Frequently asked questions
Q: What is AR37?
A: AR37 is a novel endophyte developed
by AgResearch. It is a fungus that lives inside seed,
and plants that grow from that seed. It is a natural
organism with no genetic modification or engineering.
Q: What are the advantages of AR37?
A: Compared with a ryegrass of the
same cultivar infected with AR1 or standard endophyte
(SE) that were sown in 11 trials over 4 years, AR37
provided ryegrass plants with protection from a wider
range of insect pests; increased dry matter production
(average of 12% annually); larger and deeper root mass;
and better persistence. (Hume et al 2004: In Proceedings
of the 5th International Symposium on Neotyphodium/Grass
Interactions; Hume et al 2007: Proc NZ Grassland Assn,
69: 201-05)
Q: What insects does AR37 protect against?
A: Like the AR1 endophyte, AR37 provides
protection from Argentine stem weevil larvae and pasture
mealy bug with better control of black beetle. (Popay
& Thom: Proc NZ Grassland Assn, 71: 121–27).
AR37 controls the life cycle of Black Beetle at the
adult stage rather than the larval stage. AR37 also
protects plants from root aphid, and in laboratory trials
has been shown to be both a deterrent and toxic to porina.
(Jensen & Popay 2004: NZ Plant protection 57: 323-28)
In a field trial no porina were found in plots of AR37
whereas endophyte free and AR1 plots measured 10 larvae/m2.
(AJ Popay Unpublished data)
Q: What is the risk of ryegrass staggers?
A: While AR37 does not produce the
alkaloid lolitrem B it can cause ryegrass staggers in
grazing livestock. In grazing trials at Lincoln the
incidence of ryegrass staggers on pure ryegrass with
AR37 has been less frequent and usually only as half
as severe as on ryegrass with standard endophyte. However
these trials have shown that spasmodically AR37 can
cause serious staggers. (Fletcher & Sutherland 2009:
Proc NZ Grassland Assn, 71: 127-33).
To date, no ryegrass staggers have been observed with
any class of cattle on AR37 in trials or on commercial
farms. Due to the fact that no trial work has been undertaken
on deer or horses, pastures with AR37 are currently
not recommended for these livestock classes or other
untested species.
Q: How well do animals perform on AR37?
A: The performance of sheep on pure
ryegrass pastures have been better on AR37 than on the
same ryegrass cultivar infected with Standard Endophyte.
This is greatest in the summer and autumn when endophyte
toxins are likely to be the highest. Growth rates on
AR37 are similar to the same ryegrass cultivar without
endophyte or AR1 and superior to Standard endophyte
when the average ryegrass staggers score is less than
2 (Fletcher & Sutherland, 2009: NZ Grassland Assn,
71: 127-33). The DairyNZ trial on Scott Farm (Waikato)
compared Commando perennial ryegrass-based pasture infected
with AR37, AR1, Standard (HE) or without endophte (Nil).
The project aimed to measure ryegrass persistence and
pasture yields and to assess any effects of the AR37
endophyte on cow health and milk production. In the
fourth and final milking season white clover was removed
to test the effect of endophyte/ryegrass association
in isolation from any effect on clover content of pastures.
The following bullet points present a summary of results
from the four seasons.
Overall conclusions:
- AR37 ryegrass was clearly more persistent than
either AR1 or Standard (HE) ryegrass. This supports
findings from previous work.
- The greater persistency translated into a reduced
need for renovation of AR37 pastures after the 2008
drought, but in the three years before that time there
was no difference in total pasture yield.
- There was no sign of ryegrass staggers or any other
animal health issues in cows grazing AR1 or AR37 pastures
– even at times when cows grazing HE were affected
by ryegrass staggers.
- With ryegrass/white clover pastures, there was
a trend for slightly lower milksolids (MS) production
over summer from cows grazing AR37 or HE compared
with AR1. With pure ryegrass pastures there were no
significant differences in MS production. These results
suggest that the higher clover content of the AR1
mixed pasture was a contributing factor to the observed
MS production differences.
- Where pasture persistence is the top priority then
AR37 will clearly deliver benefits. Where persistence
of AR1 ryegrass is not a problem, continuing to sow
AR1 is advised. DairyNZ cannot envisage any situation
in which farmers should sow HE ryegrass.
