Post-Bloom Fruit Drop Survey

Tacy CalliesPests

A Citrus Research and Development Foundation (CRDF) Research Management Committee meeting was called on June 29, 2016, to discuss post-bloom fruit drop (PFD) caused by Colletotricum spp. in Florida. In this meeting, it was suggested that there is an opportunity to retrospectively investigate PFD management strategies from 2016 to determine if grower treatment programs led to variable results. A survey and protocol for data collection has since been developed. This retrospective investigation will engage 25 to 30 growers from throughout the state by collecting survey information on:

• The history of PFD in specific groves
• Production history
• Previous PFD treatment programs
• Horticultural practices
• Flowering timing
• Past weather conditions recorded by grower weather stations
• Weather data from the local FAWN weather stations

The survey will be accompanied by the collection of current field counts of residual fruit calyx buttons and the numbers of set fruit to determine the results of individual grower PFD programs. A field crew will collect this data using the following standardized methods:

• Twenty trees per location
• Trees of similar in age, variety and disease severity within the site
• Fruit and residual fruit calyx buttons will be quantified within a 0.5 square meter frame twice on each side of the tree (4x total)
• Calculation of canopy surface areas for each tree

Deliverables for this project include the following:

• Standard location, weather, grove history and grove management information.
• Persistent calyces and fruit counts (all except dry, brown buttons).
• A regression analysis using survey data, weather information and data collected to identify variables contributing to greater or lesser incidence of PFD.
• Analyzed data will be shared back to the industry by way of a summary that shows the general trends associated with weather, disease pressure and resulting fruit load across those who participated.

Please contact Stephanie Slinski at or call 863-956-8678 to participate in this project.

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