Eyespot – variety tolerance and
fungicide efficacy
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Location:
Edillilie
Joe and Tracy Dahlitz
Rainfall
Av. Annual: 424 mm
2015 Total: 360 mm
2015 GSR: 303 mm
Paddock History
2014: Bread wheat
Soil Type
Sand over clay
Plot Size
2 m (6 rows) x 8 m (variety) x 3
reps (fungicide)
Key messages
• Eyespot has the potential to
cause significant yield losses
on lower Eyre Peninsula in a
susceptible variety such as
Mace. Losses in the range
of 22-27% (1.11-1.36 t/ha)
or more might be expected
from eyespot lesions alone
and the more harvest is
compromised
by
crop
lodging due to weakened
stems, the higher the yield
losses are likely to be.
• Findings from 2014 and
2015 indicate that where
eyespot is a problem, avoid
the varieties Scout, Mace,
Axe, Shield, Cobra, Corack,
Cosmick and Wyalkatchem.
In preference select Trojan
or Emu Rock.
• Findings for barley varieties
are less clear, but generally
they have a lower incidence
of eyespot than bread wheat
varieties and La Trobe
and Hindmarsh are most
affected while Compass is
least affected. There is also
some indication that barley
with stems weakened by
eyespot might be more at
risk of yield losses due to
harvest difficulties caused
by lodging than bread wheat.
• Fungicide
application
resulted in significant yield
improvements where high
levels of eyespot inoculum
was present. Remember that
no fungicides are currently
registered
for
eyespot
control in Australia.
• Plant
growth
regulants
assisted in reducing lodging
due to eyespot, but the
economics of using these
products will need to be
considered carefully.
• It is anticipated that at
least two fungicides will
be registered/have label
extensions
for
eyespot
control in cereals in Australia
in 2016.
Why do the trial?
These variety and fungicide
efficacy trials have assisted in
identifying resistance sources for
eyespot and have provided data
to support chemical companies
acquiring label extensions to
register fungicides for use against
eyespot in cereals in Australia.
Eyespot is an increasing problem
in the higher rainfall grain growing
areas of SA such as lower Eyre
Peninsula, the Cleve Hills, the mid
North, the Adelaide Plains and
the South East. This increase is
mainly due to farming systems
moving to stubble retention,
direct drill and more cereals in
rotations. In Australia, eyespot in
cereals is caused by the fungus
Oculimacula yallundae (previously
known as Pseudocercosporella
herpotrichoides) which infects
stem bases causing the eye-
Eyre Peninsula Farming Systems 2015 Summary
h
c
Resear
like lesions which gives eyespot
its name. Yield losses from this
disease occur as a direct result of
the stem lesions and, secondarily,
from plants lodging due to
weakened stem bases which can
make it difficult or impossible to
harvest affected plants. Overseas,
eyespot control includes fungicide
application and the use of
partial resistance in varieties. As
eyespot has had a very restricted
distribution in Australia, no
fungicides have been registered
for control of eyespot in cereals
and little has been known about
resistance levels in Australian
varieties.
GRDC has funded a two year
program to assess fungicide
efficacy and varietal resistance in
Southern Australian germplasm.
Information presented here is from
the second year of the research
and follows on from an article
which can be found in EPFS
Summary 2014, p 119-121.
How was it done?
The Edillilie site was located in
a paddock which had eyespot
problems in the 2014 wheat crop
and had significant cereal residues
and medium levels of eyespot
inoculum (19,875 copies of
eyespot DNA per g of soil) present
at the start of 2015. To encourage
eyespot expression, the trial was
sown early in the seeding window
(14 May 2015) at a high plant
density (250 plants/m²) and with
high nitrogen inputs (190 units of
N). Trials were sown, managed
and fungicide treatments applied
by Cummins Agricultural Services.
Plots were 5 rows (2 m) wide by
8 m long. The variety trial had 3
replicates and the fungicide trial
had four replicates.
