident vegetation or a sown cover crop in the non-tilled rows.
All common grapevine fungal pathogens exist inside vineyards and the relative importance of allowing unsold fruit to remain on the vines should be put into perspective of other vine tissues that are also decomposing. Clusters that remain in the vineyard are not likely to have a noticeable effect on disease the following year if common vineyard floor management practices are followed.
Acknowledgement: Valuable input provided by Dr. Akif Eskalen, Cooperative Extension Plant Pathologist, UC Davis.
- Author: Ann King Filmer
Not until students turn 21 can they taste the wine and beer they make and learn to assess its sensory quality. Learning the characteristics of a wide assortment of good (and not-so-good) wines and beers is an important component of winemaking and brewing. Having to wait until their junior or senior year to learn these skills is a disadvantage for these students.
Legislation (AB 1989) has been proposed by California Assemblyman Wesley Chesbro (D-North Coast) that will allow students, ages 18 to 21, enrolled in winemaking and brewery science programs to taste alcoholic beverages in qualified academic institutions. The students can taste, but not consume — which means they must learn the professional practice of spitting during the tasting process.
Professor Andrew Waterhouse, an enologist in the Department of Viticulture and Enology at UC Davis, notes that tasting is critical to the students' education.
“Winemakers taste wine daily during harvest to quickly make critical decisions as the winemaking is underway,” Waterhouse said. “Our students need to start learning this skill here, with our guidance. And, they also have to get over the embarrassment of spitting — after every taste.”
Chik Brenneman, the UC Davis winemaker, said that the bill, if passed, “will allow students to move on to the sensory program a lot sooner, before they've finished most of their winemaking classes. Earlier sensory training will help them when they go to work in the industry.”
If the legislation passes, it will benefit enology and brewing students at UC Davis, which is the only University of California campus to offer undergraduate degrees in viticulture and enology and in brewing science (an option within the food science major).
While parents of college students may worry that the bill will open the door to widespread drinking, Waterhouse and Brenneman both noted that the focus of the bill is so narrow that its impact will benefit a limited number of students, and that it's unlikely to lead to excessive drinking. They say that the over-21 students routinely spit what they're tasting in a standard industry manner, and that “drinking” in class is not a problem.
With passage of this bill, which is backed by the University of California, the state will join 12 other states that have allowed this educational exemption for students.
Read more:
- California legislative information on AB 1989
- NBC Bay Area: Reality check: Bill calls for underage tasting on college campuses, Feb. 27, 2014
- Bill by Wes Chesbro would allow underage beverage students to sip; PressDemocrat.com, Feb. 28, 2014
- Author: Laura J. Van der Staay
Over 115 people came to the 2013 Grape Day at KARE on August 13. Attendees visited a wine grape plot where Larry Williams, professor and plant physiologist in the Department of Viticulture and Enology at UC Davis and Kearney Agricultural Research and Extension Center, demonstrated and discussed the effects of water deficits on water relations and productivity of about 20 different red wine grape cultivars grown in the San Joaquin Valley. The field tour was followed by PowerPoint presentations. Teresa O’Keefe and Jeffrey Palumbo, scientists at USDA-ARS, provided information on the ecology of mycotoxin-producing aspergilli in raisin vineyards. Matthew Fidelibus, associate CE specialist at Kearney Agricultural Research and Extension Center, provided information on the effects of pre-harvest calcium chloride and chlorine dioxide applications on fruit quality of crimson seedless table grapes. Philippe Rolshausen, assistant CE specialist at UC Riverside, shared information on wood disease management options for grapevines in the San Joaquin Valley. David Haviland, academic advisor, Kern County UC Cooperative Extension, provided information on Movento in table grapes: understanding use patterns and expectations. Andrew Waterhouse, professor in the department of Viticulture and Enology at UC Davis, discussed understanding wine oxidation. More information can be found at the California Ag Today blog.