Pest Management Under Bags

Ernie NeffCitrus Expo, Pests

pest management

Many Florida citrus growers in recent years have used individual protective covers (IPCs), often referred to as “bags,” for pest management, especially to protect young trees from HLB-spreading Asian citrus psyllids. Lauren Diepenbrock addressed the benefits and challenges of IPCs at this year’s virtual Citrus Expo. Diepenbrock is an assistant professor of entomology at the University of Florida Institute of Food and Agricultural Sciences Citrus Research and Education Center.

In addition to reducing psyllid access to young trees, IPCs help promote rapid tree growth and offer growers the potential to save on insecticide applications, Diepenbrock stated.

Challenges posed by IPCs include scouting and treatment of trees. Scouting issues include how often to scout and whether to do so with bags on or off the trees.

Trees in bags can be treated with soil-drench insecticides and with foliar applications. Foliar applications require removal of the bags to allow coverage.

Although canopy development is greater in bagged trees, it is unknown what size bags are optimal, Diepenbrock stated. Other concerns about the bags include how long to leave them on the young trees, whether they should be replaced with larger bags as trees grow, and the bags’ potential impact on tree roots.   

Pests that get in the bags include spider mites, snails and lebbeck mealybugs.

A snail recently found in Florida groves is Bulimulus sporadicus. Diepenbrock said the snails are unlikely to cause direct feeding damage to young citrus trees under open field conditions, but their bodies are clogging microsprinkler irrigation systems.

Diepenbrock reported that in one grove, lebbeck mealybug caused 75 percent loss of young trees that were bagged and became infected by the mealybug. Lebbeck mealybug, now found in commercial groves in 10 Florida counties, might best be controlled long-term by predatory bugs, the entomologist stated. The mealybug causes fruit distortion, making fresh fruit unmarketable. It also can cause fruit drop, leaf chlorosis, branch dieback and death of young trees.

“As we continue to grow in an era of endemic HLB, pest management will continue to evolve,” Diepenbrock stated. Pest management tools will include IPCs, new HLB-tolerant varieties, windbreak enhancements and new insecticide modes of action.

See Diepenbrock’s full Citrus Expo presentation here. The presentation, and the continuing education units available to those who watch it, will remain online through the end of 2020.

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About the Author

Ernie Neff

Senior Correspondent at Large