Tag Archives: citrus greening disease

Man’s Best Friend

Sherman wishing he could be a Detection Dog

Dogs are amazing. They can do incredible things. Well maybe not my dog, Sherman, who is more likely to get into mischief than save mankind but we’ve all heard stories about detection dogs sniffing out drugs, explosives, cadavers and disaster survivors. In the mid 90’s, handlers started training them for conservation tasks such as sniffing out scat from endangered species and detecting trafficked ivory. Now their olfactory prowess is being used in the fight against invasive plants and insects.

It was my friend Cindy who told me about this latest use of detection dogs while we were walking on the beach. Her rescue dog, Sienna is obsessed with retrieving a ball thrown into the surf so she’d be the perfect candidate for a detection dog, assisting conservationists in the fight against invasive species.

Although I come across more French broom than Scotch in our area detection dogs can be trained to sniff out all invasive broom. They’re doing this in New York where Scotch broom is just starting to invade and land managers hope to eradicate it before it becomes widespread like it is here and all along the Pacific Northwest. Broom displaces native plants with thickets impenetrable to wildlife and changes the chemistry of the soil around it so that native plants can’t grow there. Broom grows quickly as it is able to fix nitrogen from the air giving a competitive advantage to other non-native weeds. It poses a serious threat to birds, butterflies and biodiversity. Broom contains a high amount of oil, which is flammable and increases the fire hazard. It’s also toxic to livestock and dogs depending on the amount ingested. And those are just some of the reasons why New York wants to keep broom away.

“Our field in the last 15 years has just exploded.” said Pete Coppolillo, executive director of the nonprofit Working Dogs for Conservation in Bozeman, Montana. The organization partners with government agencies, researchers and nonprofits on five continents to provide trained dogs and handlers for conservation projects. Besides helping to detect New York broom they have provided trained dogs to find invasive knapweed in Montana, Chinese bush clover in Iowa, yellow thistle in Colorado as well as invasive zebra and quagga mussels on boats here in California.

Working Dogs for Conservation trains shelter dogs for detection work, screening 1000 dogs for every one they put to work. To make the cut, the dogs have to be not only good sniffers and high-energy, but also seriously obsessed with toys so they’ll stay motivated to work for a reward – the chance to play with a ball.

Because I eat a lot of oranges and lemons I looked up recent papers to see if dogs were still being used to detect citrus greening disease. Sure enough what started 5 years ago with just a few dogs has increased dramatically and many dogs are now being trained. Tim Gottwald, a U.S. Dept. of Agriculture plant pathologist, said during a recent presentation in Riverside that dogs in Florida have been 99% accurate and in tests just this last December and February in Southern California backyards, they were more than 92% accurate even when distracted by the homeowners. Because dogs can actually smell the bacteria that causes greening disease within a few weeks after infection well before lab tests can confirm, their work is vitally important.

So when you’re petting “man’s best friend” tonight appreciate all the great things he does for you and for our planet.

Man’s Best Friend Detects Deadly Citrus Disease

The author and Sherman, a Welsh Springer Spaniel, at the Bonny Doon Ecological Reserve. Photo by Tom Trower
The author and Sherman, a Welsh Springer Spaniel, at the Bonny Doon Ecological Reserve. Photo by Tom Trower

If you have a pet dog it’s no secret that they are always happy to see you. Dogs provide us with companionship. They love us unconditionally and never seem to have a bad day. Their ability to read human gestures is remarkable. Even our closest relatives- chimpanzees and bonobos- can’t read our gestures as readily as dogs can. They pay attention to us as human infants do. This accounts for the extraordinary communication we have with our dogs. Some dogs are so attune to their owners that they can read a gesture as subtle as a change in eye direction.

Another picture of Sherman ‘cuz he’s just so cute. Dressed up for the Fourth of July.
Another picture of Sherman ‘cuz he’s just so cute. Dressed up for the Fourth of July.


Studies have shown that dogs were the first animal that humans started keeping as pets. No one can pinpoint the exact date, but estimates range from roughly 13,000 to 30,000 years ago. Archaeologists can tell domesticated canines apart from wolves through skeletal differences. The earliest dog bones, discovered in Belgium in 2008 are from 31,700 years ago. Ancient dog skeletons have also been unearthed near Ukraine and elsewhere across Europe, Asia and Australia, suggesting that canine domestication was a widespread phenomenon.

How did dogs become domesticated in the first place? The first ones were basically just tame wolves. Instead of the survival of the leanest and meanest wolf it came down to survival of the friendliest around the garbage pile at the edge of human settlements. Aggressive wolves would have been killed by the humans. Friendliness caused strange things to happen in the wolves. They started to look different. They no longer needed strong jaws and sharp teeth. Their noses got smaller, their ears floppy and they evolved the ability to read human gestures.

Fast forward to 2016 when the California Dept of Food and Agriculture reported in their ‘Food and Farming News’ that dogs are being enlisted to help protect citrus trees. Mary Palm, the USDA Animal and Plant Health Inspection Service (APHIS) national coordinator for the citrus pest program, said dogs have been successfully trained to detect canker disease and now Huanglongbing or greening disease in citrus.

Espalier lemon
Espalier lemon

Huanglongbing or greening disease (HLB) is a deadly bacterial disease that has decimated the citrus industry across the world. The USDA has already spent hundreds of millions of dollars looking for a cure. In California, nearly one-third of the state’s entire land mass or 21 counties are in quarantine for the bug- the Asian citrus psyllid- that can spread the disease HLB in citrus groves. The quarantine requires that fruit moved from those areas be free of leaves and stems and movement is restricted of any nursery stock that isn’t grown in a USDA-approved facility. In addition to many Southern and Central California counties, San Fransisco, Alameda, San Luis Obispo, San Mateo and Santa Clara counties are also under quarantine.

Dogs have long been known to be able to use their senses to detect things that humans require extensive technology to detect. “Over the past four to five years,” Palm said, “a researcher in Florida first determined dogs could actually detect citrus canker. They were very good at it.” Through research funded by USDA, there are now five dogs trained and tested daily to detect huanglongbing disease. Palm said in the next year or two certification criteria will be in place for other companies to train dogs and certify them as detectors. The dogs in this program have a 99 percent success rate at detecting HLB disease in blind studies.

So when you’re petting man’s best friend tonight appreciate all the great things he does for you and for our planet. What would the world be like without lemons and oranges?