Managing eyespot in winter wheat (HGCA Topic Sheet No. 111)
Topic Sheet 111/Spring 2012

Managing eyespot in winter wheat

Action

Identify individual fields with a high eyespot risk prior to sowing using the pre-sowing assessment.
Consider integrated crop management to reduce eyespot risk by choosing to grow varieties with eyespot resistance on high risk fields.
Avoid early sowing on high-risk sites.
In spring, assess stems for visible eyespot symptoms and combine this information with the individual field risk score to justify treatment using fungicide with good activity against eyespot.
Fungicides containing prothioconazole, boscalid and cyprodinil have been found to have activity against eyespot.
Always consider your local conditions and consult a professional agronomist if necessary.

Eyespot in winter wheat

Eyespot is a common disease in intensive cereal rotations. The causal organisms, Oculimacula yallundae (W-type) and O. acuformis (R-type), infect stem bases and reduce water and nutrient uptake, causing whiteheads, lodging and yield loss in the crop.

Eyespot severity can, however, vary significantly between individual fields and, consequently, it is hard to predict which will require management intervention.

Assessing eyespot risk

Traditionally, eyespot assessment in wheat crops was carried out in the spring (GS30-31) to judge the need for chemical control. The new risk assessment method described here includes an early, pre-sowing, assessment of agronomic risks. This enables individual fields at greater disease risk to be identified, allowing an integrated management approach through cultural control measures, such as the use of eyespot-resistant varieties and delayed sowing.

For fields judged to be at low or moderate risk in the autumn, the decision to treat against eyespot in the spring is made using the second part of the new risk assessment, which takes account of the incidence of stem base lesions as the crop approaches stem extension.

Pre-sowing assessment
The pre-sowing assessment enables identification of high-risk fields that would need fungicide treatment in the spring. At this stage, there are a number of options for high-risk fields:

  • Select a different crop for the chosen field
  • Select a variety with higher resistance to eyespot
  • Delay sowing until after 7 October

GS31-32 assessment
Combine the pre-sowing risk score with the amount of disease visible in the crop at GS31-32 to determine a final eyespot risk.

Fungicide treatment
Once a final eyespot risk has been assigned to a field, the decision to treat or not can be made. Previous knowledge of individual fields should be taken into account. Yield responses to individual fungicide product treatments against eyespot are shown in Figure 1.


Figure 1 Yield response to fungicide treatment in trials 2004-2010 in comparison to no fungicide application at GS31/32.

1. Calculate the pre-sowing risk score

Factor Level Risk points Score
Region map.gif (7462 bytes) East 0 s
North 1 s
West 5 s
Soil type Light 0 s
Medium 1 s
Heavy 4 s
Previous crop Non-host 0 s
Other cereal 7 s
Wheat 8 s
Tillage Minimum till 0 s
Plough 6 s
Sowing date
(before or after 6 October
Late 0 s
Early 2 s

Pre-sowing risk score

s

Take action based on the pre-sowing risk

Pre-sowing risk score Pre-sowing risk category Action*
1-4 Low risk (L) Assess in spring
5-9 Low-medium risk (LM)
10-14 Medium risk (M) Consider agronomic control;
assess in spring
15-19 Medium-high risk (MH)
20-25 High risk (H)

*The actions are advisory rather than prescriptive. If action is taken that would alter the presowing risk score, recalculate this score before moving to step two.

2. Assess eyespot disease in spring

Assess eyespot in the field as the % incidence of plants at GS31-32 with eyespot symptoms.

Determine final
eyespot disease risk
Eyespot disease assessment
1%-4% 5%-9% 10%-14% 15%-19% >20%
Pre-sowing
risk score
1-4 L LM M MH H
5-9 LM M M MH H
10-14 M M MH MH H
15-19 MH MH MH H H
20-25 H H H H H

Take action based on the final eyespot risk

Final eyespot disease risk Action
Low risk (L) Specific eyespot treatment may not be justified
Low-medium risk (LM)
Medium risk (M) Treatment may be justified where eyespot has been a recurring disease on individual fields, leading to consistent yield loss
Medium-high risk (MH)
High risk (H) Treatment may be justified even in fields where eyespot has rarely been known to cause yield damage

Overview

  • The new risk assessment methodology combines an autumn and spring risk assessment and allows for integrated crop management options to be chosen to reduce risk, such as resistant varieties or delayed sowing.
  • Average eyespot control with varieties with the Pch1 resistance gene was 27%.
  • Average eyespot control with fungicides was 20%.
  • Average yield response to fungicides with eyespot and foliar disease efficacy was 0.4 t/ha compared to fungicides with foliar disease efficacy alone on high-risk sites.

Further information

Fiona Burnett, SAC
fiona.burnett@sac.ac.uk
Stuart Knight, NIAB TAG
stuart.knight@niab.com
Rumiana Ray, University of Nottingham
rumiana.ray@nottingham.ac.uk
www.hgca.com/diseasecontrol
www.hgca.com/varieties
www.hgca.com/publications


For a copy of 'Cereal growth stages - a guide for crop treatments', visit www.hgca.com/publications or contact 0845 245 0009.

Acknowledgements

Experimental work was carried out by NIAB TAG, Harper Adams University College, University of Nottingham and SAC. This work was funded by HGCA and the trials carried out between 2004 and 2010 were funded by BASF, Bayer CropScience and Syngenta Crop Protection UK, with involvement from the British Wheat Breeders Association.

While the Agriculture and Horticulture Development Board, operating through its HGCA division, seeks to ensure that the information contained within this document is accurate at the time of printing no warranty is given in respect thereof and, to the maximum extent permitted by law, the Agriculture and Horticulture Development Board accepts no liability for loss, damage or injury howsoever caused (including that caused by negligence) or suffered directly or indirectly in relation to information and opinions contained in or omitted from this document.
Reference herein to trade names and proprietary products without stating that they are protected does not imply that they may be regarded as unprotected and thus free for general use. No endorsement of named products is intended, nor is any criticism implied of other alternative but unnamed products.
HGCA is the cereals and oilseeds division of the Agriculture and Horticulture Development Board.

Managing eyespot in winter wheat
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Topic Sheet 111/Spring 2012
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Development Board
2012
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