United Kingdom
March 12, 2014

Overview

• Many of the UK’s wheat crops were early drilled last autumn, and with the very mild and wet autumn and winter and the number of susceptible varieties in the ground indications are that this could be a potentially very high eyespot disease year.
• Yield losses in a bad eyespot year have been estimated to cost the industry up to £20M.
• Eyespot can reduce yields by as much as 10-30% and additionally through lodging if it occurs. The disease can also reduce quality TGW and specific weight and where lodging has occurred can result in crops that are more prone to sprouting and contamination with Fusarium spp. and mycotoxin accumulation.

Dr Rumiana Ray has just completed a two year project surveying wheat fields to identify the population dynamics of the two eyespot species and to determine the effect of agronomy on stem based disease.

Ben Freer, Business Development Manager, has recently joined BASF from NIAB TAG. Mr Freer agrees that all indications are such that this year will potentially be a high risk year for eyespot and that growers should be seriously considering their approach for the most effective control.

Comments from Dr Rumiana Ray, Lecturer Crop Science, Nottingham University.

I. Conditions and situations that pre dispose for eyespot

The main factors which influence the disease epidemics are:

1. High inoculum potential - determined by the pathogens surviving on crop residues and in soil.

2. Favourable conditions for infection at GS 12, 8 to 10^oC temperature and abundant rainfall and humidity above 80%.

3. Establishment of severe lesions at GS 30/32 determined by the same environmental conditions around 10^oC and high moisture on a susceptible variety.

II. What is the risk this season and in which particular situations?

• The risk this year is high because of the excessive rainfall and moisture and mild winter and spring that we had. The risk is high in all varieties that do not carry any resistance genes such as Pch1 or Pch2.
• Even highly resistant ones as assessed in the recommended list (Scout, HGCA rating of 8) benefitted from fungicide application last year- I have data from our BASF trial work.

III. High risk situations are :

• First and second wheats this year (as we had very favourable environment), sown early – before the beginning of October, especially if soils ploughed before sowing.
• Most varieties are susceptible.

IV. What is the difference between W-type and R-type eyespot?

• The main difference between W and R-type is that W type causes symptoms earlier during crop development and it is associated with lodging, whilst R-type causes symptoms later in the season and it is associated with whiteheads.
• Both reduce yield via harvest index and have impact on water relations in the plant affecting its ability to utilise water efficiently for physiological processes such as for example photosynthesis.

V. What is the PCH1 resistance gene and how does it help to protect a crop and which of the current varieties have it?

• Pch1 is derived from wild grass (Aegilops ventricosa) and it is very effective against eyespot, the only confirmed variety that I know of with this gene is Skyfall.
• There have been some agronomic issues in the past with this gene as it causes also some deleterious effects on yield.

VI. What fungicides and at what timing would you recommend for eyespot control?

• Boscalid is very effective and considered the top commercial control. Prothioconazole and cyprodinil based treatments are also effective. Some of the new SDHIs are active as well but not as active as boscalid under high disease pressure.
• Depending on disease pressure between 0.75-1.5 l/ha Tracker at T1, but this year I would be going with at least 1l/ha because of high eyespot and septoria disease pressure.

Comments from Ben Freer, Business Development Manager, BASF

• The thick forward crops that we are currently seeing are at a high risk from eyespot based on the weather conditions outlined above. However crops are showing good yield potential that should be protected.
• Risk is high so prevent infection wherever possible. Don’t chase disease.
• T0 can offer some control using a Capalo based approach but the most effective timing is T1 (from BASF and independent trials).
• 1 l/ha Tracker will control the eyespot.
• 1l/ha CTL should also be added to this to maximise yield, disease protection and resistance management.

Website: http://www.agricentre.basf.co.uk/agroportal/uk/en/startpage.html

Published: March 13, 2014