Septoria and Stagonospora Diseases of Cereals - CIMMYT ...

Calingiri (Chino/Kulin//
Reeves) also exhibited resistance
and while some of this low disease
expression may have been due to
later maturity, the performance was
measurably superior to the similar
maturing but susceptible variety
Stiletto. Crossbreds 483W3, 78Z976
and 77Z893 (Corrigin sib) also
expressed high levels of resistance,
as indicated by low disease scores,
the non-significant yield losses, and
the resulting high relative yields
(yield diseased was 89-101%
relative to fungicide protected)
(Table 1).
Resistance to P. nodorum
Five moderately resistant lines
achieved high grain weights in
diseased plots relative to fungicide
protected plots. Variety Brookton
(Torres/Cranbrook//76W596/
Cranbrook) developed significantly
less disease and no significant
grain weight reduction when
compared with susceptible
varieties of equivalent maturity
such as Aroona or Millewa.
W48795, Tammin, and sister line
81W1137 had similar maturity to
susceptible variety Gamenya.
These lines developed significantly
less disease than Gamenya and had
smaller grain weight reductions in
the presence of disease. Line
W48433, derived from CNT2, was
similar to Tammin and developed
low disease in 1995 and high
relative grain weights in 1995 and
1996. This line was comparable
with the resistant parent CNT2 for
disease severity and relative grain
weight in 1995, though relative
grain weight appeared less robust
than that of CNT2 in 1996 (Table 2).
Varieties and Advanced Lines Resistant to Septoria Diseases of Wheat in Western Australia 147
Westonia (SpicaTimg.Tosc/
Cr:J2.Bob), Cunderdin (Cranbrook
sib/Sunfield sib), Carnamah
(Bolsena-1ch(RAC529)/77W660),
and Cascades gave responses that
were intermediate between the
resistant and susceptible lines.
Although hundred grain weight
reductions in the presence of
disease were generally significant,
the grain weight reductions were
less than for susceptible lines.
Although excellent levels of M.
graminicola resistance from diverse
sources have been observed in lines
such as 483W3 and 78Z976,
moderate resistance derived from
WW15 via Aroona and Condor
(Wilson, 1994) has had the greatest
impact in the development of
commercial varieties. While this
moderate resistance can be more
difficult to identify in intensive
disease nurseries, its effect has been
observed often in practice and
previously reported (Loughman
and Thomas, 1992).
Significant progress has been
made in developing moderate
resistance to P. nodorum.
Commercial varieties currently
exhibit improved responses
compared with their susceptible
predecessors, and some varieties
and advanced lines perform at
similar levels to resistant control
varieties. In some cases moderate
resistance to different leaf spot
diseases has been combined.
Cascades combines moderate
resistance to both M. graminicola
and P. tritici-repentis (Loughman et
al., 1998). Brookton, Cunderdin,
and Westonia have moderate
resistance to P. tritici-repentis
(Loughman et al., 1998), in
combination with partial resistance
to P. nodorum. Because P. nodorum,
M. graminicola, and P. tritici-repentis
frequently occur as disease
complexes in Western Australia,
combinations of resistance are
important for effective disease
management.
References
Loughman, R., and Thomas, G.J. 1992.
Fungicides and cultivar control of
Septoria diseases of wheat. Crop
Protection 11: 349-54.
Loughman, R., Wilson, R.E., and
Thomas, G.J. 1994. Influence of
disease complexes involving
Leptosphaeria (Septoria) nodorum on
detection of resistance to three leaf
spot diseases in wheat. Euphytica
72: 31-42.
Loughman, R., Wilson, R.E., Roake,
J.E., Platz, G.J., Rees, R.G., and
Ellison, F.W. 1998. Crop
management and breeding for
control of Pyrenophora triticirepentis
causing yellow spot of
wheat in Australia. In Duveiller, E.,
H.J. Dubin, J. Reeves, and A.
McNab (eds.). Helminthosporium
Blights of Wheat: Spot Blotch and
Tan Spot. Mexico, D.F.: CIMMYT.
Wilson, R.E. 1994. Progress toward
breeding for resisance to the two
septoria disease of wheat in
Australia. Pp. 149-152 In: E.
Arseniuk (ed.). Septoria of Cereals,
Proc. Fourth International
Workshop on Septoria Diseases of
Cereals. IHAR, Radzikow, Poland.
Zadoks, J.C., Chang, T.T., and
Konzak, C.F. 1974. A decimal code
for the growth stages of cereals.
Weed Research 14: 415-21.