Save Our Citrus: How Your Garden Can Fight a Pandemic
Invasive argentine ants inhibit the effectiveness of natural pest predators. They’re also really annoying.
When The Vine spoke with Dr. David Morgan about the fight against Huanglongbing, or HLB, he shared what he and the state of California are doing to protect our citrus trees. During the interview, he also mentioned that we all have a role to play. Through your garden, you can make a difference in protecting our community’s citrus trees as well as the state’s billion dollar citrus industry.
It starts with stopping ants that live around citrus trees. Ants make it hard for the parasitic Tamarixia radiata wasp to kill the Asian citrus psyllid, which spreads HLB.
“They say that we've got really only one insect nowadays in urban areas of Southern California, and that's the Argentine ant,” says Morgan. “That's a foreign ant. It's an introduced invasive species, so people shouldn't be too worried about killing that insect. The fewer of that insect we have around the place, the better it will be for the environment in general. Those ants protect pests and stop them getting eaten. And they kill off other ants so that we don't have lovely little native ants. They get in the way of all kinds of things, so yes, by all means, please control them.”
As for how to control ant populations in your garden, there is a right and wrong way to go about it. And it requires patience.
Know your friends: this lacewing is an important pest exterminator.
Photo credit Matt Kaiser, CDFA
“Killing ants is not something you can do overnight,” says Morgan. “There are techniques for killing ants, and the best one is to use a bait which is toxic, that they then take down into their nest and it kills the nest. Spraying them with a spray can or something like that really doesn't do anything, because there are so many millions of them that killing a few doesn't do anything. Using the baits to kill ants actually takes time. It could take up to a month to kill the nest. So it's an ongoing job. Probably during the winter, I wouldn't worry too much about controlling ants, but as the spring comes along, trying to find places to put out the baits to kill them is a really good strategy.”
When it comes to choosing which bait is the right one to manage ant populations, Morgan recommends following guidance from the University of California’s Integrated Pest Management Program. He also wants gardeners to differentiate friend from foe. While some insects are harmful, many are beneficial and need to be protected as both pest predators and plant pollinators.
“Not all insects are bad,” says Morgan. “Some people will see an insect, and they get freaked out because it's on their tree and they think they need to spray chemicals. And so they're inadvertently causing all kinds of pollution if they're not well educated on this. Know that there are good insects out there as well. We all know about honeybees. But that's only one pollinator. We've got a whole lot of pollinators. We've got these light green sort of lacey winged insects flying around - they're called lacewings - and they're really important predators. We've got ladybugs. And then we have these really small insubstantial looking insects, these little wasps. Most of them spend all their time killing other insects. And so letting them do their job and helping them is always great. Growing flowers is always really good, or plants that have nectar sources. A lot of these good insects, they need a sugar source to feed on. And so they really love flowers. Having pretty flowers brings in your butterflies as well, which of course, are important pollinators as well. It protects your other plants by allowing some of the predacious insects to get a sugar source.”
In addition to being a strategic gardener, it’s also important to be an observant one. The most effective way to eradicate HLB is to identify and remove any infected trees before they can spread the disease to others. But following Morgan’s gardening tips will hopefully bring not only health but also happiness to Irvine’s residents, including our new favorite wasps.
Contact the Citrus Tree Pest and Disease Prevention organization for more information on identification and removal of diseased citrus treese.