Released by UF/IFAS …
By Amir Rezazadeh
Huanglongbing (also known as HLB or citrus greening) is a disease affecting citrus production all over the globe. Citrus greening affects all citrus cultivars and causes tree decline, a serious threat to Florida’s citrus industry. The disease is believed to be caused by the bacterium Candidatus Liberibacter asiaticus. The Asian citrus psyllid transmits the bacterium and is found throughout Florida.
Now our growers are willing to do whatever it takes to destroy the psyllids, such as spraying the trees with industrial-strength pesticides, pyrethroids and neonicotinoids, that are toxic to bees.
But let’s see this issue differently. If you are a home owner, you are not willing to use industrial insecticide on tree that you will eat its fruit. So, why not biological control? One choice is Tamarixia. Tamarixia radiata, tiny parasitoid wasps that lay their eggs on the backs of psyllid toddlers (a.k.a. nymphs). Once those wasp eggs hatch, the baby wasps burrow inside the nymphs and devour them from the inside out, leaving only a hollow husk.
Here are three tips for saving your citrus trees:
- Search for psyllids
Concentrate your search on the tree’s tender new growth — the psyllids won’t eat older wood or leaves. The nymphs are always found on new growth, and move in a slow, steady manner when disturbed. The adults leap when disturbed and may fly a short distance. They are usually found in large numbers on the lower sides of the leaves with heads almost touching the surface and the body raised almost to a 30° angle. The period of greatest activity of the psyllid corresponds with the periods of new growth of citrus. There is a video that explains ways to search for the psyllids on your trees.
Citrus pysillid laying egg
- Kill the ants
If you see ants streaming up and down your citrus trees, that’s a sign that they’re tending sap-sucking pest. The trick is using a bait that will slowly kill the ants, over a period of days, allowing the workers time to bring the bait back to the nest where it will be consumed by the queen and others. If the poison is too strong, it will kill the ants before they get back to the nest.
Ants sucking sap around psyllid
- Plant alyssum
Once you’ve tamed the ants, parasitoid wasps will be able to do their work without interruption, but you need to entice them into your yard by planting sweet alyssum (Lobularia maritima), a sweet-smelling, tiny-flowered ground cover that provides the nectar and pollen parasitoids and other beneficial insects love. Alyssum thrives in full sun, if it gets an inch or so of water once a week in well-drained soil.
You won’t see the wasps. They’re about half the size of ants, but the flowers will draw them in. You don’t need a lot; just a couple of pots will provide a lot of food for natural enemies of psyllids.
Alyssum (Lobularia maritima)