New Zealand Journal of Agricultural Research abstracts
Effects of natural reseeding and establishment method on contamination
of a novel endophyte-infected perennial ryegrass dairy pasture with other
ryegrass/endophyte associations
S. J. Bluett
E. R. Thom
B. W. Dow
V. T. Burggraaf
Dexcel
Private Bag 3221
Hamilton, New Zealand
D. E. Hume
E. Davies
B. A. Tapper
AgResearch Grasslands Research Centre
Private Bag 11 008
Palmerston North, New Zealand
Abstract The contamination of a perennial ryegrass (Lolium
perenne) dairy pasture infected with a novel endophyte with other ryegrass/endophyte
associations was studied over 2 years in Hamilton, New Zealand. Five management
treatments (turnip crop, usual rotational grazing, usual rotational grazing
followed by topping, silage making, hay making) were applied to produce a
range of natural reseeding levels, and then three establishment methods (spray/cultivation,
double-spray/fallow, hard-grazing) were used before drilling AR1 endophyte-infected
perennial ryegrass (no lolitrem B or ergovaline production). Contamination
from wild endophyte (Neotyphodium lolii)-infected perennial ryegrass,
endophyte-free perennial ryegrass, wild endophyte-infected hybrid (L. boucheanum
syn. L. hybridum)/Italian ryegrass (L. multiflorum), N. occultans
endophyte-infected hybrid/Italian ryegrass and endophyte-free hybrid/Italian
ryegrass tillers was determined. Contamination was assessed in the two summers
following the autumn (May 2000) sowing by measuring lolitrem B concentration
in bulk ryegrass samples and by sampling individual ryegrass tillers for
endophyte identification in late summer of Year 1. Within the hard-grazed
establishment treatment, the percentage of ryegrass tillers infected with
AR1 in late summer of Year 1 was highest (73%) following the turnip crop
pre-sowing treatment and lowest (4%) after hay making (SED = 5.3%, P
< 0.001). The percentages of AR1-infected perennial ryegrass tillers in
pastures established following spray/cultivation and double-spray/fallow treatments
were 86 and 76%, respectively, compared with only 15% in the hard-grazed treatment
(SED = 2.5, P < 0.001) (turnips excluded). The spray/cultivation
and double-spray/fallow establishment treatments consistently had lower concentrations
of lolitrem B in bulk ryegrass samples than the hard-grazed treatment, for
example in early autumn of Year 1 (0.3, 0.5, 1.1 mg kg–1 DM, P
< 0.001) and Year 2 (0.1, 0.2, 1.0 mg kg–1 DM, P <
0.001). Pasture production from August 2000 to August 2001 was similar following
the spray/cultivation, double-spray/fallow and hard-grazed establishment treatments,
averaging 14.9 t DM ha–1. It is recommended that ryegrass pastures
containing a novel endophyte be sown after a summer crop, or following a
spray/cultivation or double-spray/fallow establishment method, instead of
under-sowing into existing hard-grazed pasture. Methodology for assessing
pasture contamination with different ryegrass/endophyte associations is also
discussed.
Keywords AR1 endophyte; chemotyping; cultivation; glyphosate;
hybrid ryegrass, Lolium perenne; Lolium multiflorum; Lolium
boucheanum syn. Lolium hybridum; lolitrem B; Neotyphodium lolii;
Neotyphodium occultans
A03052; Online publication date 17 August 2004; Received 17 September
2003; accepted 24 March 2004
New Zealand Journal of Agricultural Research, 2004, Vol. 47: 333–344
0028–8233/04/4703–0333 © The Royal Society of New Zealand 2004
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