| Knowing how to spot vine mealybug is vital for Diego
Smart,
because using insecticides in the organic vineyard where he works is
not an
option.
Smart, a foreman at Enterprise Vineyards in Sonoma, and supervisors
from several other vineyards attended a workshop to train them to recognize
the key signs of vine mealybug.
Vine mealybug infestations were first
found in North Coast vineyards in 2002. The pest spread from initial
infestations in southern California
and is now present in 16 counties. The culprit contaminates bunches
and can also transmit viral diseases.
With funding from UC IPM, Lucia Varela, IPM advisor for the North
Coast, conducted five educational sessions in Spanish at Sand Hill-Durell
Vineyards in Sonoma in June.
"If vineyard employees know the signs, they can find an infestation
early when its population is low and be able to stop the spread," says
Lucia. She shows workers a slide presentation outlining the different
stages of vine
mealybug infestation, how to monitor it with traps, what signs to look
for seasonally, and sanitation measures to reduce the spread of the pest.
Afterward, participants
have a chance to examine the insect under a microscope.
"Lucia's presentations are really clear and straightforward,"
says Smart. "She's not giving a lesson to a professor
but to those who work in the vineyard. The pictures and the chance to
see
it under the microscope
make it interesting and informative."
Lucia conducts training in May through July when workers are most likely
to see vine mealybug. As temperatures warm in spring, pest populations
increase and
become more visible as they move from under the bark on the trunk
and cordons of the vine to the canopy. By late spring and summer, vine
mealybugs are
found
on most parts of the vine. The pest produces honeydew that drops
onto
the bunches and other vine parts and produces a black, sooty mold.
"Infested leaves fall to the ground prematurely in late
summer, which can spread the infestation throughout and to adjacent vineyards,"
says Lucia. "Honeydew can cause these leaves to stick to vineyard
machinery and harvest equipment,
which also moves the pest to new areas. The most effective time
to control vine mealybug is immediately after harvest because a larger
proportion of the population
is exposed. However, it's important to obtain clean fruit
and to avoid spreading the insect due to premature leaf drop and
at harvest. So, early detection
and control is crucial."
Starting in June, many growers in the North Coast region place
pheromone traps in their vineyards to see if the male vine mealybug
is present.
The lure placed
inside each trap contains the sex pheromone that female vine
mealybugs give off to attract winged adult males. If males are caught
in
a trap, the infestation
that was the source of those males has to be located, and well-trained
workers can help find them.
Currently, vine mealybug can be controlled
only with insecticides, so if this insect becomes widespread, insecticide
use could increase.
In 2002, a team of University of California Cooperative Extension
IPM and county-based advisors developed new methods to detect
and manage
the pest
in grape nurseries.
They modified a hot-water treatment of dormant nursery stock,
and it became an effective and nontoxic control method used
to kill
99 percent
of the
mealybugs present on the stock. Commercial nurseries now
treat their planting stock
by immersing it for 5 minutes into three water tanks—a
warming tank, a treatment tank of water above 125 degrees
F, and then a cooling tank. In less than a year,
this UC IPM research effort produced a safe and effective
management method that was adopted by several nurseries.
UC IPM staff takes this information to workers out in the
field and trains them in management practices that can reduce
the
movement of vine mealybug
in vineyards
that are already infested. Lucia has given her presentations
during the last three years and trains about 400 workers
annually. "We target the presentations
to crew leaders since they are the vineyard's permanent
employees," she
says. "We empower them to take the information we've
given them, along with some handouts, to go back and train
their crews. Our goal is to identify
infestations of vine mealybug early to limit its spread."
Lucia noted during her session that one participant asked
whether the damaging effects of vine mealybug are the same
in young
and older plants. "Older
plants have the ability to create larger colonies," she
says. "One
worker commented that older vines have thicker bark so vine
mealybug has more places to hide. That let me know that this
group quickly understood what I was
explaining to them."
Workshops were held in seven locations on 10 dates in May
through July, with one to three training sessions on each
date.
Other instructors are UCCE Sonoma County Viticulture Advisor
Rhonda Smith; Napa County Viticulture Advisor and County
Director Ed Weber;
and Lake
County Director
Rachel Elkins.
|
2005
Annual Report 