Stripe rust and other leaf diseases
Peter Wilkinson, DPI&F Plant Pathology, Toowoomba
P lenty of leaf and head diseases were
seen in the 2007 wheat crops, possibly
because of the unusual patterns of rain-
or, at latest, March. This eliminates or
greatly reduces the inoculum in a region
and can prevent or delay the onset of the
fall. next stripe rust epidemic. In addition to
your paddocks, check road sides, ditches
Stripe rust and anywhere else where volunteer wheat
Stripe rust was endemic throughout wheat plants might be found.
-producing areas of south and central Genetic resistance
Varieties with intermediate levels of resist-
ance to stripe rust may have adult plant
resistance (APR). This is genetic resistance
where the seedling is more susceptible
than the adult plant. Crop vigour, above-
average moisture, high fertility and early
disease onset may affect variety response
Wheat varieties with high levels (above 7)
of resistance to stripe rust are unlikely to
be affected by the disease and will restrict
the build-up of inoculum in the crop. This
will limit any epidemic and subsequent
New pathotype not yet in Queensland
A new pathotype of stripe rust (Pugs-
ley Pathotype 134 E16 A+YR17+) has
evolved from the WA pathotype 134 E16
A+ which has been present in eastern
Australia for the past four wheat growing
Stripe rust was common in 2007
seasons, but this new pathotype was not
found in Queensland in the 2007 season.
If there was any economic damage, it The response of varieties carrying the
occurred in wheat varieties that are Yr17 resistance may be different to the
susceptible—those rated 5 or 4 and less. response of those with the current WA
Check your The late-planted crops seemed to develop pathotype resistance. Should the new
2008 more stripe rust, probably because of the Pugsley Pathotype move into Queensland,
build-up of inoculum through the season,
Wheat Variety coupled with late rains.
current and projected varietal reactions
to stripe rust can be found in the 2008
Guide for High prices for wheat reduce the margin Wheat Variety Guide.
levels of for economic damage, and increase the Fungicides – Seed treatment
value of fungicide application.
disease Seed dressings and in-furrow treatments
Controlling stripe rust can suppress the development of early
resistance stripe rust; most are also effective against
smut. However, seed dressings and in-fur-
Stripe rust cannot survive for any length
row treatments can shorten the germinat-
of time on dead plants. It needs the ‘Green
ing shoot of the wheat plant, reducing
Bridge’ of living wheat plants that sur-
crop establishment, particularly when
vive through the summer to last from one
seed is sown deeply, in uneven seedbeds,
season to the next.
or when seed is of poor quality, such as
So your ﬁrst priority should be to destroy shrivelled.
all volunteer wheat plants by February
8 Winter grains 2008
Wheat cultural and chemical trials un-
dertaken by QDPI&F in 2007 validated Loose smut
previous ﬁndings. The best returns from There were a number of reports of loose
applying fungicide applications come smut over the 2007 wheat season.
when wheat infected with stripe rust is
Loose smut indicates poor seed quality
sprayed between “second node visible”
and/or a lack of the use of smut-control-
(stage 32) and the emergence of the ﬂag
ling seed dressings.
leaf. As the ﬂag leaf is the primary fac-
tory for grain production, protecting it is
essential for high yield and quality. Dam- Yellow spot
age to the ﬂag leaf by a foliar disease Some wheat-growing regions that re-
translates directly to yield loss. ceived late rains in the 2007 winter wit-
nessed a late infestation of yellow spot. Loose smut
However, fungicides will only give a
ﬁnancial return if stripe rust is present. This infestation was of little economic
Crops should be inspected for stripe rust consequence and was hardly noticed by
at regular intervals, especially after stage growers. However, you should be alert to
32 (second node visible) and after cool, the fact that the yellow spot inoculum has
wet weather, which favours the disease. now had a chance to build up and could
Check the crop for stripe rust even if you pose a risk to the 2008 crop if the wetter
have sown a resistant variety, in case the conditions forecast persist.
new pathotype is present.
Scouting the crop for pests and diseases
and applying fungicides at the ﬁrst sign A head-blight was seen this year. Speci-
of rust would seem the best strategy in mens were collected by DPI&F and we
controlling the disease and minimising are conﬁrming the identity of the fungal
losses. pathogen that caused the disease.
A list of fungicides is in the DPI&F pub- If you see any of these symptoms, please
lication: “Wheat – managing stripe rust” phone the DPI&F Business Information
available from the DPI&F or online at: Centre on 13 25 23 for your local DPI&F
www2.dpi.qld.gov.au/ﬁeldcrops/17139.html development ofﬁcer.
Phone: (07) 4639 8884
Wheat heads affected by various levels of severity of head blight
Future Grains 9