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Fungicide Application for Leaf Diseases in Cereal Crops

Many areas of western Canada have received moisture this spring. As growers are completing their herbicide applications, it is a good time to start planning for fungicide needs.

With the recent moisture, there have been reports of the presence of the diseases lower in the crop canopy for cereal crops. Additionally, there have been reports of stripe rust being found in cereal crops in the United States1.  Rusts move into the prairies from south winds that transfer the pathogen into Canada. Growers in western Canada should be on the look out for rusts as they can have a significant impact on the cereal yields.

Below is a table listing the common diseases for cereals in western Canada.

Wheat Barley Oats
Rusts, Septoria Leaf Blotch,
Tan Spot
Net Blotch, Rusts, Scald,
Septoria Leaf Blotch
Rust, Septoria Leaf Blotch

When it comes to grain filling, it’s well documented that the flag leaf and the penultimate leaf (leaf below the flag) are the most important leaves to protect against disease.  In wheat, the flag leaf and penultimate leaf contribute about 65% of grain filling for yield2, for barley it’s about 50%2 and for oats it can be as high as 75%.3 Protecting the flag leaf and penultimate leaf are absolutely critical to maximize yield.  The flag leaf stage is often referred to as a T2 timing in cereals.

ADAMA has products that are available to help protect your cereal crop at the critical flag leaf stage. There are three products that fit very well for cereal growers at the flag leaf are CUSTODIA®, ORIUS® 430 SC and TOPNOTCH.

T2 Fungicide Product Information

Fungicide Product Active Ingredient Ac/Unit Rates
CUSTODIA® Tebuconazole + Azoxystrobin 40 – 53 ac/jug 190 – 250 ml/ac
ORIUS® 430 SC Tebuconazole 80-100 ac/jug 89-118 ml/ac
TOPNOTCH Propiconazole + Azoxystrobin 40 ac/jug 210 ml/ac

CUSTODIA® is a great choice for western Canadian cereal growers as it contains 2 modes of action (Group 3 and 11)  which provides broad-spectrum disease protection. CUSTODIA can be used in wheat, barley and oats and provides control of the common diseases in western Canada. CUSTODIA is especially a great choice when rusts are expected to be an issue.  Rusts are not an issue every year but when present can cause significant yield losses. The risk of rusts increase when there are southerly winds and when rusts are present in the northern US.

ORIUS® 430 SC contains a Group 3 active ingredient - tebuconazole. This product fits in well for growers that have fields with variable crop staging and are worried about the use of a strobilurin product during head timing. ORIUS also has a flexible window of application while controlling key diseases in cereals without the risk of delaying maturity.

TOPNOTCH is an effective choice when there is not as great of a concern for rusts. TOPNOTCH also provides the benefits of multi-mode of action, broad spectrum fungicide and can be used in pulse crops such as field peas and lentils.

To get the most out of your CUSTODIA, ORIUS or TOPNOTCH application remember to keep your water volume up as coverage of the flag leaf is critical.  Using 10 gallon/ac of water is recommended.  As for the ideal timing of the fungicide application it’s when the flag leaf is completely emerged.

Sean Dilk -Technology Development and Transfer Manager

Always read and follow pesticide label directions. Any questions can be directed to your local Area Business Manager or Technical Sales Agronomist here.


  1. Connie Strunk, Stripe Rust Confirmed, May 24, 2024. Stripe Rust Confirmed (
  2. Top Crop manager, 2017
  3. Prairie Oat Growers manual