Dogs and Citrus Greening

For decades, humans have relied on dogs to detect explosives, illegal drugs, lost people and wildlife. More recently, they have been used to detect pests such as termites, bedbugs and agricultural insect pests. Now, they're helping us detect citrus greening, the major disease limiting citrus production in Florida.
Citrus greening, also known as Huanglongbing (HLB) is responsible for the 75 percent decline in Florida's $9 billion citrus industry. The disease is caused by a bacterium and spread primarily by the Asian citrus psyllid, although it can also be transmitted through infected plant tissue.
Once a tree becomes infected with the disease, there is no cure, and visual symptoms of the disease after infection may take months, even years to appear. During that time, the disease can spread rapidly, destroying existing groves and trees. Early detection and the removal of infected trees is the most effective method to prevent an epidemic.
At present, the most common method for diagnosing citrus greening is through visual inspection; however, once the disease is observed, it is likely too late. Scientists with the United States Department of Agriculture (USDA) Agricultural Research Service (ARS) have been evaluating the use of scent-detecting dogs for the early detection of trees infected with citrus greening and their method is proving to be successful.
The multi-year study has been funded by a grant from the USDA Animal and Plant Health Inspection Service (APHIS) HLB Multi-Agency Coordination (MAC) program, and a partnership between F1K9 Kennels. Through the F1K9 training academy located in central Florida, 20 dogs have been trained to recognize the volatile compounds emitted from trees infected with citrus greening. In the field, the dogs run with their handler along the grove row, sniff each individual tree and alert on diseased trees. After alerting to an infected tree, dogs are rewarded by verbal praise and short playtime with their handlers.
Data from studies show that the dogs have a 99 percent detection accuracy rate, and when two or more dogs alert to the same tree, the tree has a 100 percent probability of infection. Additionally, the dogs were able to detect trees infected with citrus greening within 2-3 weeks after infection. The same trees were sampled using standard citrus greening detecting methods and the results showed that the trees did not test positive for the disease until three to six months after infection, confirming that the scent-detecting dogs are a useful tool for early detection of citrus greening.
In the Florida Panhandle, confirmed cases of citrus greening and established psyllid populations have been geographically isolated, with the majority being in residential citrus plantings and not commercial groves. Therefore, an early detection method like this, paired with a rapid removal of infected trees may be a useful tool to help minimize disease spread and optimize planting longevity for newly planted acreage in North Florida and South Georgia where disease incidence is low.
Citrus greening has not yet made its way to Jefferson County and we intend to keep it that way! If you suspect you may have citrus greening or would like more information, contact the Jefferson County Extension Office.