NORTHERN STRIPE RUST MANAGEMENT: AN EVALUATION OF
SEED TREATMENT EFFICACY AND BENEFITS
Richard Daniel, Northern Grower Alliance (NGA)
Key words
Wheat, stripe rust, leaf disease, fungicides, yield
GRDC code
NGA00001: validation and integration of new technology through grower groups
in north-west NSW and south-west Queensland grain growing zones
Take home messages





Plant establishment counts showed good levels of crop safety from the
seed treatment under a range of conditions
Seed treatment still provided significant suppression of stripe rust in the
variety Lang, over 100 days after planting
No impact of seed treatment on yield in the absence of stripe rust
No yield impact from either seed treatment or foliar use where stripe rust
severity was very low and moisture/ heat caused major yield limitations
Seed treatment will be a valuable risk management tool in situations of
moderate to high stripe rust risk (susceptible varieties/ higher yield
potentials)
Background
In recent years stripe rust has re-emerged as a disease of significance across all
Australian grain growing areas. Plant breeding incorporating resistant germplasm
represents the most effective method of long term disease management.
However fungicides are an additional tool that will enable disease management
in varieties without effective genetic resistance.
Currently there are no varieties with effective stripe rust resistance combined with
useful tolerance to crown rot. Until such varieties are released, northern growers
and advisers need to select varieties firstly on the basis of crown rot risk and then
manage for stripe rust accordingly.
Research conducted in 2005 by Steven Simpfendorfer, NSW DPI Tamworth,
demonstrated significant yield benefits from the use of ‘at planting’ treatments for
stripe rust management on susceptible varieties (ratings 1-4). Two planting
options provided greatest benefit; Jockey® - a long acting seed treatment and
Impact® - a fertilizer treatment. Although disease onset did not occur until GS49
(awn peep), yield benefits of 17%-27% were obtained from the use of Jockey (at
300-450 mL/100 kg seed) and 19% from Impact. The level of yield benefit was
similar to the 23% obtained from a single high rate fungicide application at GS49.
This project focused on examining the crop safety, length of efficacy and
economic benefit available from Jockey under northern conditions. The aim was
to validate the 2005 NSW DPI results and generate additional data to enable
improved advice for regional stripe rust management.
Methods
Five commercial replicated trials were established in 2006 in the Wyaga, Billa
Billa, Boomi, Garah and Edgeroi districts. Trial co-operators were selected who
were growing moderately susceptible varieties (ratings 4-5) and intended to treat
with Jockey. Jockey was evaluated in all trials at the 300 mL/100 kg seed
application rate. In each situation a small amount of the same seed batch was
left untreated. Varieties evaluated were Sunco and Lang (both rating 5) and EGA
Wylie (rating 4).
Individual plot sizes ranged from 12-72 m wide x full field length with row
spacings from 22-40 cm. Trials were assessed for plant establishment, stripe rust
efficacy and taken through to commercial harvest for grain yield and quality.
Weigh bin yields were taken at 4 of the 5 sites. The Wyaga site was not
harvested due to extremely low yields (<200 kg/ha) and high site variability from
non-treatment effects.
Results
Plant Establishment
All sites were assessed between 17 and 34 days after planting. Relatively deep
planting was evident at both the Boomi and Garah sites (seed 7-10 cm below
surface) with moderate moisture stress already evident at the Wyaga site. There
was no significant difference in establishment counts evident at any location or
over the entire series of trials (Figure 1).
160
Untreated
Jockey 300 mL
140
Plant stand/ sq m
120
100
80
60
40
20
0
NGA0601 Wyaga
NGA0602 Billa Billa
NGA0603 Boomi
NGA0604 Garah
NGA0605 Edgeroi
No significant difference in any trial
Figure 1: Plant establishment across all sites
Disease progression
No stripe rust was found at the Wyaga site with trace levels only at Billa Billa,
Boomi and Garah. Significant levels of stripe rust only occurred at the Edgeroi
site (Figure 2). Disease levels at the end of September combined with crop
potential at that stage resulted in a preventative foliar spray being applied to half
of each plot on October 2. Hot and dry conditions during early October however
largely stopped any further spread of the disease. Stripe rust at all sites was
confirmed as the WA pathotype (134 E16 A+).
This trial represents a situation with late onset of disease and both very
low stripe rust incidence and severity.
