Under the Microscope: A four part look at Endophytes

Part 1: Ergovaline – A Toxin To Avoid in Pastures

Endophytes are fungi that live inside plants and are often required in tall fescue and ryegrass pastures to ensure persistence against attacks by insect pests and environmental impacts such as drought. These endophytes enable plant survival through the production of a range of compounds known as alkaloids. Some of these alkaloids such as ergovaline are toxic to mammals.

A recent review on the impact of ergovaline in pastures has highlighted again the reasons why it should and can be avoided.  Some have argued that low levels of ergovaline can be tactically used to provide resistance or deterrence to insect pests as well as deterring grazing animals. There is a significant risk in assuming that an endophyte strain that expresses low concentrations of ergovaline in a variety will have the same low alkaloid expression irrespective of the genetics of the host plant as well as the environment in which it is grown.

Strains of endophyte that produce no ergovaline and yet provide good grass persistence are available and should be used preferentially. Future endophyte strains in development should seek to avoid any ergovaline expression. One cannot assume that farmers graze swards to ensure that portions of the plant with highest ergovaline content are avoided, and that seasonal spikes in concentrations of ergovaline do not occur.

This is a summary of the research paper Ergot Alkaloids in New Zealand Pastures and Their Impact in the New Zealand Journal of Agricultural Research. You may read the full paper here.

~ Dr. John Caradus, Grasslanz Technology.

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

Kentucky producer Buddy Smith views the tall fescue endophyte through a microscope at a Novel Tall Fescue Renovation Workshop, hosted by the University of Kentucky and The Alliance for Grassland Renewal.

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