A rodent crisis is currently spreading through the almond orchards in the Central Valley of California.
Farmers in counties such as Merced, Fresno, Kings, and Kern are facing severe infestations of roof rats, leading to over 100,000 acres of orchards being damaged, resulting in economic losses exceeding tens of millions of dollars.
According to a report from the Almond Board of California (ABC) on August 1st, these rodents are able to swiftly move between orchards through irrigation channels and other waterways, making prevention and control efforts quite challenging. A spokesperson for the board mentioned in an email response to Epoch Times that ABC is not certain why the rodent problem is particularly severe this year, attributing it to various factors such as abandoned orchards or vineyards, although these are just speculations.
In recent years, researchers have discovered that rats create nests by burrowing holes in trees, causing damage by nibbling on nuts, girdling branches, and disrupting the roots of trees. In addition, irrigation systems and other agricultural equipment have suffered significant damage from rodents. Standing water attracts rats, prompting farmers to gradually transition to drip irrigation or micro-sprinkler systems to replace the old ones. However, the existing systems yet to be replaced are still attractive to the pests.
According to data from the California Department of Food and Agriculture, the total losses caused by rodent damage range between $109 million to $311 million. Just the cost of replacing drip irrigation pipelines alone amounts to $56 million to $168 million, with estimated crop yield losses ranging from $43 million to $129 million. The losses also include equipment repairs, replacement of damaged trees, and disinfection costs for contaminated machinery.
In an extreme case, a farmer was forced to replace the entire drip irrigation system after rodents chewed through wires, causing a fire and resulting in a $20,000 loss. Another grower had to eliminate 50 to 100 rats daily, eventually facing a 50% crop loss.
Various methods that farmers have tried to eradicate the rats include setting up bait stations, using aluminum phosphide to treat burrows in winter, employing traps and owl boxes, as well as releasing carbon monoxide or dioxide into rodent holes. The California Almond Board has stated that they are actively assisting growers and Pest Control Advisors (PCAs) in understanding how to utilize these methods. The board is also involved in industry-wide activities, distributing bait stations or owl boxes to farmers in need. However, while bait stations and owl boxes are effective, they are costly and labor-intensive, and rats have gradually become wary of these measures.
Scientists from the University of California’s Agriculture and Natural Resources department suggest that farmers implement integrated pest management strategies targeting roof rat behavior, using tracking tunnels, ink cards, and trail cameras within nut orchards. The goal is to monitor changes in rat behavior and population over time.
Meanwhile, the California Department of Food and Agriculture is updating pesticide labels for rodent control, aiming to provide farmers with more prevention and control options. Relevant regulations will be discussed in meetings scheduled for October and December. ◇