Rats have infested significant portions of almond orchards in California, where 80% of the world’s supply of the product is grown. The damage from the rats has caused a significant economic loss to growers.
Rat infestation
A survey from the California Department of Food and Agriculture (CDFA) found the infestation is impacting more than 100,000 acres across the southern and western San Joaquin Valley. That includes parts of Merced, Fresno, Kings and Kern Counties.
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The survey monitored several areas of those counties and found up to 32 rats per night in some locations.
“Roof rats are arboreal, meaning they spend a considerable amount of their life above ground, often building nests in trees,” the Almond Board of California said in a statement. “However, for several years, researchers have noted that in almonds and other tree nuts, they use burrows extensively. Although it’s undetermined as to why, some believe it’s the lack of cover in the winter months that drives this behavior.”
The rats have reportedly caused issues, ranging from direct damage to the trees to the need to replace them altogether. The tree damage results from rats burrowing in the root zone, consuming nuts, and disrupting the tree’s vascular system.
Additional costs included farm equipment repairs, machinery cleaning and replacing damaged trees. One grower reported a fire caused by rats chewing through irrigation wiring.
The cost of infestation
The CDFA said the damages total anywhere from $110 million to $310 million.
Despite the extent of the infestation and California’s place in the ecosystem of almond growing, it’s unclear if the price of almonds will go up for Americans.
It’s an industry that’s already had a tough year due to President Donald Trump’s trade war. China is the third-largest market for almonds.
During Trump’s first term, retaliatory tariffs from China on the U.S. cost California almond growers hundreds of millions of dollars.
California Gov. Gavin Newsom has asked other countries to exempt California from retaliatory tariffs.
The almond industry is also no stranger to headlines, with heavy concerns over water usage from growers. A recent report revealed that producing one almond requires over a gallon of water, representing a significant water footprint in a state frequently affected by drought.
The almond farmers are also involved in a contentious negotiation over rights to Colorado River water. Many of the farms predate agreements for water inked by other states and Mexico, meaning they have more say in how water usage is reduced during times of drought.
Fixing the rat problem
The Almond Board of California compiled a list of recommendations to halt the rat problem, including the development of an Integrated Pest Management plan.
The cornerstone of that plan is to monitor the rodents using tracking tunnels and ink cards. Using that information, growers can then implement “targeting-based programs.”
“Elevated bait stations containing diphacinone-treated oats, positioned every 165 feet, align with roof rats’ natural climbing behavior while minimizing risks to non-target species,” the statement read.
The recommendations also included strategically placed snap traps and burrow fumigation.
The Almond Board of California is partnering with the California Association of Pest Control Advisers to provide abatement stations or owl boxes to affected regions.
