Ag at large: Dogs detect scent of citrus disease

A F1-K9 trainer and his K9 in action looking to detect signs of agricultural disease in an orchard. The K9s are able to detect two particular diseases: HLB- Huanglongbing and PPV- Plum Pox Virus. (Photo courtesy of

A few well-trained dogs have been recruited in the industry-wide effort to track movements of the Asian citrus psyllid, noted carrier of a disease that has devastated Florida’s citrus industry and threatens California’s Citrus growers in Ventura County. So much faith was put in the dogs’ ability that they have removed nearly three dozen trees that attracted the dogs’ attention among thousands of trees the dogs were introduced to a few months ago.

Efforts by the sensitive canines join those of researchers at the Citrus Research Center at the University of California, Riverside, and scientists elsewhere in the university system as well as industry researchers throughout the state’s citrus belt. The dreaded Huanglongbing (HLB) disease carried by the psyllid has already infected hundreds of citrus trees in California.

Until the dogs provided evidence to the contrary, those who have been tracking the disease thought all the affected trees were confined to residential settings in Southern California – backyard trees. Now, they’re not so sure. The trees noticed by the dogs in Ventura County were all in several commercial groves.

One of the puzzling characteristics of the deadly HLB disease is its reluctance to reveal itself once a psyllid has transmitted it to a tree.  Currently, sophisticated detection methods might not detect its presence for months, but the dogs seem to know immediately if a tree is infected.  They indicate it to their handlers by a subtle nod, identified as an alert.  That results in a tasty treat, a short play period and then a return to work.

The specially trained dogs used in the Ventura County experience are part of a group of 20 maintained in Florida by a company identified as F1K9.  It obtains, trains and maintains a special group of canine detectives that specialize in knowing and responding to the HLB disease, also known as citrus greening.  Training can be extended to other dogs to detect other diseases and circumstances.   

The group of four dogs that sniff out the HLB disease in Ventura County citrus groves included two German shepherds, a Malinois-German shepherd mix and a jolly springer spaniel.  When they were not busy with their detection duties, they offered the kind of friendly responses to growers and others typical of pets.  Observers were impressed with the dogs’ apparent enjoyment of their work and their satisfaction when detections occurred.

The dogs’ responses have brought a degree of satisfaction to citrus growers and others in the California industry because they can detect HLB’s presence immediately after it has been transmitted by the psyllid.  Established methods take longer to reveal the disease’s presence, and it can spread while detection methods operate.  Early detection and removal of infected trees is the most effective method of preventing the spread of the disease.

Data from studies show that the dogs have a 99 percent accuracy rate, and when two or more dogs alert on the same tree it has a 100 percent probability of infection.

The F1K9 dogs are scheduled to return to California next February, probably to investigate further in Ventura County and perhaps elsewhere.  Researchers, especially if they are dog owners, are preparing to give the talented tail-waggers their own category and full recognition in their esteemed fraternity.

Don Curlee is your man when it comes to Agriculture. His Ag Alert column in our publication is sure to inform you on what you need to know when it comes to the agricultural industry.