NatioNal variety trials supplemeNt - Grains Research ...

Coordinated disease assessment
Disease ranking for wheat and barley lines and cultivars in NVT is now carried out
independently through nationally coordinated projects
Weeds and disease
10
By Emma Leonard
The use of varietal resistance remains
at the forefront for the management of
most important diseases of cereals.
To ensure growers have reliable
disease ratings on newly released
cereal cultivars, wheat and barley
pathologists are taking a very proactive
approach to gathering disease data from
inclusions within the National Variety
Trials (NVT) evaluation system.
To provide an independent disease
ranking system for the commercially bred
winter crops – wheat, barley and canola – the
GRDC has established several projects that
are run by disease experts across Australia
These screening and monitoring
projects include all the NVT lines prior
to commercialisation as well as an agreed
set of commercial cultivars. While
independence remains a cornerstone of
this work, good collaboration with the
breeding companies is also important.
Disease screening remains part
of the breeding programs run by
Pulse Breeding Australia, which is
an unincorporated joint venture.
Wheat
For the past five years a coordinated
disease assessment project for
wheat has been applied to NVT.
The project is coordinated by Dr
Grant Hollaway, senior plant pathologist
at the Victorian Department of Primary
Industries (DPI) and NVT. With his
colleagues at Horsham he coordinates
all the disease rankings work for wheat,
which is carried out with seven other
pathology teams across Australia.
The seed distributed to all collaborators
is from a single source for each variety
and supplied to the Victorian DPI by
the breeding companies. In addition,
the team maintains a current set of
wheat varieties already available to
growers, known as the AUSVAR set.
“Each year we distribute seed for about
120 NVT lines of bread wheat, durum
and triticales as well as about 100 from
the AUSVAR,” Dr Hollaway explains.
“Just for the Victorian component of
the project we are managing field nurseries
for the three rusts (stripe, leaf and stem)
and yellow leaf spot. In others states the
pathology groups evaluate the set of wheat
lines for diseases relevant to their district
and within their area of specialisation.”
In total, across Australia this
network of plant pathologists annually
evaluates the NVT lines against 14
different diseases of wheat (Table 1).
Within Australia the plant pathology
groups involved in the screening include
the state departments of agriculture in all
mainland states and at the University of
Sydney. The disease/s to be screened are
agreed between the GRDC, the NVT trial
management and the pathologists and are
often based on the environment and the skills
held by various pathologists around Australia.
“Not every disease will be screened
at every location, but duplicate locations
help reduce the risk of unconducive
seasons and enable better screening of
diseases with multiple pathotypes.”
In addition to trials in Australia,
some material is screened in the UK,
New Zealand and Mexico. This is to
establish disease ratings for pathogens
or pathotypes that pose potential
biosecurity threats to Australia.
While the pathologists observe the
NVT trial plots, the data for disease
ratings is collected from disease nurseries
in the field, mini plots or glasshouse.
To ensure the target diseases and
pathotypes are present, the pathologist
inoculates the trials with disease inoculum
they have gathered, tested and multiplied.
Data is recorded using a standard
template and returned to the NVT manager.
The whole process is run on a strict
timetable to ensure data is available to
growers at the start of the following year.
A pathologist with specialist
knowledge will nominate the ratings
for specific diseases, based on the
current and previous year’s data.
Where possible, a single national
rating will be assigned for each disease.
Where there are pathotype differences then
regional ratings are assigned as appropriate.
All plant breeders and relevant
parties are informed of the ratings
photo: Emma Leonard
Local agronomists are an important source
of information about the emergence of new
pathogens for pathologists. SARDI's Dr Hugh
Walwork (left), who is involved in the wheat
and barley screening work in South Australia,
discusses a new pathotype identified by Yorke
Peninsula agronomist Sam Holmes (right).
Table 1 Wheat and barley
diseases screened as part of
the nationally coordinated,
independent disease rating
system for NVT
Wheat
Black point
Bunt
Cereal cyst nematode
Crown rot
Common root rot
Flag smut
Leaf rust
Pratylenchus neglectus
Pratylenchus thornei
Powdery mildew
Septoria nodorum blotch
Stripe rust
Septoria tritici blotch
Yellow leaf spot
Barley
Barley yellow dwarf
virus
Cereal cyst nematode
Common root rot
(Bipolaris)
Covered smut
Net form net blotch
Spot form net blotch
Leaf rust
Pratylenchus neglectus
Pratylenchus thornei
Barley grass stripe rust
Barley stripe rust
Powdery mildew
Stem rust
Scald
Spot blotch