By Lauren Diepenbrock
Pest management is a year-round challenge in Florida citrus. But with knowledge of insect, mite and snail seasonal biology in relation to tree phenology, plans can be developed to protect fruit and maintain productive citrus trees.
Populations of some highly problematic pests (Asian citrus psyllid and citrus leafminer) generally increase with flush/new growth development, so targeting peak flush periods can help keep pest populations from exploding.
LEBBECK MEALYBUG
The first major population increase of lebbeck mealybug generally occurs with initial fruit setting. Damage from feeding at this stage of fruit development will cause high rates of fruit drop. Protecting developing fruit is key to protecting your crop. For early spring applications, be sure to check the label for use in relation to bloom for pollinator protection. Lebbeck mealybug will need to be managed throughout the year, though the extent of management depends on the intended market for your fruit.
MITES
Rust mite and citrus rust mite damage to fruit can be minimized by targeted management in late spring (April/May) when populations first start to develop. Keeping mite levels low while fruit are in the early stages of development can prevent high levels of damage. Scouting and management recommendations for mites can be found here.
Photo by Allan Busuulwa, UF/IFAS graduate student
THRIPS
Thrips can be a challenge, especially for fresh market producers. Flower thrips cause damage during bloom if populations are increasing and should be managed prior to bloom to reduce flower abortion. Orchid and greenhouse thrips feeding on developing fruit cause rind blemishing. Information on scouting and treatment of thrips can be found here.
More recently, chilli thrips have become problematic for citrus under protective screen (CUPS) growers. The spring influx of chilli thrips into the screen structures coincides with citrus bloom and the blooming of weedy plants both in and outside of CUPS. Reducing non-crop hosts will help reduce pest pressure while fruit are developing. Management for chilli thrips is still under development.
ROOT WEEVILS
Root weevils are present in groves in various life stages throughout the year. Because the primary damage from root weevils occurs underground, it can be hard to time management actions appropriately. The citrus root weevil chapter of the Florida Citrus Production Guide describes the life cycles of the root weevils that attack citrus and explains management options that take advantage of their biology.
GHOST SNAILS
Bulimulus bonariensis, the ghost snail, continues to be problematic in Florida groves. Ghost snail activity usually begins in March. High populations build by June/July. These snails are known to impede the delivery of irrigation from microjets as well as cause some direct feeding damage under specific conditions.
Reducing the snail population prior to the early summer dry period is critical for supporting tree health. Similar to chilli thrips, ghost snail management is under development. Any chemical management actions taken should be targeted to the active periods of this organism, which is tied to moist periods — when dew has formed, relative humidity is high, after rainfall and after irrigation events.
GET HELP
For help making pest management decisions, consult the Citrus Production Guide and the University of Florida Institute of Food and Agricultural Sciences citrus agents.
Lauren Diepenbrock is an assistant professor at the UF/IFAS Citrus Research and Education Center in Lake Alfred.
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