A fungicide application after a hail storm can be highly successful in protecting corn yield if the field's corn plants were not catastrophically damaged, according to Nicholas Fassler, BASF technical marketing manager for Headline fungicide.
The company bases its labeled Headline use on a simulated hail-storm research project in Ontario, Canada, and real-world use by farmers. "We've had a lot of positive responses from growers who have applied Headline before or after a hail event, and also consultants who make recommendations on fungicide applications," Fassler said.
"By no means are we making recommendations for a Headline application after a catastrophic hail event where a grower has 50 percent or greater leaf loss. Before we make an application recommendation after a hail event, we are going to look at a field's overall crop canopy and weigh its yield potential. If it's still got a good yield potential, then Headline is going to help in a lot of ways such as reducing plant stress and mitigating the overall disease pressure. After hail, there is greater potential for disease to attack a wounded plant.
"With the fungicide application, we see a longer stay-green effect by the plant. If the plant loses leaf tissue but all remaining leaf tissue stays productive, then there is greater yield potential," Fassler said. He also suggested that standability of the corn can be improved if the corn plant stays green.
There is no unconditional recommendation to apply a fungicide after a hail storm, he explained. Every field has to be evaluated based on the time of year, health of the corn plants before the hail, degree of damage from the hail and yield potential of the corn.
If a hail event occurs early in the corn plant's life cycle, then a fungicide application is less likely to show positive effect. It is when the hail occurs as the corn is close to or in the reproductive stages that diseases can typically have a significant negative effect on the final corn yield.
"If a farmer is only going to make one fungicide application and there are several leaves yet to come out of the corn plant when the hail event occurs, then the grower might want to wait on applying Headline until those leaves come out to protect all the leaves from disease," Fassler said. Typically, Headline is applied after full tasseling occurs.
The pyraclostrobin active ingredient in Headline is a strobilurin class fungicide, and research has shown that it provides plant health benefits because of its interaction with the plant's mitochondrial respiration inhibition and increased nitrate reductase, noted Fassler. The result is increased levels of the enzyme that is important for making a form of nitrogen, which can be used by plants, and increased levels of nitric oxide that triggers plant defense mechanisms.