Managed lower fungicide inputs: Strategic Cereal Farm West

Our Strategic Cereal Farm West is testing the cost-benefit of different fungicide input programmes. Here are the results so far from our Harvest 2021 trials.

Managed lower fungicide inputs trial summary

  • Start: September 2020
  • End: Harvest 2021

Objective

To test whether a managed approach to lowering fungicide inputs can be used on varieties with different disease ratings, without compromising yield, but improving the cost of production.

Why test a managed lower fungicide input programme?

Disease management in cereals is a challenge. The loss of chemistry and fungicide resistance means that we need new ways to manage cereal diseases.

Our projects help support farmers and agronomists to manage cereal disease on farm. The fungicide performance research we fund provides information on the effectiveness of new products. The Recommended List can help with selecting the best varieties for your farm.

This trial is testing the cost-benefit of different fungicide input programmes.

How is the managed lower input fungicide trial run?

The replicated tramline trial is in Field 13 in KWS Extase and KWS Siskin winter wheat. Strategic Cereal Farm host, Rob Fox, drilled the trial in an 18-hectare field on 30 September 2020 at a rate of 208 kg/ha. The main soil types in the field are heavy red marl and medium to heavy loam.

The design of the trial minimises the effect of the soil variation in the field on the data. It focuses on the comparison between fungicide inputs on each variety. The area untreated is small to prevent significant yield loss.

Designing the fungicide programmes

The fungicide programmes were designed to produce three different levels of input, without having a detrimental effect on yield and were tailored to the season. 

Treatment

T1 Applied 26/04/2021

T2 Applied 26/05/2021

T3 Applied 10/06/2021

1 - High

Ascra Xpro 0.8l/ha

Revystar XE 0.9l/ha

Tebuconazole 0.7l/ha

2 - Medium

Tebuconazole 0.7l/ha + Arizona 1.5l/ha

Revystar XE 0.9l/ha

Tebuconazole 0.7l/ha

3 - Low

Untreated

Revystar XE 0.9l/ha

Untreated

How did the weather contribute to disease pressure?

March and April were very dry for most of the UK and temperatures in April were below average. This meant that disease pressure was low early in the season.

  • Low input programme was left untreated
  • Medium input programme was based on an azole and multisite to provide protectant activity
  • High input programme used an azole/SDHI mixture

May was very wet with above average rainfall increasing the risk of a damaging septoria epidemic. It was therefore decided to use the same, high input strategy of an azole/SDHI mix to protect the crop on all treatments. Tebuconazole was applied at full rate at T3 to provide some protection against rust and ear disease in the medium and high input strategy but the low input was left untreated.

Results from the lower fungicide input programme 

Effect of variety and fungicide on crop biomass

The main differences in the biomass assessments were between varieties. There were no significant differences between the different fungicide treatments.

The variety blocks weren’t replicated. This means that any variety effects should be interpreted with caution. The effects may have been influenced by the location of each block in the field.
Plant counts were lower than benchmark values on the 7 April:
  • Extase produced 117 plants/m2
  • Siskin produced 126 plants/m2

Green area index and NDVI

GAI and NDVI were assessed on 7 and 20 April, 26 May, 28 June and 14 July.

Extase had higher values than Siskin at all assessments except the 14 July where Siskin was higher. This could be because Extase tended to be ahead of Siskin in growth stage.

GAI peaked in Siskin on the 26 May (GS39) at 3.6 and in Extase on the 28 June (GS65) at 4.2. These values are also lower than benchmark values.

Field scale trials tend to be less accurate than small scale plot trials. This is because they cover a larger area and can be more affected by any in field variation. GAI and plant counts were assessed in 3 places per tramline by destructive sampling to give an indication of treatment values. It is thought that this data has been affected by variation and these values may not be a true reflection of field values.

For NDVI, Extase had higher values until the 26 May onwards where Siskin overtook Extase. This is not uncommon as both varieties are likely to have differences in growth that will influence NDVI values. For example, Extase tended to be ahead of Siskin for growth stage which is likely to explain the higher values early in the season.

This data was seen in satellite imagery of the field. Extase on the left hand side of the field appeared to have higher NDVI than Siskin on the 27 December. But, on 31 May, Siskin looked to have higher NDVI. These images also show that there is some variation within the field with patches of lower NDVI in both varieties. This is most likely associated with underlying soil variability.

Graph: change in GAI (left) and NDVI (right) over the growing season

NDVI imagery on the 27 December and 31 May

Effect of variety and fungicide on disease

This data shows that in this field, in 2021, the low input fungicide programme achieved sufficient disease control in both Extase and Siskin.

Septoria

The main disease recorded was septoria. Due to the dry conditions in March and April, septoria was initially slow to develop, but reached high levels by the end of the season.

The biggest differences were therefore seen on the 8 and 15 July. There were clear differences in the level of septoria between varieties, on all leaves assessed.

When averaged across fungicides, Siskin had higher disease severity values than Extase. This reflects the variety resistance ratings as Siskin is rated 6.5 out of 9 whereas Extase is rated 8 (AHDB Recommended List 2021/22).

The untreated blocks also had higher disease severity and lower green leaf area (GLA) remaining than the treated tramlines, showing that fungicides were required to achieve adequate control of disease and were likely to have had a positive effect on yield.

When comparing fungicide treatments within the same variety, the differences were much smaller and rarely statistically significant. There were significant differences between fungicides and a variety.fungicide interaction for leaf 2 on the 15 July.

When averaged across variety, the low input programme had significantly higher septoria severity than the medium input programme. However, when each variety was analysed in isolation there were no significant differences.