97
Disease
Margaret Evans and Hugh Wallwork
SARDI, Plant Research Centre, Urrbrae
Variety screening. Twelve bread
wheat, 4 barley and 1 triticale
varieties as well as 7 breeders’
lines were screened for resistance
to eyespot. Entries were chosen
to represent a range of genetic
backgrounds (including genes
for resistance to crown rot) and
maturities.
Fungicide efficacy. The variety
Mace was used in the fungicide
trial and products assessed were
all registered for use in cereals
in Australia, but not for eyespot
control. Twelve products (including
plant growth regulants) were
represented in the fungicide trial,
which was done in collaboration
with Adama Agricultural Solutions
Ltd, BASF Australia Ltd, Bayer
CropScience
Australia
and
Syngenta Australia Pty Ltd. Details
of fungicides assessed cannot be
presented here as they are not
registered for control of eyespot
in cereals in Australia. Fungicide
treatments were applied using a
hand boom on 17 July 2015 early
in stem elongation (GS31), before
canopy closure.
Stem samples were assessed for
eyespot expression on 23 October
2015, when plants were at late
grain fill. A total of 25 stems were
assessed in each plot, with 8-9
stems taken from each of the 3
inner rows of the plot. A scoring
scale of 0-3 was used, where:
0 = no lesions.
1 = slight eyespot – small
lesion(s) on less than half the
stem circumference.
2 = moderate eyespot - lesion(s)
on at least half the stem
circumference.
3 = severe eyespot – lesion(s)
girdling the whole stem; tissue
softened, lodging would occur
readily.
This scale was taken from Scott
and Hollins (1974) and their
formula was used to calculate a
disease index: (1*tillers with score
1 + 2*tillers with score 2 + 3*tillers
with score 3) / total tillers scored)
* (100 / 3).
Plots were scored for lodging on
23 October and 16 November
2015, with the % of the plot
showing lodging being recorded.
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What happened?
The trials established well, but
levels of eyespot (76% incidence
on Mace stems) were intermediate
due to few rainy days during
tillering and early stem extension.
Weeds, other diseases and insect
pests were adequately controlled.
Variety screening. Wheat varieties
with highest incidence of eyespot
included Scout, Mace, Wallup and
Wyalkatchem (Fig. 1). The least
affected wheat varieties included
Trojan, Spitfire and Emu Rock,
which all carry a gene that confers
MS resistance to crown rot. Emu
Rock, Trojan, Gazelle and Scope
had the lowest lodging levels and
Suntop and Scout had the highest
lodging levels (Fig. 2). Lodging in
Spitfire, Suntop and Scout (Fig. 2)
was consistent with the incidence
of eyespot in their stems. All
other wheat varieties generally
had lower lodging levels (Fig. 2)
than indicated by the incidence of
eyespot in their stems (Fig. 1).
Barley varieties generally had
lower rates of eyespot incidence
than did the wheat varieties (Fig.
1) and the levels of lodging (Fig.
2) for all barley varieties was
consistent with the incidence of
eyespot in their stems.
Fungicide efficacy. All the
products applied provided some
protection against eyespot with
the incidence of eyespot in stems
ranging from 14% (most effective)
to 41% (least effective), compared
with an eyespot incidence of 76%
for the untreated control. Most
fungicide products provided a
significant lowering of lodging
levels when compared with the
control, particularly where a
PGR was added (Figure 5). Yield
improvements over the untreated
control were also achieved, with
yield increases ranging from 7%
to 22% (0.35-1.11 t/ha) across the
products applied.
What does this mean?
Yield loss. In Mace (susceptible)
in our trials, yield losses from
eyespot were at least 27% (1.36
t/ha) in 2014 (entirely due to
eyespot lesions) and at least 22%
(1.11 t/ha) in 2015 (some influence
of lodging on yield). Given the
differences in eyespot inoculum
levels and seasonal conditions at
the 2014 and 2015 trial sites, these
results suggest that significant
yield losses can be expected from
eyespot on lower Eyre Peninsula
if eyespot inoculum is present at
high levels. Where harvest is badly
compromised by lodging due to
eyespot, yield losses could be
considerably higher than this.
Variety screening. Results from
2015 showing Trojan and Emu
Rock were least affected by
eyespot and Mace, Scout and
Wyalkatchem were worst affected
is consistent with 2014 results.