5
Flag-3
Flag-2
Flag-1
Flag
Severity
(% leaf area infected)
4
3
2
1
0
GS33-39 (Flag -1 to flag emerged)
GS55 (50% head emerged)
GS77 (late milk)
20 Sep
(88 days after planting)
30 Sep
(98 days after planting)
17 Oct
(115 days after planting)
No disease evident
Disease evident on 14% of
leaves
Disease evident on 15%
of leaves
Figure 2: Stripe rust progression in variety Lang (5) NGA0605
Fungicide performance
Figure 3 shows the performance of the range of treatments at both assessments.
Jockey alone still provided significant reductions in stripe rust severity up to 115
days after planting. The application of Tilt® 250 mL/ha, on Oct 2, on plots where
seed had been untreated provided equivalent levels of stripe rust management to
the seed treatment alone. No disease was found in plots where Jockey had been
used at planting and then followed up with Tilt. However this was not significantly
different to the suppression achieved by the seed treatment or foliar application
alone.
0.3
Severity
(ave % leaf area infected)
DAS 98
DAS 115/ 1DAA 15
a
0.2
0.1
b
b
b
0.0
Untreated
Jockey 300 mL
UTC + Tilt 250 mL
Jockey 300 mL + Tilt 250
mL
Treatments sharing the same letter (in each timing) are not significantly different
LSD value: DAS 113/1DAA 15 = 0.11%
Figure 3: Fungicide efficacy on stripe rust in variety Lang (5) NGA0605
Grain yield and quality
There was no significant difference in grain yield between Jockey and the
untreated at any of the four sites harvested (Figure 4).
There was no apparent treatment impact on grain quality.
3500
Untreated
Jockey 300 mL
3000
Grain yield kg/ha
2500
2000
1500
1000
500
0
NGA0602 Billa Billa
NGA0603 Boomi
NGA0604 Garah
No significant difference in any trial
NB No stripe rust at sites NGA0602/03 and 04, very low incidence and severity at NGA0605
NGA0605 Edgeroi
Figure 4: Grain yield across all sites
There was no significant difference in grain yield between any of the fungicide
treatments and the untreated at the Edgeroi site (Figure 5).
There was no apparent treatment impact on grain quality.
4000
Grain yield kg/ha
3000
2000
1000
0
Untreated
Jockey 300 mL
Untreated + Tilt 250 mL
Jockey 300 mL + Tilt 250
mL
No significant difference between treatments
Figure 5: Grain yield in variety Lang (5) NGA0605
Commercial benefit – combined data
Figure 6 below details the net benefit/cost of the seed treatment across all trial
sites. Net benefit has been calculated on two different grain prices after
deduction of product cost.
Across all trials the Jockey treated area resulted in a net cost of $13-14/ha.
5
@ $270/t (2006 del)
@ $200/t
0
Net $/ha benefit
-5
-10
-15
ave -$14/ha
-20
-25
ave -$13/ha
-30
-35
NGA0602 Billa Billa
NGA0603 Boomi
NGA0604 Garah
NGA0605 Edgeroi
NB No stripe rust at sites NGA0602/03 and 04, very low incidence and severity at NGA0605
Figure 6: Combined net benefit of seed treatment use
Conclusions
The plant establishment data showed good crop safety levels from Jockey under
a range of northern conditions. This supports results from other regions.
Although stripe rust was present in northern NSW in 2006 it was generally at very
low levels with non-conducive conditions for disease epidemics. Efficacy data
was only generated from the Edgeroi site. Jockey at 300 mL clearly still provided
suppression of stripe rust in excess of 100 days after planting on the variety Lang
(rating 5). This supports the length of activity seen by NSW DPI at Tamworth in
2005.
The absence of yield responses was not unexpected given the seasonal
conditions. Jockey is a product that provides extended protection against stripe
rust. In situations where stripe rust is only present in trace levels (Billa Billa,
Boomi and Garah) no yield benefit would be expected. At the Edgeroi site, stripe
rust levels looked to be taking off at the end of September but moisture and heat
stress became the major yield limitations not disease. Yield results are likely to
have been different if a reasonable end to the season had been experienced.
Acknowledgements
Sincere thanks to the growers and consultants involved in this trial work.
Contact details
Richard Daniel
Northern Grower Alliance
Ph: 07 4698 7983
Email: richard.daniel@nga.org.au