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Protect the flag with correct fungicide timing

Read Time: 8 minutes

By Laura Sytnyk June 07, 2021

Keeping the flag clean is critical for achieving cereal yield goals

Cereal crops certainly save the best for last when it comes to their development throughout the season. That last leaf to un-whorl is known as the flag leaf and is the main contributor to yield, accounting for approximately 65% of yield. So why does it seem we’ve begun to move away from protecting this precious leaf?
Sometimes in the blink of an eye you see flags emerging. Then suddenly you’re chasing after flowering. It can be easy to forget that as the plant begins to transition and move into these reproductive stages its ability to fend off disease diminishes.

Current Trends

The most common practice is to protect the head and target fusarium fungicide applications there. We do this by timing fungicide applications for when at least 75% of the heads have emerged but no more than 50% of those heads have flowered. Of course fusarium is a major concern here on the Prairies but we should also be scouting early for other cereal diseases.

Scout Early

Those other cereal diseases – leaf rust, tan spot, net blotch and septoria leaf spot – have fallen off the radar a bit. Many of these are spread by the wind and it’s important to scout regularly because it can be difficult to predict when they will show up in your fields.

Remember fungicides are not a curative, fix-all treatment. They are preventative tools to help keep crops healthy. Disease can start fairly early, and on the lower leaves first, so it’s important to scout early and diligently for its presence.
Hot and dry conditions can slow the spread of leaf diseases, but as a rule of thumb, the more disease pressure you see on the lower leaves, the more pressure you’ll surely have on the flag leaf once it emerges.
If you are seeing disease symptoms on the leaves below the flag, consider an early season fungicide in order to keep the flag leaf clean.

Nexicor™ Fungicide

BASF’s Nexicor fungicide is a great option for those who want to do an early season application for broad-spectrum control of key cereal leaf diseases. With three modes of action and the unique translocation properties of Xemium®, you get more consistent control and the plant health benefits of AgCelence®.
This gives your plants not only an excellent disease package but also the ability to better manage the climatic stressors that we inevitably face throughout the season. One case of Nexicor treats 80 acres and is registered for barley, oats, rye, triticale, wheat and canola.

Timing is Everything

Early fungicide application is another tool in the toolbox you can use to help achieve healthy crops and good yields. When trying to protect the flag, keep in mind the leaf should be 50% to fully emerged when you apply. If you’re undecided on whether an early fungicide application is warranted give your local Cargill agronomist a call. We will be more than happy to come walk your fields to provide you with a sound second opinion.


Nexicor™, Xemium®, and AgCelence® are trademarks of BASF Canada Inc.

Laura head shot

Laura Sytnyk

Laura grew up on a grain farm near Shoal Lake, Manitoba. She says helping out with farm chores really gave her a passion and interest in the agriculture industry. After graduating high school, Laura moved to Brandon, MB, where she received a Degree in Rural and Community Development from Brandon University and an Agribusiness Diploma from Assiniboine Community College. She worked for an irrigated potato and grain farm for a few years which gave her experience with many different crops. New to Cargill in 2018, Laura has a special interest in weed management and a desire to learn more about crop solutions and soil fertility. Laura is looking forward to using her knowledge and determination to help farmers make informed smart decisions for their crops.