The Good (and Bad) News About Fungicides

Steve Sick

Feb 07, 2019

Ever found yourself thinking about whether or not to make a fungicide application? You’re not alone in that. Maybe it’s because you’ve seen disease popping up in your crop, or because conditions are right for disease and you want to head them off.Or maybe you’re considering a fungicide application because you’re anticipating big yields and you don’t want a last-minute pathogen to ding that number.

Chances are good that you’ve thought about whether or not you should add a fungicide into your annual crop budget, or even considered trialing one.

How Fungicides Can Help You Make Your Money Back

Fungicide applications have increased dramatically over the past 15 years, so it’s safe to say that many farmers see the value of a fungicide application. And because many fungicides are preventative (as opposed to curative), that means farmers are often applying them based on the likelihood of disease, but before they would see any symptoms.

Fungicides can provide a return on investment in several ways:

  • Fungicides have varying control of and residual activity against diseases. By selecting a fungicide that provides control of the most common diseases for your geography, you can increase the likelihood of effectiveness, which means you’re improving the odds that your fungicide will be worth it’s cost and then some.

  • When a fungal disease is present at application, a fungicide can halt the growth of the current pathogens and protect against another disease incidence. If no disease is evident at the time of application, a fungicide can also help to provide protection from any potential fungal diseases.

What Dodging Disease Means for the Plant

So, you’ve stopped or avoided a disease… what exactly does that mean for the plant?

  • Increased photosynthesis: With more healthy leaf area, plants can more effectively use nutrients to achieve maximum yield.

  • Greater stress tolerance: Vigorous plants are better at withstanding stressors, such as drought conditions or extreme temperature variation.

  • Increased water use efficiency: Healthy stalks and leaves are more efficient at using water, leading to an extended grain fill period, thus more opportunity to develop yield.

  • Increased standability: With fewer stalk diseases, farmers will see fewer stalk issues and less lodging, leading to increased yield (because you're reducing ear loss at harvest). 

Is There a Catch to Fungicides?

Maybe you’re wondering if there are any downsides to a fungicide application (other than the potential added expense). Well, it depends.

Here are three things to keep in mind:

  • In some instances, having a healthier crop can lead to a longer growth phase and a later harvest. This extended time in the field (maturation can be delayed by 5-10 days) means increased vulnerability to weather events. And weather events can cause harvest losses.

  • If grain must be harvested earlier to avoid weather events, or to keep on an appropriate schedule, there could be an increase in drying costs.

  • It’s possible that continued application of fungicides could lead to a resistance issue. With known Frogeye Leaf Spot resistance to strobilurin fungicides, there is a reason to think that this could begin to occur more with continued use, so this a good argument for treating only when necessary.


If you’re planning to wait and see: Many farmers treat with fungicides only when they’ve spotted disease in their crop, or they have good reason to believe it’s coming. Here are a few things to do before you decide to sit back and, “wait and see:”

  • Start with an in-depth study of the planned varieties information provided by the seed source, checking each hybrid/ variety’s susceptibility to various diseases.

  • Consider tillage practices, such as no-till and level of crop residue on land to be planted.

  • Check the farm’s disease records and if crop rotation is practiced.

  • Analyze the planting date, hybrid/variety maturity, weather forecasts, grain price and yield potential.

  • Scout diligently for any sign of disease.

Read next: How Fungicides Work (2 min read)

ALWAYS READ AND FOLLOW LABEL DIRECTIONS. It is a violation of federal and state/provincial law to use any pesticide product other than in accordance with its label. The distribution, sale and use of an unregistered pesticide is a violation of federal and/or state law and is strictly prohibited. We do not guarantee the accuracy of any information provided on this page or which is provided by us in any form. It is your responsibility to confirm prior to purchase and use that a product is labeled for your specific purposes, including, but not limited to, your target crop or pest and its compatibility with other products in a tank mix. 


Steve Sick

Feb 07, 2019