Battling invasive plants and diseases – San Lorenzo Valley Press-Banner

I have a nice Improved Meyer Lemon tree where I live. Because of water restrictions by the Big Basin Water Company, it doesn’t get as much irrigation as I’d like but it still looks pretty good and has quite a few ripening lemons on it. I save water while I’m waiting for the shower to warm up so I can water it and my few fire survivors. 

I ran across an article recently from the California Department of Food and Agriculture that portions of San Diego and L.A. counties are still included in the Citrus Greening Disease quarantine area. All this made me think about how creative we are in discovering ways to combat plant diseases and invasive species that impact our food supply.

We’ve all heard stories about detection dogs sniffing out drugs, explosives, cadavers and disaster survivors. In the mid-’90s, handlers started training them for conservation tasks such as sniffing out scat from endangered animal species and detecting trafficked ivory. Now their olfactory prowess is being used in the fight against invasive plants and insects. And dogs are being trained to sniff out Covid 19 odor with 82 percent accuracy. The list of how man’s best friend is helping us just keeps getting longer. 

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, Mont. 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 1,000 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 five years ago with just a few dogs has increased dramatically and many dogs are now being trained. Tim Gottwald, a U.S. Department of Agriculture plant pathologist, said during a recent presentation in Riverside that dogs in Florida have been 99 percent accurate and in tests a couple years ago in Southern California backyards, they were more than 92 percent 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.

Jan Nelson, a landscape designer and California-certified nursery professional, will answer questions about gardening in the Santa Cruz Mountains. Email her at [email protected], or visit