What are endophytes – in plain terms?
An endophyte is a fungus that lives inside grass, silently and symbiotically. The grass gives it nutrients, and in return, the fungus helps protect the grass from insect pests.
However, not all endophytes are created equal. Some have trade-offs: better insect defense, but adverse effects on livestock. Others are safer for animals, but weaker against pests. The goal is to pick the one that best matches your paddock’s risks and your animals’ sensitivity.
What endophytes can mean for your farm
| Core Benefit | What it means for your farm |
|---|---|
| Stronger pest resistance | These act as a built-in deterrent — insects can stop feeding, lose appetite, or die soon after feeding — which means fewer plants are damaged and more survive to persist. |
| Better pasture persistence | With less pest damage, ryegrass tillers live longer, giving a denser, more productive pasture. |
| Improved feed supply in tough conditions | Pastures with the right endophyte hold their density longer under insect pressure and dry stress. By keeping more plants alive and productive, they maintain feed supply when unprotected pastures would thin out. |
| Reduced re-sowing costs | Longer-lasting pastures mean fewer paddocks needing re-sowing — saving time, diesel and seed etc. |
| Animal safety (depending on strain) | Novel endophytes are designed to give insect protection without the animal health issues once seen with older “wild” endophytes. Dependent on your strain. |
| Better farm resilience overall | Choosing the right endophyte for your area builds more stable, lower-risk feed systems that keep performing even in tough years. |
Breakdown of common pasture endophytes
Types of endophytes
There are various types of endophytes: standard, novel and low, each differing in persistence, yield and level of insect protection.
Standard Endophyte
The standard strain indicates that the cultivar contains a naturally occurring wild-type endophyte, which helps resist insect attacks (e.g. Argentine stem weevil and Black Beetle) and prevents over-grazing. However, in dry summer conditions, it may cause ryegrass staggers, heat stress, and reduced animal growth rates. An option where price is crucial and high animal production is not a major issue. Stock grazing these pastures can often suffer from ryegrass staggers and experience reduced weight gains throughout the warmer months.
Low or Nil Endophyte
Low endophyte indicates minimal or no endophyte infection in the seed, making it a great choice for areas with low insect predation and high summer moisture. Nil Endophyte pastures are animal safe and deliver excellent animal performance. However, you can expect less persistence in areas where pasture pests are present. Low endophyte (LE) implies low or nil endophyte infection levels in the seed and its use is best suited to areas of low insect predation generally associated with high summer moisture.
Novel endophytes
New novel strains are currently being developed that may cause ryegrass staggers or may not, but they generally possess some toxicity to specific pasture insects. The effectiveness of these strains varies depending on the specific endophyte and the grass cultivar’s response to it.
Over time, the industry has created a range of endophytes that mitigate animal safety concerns while maintaining a degree of resistance to insect pests, including the CM142, AR37, AR128 and NEA12.
AR1 Endophyte
High animal performance novel endophyte option. Delivers excellent animal performance & provides a moderate range of insect protection. Has demonstrated poor persistence in areas with major insect pest pressure from Black Beetle and Root Aphid.
Endo5 Endophyte
Contains no Lolitrem B, the main cause of ryegrass staggers. Provides good control of Black Beetle, Argentine Stem Weevil, Root Aphid and Pasture Mealy Bug. Produces less ergovaline than many ryegrass cultivars containing standard endophyte. This said, it may produce lower animal performance levels over summer/autumn compared with AR1 and nil endophyte options.
Endophytes in further detail
Endophytes are fungi that exist inside ryegrass plants as well as in some other closely related species.
Endophyte infection results in the production of many alkaloids of which those thought to be of most significance currently are:
- Peramine, which provides the plant protection from Argentine Stem Weevil attack primarily and some resistance to Black Beetle.
- Lolitrem B, which provides some protection against some insect pests but is a neurotoxin that causes ryegrass staggers in stock
- Ergovaline, which provides some protection against black beetle attack, but causes heat stress in stock.
There is thought to be an interaction between the effects of ergovaline and lolitrem B worsening the impacts on stock. The most common effect of these compounds is to reduce animal performance, although in extreme cases, death through misadventure can result.
Most grazing animals will preferentially graze endophyte free pasture over comparable endophyte infected pasture. However there are now endophyte strains available commercially that provide some of the same insect attack protection without all the negative side effects.
Understanding endophytes
Endophytes exist in a symbiotic relationship where by they are provided the nutrients needed to exist from the plant and in return provide benefits to the host plant such as protection from insect attack.
Endophytes take at least 6-8 weeks to fully establish in newly sown seedlings, so it is important to use other control options to prevent damage to grasses during early establishment. Once grasses are well established with multiple tillers, then you can rely on protection from the endophyte.
Different strains of endophyte are available in many of the grass cultivars.
