Forecasting eyespot development and yield losses in winter wheat

Summary

Sector:
Cereals & Oilseeds
Project code:
PR491
Date:
01 September 2007 - 31 March 2010
Funders:
AHDB Cereals & Oilseeds.
AHDB sector cost:
£187,000 from HGCA
Project leader:
Fiona Burnett1 , Clare Butler-Ellis2 , Gareth Hughes1 , Stuart Knight2 and Rumiana Ray3 1 SAC, West Mains Road, Edinburgh EH9 3JG 2 NIAB TAG, Huntingdon Road, Cambridge CB3 0LE 3 University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD

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About this project

Abstract

The aim of this project was to help growers to predict which crops are at risk from eyespot and are likely to give a cost-effective yield response to treatment. Data on yield, disease and agronomy were collected from field trials located throughout the UK between 2000 and 2010. Two approaches to providing decision guidelines relating to treatment of eyespot were developed.

In the first, the decision-making process is driven by the predicted final level of eyespot disease in the crop in a two phased approach. Using region, previous crop, sowing date, tillage method and soil type, a pre-disease score can be calculated and a decision made on field selection or varietal choice to include eyespot resistance. In the spring fungicide treatment decisions can be made by combining this pre-disease score with an assessment of eyespot incidence in the crop at GS31-32 to place the crop in a risk category ranging from low to high. In the second approach, the decision-making process is driven by the cost of treatment relative to the predicted yield loss due to eyespot disease if the crop were not treated. A revenue calculator was then developed.

No consistent relationship could be established between eyespot levels and yield, with variation between sites. Yield response and eyespot control following fungicide treatment was significant using the whole data set. Significant control and yield benefits were noted for varieties with moderate or good eyespot resistance. Fungicide efficacy varied but up to 50% control was achieved. Alternative spray technologies were evaluated to see if they could improve targeting of the stem base, and hence efficacy. Applications at a later growth stage resulted in significantly less deposit on the lower stem. Angled spray nozzles and small droplet air induction nozzles improved deposition on the stem base.

Inoculated studies showed that initial inoculum level was a significant driver of disease development and subsequent yield loss. Yield loss and response to fungicide treatment were significantly greater when eyespot was associated with whiteheads and lodging. There were differences in how yield losses accrued between the two eyespot species: Oculimacula yallundae was associated with the occurrence of eyespot-induced lodging, whilst inoculation with O. acuformis resulted in greater number of whiteheads scattered within the crop.

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