Flanary, W., Agronomy Specialist, University Of Missouri Extension
Crawford, J.J.W., Graves Chapple Research Center Superintendent, University of Missouri Extension

ABSTRACT

Corn acres treated with fungicides have increased with increasing corn profit margins. University recommendations suggest fungicides should be applied to corn when foliar diseases are present, hybrids lack disease resistance and environmental conditions are suitable for increased disease development. Growers have been encouraged to apply fungicides to protect yield and the cost of the application will be off-set by grain yield. At the Graves Chapple Research Center, University of Missouri, a fungicide application was made to different corn hybrids in 2011, 2012 and 2013 with the objective of measuring the impact of fungicide application on corn yield. In 2011, Quadris fungicide was applied at a rate of 16 ounces per acre and during 2012 and 2013. Headline fungicide was applied at 6 ounces per acre with 23 gallons of water as a carrier. The fungicide treatment was applied using an off-set boom attached to a front-end loader tractor. Statistical analysis from three years data and four hybrids tested each year indicated no significant yield response from the application of fungicide compared to the non-treated check. Growers should carefully scout fields before making any fungicide application to corn.

Introduction

The application of corn fungicides has increased with increased corn grain prices. Fungicides are used as a risk management tool to protect corn yield from corn foliar fungi diseases. The University of Missouri Extension Service recommends management options for corn foliage diseases include selecting disease resistant corn hybrids and rotating crops one year out of corn (Sweets, 2008). Furthermore, corn fields should be scouted before making any decision to apply a foliar fungicide treatment. Growers should scout fields to determine if foliar corn diseases are present, the severity of the diseases and if the conditions are suitable for increased disease development (Sweets, 2013-2011). Foliar fungicides should be applied only if warranted (Sweets, 2011, 2012). The objective of these experiments was to provide unbiased data to determine if fungicides will significantly increase corn yields in Northwest Missouri.

Materials and Methods

The studies were conducted on a Dockery silt loam soil located at the Graves Chapple Research Center, University of Missouri, located at Fairfax, Missouri.  The experimental design was a randomized complete block design with five replications. Four corn hybrids were randomly selected to be treated with and without a fungicide each year and were analyzed as individual experiments. Quadris fungicide was applied to corn at R-1 stage at a rate of 16 ounces per acre in 2011. Headline fungicide was applied at a rate of 6 ounces per acre in 2012 and 2013 at the R-1 to R-2 stage. The fungicides were applied with an off-set boom mounted to a front loader tractor and with 23 gallons of water carrier per acre. Corn and soybeans were planted in alternating strips to allow the loader tractor pass to through the soybeans and spray the standing corn. Yield data was analyzed by Proc ANOVA using AGSTATS (Oregon State University, 1990).

Results and Discussion

The experiments in 2011 followed corn and soybean residue. Typically, producers plant a corn and soybean rotation rather than continuous corn in our local area. There was a slight increase of gray leaf spot disease pressure when following corn residue compared to soybean residue. However, fungicide application in the five tests did not significantly increase corn yield. Three of the five tests had higher yields when treated with fungicides, but were statistically insignificant.

Table 1. The effect of Quadris fungicide on corn yield 2011.

	N.K.KB57W	Pioneer P1395	Pioneer P1395*	DeKalb DKC62*	Pioneer P33D49*
	bu/ac	bu/ac	bu/ac	bu/ac	bu/ac
Quadris	173	202	158	153	180
Check	171	215	137	157	177
LSD 0.05	NS	NS	NS	NS	NS
CV%	7.2	6.7	8.1	5.5	7.6

*Corn planted into corn residue.

Headline fungicide was used in 2012 and 2013 and all experiments were planted into soybean residue. The 2012 growing season was hot and dry which limited corn foliage diseases. Disease incidence was low levels of gray leaf spot. Below in Table 2, the two Pioneer hybrids, yields were relatively the same when the treated was compared to the untreated. The Mycogen hybrid with the fungicide treatment yielded more than the untreated, but had a higher CV. The DeKalb hybrid yields were relatively the same.

Table 2. The effect of Headline fungicide on corn yield 2012.**

	Pioneer 1395	Pioneer 33T57	Mycogen 2A787	DeKalb DKC64-69
	bu/ac	bu/ac	bu/ac	bu/ac
Headline	241	219	158	153
Check	242	218	137	157
LSD .05	NS	NS	NS	NS
CV%	4.2	4.6	10.0	2.9

**Corn planted into soybean residue.

In 2013, two hybrids had relatively the same yields whereas the other two had considerable yield differences. Statistically, there was no difference between the fungicide treated hybrids and the untreated.

Table 3. The effect of Headline fungicide on corn yield 2013.***

	Pioneer P1395	Pioneer P1420HR	Producers 7254	Pioneer P1319
	bu/ac	bu/ac	bu/ac	bu/ac
Headline	159	150	137	155
Check	162	151	167	146
LSD .05	NS	NS	NS	NS
CV%	10.6	10.0	7.8	11.0

***Corn planted into soybean residue.

Summary

Data from three years with four corn hybrids tested each year indicate no significant yield response from fungicide application. Corn fungicide application decisions should be carefully considered. Our data indicates there is limited opporunity for corn fungicide application to benefit yield and corn fields should be scouted before making a decision to apply a fungicide.

References

Sweets, L. (2008). Corn Diseases. Extension Publication IPM 1001. University of Missouri Extension.

Sweets, L. (2013-2011). Corn Disease Management. M171. Missouri Pest Management Guide. University of Missouri Extension.

Sweets, L. (2011, July 7). Corn Foliage Diseases. IPCM Newsletter. Volume 21, Number 13. University of Missouri Extension.

Sweets, L. (2012, August 21). Field Crop Disease Update. IPCM Newsletter. Volume 22, Number 9. University of Missouri Extension.

 

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