Flooded fields in Tulare County, in the Central Valley.

May 18, 2023
Never-ending rain leads to pest, disease concerns

A seemingly endless flow of water saturating their fields is burdening California growers with pests and diseases. Growers of strawberries and other fruits expect the heavy rains to delay some planting and harvesting and cause other crop problems.

From February into April, at least 14 “atmospheric rivers” deluged the Golden State from Southern California to northern regions, jeopardizing crops in the central coast region, the San Joaquin and Central valleys and other regions.

California farms were jeopardized by torrential rains that deluged fields, like this strawberry field near Salinas.
California farms were jeopardized by torrential rains that deluged fields, like this strawberry field near Salinas. Photo courtesy California Strawberry Commission.

“If we’re not in a drought, we’re drowning,” said Juan Hidalgo, Monterey County Agricultural Commissioner. “Certainly, this year has really been hard for a lot of
our counties.”

Despite the storms bringing much-needed water to areas facing drought conditions for three years, flooding, over-saturated fields and waterlogged plants delayed strawberries and leafy greens and caused numerous other challenges.

Agronomic pressures

Fields that were flooded but drained quickly may see more weeds and soil diseases, said Paul Pezzini of Pezzini Berry Farms in Salinas.

“They won’t make it in heavily flooded fields,” he said.

If rains continue, they could damage crops starting to produce. The effect on quality could change the crop from a fresh harvest to a clean-up type of harvesting for processing buyers, and sometimes, the berries won’t be fit for that market, Pezzini said.

An extended period of rain is expected to bring more pestsand disease to California fields.
An extended period of rain is expected to bring more pests
and disease to California fields. Photo courtesy California Department of Water.

In general, grower members of the California Fresh Fruit Association (CFFA) report escaping serious damage, based upon where they are growing, but face more challenges, said Ian LeMay, president.

“For many areas in California, this has been an unprecedented year,” he said. “While the eyes of the nation might be on us because of the initial impacts here, for many in California, because of the immense snowpack in the Sierras,
this for them will not be over quickly. We will continue to have spring and summer runoff and many areas will continue to see an increased pressure associated with hydrology.”

Spring is pivotal for fruit set, and orchardists welcome the rain-soaked root zones and an abundance of chill hours. Growers await drier and warmer days to help move the process along.

The rains allowed Firebaugh-based Del Bosque Farms, which grows organic melons and conventional almonds and cherries in the southern part of California’s Central Valley, to skip some irrigation cycles, said Joe Del Bosque, CEO/operations.

Changing practices

However, the water caused harvest delays and altered some of Del Bosque’s management practices. Saturated ground spurs weed growth while keeping heavy equipment from entering fields.

“There will be some challenges trying to get those weeds down as moisture brings increasing weed pressure,” Del Bosque said. “As the ground is wet when it’s typically dry, we have to adjust our program to approach planting in a different way.”

Floodwaters damaged fields and property south of Corcoran.
Floodwaters damaged fields and property south of Corcoran, in Kings County, in this late March photo, courtesy California Department of Water Resources.

While some years require only one application of fungicides to protect blooms, this year, most growers will have made two applications.

“If the storms continue, we may have to do another one, which is added costs,” Del Bosque said.

Plant diseases multiply in wet conditions, said Gerald Holmes, director of the Cal Poly Strawberry Center in San Luis Obispo.

“Diseases love water,” he said. “Most diseases thrive in wet conditions. Rain splashes fungal spores around. Most diseases are worse when there’s a lot of moisture.”

Phytophthora root rot flourishes in wetness, and Holmes said growers should prepare for more diseases and other fungal pathogens, including botrytis rot on fruit, and angular leaf spot, a bacterial disease on foliage.

“It’s really difficult for growers to treat disease when it’s raining because they can’t get their rigs into the fields,” Holmes said. “They have had so much rain. We expect a lot of losses will be due to botrytis.”

Damage estimates were not immediately known. Growers report it may take weeks before the full extent of damage is revealed. Disaster assistance information can be found at www.cdfa.ca.gov/FloodRecovery/.

The state is working with county officials and the U.S. Department of Agriculture to tally the extent of damage and to bring aid to farmers, ranchers and landowners affected by flooding, said Brian Ferguson, deputy director of the California Governor’s Office of Emergency Services.

“The flooding, particularly in the Central Valley, is very much an ongoing and evolving challenge,” he said. “Work is happening rapidly on the ground now to get clarity on impacts, and we are likely to have a much clearer picture in the weeks and months to come as the water recedes.”

During an April 5 California State Board of Food and Agriculture meeting, Asha Raj, emergency management coordinator with the California Department of Food and Agriculture, said the agency is coordinating with county ag commissioners in flood-affected counties and working with trade associations.

“We are working with ag commissioners to gather crop loss information to get a USDA designation,” she said.

— Doug Ohlemeier, assistant editor

Top photo: Flooded fields in Tulare County, in the Central Valley. Photo courtesy California Department of Water.



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