Agronomic Management Strategies to Reduce the Yield Loss Associated with Spring Harvested Corn in Ontario

Abstract

Some growers in northern corn (Zea mays L.) producing regions forgo the typical autumn harvest for various reasons, but not without the risk of significant yield loss. Therefore, strategies are needed for managing the risks to yield when harvesting corn in spring. Field experiments, with various management strategies, were initiated in Ontario, Canada near Belmont and Ridgetown in 2009 and near Belmont, Ridgetown, and Lucan in 2010. Management strategies investigated the use of hybrids with a range in maturity, the use of standard and reduced plant populations, and the use of a foliar fungicide applied around tasseling. The parameters examined were stay-green in autumn, lodging in spring, and grain yield, moisture, and test weight of corn harvested in autumn and spring. Standard corn production practices consist of using a full-season hybrid planted at 80,000 plants&middotha-1 with no late-season fungicide application; however, if over-wintered at Belmont, corn managed using these practices resulted in a 23.1% yield loss (12.1 vs 9.3 Mg&middotha-1) averaged across years when the crop was harvested in the spring. An overwintering management strategy for corn was identified, which consisted of planting at a reduced plant population (60,000 plants&middotha-1) and spraying the crop with QUILT&reg (azoxystrobin + propiconazole at 200 g a.i. ha-1) at the VT to R1 growth stage. Averaged across all hybrids, this strategy minimized yield losses through improvements on corn standability with only a 3.5% yield loss at Ridgetown and a 13.2% yield loss at Belmont. Furthermore, grain test weights for corn with the overwintering strategy were similar to or greater than corn overwintered with the standard production practice. However, weather conditions have the potential to overwhelm any management strategy. In spite of the favorable data indicating reduced risks with a spring harvest, lodging was still higher than expected and yield losses would likely be unacceptable for most growers to make a spring corn harvest a widely accepted practice, unless autumn grain moistures are extremely high, drying charges are high, and if stalk strength going into the winter was exceptional.