August 2023 - 33

PLANT & SOIL HEALTH
Growing disease-resistant varieties is the most
effective disease management strategy in fields with Fof
race 1. This tool, however, is removed from the toolkit for
fields infested with Fof race 2.
" This strain could greatly affect the industry if it
becomes widespread and growers will benefit from
stringent sanitation practices for equipment moving
between fields, " Henry said.
" This should be a wake-up call to all growers to
practice good sanitation and diligently clean equipment
between fields, " Henry said. " Even if the field has no
observable disease, the pathogen could be present below
the threshold of disease and it would be possible to
unknowingly spread it to other fields. "
In Oxnard, only three fields have been confirmed to
contain the second race. This year's field sampling will
provide a comprehensive picture of how widespread the
pathogen is in California. Henry said researchers hope
distribution is limited and that it can be contained to its
current spread.
Henry's work includes extensive statewide sampling
Fusarium wilt damage. To prevent spread of a
new fusarium strain to other fields, researchers
recommend growers practice good sanitation and
diligently clean equipment between fields.
was discovered in 2006. It took 15 years for the pathogen
to become widespread throughout the state. The
destructive potential of fusarium wilt is exemplified in
the Watsonville/Salinas growing region, where Fof race
1 is the most common pathogen of susceptible cultivars.
Monterey, the most common variety, is susceptible.
Fumigation often fails to adequately control Fof race
1 and FW1-resistant cultivars have been a lifeline to
growers in highly infested fields.
" New varieties with resistance to CA Fof race 2 are
urgently needed to provide a management solution
for growers facing this pest, " Henry said. " Hopefully,
the spread of this new strain will be much slower than
that of Fof race 1, which will allow breeders the time
necessary to produce agronomically-suitable cultivars
with this trait. "
While scientists breed resistant varieties, growers
must rely on other control methods, including
abandoning infected fields to prevent the build-up of
inoculum that is inevitable when a susceptible strawberry
variety is grown in an infested field. If abandonment is not
possible, Henry recommends soil disinfestation methods
such as fumigation and steam to keep inoculum under
control, although neither method is perfect. Lengthening
crop rotations is also recommended and can help to
delay the increase in inoculum, he said.
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August 2023

Table of Contents for the Digital Edition of August 2023