Yellow rust

Yellow rust was recorded in trace amounts from the 6 June but did not reach significant levels (<5% leaf area affected), even in the untreated plots

Brown rust

Brown rust was recorded from the 8 July in both varieties. In untreated plots, Extase had 1.3% severity on leaf 1 and 0.6% on leaf 2, whereas Siskin had 5.8% on leaf 1, 4.0% on leaf 2 and 0.8% on leaf 3. All fungicide treatments reduced this to trace levels (<1%). By the 15 July, untreated Extase had 6.8% on leaf 1 and 5.3% on leaf 2, whereas untreated Siskin had 12.1% on leaf 1 and 1.3% on leaf 2. Again all fungicide treatments reduced this to trace amounts. These results reflect variety resistance ratings as Siskin is rated 5 out of 9 for Brown rust whereas Extase is a 7 (AHDB Recommended List 2021/22).

Ear and stem diseases

Ear diseases were assessed on the 8 July and no ear disease was recorded. On the 15 July, stem disease was assessed.

Eyespot was present in both varieties. As with septoria, there was an effect of variety as the incidence of eyespot was higher in the Extase than the Siskin. This again reflects variety resistance ratings as Siskin is rated 5 out of 9 whereas Extase is rated 4 (AHDB Recommended List 2021/22).

Eyespot incidence in the untreated Extase plot appeared a lot lower than treated tramlines. It is likely that this is because there was only one small untreated area, which may have been located in a lower pressure area for eyespot, whereas the fungicide treatments were replicated in full tramlines giving a more reliable indication of disease levels.

The differences between the different fungicide inputs were small and not statistically significant.  

Leaf 1-Septoria

Leaf 2-Septoria

Leaf 3-Septoria

Leaf 3-GLA

Extase

0.3*

1.9*

7.4*

50.3*

Treatment 1 - High

0.2

1.8

6.5

51.1

Treatment 2 - Medium

0.4

1.8

6.7

48.2

Treatment 3 - Low

0.3

2.1

8.9

51.8

Siskin

1.3*

9.6*

67.6*

13.2*

Treatment 1 - High

1.4

8.4

73.4

10.3

Treatment 2 - Medium

1.2

7.5

57.9

17.4

Treatment 3 - Low

1.3

12.9

71.6

11.9

Not statistically analysed

Untreated Extase

3.2

10.8

31.8

47.9

Untreated Siskin

8.4

24.7

90.0

3.3

Foliar disease assessment on 8 July. Values represent % leaf area affected. * differences were statistically significant at P<0.05

Leaf 1-Septoria

Leaf 2-Septoria

Leaf 2-GLA

Leaf 3-GLA

Eyespot Incidence

Extase

1.5*

2.7*

60.2*

3.2*

48.5*

Treatment 1 - High

1.4

2.1*

56.0

1.1

43.3

Treatment 2 - Medium

1.4

2.8*

55.9

4.3

52.2

Treatment 3 - Low

1.5

3.1*

68.8

4.2

50.0

Siskin

6.1*

13.6*

35.6*

0.0*

27.4*

Treatment 1 - High

6.2

13.5*

40.4

0.0

25.6

Treatment 2 - Medium

5.3

9.6*

39.6

0.0

27.8

Treatment 3 - Low

6.8

17.7*

26.9

0.0

28.9

Not statistically analysed

Untreated Extase

28.6

38.2

23.5

0.0

6.7

Untreated Siskin

55.8

73.0

3.6

0.0

36.7

Foliar and stem disease assessment on 15 July. Values represent % leaf area affected.  * differences were statistically significant at P<0.05

Effect of variety and fungicide on yield

Methods

Yield map data was analysed using ADAS agronomics software.

Data was first cleaned to remove headlands, locally extreme data points, the untreated areas and any combine runs that spanned both varieties. They were corrected for any offset created by changes in combine direction. A statistical model was fitted to the data to account for spatial effects along and across rows, and affects were associated with the treatments. The agronomics software models the effect of one treatment in comparison to another.

Results

The results show very small differences seen between fungicide treatments. In this case the low input programme was sufficient for disease control and yield in both Extase and Siskin.

Extase did appear to yield higher than Siskin from the yield map. The average measured yield for Extase was 10.29t/ha, this was 0.465±0.343 t/ha more than Siskin. However this was not found to be statistically significant (LSD 0.672).

To understand the effect of fungicide programme, each variety was analysed in isolation and the yield effect was estimated compared to the medium input strategy.

For Extase, the high input strategy yielded lower than the medium, and the low input higher. But these differences weren’t statistically significant.

In Siskin, both the high and low input strategies yielded lower than the medium input strategy. However, these differences were not statistically significant, therefore these differences could be due to underlying variation in the treatment areas.

Variety

Mean yield for the medium input strategy (t/ha)

Estimated effect of the high input strategy compared to medium

Estimated effect of the low input strategy compared to medium

Extase

10.30

-0.305 ± 0.306

0.323 ± 0.336

Siskin

9.10

-0.343 ± 0.398

-0.269 ± 0.398

Modelled yield effects compared to the medium input strategy (estimated treatments effect with 95% confidence limit)

Results from Harvest 2019 fungicide trial 

For harvest 2019, a similar trial looked at fungicide inputs on a single winter wheat variety. The split field trial looked at Graham winter wheat under two input programmes. The farm standard treatment used dressed seed and received a conventional programme. The second treatment was a reduced input programme, which used untreated seed. The results showed that there was no significant difference in yield between treatments.

Read the harvest 2019 report

Useful resources

Our Strategic Farms are an opportunity to see how to use our research on a commercial farm. Find out more about our Strategic Farm Programme

Integrated pest management of cereal diseases

Recommended List

Fungicide performance in cereals and oilseed rape

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