One Year Assessment of Three St. Augustine Cultivars Resistance to Take-All Root Rot
Applied Research
Grantly Ricketts
County Extension Director and Commercial Horticulture Agent
UF/IFAS EXTENSION, ST LUCIE COUNTY
Fort Pierce
Abstract
Introduction
Take-all root rot is a one of the major problems faced by Florida homeowners. The disease is known to affect all warm season turf grass species. Not all turf species and cultivars are equally susceptible to take-all root rot and not all species express the same symptoms.
Take-all root rot is caused by the fungus Gaeumannomyces graminis var. graminis (GGG). The disease not only affects roots but also found on rhizomes and stolons. The disease mostly occurs in the wet, humid summer months. In January 2021, we established a take-all root rot trial in Kenansville, FL on three cultivars of St. Augustine: Floratam, CitraBlue
Methods
This was a completely randomized block design with eight replications at one square meter each. This area was inoculated with GGG in 2018. These were evaluated using a visual assessment of turf, using the Horsfall-Barrat Scale to indicate disease severity. Drone imagery and the enhanced normalized difference vegetative index (endvi) algorithm were also utilized in the assessment. All plots were cared for according to BMP recommendations. A visual assessment was conducted a year post planting using the Horsfall-Barratt Scale. The disease was confirmed via microscopic observation.
Results
The Horsfall-Barratt score for CitraBlue was 4.5 (indicating 12% disease). Floratam scored 9.3 (indicating ~90% disease). ProVista scored 10.5 (indicating ~97% disease). Drone imagery was also incorporated into the assessment for later correlation with the Horsfall-Barratt assessment.
Conclusion
When replacement of a Floratam lawn is needed, CitraBlue is currently a very tolerant cultivar of St. Augustine turf to take-all root rot. We intended to establish these plots for a two-year assessment, but the Floratam and ProVista turf plots are unlikely to survive for a two-year assessment.
Poster has NOT been presented at any previous NACAA AM/PIC
This poster is being submitted only for display at AM/PIC. Poster is not to be judged, but the abstract will be published in the proceedings.
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Authors: Grantly Ricketts, Joseph Strickland, John White
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Ricketts, G. County Extension Director and Commercial Horticulture Agent, University of Florida /IFAS Extension, Florida, 34945
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Strickland, J. County Extension Director and Agriculture Agent, University of Florida /IFAS Extension, Florida, 34744
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White, J. Soil and Water Specialist, Osceola County Government, Florida, 34744