OF June July 2021 e

A key for all strawberry growers is to remain vigilant in finding, treating
and preventing Fusarium at all stages (photo courtesy M. Bolda.)
According to UC data, field tests have shown that cultivars such as
Fronteras, Portola and San Andreas are resistant to Fusarium wilt
(photo courtesy M. Bolda.)
Continued from Page 22
gation, they’re losing too many plants.
But what happens is, at least within the
University of California, our best, most
flavorful varieties are not the resistant
ones,” he said. “So if you’re a direct
marketer of strawberries, you want
to identify and grow the best tasting,
most productive varieties, and those
are not resistant. There have been some
new ones that have come out which
are resistant, but there have been some
questions about the flavor. And we’re
talking strawberries. We’re not talking
spinach. It’s all about flavor.”
If a grower does have Fusarium, they must be diligent
to not spread it (photo courtesy M. Bolda.)
According to UC data, field tests have
shown that cultivars such as Fronteras,
Portola and San Andreas are resistant
to Fusarium wilt. Albion and Monterey
are susceptible.
Bolda also pointed out that even
though a cultivar is resistant now, it
may not be resistant in the future.
“We’re not done here,” he said. “We’ve
seen pathogen resistance break in other
crops. It hasn’t happened in strawberries
yet, but it could. As we move forward,
that resistance may be overcome
by just all the genetic variations
within the Fusarium
population.”
Additional Considerations
Another method to managing
Fusarium in strawberries is
to manage crop stress. Bolda
explained the Fusarium
affects the vascular system
within the plant, which is why
growers tend to see the problem
expand in June and July
when the plant is producing a
lot of fruit and drawing a lot
of water.
“So, the plumbing is getting
backed up by this disease and
it’s making it more difficult to
draw water,” Bold explained.
“You’re not going to void the
problem, but you can mitigate
the problem by making sure
that plant has enough water.”
Bolda and Henry are also researching
the effects of soil temperature on
Fusarium. Fusarium needs a warmer
soil temperature to thrive, so they are
researching the effects of cooling the
soil down using a light-colored plastic
to reflect heat away from the bed.
A critical point Bolda said he wanted
to make was if a grower does have
Fusarium, they must be diligent to not
spread it.
“Especially if you’re an organic grower
because you have no way out, if you
have a tractor and you move it from a
contaminated field to a field that’s clean,
you are contaminating that clean field,”
he said. “That’s a big mistake and it’s
completely avoidable.”
He mentioned a grower in the epicenter
of the Central Coast Fusarium outbreak
with little or no Fusarium in his
field. “Because he’s super strict about
what comes in and out of his field,”
Bolda said. “This is backed up by Tom
Gordon and his researchers up at UC
Davis. They tested people’s shoes and
shovels and, sure enough, they were
transferring Fusarium from one field to
the other.”
Bolda said a key for all strawberry
growers is to remain vigilant in finding,
treating and preventing Fusarium at all
stages.
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24 Organic Farmer June/July 2021