The Blueberry News – July 2019

FloridaBlueberryGrowers.org The Blueberry News | 11

topic of the season

Management Strategies for Pest and Disease

Problems in Post-Harvest Blueberries

by JEFFREY G. WILLIAMSON, Horticultural Sciences Department, PHILIP F. HARMON,

Department of Plant Pathology, OSCAR E. LIBURD, Entomology and Nematology Department,

and PETER DITTMAR, Horticultural Sciences Department, all with the University of Florida/IFAS.

The following tables were updated from the 2019 UF/IFAS Florida Blueberry Integrated Pest Management Guide found at edis.ifas.ufl.edu/

hs380. This publication is intended for use only as a guide. Specific rates and application methods are on the pesticide label, and these are subject

to change at any time. Always refer to and read the pesticide label before making any application! The pesticide label supersedes any information

contained in this guide, and it is the legal document referenced for application standards.

POLLINATOR PROTECTION

Before making insecticide applications, monitor insect populations to determine if treatment is needed. If insecticide

application is necessary:

1. Use selective pesticides to reduce risk to pollinators and other non-target beneficial insects.


2. Read and follow all pesticide label directions and precautions. The label is the Law! EPA now requires the
   addition of a “Protection of Pollinators” advisory box on certain pesticide labels. Look for the bee hazard
   icon in the Directions for Use and within crop specific sections for instructions to protect bees and other
   insect pollinators.


3. Minimize infield exposure of bees to pesticides by avoiding applications when bees are actively foraging in
   the crops. Bee flower visitation rate is highest in early morning. Apply pesticides in the late afternoon or early
   evening to allow for maximum residue degradation before bees return the next morning. Bee foraging activity is also dependent upon
   time of year (temperature) and stage of crop growth. The greatest risk of bee exposure is during bloom.


4. Minimize off-target movement of pesticide applications by following label directions to minimize off-target movement of pesticides. Do not
   make pesticide applications when the wind is blowing towards bee hives or off-site pollinator habitats.

continued on next page

TABLE 7. MANAGEMENT STRATEGIES FOR PEST AND DISEASE PROBLEMS IN

POSTHARVEST PLANT MANAGEMENT

Blueberry bud mites: This is an occasional pest of blueberries in Florida. Use high-volume (300 gal. per acre), high-pressure

(200 psi) applications of a postharvest insecticide/miticide and horticultural oils. In blocks infested with blueberry bud mite,

make two postharvest applications using carbaryl. Pruning and removing or destroying old blueberry canes can help reduce bud

mite populations. Summer topping or hedging immediately after harvest is a common practice used to manage bush height; this

practice also greatly reduces bud mite by removing old, infested fruiting twigs. Blueberry bud mite is a tiny eriophyid mite, best

visible with a dissecting microscope. In early ripening cultivars, sanitation in the form of postharvest hedging and cutting back into

one- and two-year-old wood should be the primary management response for mite-infested blocks. Postharvest application(s) of

carbaryl may be helpful to augment this critical cultural practice.

Imported fire ants: Imported fire ants can be very important pests in orchards, vineyards, or fields. Ant baits employed after

harvest into fall as a broadcast treatment should eliminate most, but seldom all, fire ant mounds within treated areas. When ant

populations are high, use a dormant or early spring broadcast application in addition to the postharvest application to get better

fire ant control. Ant baits are slow acting. They require up to 8 weeks to control active mounds. Worker ants must be attracted to

baits so that they will carry the baits back to their colonies. Most ant baits interfere with reproduction, which causes a gradual

colony die-off. Extinguish® Professional Fire Ant Bait (0.5% methoprene) is labeled for use on all crop land sites. It is effective, but

since it is an insect growth regulator, it is somewhat slower acting than Esteem® Ant Bait (0.5% pyriproxyfen). Ant baits work best

when soil is moist but not wet. Active ant foraging is essential. Ideally, temperatures should be warm and sunny. Avoid applying

ant baits when conditions are expected to be cold, overcast, rainy, or very hot. Individual mound treatments are most effective