An endophyte is a fungus found naturally in many grass species, including ryegrass. The fungal strands grow between the plant cells, and transmit themselves to the next grass generation by growing into the developing seed head and then growing out of the seed into the subsequent grass seedling.

Endophyte provides the plant with protection from insects, and in return the plant provides the endophyte a place to live and reproduce. New endophyte strains can be introduced into different ryegrass cultivars, but there is no transmission between adult plants growing in pasture.

Why is it important?

Endophyte enhances the yield and persistence of the grass, because the endophyte produces a number of compounds that are toxic to various insects, and other grass pests. However, endophyte can also cause stock health problems, such as ryegrass staggers. Several novel endophytes that are less toxic to stock have been discovered, and these are currently available in a range of ryegrass and tall fescue cultivars. When used correctly, these novel endophytes can improve animal performance, and/or provide improved grass yield and persistence.


Major endophyte compounds in ryegrass:

  • Peramine - a natural insecticide that controls some important insect pests; non-toxic to stock.
  • Lolitrem B - may provide some insect protection; causes summer ryegrass staggers.
  • Ergovaline - a compound that in moderate to high amounts could reduce animal performance, but provides protection against some important pests.
  • Epoxy-janthitrems- a unique alkaloid thought to have a role in protection against insects.
  • Epoxy-janthitrems may cause ryegrass staggers.






Ryegrass with AR37 endophyte provides the best insect control in ryegrass of all commercially available endophytes, with resistance against Argentine Stem Weevil, Pasture Mealy Bug, Root Aphid, Black Beetle and Porina. AR37 can cause ryegrass staggers. AR37 endophyte is not suitable for deer or horse pastures.


Ryegrass with AR1 endophyte provides moderate insect control, but is safe for grazing stock. AR1 pastures protect against Argentine Stem Weevil and Pasture Mealy Bug. Care is needed in areas with high Black Beetle numbers (Northern North Island) as AR1 only gives moderate resistance to this pest. AR1 pastures are susceptible to Root Aphid.

Max P:

MaxP® is a novel tall fescue endophyte that improves the ability of tall fescue pastures to handle pest attack and moisture stress. Unlike ryegrass endophyte, MaxP endophyte produces a loline compound. This compound along with peramine is likely to be a key factor in providing protection against Argentine Stem Weevil, Black Beetle, Pasture Mealy Bug and Root Aphid. MaxP can improve the drought tolerance of tall fescue. In areas where there are few insect pests and little moisture stress, MaxP may not be essential, but may still improve pasture production.

Standard Endophyte:

With the introduction of novel endophytes, this endophyte option is now outclassed. Stock grazing these pastures may suffer from ryegrass staggers and reduced animal performance during the warm part of the year. These effects may be reduced by adjusting summer/autumn grazing management.

Without Endophyte / Low Endophyte:

In areas with cooler summers and good rainfall or irrigation, (Westland, Southland, parts of Otago and some irrigated land in Canterbury), cultivars without endophyte, or with low levels of standard endophyte, can be used. Such pastures are animal safe, and will give very good animal performance. However, ryegrass without endophyte provides little or no protection against common insect pests.


Thought to provide insect protection similar to Endo5. NEA2 pastures contain low levels of Peramine and Ergovaline and very low levels of Lolitrem B.


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