Toxic Endophyte Infection in Georgia Fescue Pastures is Severe and Widespread

Tall fescue, a year-round forage in Georgia

There are more than 30 million acres of tall fescue in the United States with 1 million acres in Georgia alone, which are primarily in the north Georgia. It is a cool season perennial grass available for grazing for an extended period from early spring to fall.  Furthermore, stockpiling this grass in pastures and hay fields during late summer to early fall allows grazing during late fall to early winter, which can considerably reduce the fall and winter feed costs. 

Association of endophyte with tall fescue

The majority of fescue pastures are infected with the fungus Neotyphodium coenophialum that grows inside (hence called “endophyte”) the tall fescue plant and is transmitted via seed.  Tall fescue benefits from endophyte in several ways such as drought and stress tolerance, insect and diseases resistance, and grazing persistence.  At the same time, the plant provides energy and a sustainable environment for the fungus.  This mutually beneficial or symbiotic relationship between the plant and fungus is considered necessary to ensure optimal production and survival for fescue pastures.  However, the endophyte produces toxins called ergot-alkaloids exert an array of toxic effects in livestock collectively called “fescue toxicosis”. Grazing livestock in infected pastures and consumption of hays from infected field cost beef cattle farmers a billion dollars annually in lost revenue each year in the United States.  Various adverse effects of fescue toxicosis on animals include “summer syndrome”, “fescue foot”, reproductive difficulties, reduced weight gain, decreased milk production, slightly elevated body temperature, impaired heat tolerance, excessive nervousness, and failure to shed winter hair coats in the spring.

How severe is toxic endophyte infection in Georgia tall fescue?

It is expected that the vast majority of tall fescue in Georgia and other places in USA is infected by the toxic endophyte but there is a lack of clear and precise information about the nature and extent of endophyte infection in the tall fescue stands.  To address this lack of information, we conducted a survey to assess the severity of toxic endophyte infection in tall fescue critical to the beef cattle industry in Georgia. This baseline survey was conducted with a grant funding from Georgia Commodity Commission for Beef Cattle to have a preliminary assessment of the extent and severity of toxic endophyte infection in the one million acres of tall fescue in Georgia. 

Samples were collected through collaborative efforts of the grant team and the ANR Extension Agents of various counties. Emphasis was given to have samples collected as broadly as possible throughout the mountain and upper piedmont regions of Georgia (north of the 33°N parallel).  As the goal of this project was to evaluate the nature and extent of toxic endophyte infection, all necessary measures were taken to exclude samples from the fields that are known to be novel-endophyte varieties.

Different components of a tall fescue endophyte sampling kit used for the study.

The project team developed a special sample submission form, an easy-to follow step-by-step sampling protocol, and an instructional video to ensure all samplers uniformly followed the recommended protocol. Sampling kits were provided to each Extension Agent to ensure uniformity in sample collections (Figure 1). Full details on the methodology of this project and these resources may be found here:    https://aesl.ces.uga.edu/publications/grantreports/.

We received and analyzed samples from 50 tall fescue fields in 21 Georgia counties. Endophyte analyses of the tiller samples were conducted using proprietary testing methods (Agrinostics Ltd. Co, Watkinsville, GA, agrinostics.com).  All laboratory analyses were conducted by staff of the University of Georgia Agricultural and Environmental Services Laboratory, Athens, GA (aesl.ces.uga.edu). 

Salient findings of endophyte survey:

All 50 tall fescue fields sampled from 21 counties turned out to be severely infected by endophyte (Table 1).  Except for one sample from Walker County which had 70% infected tillers and 3 from Upson County that had a mean infection level of 73%, the mean infection levels in the rest of the samples from 19 counties varied from 87 to 100%.  The lowest infection of 25% was observed in a pasture from Upson County, but the other two pastures from this county had 95 and 100% infection.  The mean infection level for the whole study was 94% with a median of 100%.  Out of 56 samples tested, 30 had 100% infected tillers. Thus, we found endophyte infection in the tall fescue fields in Georgia is widespread and mostly severe. A color coded map using the mean endophyte infection levels observed in the 21 counties is presented in Figure 2.

Figure 2: A map showing the severity of endophyte infection in fescue pastures in various Georgia counties observed through this study.

Recommendations to address “fescue toxicosis” in Georgia pastures

In general, if a field has less than 20-35% endophyte infection the toxins can be diluted by inter-seeding legumes (usually white clover or red clover).  However, only one sample from Upson County with 25% endophyte infection would qualify for applying this recommendation.  Renovation with tall fescue varieties that are infected with a novel-endophyte that do not produce toxic ergot alkaloids is the best option for fields that have 60% or greater endophyte infection.  Thus, all other 49 fields of this study, with 70-100% endophyte infection, merit renovation with newer novel-endophyte tall fescue varieties.  This replacement would be a costly investment initially, but this is going to be a cost effective intervention for the tall fescue-based livestock systems in the long run as found by the economists from UGA.

We also believe that this baseline survey results will serve as a teaching tool to convince farmers to have their own pastures tested in order to assess the need for remedial management.  Since NRCS offers cost-sharing for renovation of tall fescue pastures with novel endophyte varieties of fescue in Georgia, the impact of this survey results is much higher.  Furthermore, the outcomes of this survey will help with the current work of the Alliance for Grassland Renewal (https://grasslandrenewal.org). 

Table 1. Summary of survey results for the preliminary assessment of the extent and severity of toxic endophyte infection in tall fescue grown in Georgia.

Descriptive statisticsInfection (%)
Minimum25
Maximum100
Average95
Median100
Mode100

Extension Agents Contributors

Zach McCann, Banks County; Paul Pugliese, Bartow County; Paula Burke/Angie Stober, Carroll County; Josh Fuder/John Bennett, Cherokee County; Clark MacAllister/Jason Hamby, Dawson County; Ashley Hoppers/Jake Williams, Fannin County; Keith Mickler/Kimani Grey-Campbell, Floyd County; Raymond Fitzpatrick, Franklin County; Garrett Hibbs, Hall County; Greg Pittman, Jackson County; Lucy Ray/Tatumn Behrens, Morgan County; Ashley Best, Newton County; Mary Carol Sheffield, Paulding County; Brooklyne Wassel, Pike County; Thad Glenn, Stephens County; Deborah Xavier-Mis, Troup County; Jacob Williams, Union County; Hailey Robinson/Wes Smith, Upson County; Wade Hutcheson, Walker County; and Roger Gates, Whitfield County.

Funding

Funding for this research was provided by the Georgia Beef Cattle Commodity Commission.

Authors

Dr. Uttam Saha: Senior Public Service Associate and Program Coordinator, Agricultural and Environmental Services Laboratories, UGA

Dr. Lisa Baxter: Assistant Professor and State Forage Extension Specialist, Department of Crop & Soil Sciences, UGA

Dr. Lawton Stewart: Professor and Extension Coordinator, Department of Animal and Dairy Science, UGA

Dr. Abdolmajd Ronaghi: Research Professional, Agricultural and Environmental Services Laboratories, UGA

David Parks: Laboratory Manager, Agricultural and Environmental Services Laboratories, UGA


The Alliance for Grassland Renewal is a national organization focused on enhancing the appropriate adoption of novel endophyte tall fescue technology through education, incentives, self-regulation and promotion.  For more resources or to learn more about the Alliance for Grassland Renewal, go to www.grasslandrenewal.org

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: