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Endophytes: their uses and suitability

Endophytes: their uses and suitability

Endophytes: their uses and suitability

Your first question might be what is an endophyte? Well an endophyte is a fungus found naturally in many grass species, including ryegrass and fescue. It provides the plant protection from insects, and in return, the plant provides the endophyte with a place to live and reproduce.

The endophyte protects the plant by producing alkaloids which are toxic to whatever organism decides to try to eat it. This is great for protecting the plant against insect attack, but as farmers, we also feed grass to livestock who are susceptible to health issues from some of these alkaloids.

The alkaloids produced by endophytes are called peramine, ergovaline, lolitrem B and epoxy-janthitrem. Unfortunately ergovaline can cause heat stress in cattle and lolitrem B can cause ryegrass staggers in both cattle and sheep, reducing performance in milk solid production and liveweight gain. Epoxy-janthitrem can also cause ryegrass staggers but to a lesser extent.

Endophytes on ryegrass species fall into two camps: naturally occurring or artificial. Naturally occurring endophytes include wild endophyte, high endophyte and standard endophyte. These endophytes may give off alkaloids to protect the plant from many native pests but they can also cause detrimental health issues to livestock.

Novel or artificial endophytes contain low levels or no ergovaline or lolitrem B and therefore the associated health risks to animals is reduced. Novel endophytes are usually taken from another grass species or from overseas and placed into ryegrass seed in New Zealand. Each alkaloid has varying activity on different pests which is why it is important to know what the pest pressure is in different parts of the country.

The main pasture pests affecting establishment and persistance are Argentine stem weevil, black beetle, pasture mealy bug, root aphid and porina. These pests can build over time and reduce the longevity of pasture, and tend to affect long term hybrid and perennial cultivars more.

The key to novel endophyte selection is knowing which pest is prevalent in your area. For instance black beetle is a prevalent pest in the Upper North Island and so a ryegrass with NEA2 or AR37 is strongly recommended (table 1).
AR37 is a stand out endophyte developed by AgResearch, and ryegrasses with AR37 provide control of more insect pests than pastures containing standard endophyte or AR1. It is also the only endophyte with proven protection against porina caterpillar.

Contact your local PGG Wrightson Technical Field Representative for advice on endophyte and ryegrass selection.