Scientists in the United States are training dogs to detect a disease that is destroying the world’s orange trees. The devastating disease was first documented in Guangdong Province in southern China in the early 1900s. In Florida, where the disease emerged in 2005, it has caused a more than 70% drop in production of oranges. It has spread to Texas, California, Georgia and Louisiana and is threatening to wipe out the USD 3.35 billion US citrus industry.

Early detection is vital; and farmers try to find and destroy infected trees as quickly as possible. However, it turns out that canines are much more adept than humans at identifying the sick trees.

Paw patrol

Plant epidemiologist Timothy Gottwald and colleagues at the US Horticultural Research Laboratory in Fort Pierce, Florida trained 20 dogs to sniff out Candidatus Liberibacter asiaticus, the bacterium that causes HLB.

Every time the dogs correctly identified the bacterium in a tree and sat down next to it, the researchers rewarded them with play time with a toy. The dogs were able to detect diseased trees with about 99% accuracy – within two weeks of infection, according to a paper published in the journal Proceedings of the National Academy of Sciences.

By comparison, a DNA-based test – the only US Department of Agriculture-approved method for confirming the presence of HLB – detected less than 3% of infected trees at two months. Gottwald’s research suggests using sniffer dogs combined with removal of infected trees is the most effective way to suppress the spread of the disease, and would allow the US citrus industry to remain economically sustainable for another 10 years.