What is it?
Endophyte is a fungus that is associated with many types of grass
including perennial ryegrass. The endophyte produces chemicals
that protect the grass from things that want to eat it, including
insects and grazing animals. Endophyte grows between the plant
cells and when the plant runs to head the endophyte grows into
the developing seed and in this way infects the next generation of
ryegrass.
Why is it important?
Endophyte is important because it can help protect the plants
from insect damage, improving ryegrass persistence - but
sometimes it can also cause animal health problems. Ryegrass
Endophyte produces a number of chemicals, with three major
chemicals identified so far:
- Peramine - a natural insecticide that acts as a deterrent to
some important pests
- Lolitrem B - causes summer ryegrass staggers
- Ergovaline - deters at least one pasture pest, but can
reduce animal performance
Endophyte chemicals are found in highest concentrations during
the warmest time of the year. Drought can cause marked
increases in endophyte chemical concentrations. Ergovaline and
Lolitrem B are mainly at the base of the plant or in seed heads,
while Peramine is more widely distributed. Therefore, effects from
Ergovaline and Lolitrem B can be worse under prolonged hard
grazing during dry summers.
Standard and “Novel” endophytes
Most perennial ryegrasses contain their own unique endophytes.
These ‘standard’ endophytes (sometimes also called ‘feral’,
‘wild’ or ‘wild type’) all produce Peramine, Lolitrem B, and
Ergovaline, but in varying amounts, depending on both the
endophyte strain and the ryegrass cultivar they live in. Many
hundreds of these endophyte strains have been examined and
occasionally one is found that produces a very different chemical
signature to ‘standard’ endophytes. These are called ‘novel’
endophytes, of which AR1, AR5 (Endosafe), AR6 and NEA2 are
commercially available.
Once found, novel endophytes can be removed from their
original ryegrass host, and injected into commercially useful
cultivars.
Nil endophyte commercial cultivar at left compared to Fitzroy with wild
type endophyte three years after sowing.
Endophyte Research
Wrightson continue to monitor trial results in both Australia and
New Zealand to develop the appropriate perennial ryegrass and
endophyte strategy to suit the various climates within Australia.
Our trials consistently show that the commercially available nil
endophyte varieties do not persist as well as commercial cultivars
with novel or wild type endophyte.
Local and overseas research suggests that to provide maximum
persistence in the broadest range of Australian environments,
low to moderate levels of ergovaline are required in perennial
ryegrass.
We have monitored endophyte levels within cultivars to provide
various options to producers. Whilst Aries HD, Quartet and more
recently Banquet are all available in Australia with wild type
endophyte, they have shown lower levels of both Lolitrem B and
Ergovaline than many other commercial wild type cutivars.
ARI is widely recommended in various parts of NZ and Wrightson
will be marketing ARI products in dairy regions of Australia.
However, we believe a more robust endophyte is needed in black
beetle infested areas as well as marginal areas of Australia.
We have opted for other novel endophytes that we believe
provide a better compromise between persistence and animal
performance. Extreme with AR6 novel endophyte contains no
Lolitrem B and therefore will not cause ryegrass staggers. It does
have some Ergovaline which is concentrated in the crown of the
plant, so if managed correctly should pose little risk.
So Australian producers can have confidence that the Wrightson
ryegrass culivars that they sow will have a top combination of dry
matter production, persistence, forage quality and animal
performance.
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