Fungicides Help Corn Tolerate Tough Weather Conditions

Fungcides and Weather
Fungicides, such as Delaro® 325 Fungicide, help protect your corn from weather stressors.

Fungal disease in corn needs wet weather to take hold. That’s when you apply a fungicide, usually at tassel, to control the disease. It’s the only time you ever need to consider applying a fungicide to protect your yield.

Or is it?

Independent studies increasingly show that a fungicide application helps corn weather (pun intended) adverse weather conditions, including:

1. Wind Damage

Fungicide application may be able to help your corn withstand straight-line winds that would flatten your neighbor’s field. Delaro® 325 Fungicide promotes strong, healthy stalks for nutrient flow throughout the grain-fill period and helps reduce the number of downed plants.

“An early-season fungicide application (V4 to V7) is shown to improve stalk strength and reduce the risk of lodging," said Randy Myers, fungicides product development manager with Bayer. "If you have a stronger stalk, the plant is less likely to fall victim to strong winds and bend over or snap off.”

2. Dry Weather

Most diseases need moisture to thrive, so it might seem counterintuitive to apply a fungicide when it’s dry. However, fungicides have benefits beyond disease prevention.

“Common misperceptions still exist when it comes to fungicides and growers may assume there is no value in a fungicide application during dry weather,” Myers said. “A lesser-known benefit of fungicides is that they trigger beneficial physiological reactions in the plant, even with dry weather and in the absence of visible disease symptoms.”

For example, fungicides help a corn plant improve its water efficiency when rainfall seems to be scarce.

In fact, Myers has talked with several growers who made an early fungicide application in drought-impacted years, before they knew dry weather conditions would take hold. The growers reported that fields receiving the fungicide yielded better than untreated corn.

3. Hail Damage

One of the most effective ways to limit the impact of hail damage is to apply a fungicide shortly either before the hail event or very soon after, Myers explained.

“A fungicide application before you have hail means the plant’s physiological reactions are already triggered before the leaves are damaged,” Myers said. “The result is fewer latent infections that can take advantage of the weakened plants, since they have already been prevented or cleaned up by the chemistry.”

If a fungicide application wasn’t made prior to the hail event, you can still benefit from a fungicide application afterward, regardless of the plant stage. Myers explained that a fungicide, such as Delaro, helps heal the plants in two ways:

  • Fights fungal pathogens

    The plants' hail-damaged vascular system restricts the flow of water and nutrients, starving some cells and handicapping others. Photosynthetically active surfaces may not be able to export the generated sugars to the growing and recovering tissues. The injured plant is less able to respond to infections. The fungicide helps fight fungal pathogens that readily feast on this weak tissue caused by hail damage.
  • Helps heal wounded foliage

    The strobilurin component of Delaro fungicide encourages the formation of callus tissue, closing the wounds caused by hail and eliminating a pathogen’s easy access to the vulnerable interior of the leaves. This barrier preserves plant productivity, enhancing recovery.

Application Methods

Clearly, prevention is the best approach when it comes to mitigating the effects of serious weather events.

Growers can consider two approaches to preventive fungicide applications:

  • Early Season

    The practice of early-season fungicide application—between the V4 and V7 stages of corn—is becoming more common. During these stages, corn plants go through critical changes that will affect the yield potential of the field. Having to secure their own nutrients and resources for the first time, plants are more susceptible to environmental stresses and diseases. Applying fungicide at this stage is not only convenient as it can be tankmixed with a planned herbicide application, but also offers early-season disease control and more complete plant coverage.
  • At-Tassel

    An at-tassel application of Delaro delivers improved stalk strength with reduced risk of lodging, as well as preventive and curative activity against gray leaf spot, northern corn leaf blight, southern rust, and other foliar diseases.

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