Results from 2014 indicate that
Shield, Axe, Cobra and Corack
should also be avoided where
eyespot is an issue.
The incidence of eyespot in barley
varieties was somewhat lower
than that seen in bread wheat, but
this difference is less clear than for
2014. Barley varieties appear to be
less consistent in their response
to eyespot than the bread wheat
varieties which makes it difficult
to recommend one variety over
another or over bread wheat.
Lodging incurred as a result of
eyespot lesions weakening stems
was relatively higher than that
in bread wheat varieties which
suggests that barley affected by
eyespot might be more at risk
of yield losses due to harvest
difficulties.
Data from the variety screening
trials (which included breeders’
lines for which data are not
presented here) will be provided
to breeders to feed into their
breeding programs.
Fungicide efficacy. Most of the
fungicide products assessed
reduced
eyespot
incidence
and expression in bread wheat.
Although no product achieved
complete control of the disease,
the level of control was sufficient
to result in significant yield
improvements in treated plots
when compared with the untreated
plot. Significant differences were
difficult to detect between the
products which means that once
products are registered for use in
managing eyespot, it is likely that
the choice of product will mainly
be decided by the price of that
product.
Eyre Peninsula Farming Systems 2015 Summary
Plant growth regulants alone or
in combination with fungicide
products were effective in reducing
lodging due to eyespot, but the
economics of this would need to
be considered carefully.
plants. Including nozzle types,
boom heights and timing of
applications to ensure the
canopy is open. Earlier timing
of applications may also allow
application in the same pass
as herbicides, but only if this
does not compromise eyespot
control.
• Epidemiological studies to
determine timing of air-borne
spore dispersal and therefore
optimum time for sowing.
Disease
Data from fungicide trials have
been distributed to participating
companies and it is anticipated
that at least two fungicides will be
registered/have label extensions
for eyespot control in cereals in
Australia in 2016.
Future research opportunities
include:
• Further screening of cereal
varieties
(including
new
varieties pre- and postrelease).
• Quantifying the effect of varietal
resistance on the magnitude
of yield improvements due to
fungicide application.
• Improving
contact
of
fungicides with the base of
Figure 1 Effects of cereal type and variety on incidence of eyespot – Edillilie, 2015. Bread wheat varieties are
presented as grey and barley varieties as white columns.
Figure 2 Effects of cereal type and variety on lodging due to eyespot – Edillilie, 2015. Bread wheat varieties are
presented as grey and barley varieties as white columns.
Eyre Peninsula Farming Systems 2015 Summary
99
Figure 3 Effects of fungicide
(Fung) and plant growth regulant
(PGR) treatments on yield
of Mace bread wheat in the
presence of eyespot – Edillilie
2015. Treatments in the same
block as the untreated control
have yields which are not
significantly different from the
untreated.
Figure 4 Effects of fungicide
(Fung) and plant growth
regulants (PGR) treatments on
incidence of eyespot in Mace
bread wheat – Edillilie 2015.
All treatments had significantly
lower incidence of eyespot on
stems than the untreated.
Figure 5. Effects of fungicide
(Fung) and plant growth
regulants (PGR) treatments on
lodging due to eyespot in Mace
bread wheat – Edillilie 2015.
Treatments in the same block
as the untreated have lodging
percentages which are not
significantly different from the
untreated.
Acknowledgements
This project was funded by GRDC
through DAS0139 “Improving
grower surveillance, management,
epidemiology knowledge and
tools to manage crop disease in
South Australia”. Thanks to Joe
and Tracy Dahlitz for providing a
100
trial site on their property at Edillilie
and to Pat Head (Landmark –
Cummins Agricultural Services)
for managing the site and applying
treatments
and
organising
assessment of treatments. Thanks
also to those who assisted in
planning for these trials – BASF
Australia Ltd, Bayer CropScience
Australia, Syngenta Australia Pty
Ltd, Adama Agricultural Solutions
Ltd and Landmark – Cummins
Agricultural Services.
Eyre Peninsula Farming Systems 2015 Summary