Grape Day Features Mgmt.
By Patrick Cavanaugh, Editor
|Attendees gathered at Kearney for the 2013 Grape Day.|
Nearly 100 attendees were at the Kearney
Agricultural Research and Extension Center today to hear the latest from UC and
USDA researchers on many topics.
The early field tour took growers and others in
the industry to an on-site grape vineyard to see the effect of water deficits on
the productivity of numerous red wine grapes cultivars grown in the San Joaquin
Larry Williams, UC Davis Department of
Viticulture and Enology, is researching big red winegrape varieties, initially
started by Jim Wolpert, UC Davis Viticulture Extension Specialist.
Wolpert selected the varieties that looked to
have the potential to be grown in the SJV. Now, Williams is working on irrigation
management, or the effect of deficit irrigation on wine grape vine growth and
What was initially a larger trial of 60
different cultivars from Italy, France, Spain and Portugal, is now 20 different
cultivars planted in a new block in which Williams works.
“While these cultivars responded differently to
water stress, they all looked good at 50 percent ET for the season,” Williams
|Grape Day Attendees View Vineyard Trials.|
· No water between berry set and veraison. Then at veraison,
irrigation was at 50 percent ET.
· Full ET from berry set
to veraison and then cut the water off.
“Right now we are seeing visual effects, but we
have no definitive answers or recommendations,” Williams said.
“For instance, the cultivar Tanat receives no
water from berry set to veraison, and some of the berries are not coloring up.
Other varieties are responding in a similar way,” Williams said. “Cabernet and
Syrah both looked good under the treatments that were imposed.”
“We will harvest the grapes this week and start
to make wine in order to gather data on how treatments affected wine quality,”
Moving over to table grape research, Matthew Fidelibus, UC Davis Department
of Viticulture and Enology, focused on the effect of pre-harvest calcium
chloride and chlorine dioxide applications on Crimson Seedless fruit quality.
He is working with Carlos Crisosto, UC Davis
Plant Sciences, on alternative methods for controlling pre-harvest and
post-harvest fungi-decay of table grapes using a preharvest application of
calcium chloride, and chlorine dioxide.
Fidelibus reported that there were few or no
berry or leaf injuries with 0.25 percent calcium chloride; but higher
concentrations caused some damage. “Neither calcium chloride nor chlorine
dioxide affected fruit quality or field rot incidence (which was very low
during the trial),” Fidelibus said. “Both compounds provided some postharvest
rot protection of conidi-inoculated fruit, but not nesting- (packed-)
Fidelibus noted that additional testing is
needed to determine if the treatments might reduce bunch rots under conditions
of higher disease pressure.
Moving into raisin research, Teresa L. O’Keeffe, with USDA ARS, spoke about the ecology of
mycotoxin-producing Aspergilli in raisin vineyards. She noted that Black Aspergilli, are commonly observed in
agriculture as black molds. “Two species, Aspergillus
niger and A. carbonarious are
often associated with the microbial complex that causes bunch rot. In fact, A. niger infections can also lead to
vine cankers,” O’Keeffe said.
In addition, A.
niger and A. carbonarious can be
associated with a mycotoxin known as ochratoxin a (OTA) that causes kidney damage in humans if ingested at high enough
While there has been very little research conducted
in the U.S. on OTA, several EU countries have done testing in both raisins
and wine, with results that are well below harmful concentrations.
O’Keeffe noted that recent USDA studies show that
even at the highest levels of OTA in both wine and raisins, results are still
well below the EU regulatory limits. “By continuing to study vineyards in the
SJV, we hope to establish a baseline on how various black Aspergillus species
grow and interact with each other during healthy berry development,” she said.
O'Keeffe is a research technician for Jeff Palumbo, a microbiologist with USDA ARS.
Philippe Rolshausen, UC Riverside
Specialist, Botany and Plant Sciences, spoke about grapevine wood disease
management options on table grapes in the SJV.
“Wood diseases can be a big issue for
20-year-old vineyards, but when problems set into a five-year-old vineyard,
there are bigger economic problems at hand,” said Rolshausen.
Control strategies are the same for raisin,
table and winegrapes. Esca is the
main pathogen that affects table grapes. “This pathogen can be a major problem
in table grapes causing loss of wood, cordons, canes, all of which reduce
yield,” Rolshausen said. “There can also be a cosmetic impact with necrosis of
berries because of the fungi in the vine.”
Rolshausen commented that 2011 was a big year
for Esca disease spread due to environmental conditions; mainly rain, during
the previous dormant season.
The only way to prevent the disease from
infecting the vine is to apply fungicides over the pruning wounds. Manually
painting every pruning wound is very labor-intensive and cost prohibitive. “By
protecting pruning wounds, you prevent infection,” Rolshausen said.
Rolshausen said that trials suggest that a
single tractor spray application with Topsin
M, one day following pruning, is able to protect the vine. “Doing this will
extend the life of the vineyard by an extra 10 years,” Rolshausen said.
stepped to the mic and presented research on the use of Movento in table grapes
for controlling vine mealybug and nematodes.
“This is going to be a
different talk for me,” he began. “Usually I talk about the efficacy of many
different products, but this time I’m only going to talk about one product,
Movento, because it is so unique in controlling mealybugs.
“In controlling mealybug,
it’s a numbers game, but that’s not all,” he said. “You want to lower the
numbers but you do not want what remains to injure your crop.”
Haviland continued, “Reducing
crawler movement goes along with overall mealybug management. And while there
all several insecticides available for treating mealybugs, such as Movento,
Lorsban, Applaud, and Belay (Clutch), it’s important to think about resistance
management when choosing any product.”
noted that there are steps to follow for Movento to work.
· Moves across leaf
· Mealybug ingests Movento
· Movento starts to
· Mealybug continues
living on existing fat reserves
---Crawlers die within a few days.
females can survive for 6-8 weeks due to extra fat reserves.
Haviland also described nematode trials using
Movento. He noted that:
· Movento definitely has
· Movento is best applied
in the spring at 6.25 to 9 ounces per acre; however lower rates were more
effective in some studies.
· In old, heavily infested
vineyards, Movento application for nematodes pays off.
· Yield effects, if any, are
unlikely to be seen before year two.
· Use prudence with regard
to irrigation as many factors affect systemicity of Movento.
· More data should be
available next year to determine the effect of irrigation and girdling on
· Expect results to be
highly variable from site to site.
Haviland thanked his
SRA, Stephanie Rill, for all her help in his research. He also thanked the
Consolidated Central Valley Table Grape Pest and Disease Control District for funding the mealybug research, and
the California Table Grape Commission for funding the nematode research.
The final speaker,
invited to talk about wine, represented a new approach to Grape Day.
Andrew Waterhouse, UC Davis Professor of Enology, Department of
Viticulture and Enology is a leading expert on wine quality. He talked about
varietal aromas and retaining specific flavors of grape in the wine. But as
wine oxidizes, those aroma compounds can be lost. “Oxidation can be divided in
two basic steps, quinone formation from polyphenols and aldehyde formation, all
of which causes a loss in flavor,” said Waterhouse.
“Sulfites are widely
used to prevent oxidation by reacting with quinone.
Tannins in red wine are
also important as they react with quinone, thus removing oxidation from wine,”
Waterhouse noted that
the industry is also working with ascorbic acid and glutathione because both
could be useful in reducing oxidation.
Labels: Andrew Waterhouse, David Haviland, Kearney Grape Day 2013, Larry Williams, Matthew Fidelibus, Philippe Rolshausen, Stephanie Rill, Teresa O'Keeffe