Q: Is there any difference in palatability
with AR37 and AR1
A: There have been no palatability
differences noted between AR1 and AR37 pastures.
Q: What benefits can I expect from AR37?
A: While the average advantage in ryegrass
growth of AR37 over Standard Endophyte in the same cultivar
is 12% across 11 trials across the country over four
years, farms will experience advantages both higher
and lower than this.
The benefits will vary from farm-to-farm due to the
wide range of insect populations, climatic stress and
pasture management. Generally, trials have shown greater
benefits the further north they are in the country,
though AR37’s improved performance where porina
exists compared to AR1 and nil endophyte means that
it will have a key role in some South Island environments
(AJ Popay, Unpublished Data). Trials have also shown
that the greatest advantages exist where insect populations
are higher (Hume et al 2007: Proc NZ Grassland Assn,
69: 201-05).
In most environments, the advantages in pasture growth
will increase over time. This has been shown in trials
where small advantages show up in the first year, but
advantages are greater in the second and third years.
This is likely to be due to insect populations building
after establishment, and the increasing pasture production
advantages resulting from greater ryegrass persistence.
While the average annual dry matter production advantage
to AR37 is 12%, the average advantage in summer is 15%
and 21% in autumn (Hume et al, 2007: Proc NZ Grassland
Assn, 69: 201-05).
Q: Who should use AR37?
A: Farmers who want improved pasture
production, persistence and animal performance from
their pastures should use AR37, especially where damaging
insects are likely to be present. Trials that have been
undertaken show that AR37 is a suitable pasture for
dairy cows, sheep, and beef animals. Pastures with AR37
have their largest differences in dry matter results
compared to the same cultivar with standard endophyte
in regions from Taupo north. These regions normally
experience severe insect pressure.
AR37 should be used where pasture persistence is a
key factor and where improved dry matter production
is likely to occur compared to other endophyte options.
This is most likely to happen where pastures are under
pressure from a range of insect pests and/or drought.
AR37 has been tested for agronomic and animal performance
with sheep and dairy cows.
Q: How long has AR37 been around for?
A: AgResearch together with its commercial
partners began work on developing the AR37 endophyte
in 1995. AR37 ryegrass cultivars were released commercially
in autumn 2007.
Q: Which ryegrass cultivars have AR37?
A: AR37 is available in a range of
ryegrass cultivars from Agricom, PGG Wrightson Seeds
and NZ Agriseeds. To find out what will work best for
you, contact:
Agricom | Ph: 0800 183 358
PGG Wrightson Seeds | Ph: 0800
805 505
NZ Agriseeds | Ph: 03 318
8514
Commercial cultivars available with AR37 endophyte:
Q: How should pasture with AR37 be established?
A: As with new AR1 pastures, all existing ryegrass
plants should be removed from the paddock (using spraying
and/or ploughing), and old ryegrass seed buried or germinated
(following multiple spray applications or cropping)
before planting ryegrass with AR37. Re-establishment
of old ryegrass plants will not result in failure but
can reduce animal performance (if old ryegrass has standard
endophyte), pasture production and possibly persistence.
Q: Do AR37 pastures require insect protection
at establishment?
A: AR37 pastures require the same level
of insect protection as other endophyte options during
the establishment phase. This is because in all establishing
plants containing endophyte there is a lag period (approximately
six weeks) before the endophyte is present in sufficient
concentrations to provide protection. A seed treatment
such as Superstrike will provide protection during establishment.
Q: AR37 is not the perfect endophyte - so what
is?
A: At the moment AR37 endophyte provides
ryegrass with much better dry matter production and
persistence than any other commercially available endophyte.
While AR37 does not produce the alkaloid lolitrem B
it can cause ryegrass staggers in grazing livestock.
In grazing trials at Lincoln the incidence of ryegrass
staggers on pure ryegrass with AR37 has been less frequent
and usually only as half as severe as on ryegrass with
standard endophyte. However these trials have shown
that spasmodically AR37 can cause very serious staggers.
(Fletcher & Sutherland, 2009: Proc NZ Grassland
Assn, 71: 127-33).
While it is acknowledged there is a risk of ryegrass
staggers in using AR37, there are significant other
benefits from the technology for farmers. Research is
ongoing in looking to develop an endophyte that removes
this risk but like many issues until such a development
there will always be some compromise with endophyte
technology.
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