By Master Gardener Volunteer Lesley Arrandale

It feels like spring is almost with us, but I’m writing in early February when we used to expect cold snaps up until our average last frost date around March 20. All we can do is work with what the weather throws at us and plan for the unexpected — be it heat or cold, rain or drought — but I guess that’s always been the case for gardeners and farmers.

My personal spring includes a pretty flowering redbud (Cercis canadensis), creamy flowers just emerging on the Carolina cherry laurel (Prunus caroliniana), and I’m still enjoying the beautiful perfume of my winter-flowering tea olive (Osmanthus fragrans). My spiderwort’s (Tradescantia ohiensis) purple three-sided flowers are beginning to show, and they are all attracting honey bees. On Jan. 30 I spotted my first hummingbird of the year; he was feeding on shrimp plants that have been flowering sporadically since last spring.

As part of our continuing training, Master Gardener Volunteers are lucky to be able to learn from experts in various fields associated with horticulture, and this week we took a morning to learn about pest control using biological means. The most well-known agent available to homeowners is probably BT (Bacillus thuringiensis subsp. Kurstaki). Totally harmless to us, it is a strain of bacteria which can kill small caterpillars when correctly applied. It works by destroying their ability to eat once they have ingested it. It’s a good product to use on tomatoes and leafy greens. “Mosquito dunks” contain a different strain of BT, and can be worth using in water features.

It’s not just insect pests that we can control with biological methods. A number of invasive plants — plants that are disrupting our natural ecosystems by crowding out native plants — have been the subjects of experiments here in Florida for many years. One notable success has been to find a control for the air potato vine (Dioscorea bulbifera), which is native to Africa, Asia, and northern Australia.  After extensive testing for safety and efficacy, a beetle from the air potato’s home range was released and made available to the public. Currently you can request beetles online at Where beetles are released is determined by demand and location. The beetles will not eradicate the vine completely, but keep it in reasonable bounds without the use of potentially harmful chemicals.

Other plants that have been targeted with biological controls include the Melaleuca tree that almost destroyed the Everglades; alligator weed, once so prevalent in our waterways; and tropical soda apple, a problem for cattle ranchers as well as a source of pathogens (diseases) that can affect important crops like tomatoes, eggplants, and potatoes which are in the same plant family (Solanaceae).

As home gardeners, perhaps our best form of biological insect control is simply to encourage as many species of insects as possible to make their homes in our yards by avoiding the use of chemicals and providing a wide variety of nectar-rich flowering plants. More than 90 percent of insect life is considered beneficial: they are predators which use other insects as food or parasitoids that use other insects as a place to lay their eggs, and include ladybugs, lacewings, wasps, and assassin bugs. You won’t always see them at work, but work they do.

I hope this reassures you that the University of Florida Institute of Food and Agricultural Sciences is looking out for us. Research is the key to solving complex problems on the ground, and we all benefit from the results. For our part, we should never transport plants into the state as they can carry pathogens, harmful insects or just be plain thugs — remember kudzu, the vine that ate the south?

For timely tips for your yard you can find both current and archived editions of A New Leaf newsletter at

Have a great spring!

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