Teagasc Crop Report

Update no.4 2021

Update no.4 2021

Wednesday 21st April 2021
(Updated Thursday 22nd April 2021)
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Winter Wheat

Winter Wheat 

Good disease control programmes depend on accurate timing of fungicides applications. Teagasc research has shown that applying fungicides at the correct timing plays an important in maximising the control from the chosen fungicides in any given situation. As a result we now describe timings for fungicide applications by the emergence of the target leaf for control. The simple table below shows the new timing descriptions compared to the old timings.

New description Old description
Leaf 4 T0
Leaf 3 T1
Flag leaf (leaf 1) T2
Flowering T3

Timing

To ensure accuracy when applying the leaf 3 application you should first dissect the plants to see when leaf 3 is fully emerged. Teagasc have produced two videos about leaf 3 in wheat, firstly to show how to unroll wheat plants to identify the leaves and secondly the importance of the leaf 3 application in septoria control. The different varieties, sowing dates and locations will all have an impact on the emergence of leaf 3 so it is critical to correctly identify when it is fully emerged on each individual crop to enable accurate applications. Remember it each leaf requires approximately 120 degree days to emerge so if the average day and night time temperature is 10oC then it will take 12 days for the leaf to fully emerge, likewise if the leaf is 50% emerged you can predict that it will take 6 days for it to be emerged fully.

Leaf 3 Application

The choice of product at each timing will depend on the main disease that needs to be controlled, in yellow rust susceptible crops for example, Elatus Era at full rate will give good control with the inclusion of the multisite Folpet to give added control and resistance management. Revystar or the new Inatreq products Questar, Peacoq etc. also claim to give good control.

Where yellow rust is not an issue then septoria is the main target, the recent dry weather is helping to slow down the development and spread of septoria so most crops have relatively low levels of infection visible at this stage. In this situation the multisite plus Ascra Expro at 80% rate or any of the products already mentioned are good options.

IPM

When applying a fungicide to the crop a good IPM tool to evaluate the accuracy of the leaf 3 application is to apply some spray paint to a section of the crop on the day that it is sprayed. This will give the grower information later in the season as to how accurately the application was applied and also how much of the plants were covered by the fungicide. Ideally all of leaf 3 should be covered and part of leaf 2. As new growth emerges it will become clear quite quickly how much of the canopy was protected from the leaf 3 application.

IPM
Spray crops with white paint on the day of the leaf 3 application

This information will be useful when it comes to applying the flag leaf (Leaf 1) application as it will show how much of leaves 3 and 2 were covered but more importantly how much if any of leaf 3 was not covered or treated. In this case this will have allowed septoria to spread onto leaf 3 and then onto leaf 2 creating greater septoria pressure within the crop. This should then alert the grower that a robust flag leaf application is then required.

2021 Winter Wheat Monitor Crops April 21st

Location

Variety

Drilling date

Rotation

Growth stage

Disease

Mallow

Graham

20/10/20

Beans

GS 31 - L 3 25%

Septoria on leaf 5

Midleton

Costello

5/11/20

Winter oats

GS 31 L3 15%

Septoria leaf 5

Kildalton

Costello

15th October

 WOSR & Beans

GS 32 - L3 50%

Septoria on lower leaves

Oak Park

Costello

21/10/2020

WOSR

GS 30/31 - L 4 80%

Septoria on lower leaves

Cork Ballyderown

DAFM

KWS Conros

Torp

Costello

KWS Dawsum

JB Diego

Spearhead

Graham

15/10/20

WOSR

L3 5%

L3 60%

L4 80%

L4 80%

L3 15%

L3 5%

L3 70%

No rust

No Mildew

High levels of Septoria

Athy

Bennington

15/10/2020

W Oats

GS 31 - L3 30%

Septoria on L 5 , Y rust controlled

Kildare- Nth

Graham

30/9/2020

Maize

GS 31 – L 3 40%

Clean

North Dublin

Costello

Graham

25/10/2020
5/10/2020

Wheat

WOSR

GS 31 - L3 10%

GS 31 - L 3 40%

Rust has been treated

Laois

Graham

22/10/2020

W Oats

GS 31 – L3 10%

Septoria on older leaves,

no yellow rust

Louth

Conros/Graham & Costello

13/10/2020

Oats/Wheat

GS 30 – L3 10%

Clean

Wexford South

Graham

9/10/2020

Oats

GS 31 - L 3 50%

Septoria on Leaf 5

Wexford North

Conros

15/10/2020

Wheat

GS 31 – L3 10%

Septoria on lower leaves

Wicklow

Costello

15/10/2020

Beans

GS 31 – L 3 40%

Clean