Are there benefits to using foliar fungicides after hail damage?

Diane Brown-Rytlewski, Michigan State University Extension, Department of Plant Pathology - June 26, 2008

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

There have been some questions about whether or not fungicides can be of benefit in reducing foliar disease and improving yield when applied to corn after hail damage. A study to simulate hail damage in corn and the effects of fungicide application at tassel emergence was conducted at the University of Illinois last year by Dr. Carl Bradley, plant pathologist in the Department of Crop Sciences. Hail damage was simulated by damaging corn plants with weed-eater type gasoline string trimmer at tassel emergence and applying foliar fungicides the following day. In the trial, foliar fungicides significantly reduced grey leaf spot severity compared to the untreated control in both the simulated hail damage and undamaged plots, but did not significantly affect yield compared with untreated controls. Yields in the simulated hail-damaged plots were significantly lower than those from undamaged plots (Table 1).

Table 1. Effect of simulated hail damage and foliar fungicides applied at tassel emergence on grey leaf spot severity and yield of a susceptible corn variety near Champaign, Illinois, in 2007.

Simulated hail1	Fungicide	Rate/A	GLS severity2	Yield (bu/A)
No	Untreated		57	174
	Headline	6 fl oz	33	179
	Quadris	6 fl oz	42	170
	Quilt	14 fl oz	40	155
Yes	Untreated		62	141
	Headline	6 fl oz	48	144
	Quadris	6 fl oz	47	142
	Quilt	14 fl oz	35	140
		LSD3	12	11

1 Hail was simulated by damaging corn with a weed-eater type string mower.
2 Gray leaf spot severity (0-100 percent scale).
3 Fisher’s protected least significant difference (a = 0.05).

Reference: Bradley, C.A. and Ames. K.A. 2008 Foliar Fungicides in Corn Production: a Look at Local and Regional Data page 82-85 in Proceedings, 2008 Illinois Crop Protection Technology Conference, University of Illinois Extension, Champaign, Illinois.

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