CO-Horts Blog

Monday, January 20, 2020

Using Dogs to Sniff Out the Bad Guys

Posted by: Alison O'Connor, Larimer County Extension

I wrote a previous post about our U.S. Customs and Border Patrol dogs, who are stationed at airports to sniff out contraband that enters from other countries. They are amazing and impressive...and of course, mostly beagles. Yay beagles!

A Master Gardener recently sent me an article about dogs that are employed to sniff out a devastating citrus disease that is threatening Florida's industry. The disease, Huanglongbing, abbreviated to HLB (thank goodness!) is a bacterium that prevents citrus fruit from ripening. It's also known as citrus greening. The bacteria is vectored by a psyllid, a very small insect related to aphids and mealy bugs.
Psyllids on citrus leaves (photo courtesy of
HLB has been confirmed in the United States in Florida, Louisiana, South Carolina, Georgia; and in Cuba, Belize, and the Eastern Yucatan of Mexico. Since its confirmation in 2005, agriculture authorities estimate that it's caused a 75% decline in Florida's $9 billion industry. Sadly, over 5,000 fruit growers have lost their businesses.
Symptoms of citrus greening (photo courtesy of USDA California)
The leaves of HLB-infected trees are blotchy, and the fruit is smaller in size, lopsided, poorly colored, and worst of all...very bitter. In short, the citrus fruit is of poor quality and no value. The worst part is there's no cure for the disease and it can move rapidly throughout orchards, since psyllids are mobile.

Back to the dogs! You've likely read that dogs have been used for sniffing out cancer, bed bugs, and even emerald ash borer (!!!!!!). In the case of sniffing out threats to our agriculture industry, the USDA has looked at using dogs to detect HLB for over 15 years. They've found our canine companions have a 99% accuracy in identifying the disease. Ninety-nine percent! And the dogs are super fast at their job. They can quickly detect HLB in just a couple seconds, quickly sniffing each tree within the row. The reward for a find? A favorite chew toy.

Jerry Bishop, a dog trainer and handler with Florida-based F1-K9, scouts a Ventura County, Calif., lemon grove for HLB-causing bacteria with Bello, a Springer spaniel. (Courtesy Farm Bureau of Ventura County)

As soon as the dog detects an infested tree (they sit by the culprit), the tree is marked and slated for removal. Dogs are much more accurate and quicker than visual inspections and lab analyses. Compared to dogs, the lab tests, using PCR, only had a 25% accuracy rate. Dogs rule.

Head's up to my two beagles, Maple and Hazel, you could be employed any day! Get your resumes up-to-date. And try to sell yourselves as experts in something other than sleeping.
Maple and Hazel doing what they do best.


  1. Excellent post! It's fascinating how effective and efficient dogs can be for detecting invasive species. Dogs are being used to sniff out some invasive weed when seedlings - so they can be eradicated before they can flower and produce seed.

  2. I am all for getting rid of those yucky psyllids (don't tell Whitney, please) on ANYTHING !

  3. PS - Can Maple and Hazel sniff out tomato hornworms on my tomatoes this summer ?

  4. I just asked Maple, and she yawned. I'll keep working on her for the hornworm job :)

  5. Dogs are amazing. Can't scientist find a key role for cats to play in helping "bring down the bad guys"?
    Moms Stoven

  6. My old Beagle girl, Thumper, may join Maple and Hazel in the job market! Very interesting information! Dogs and their sniffers are amazing. Thanks!