Corn, Soybean, and Wheat Yield Response to Crop Rotation, Variety Rotation, and Fungicide Use to Manage Fusarium-Related Diseases.

The corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] cropping systems of the Midwest have led to increased selection pressure on diseases caused by Fusarium pathogens.  To minimize risk of disease development, growers may incorporate management practices such as longer crop rotations, use of disease-resistant varieties, and fungicide use; however, there is limited information regarding how interactions between these management practices affect yield.  A field experiment was conducted from 2010-2012 near Arlington, WI to identify interactions among disease management practices (crop rotation, host resistance, and fungicide use) that increase corn, soybean, and wheat (Triticum aestivum L.) yields.  For corn grain, significant interactions were primarily driven by crop rotation.  Highest corn yields across all three years were observed in the corn-soybean-wheat (CSW) rotation (13.55 Mg ha^-1).  Corn silage yield was influenced by variety rotation with highest yields displayed by the Fusarium-susceptible rotations (SSS and SSR).  Soybean yields were influenced by interactions involving crop rotation and variety rotation.  Highest soybean yields were found for crop rotations containing wheat and ranged from 5.1-8.4% higher than the CS rotation.  The Fusarium-resistant (RRR) variety rotation (4.14 Mg ha^-1) yielded 3.0% better than the next highest rotation (SSR).  For wheat, variety selection and fungicide use were key drivers.  Highest yields on average were observed for the Fusarium head blight (FHB) susceptible variety (5.50 Mg ha^-1) compared to the resistant variety (4.89 Mg ha^-1), and fungicide use increased yield in the susceptible variety 7.2% (5.31 to 5.69 Mg ha^-1) but not for the resistant variety.  Although interactions were not consistent for all three crops, our results suggest growers should begin with combining a high-yield potential variety, regardless of its susceptibility or resistance to Fusarium pathogens,  in a CSW crop rotation in order to maximize yield potential when managing Fusarium-related diseases.