What is Endophyte?
Endophyte is a fungus found in many grass species. 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 Life Cycle
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.
Endophyte Summary:
- Ryegrass with AR37 endophyte: Provides the best insect control 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.
- Ryegrass with Endo5 endophyte: Provides very good insect control, and does not contain Lolitrem B, the main causative agent of ryegrass staggers. Endo5 pastures protect against adult Black Beetle, Argentine Stem Weevil and Pasture Mealy Bug. Endo5 pastures should persist better than AR1 pastures in areas with Black Beetle.
For more information on Endo5 click here. - 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.
- Ryegrass containing standard (wild type) 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.
- Ryegrass with NEA2 endophyte: Thought to provide insect protection similar to Endo5. NEA2 pastures contain low levels of Peramine and Ergovaline and very low levels of Lolitrem B.
- Ryegrass without 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.
Summer/Autumn Grazing Management:
Animal health problems caused by endophyte can be reduced by adjusting summer/autumn grazing management. Hard grazing to the base of pastures containing Lolitrem B and/or Ergovaline will increase the likelihood of endophyte related animal health problems.
Note: In pastures with AR37 ryegrass, Porina can be present and feed on the other pasture mix components. Early field trial results have confirmed laboratory evidence of resistance of ryegrass with AR37 to Porina.