Mike Roberts

The Importance of Dormant Season Sprays

Asian citrus psyllid (ACP) management should be part of any Florida citrus grower’s pest management strategy; it’s an integral part of managing the impacts of ACPs, which are the vector that spreads the bacteria that cause citrus greening from tree to tree in Florida citrus. According to a December UF/IFAS Tip of the Week, winter is the time for the all-important dormant season sprays. Dormant season sprays should be part of your ACP management strategy for a number of reasons.

Benefits of Dormant Season Sprays

The UF/IFAS Tip of the Week maintains that dormant season sprays target a different part of the ACP life cycle and thus “having a greater impact on pest populations.” Since there are limited or no flush cycles occurring in the winter, offspring ACP production halts.

While sprays at the beginning of a major flush cycle—and/or throughout flush cycles—target adult and nymph ACPs, dormant season sprays target adult populations only. Targeting adult ACP populations in winter will reduce mating populations of ACPs ahead of the spring flush. Consequently, this will mean that there will be fewer nymphs during the spring flush and that ACP populations will not be able to increase rapidly when food sources from the flush are widely available.

As an added advantage, past research by two UF entomologists, Jawwad Qureshi and Phil Stansly, showed that dormant season sprays both lowered adult ACP populations and had little to no impact on beneficial insects that prey on ACPs—like Asian psyllid wasps Tamarixia radiata—and other insects that are pests to Florida citrus. The same cannot be said for spring flush sprays where beneficial insects are present and killed by insecticide sprays alongside ACPs. T. radiata control ACP populations in two ways: female wasps eat ACP nymphs and they lay their eggs on ACP nymphs and the hatched larval wasp feeds on and kills the ACP nymph.

The article maintains that UF research shows the dormant season sprays and flush sprays—like the budbreak phenology model—are more effective at reducing ACP populations than monthly spray models. Florida citrus growers should be undertaking dormant season sprays now.

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