Development of Root Nutrient and Fertilization Guidelines for Huanglongbing (HLB)-Affected Orange and Grapefruit

Development of Root Nutrient and Fertilization Guidelines for Huanglongbing (HLB)-Affected Orange and Grapefruit

Report Date: 11/08/2019
Project: 18-042C   Year: 2019
Category: Horticultural & Management
Author: Davie Kadyampakeni
Sponsor: Citrus Research and Development Foundation

Progress report for the fourth quarter of the 2018/2019 project year
The purpose of the project is to develop new guidelines for restoring root health and improving overall tree nutrition for Florida oranges and grapefruit. The objectives of the project are to:
1. Determine optimal nutrient concentrations in roots and leaves for multiple grapefruit and orange varieties.
2. Compare and contrast fertigation, soil, and foliar fertilization to identify best application method for uptake of nutrients into both underground and aboveground components.
3. Investigate the relationship between root and leaf nutrient contents to tree health, yield, and fruit quality as well as bacteria titer.
4. Generate updated and new guidelines for optimal nutrient contents for roots and leaves for HLB-affected trees.

Progress to date:
The project is being conducted at three sites: Citrus Research and Education Center (CREC), Southern Gardens Citrus near Clewiston, FL and Indian River Research and Education Center (IRREC). Data collection continued in the third quarter particularly on canopy size, soil and leaf nutrient concentrations, HLB disease ratings and root growth and longevity. Data collection continues, and analyses will be done as needed. Updates and data will be presented in future extension meetings after about a year or two of data collection and validation of results to get feedback from growers and the citrus industry.

In addition to one graduate student working on the project at CREC, a second graduate student started working on the project this summer at the IRREC.

At the start of fall 2019, an agricultural assistant was recruited at IRREC to help with data collection, and application of treatments.

In terms of outreach, some of the project co-PIs, Dr. Rossi and Dr. Johnson participated in the “International Root Workshop” in August 2019 that involved international root experts and several graduate students. Also, Drs. Ferrarezi and Dr. Kadyampakeni facilitated 4 statewide workshops on Citrus Nutrition conducted at CREC (October 8, 2019), IRREC (October 23, 2019), Southwest Florida Research and education Center (SWFREC, October 8, 2019) and Sebring (October 8, 2019). Finally, Drs. Kadyampakeni, Ferrarezi and Johnson also presented portions of their work on citrus nutrition and root health at the Materials, Innovation and Sciences in Agriculture (MISA) Conference (October 24-25, 2019) in Orlando, Florida. Two graduate students working on the project presented their proposed work at the South Florida Graduate Student Symposium.

Plans for Next Quarter
The team will continue with data collection including yield and reporting on the progress of the project.

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