Agronomy • 2023-02-08

Protecting your corn and soybeans with fungicides

Something went wrong. Please try again later...

Wheat growers were the first to reap the economic benefits of fungicide use, however, soybean and corn growers in Eastern Canada have started to experience more and more disease problems in recent years. This has led many to turn to leading fungicides to control disease in their fields to maximize their crop’s yield potential.

Prevalent diseases in soybeans

White mould is the most economically significant disease for soybean growers in Quebec, Eastern Ontario and certain pockets of Southwestern Ontario. Especially where there's a lot of manure in the rotation and where there's history of white mould build up in the soil, which puts a lot of pressure on the beans. For white mould, fungicides can have a huge effect, significantly preventing yield loss from the disease.

Key diseases in corn

In Eastern Canada, fungicide use on silage corn has shown to be the most profitable and reliable. Growers are primarily targeting leaf diseases like Northern corn leaf blight and Gray Leaf Spot, as well as Anthracnose Stalk Rot. The goal is to keep the plant free from leaf diseases for as long as possible and pack as much starch as possible into that ear. This results in more energy for the feed. The healthier the plant is, the better quality of feed.

Grain corn growers are targeting the same leaf diseases and stock rots like Anthracnose, which can really decrease a plant's late season standability, especially in years with early frost. The healthier plants are, the more likely they are to stay standing. And that's where a fungicide can really help. There is also a lot of fungicide adoption in Southwestern Ontario and across Eastern Canada in grain corn or high moisture corn, where growers are targeting Gibberella ear rot and DON (deoxynivalenol).

Fungicides 101

When we look at the different mode actions of fungicides, some inhibit spores from germinating, which stops infection, while others act directly on the fungus by stopping or limiting its ability to feed or energize itself, grow and reproduce. If you can impact any of those metabolic processes, there is greater potential in reducing the overall impact of disease. Today, there are also other products such as biologicals, which are designed to enhance the plant's natural defenses, rather than work directly on the fungus.

Assessing application payoff

Diseases can either cause minor yield losses or substantial problems in the field. When assessing risk and deciding whether to spray a fungicide, growers should treat every field individually. Each one has its own unique characteristics and disease risks, such as field history, crop rotation and weather. Rainfall and humidity play a key factor. Ultimately, all these factors must be considered before asking the question, “will this fungicide application pay for itself?”

It’s also important to remember that disease management starts before planting, with your choice of hybrids, varieties and genetics. Then, you build on that. Once your crops are in the ground, you’re much more limited in terms of options.

Timing fungicide applications

Product selection and timing are key for soybean growers. As an industry, we continue to improve our ability to time fungicide applications for maximum effectiveness, but to ensure you get it right, nothing beats walking your fields. It’s key to make the fungicide application when the plant is flowering, to get it to where it needs to be, which is on those flowers and petals.

For corn, growers don’t see as much economic benefit with early season fungicide applications. Where we do see the benefits though is at tassel application, particularly with foliar leaf diseases such as Northern corn leaf blight. In this case, you want to make a fungicide application at full silk to five days after silking. (If you're targeting DON or Ear Rot, your timing will be different). It’s all about knowing what you're trying to control and selecting the right product to stop disease where and when it's needed.

If you need help choosing the right fungicide or timing it properly, reach out to your local Pioneer Sales Representative.

Choose products with multiple modes of action

Plenty of research and evidence suggests that if you repeatedly use a fungicide with a single active ingredient, your field will see a rise in disease resistance. However, if you choose products with multiple modes of action on the disease, you will reduce the chance of resistance evolving.