Effect of foliar fungicide application timing on corn yield across different water regimes

ABSTRACT

Corn (Zea mays L.) is a major irrigated crop in the Texas High Plains (THP). Inadequate precipitation, declining groundwater resources, and inevitable seasonal drought in the area have led to a greater number of studies on crop hybrids, water regimes, and other yield-enhancing techniques. A four-year field study was conducted to investigate the effect of foliar fungicide timing on corn grain yield, grain moisture, and grain test weight under different irrigation regimes. A fungicide containing QoI + DMI was applied to four to six corn hybrids each year at various growth stages (V5, R1, and V5 + R1). For all years, corn plants were grown under three irrigation regimes to meet the seasonal evapotranspiration (ET) requirements of 50% (I₅₀), 75% (I₇₅), and 100% (I₁₀₀). Hybrid response to the timing of fungicide application and irrigation regime was not consistent over the years. However, in 2 of the 4 years, timing of fungicide application resulted in yield differences among the hybrids, especially at I₇₅ and L₁₀₀. For those years, the fungicide applied at R1 resulted in a higher grain yield, grain moisture, and grain test weight followed by the fungicide applied at V5 + R1. Results showed that hybrids reacted differently to the foliar fungicide based on the availability of water under disease-free conditions. This study further revealed that irrigation water could be reduced from I₁₀₀ to I₇₅ with a limited (5.6% in 2011, 11.3% in 2012, 1.3% in 2013, and 0.3% in 2014) yield penalty in the THP region.

KEYWORDS:

• crop growth stages
• fungicide resistance
• grain moisture content
• grain yield
• grain test weight
• thousand-kernel weight

Acknowledgement

This research was partially supported by Syngenta, Texas A&M AgriLife Research Cropping System Program, and USDA-NIFA Hatch Project TEX09438.

Disclosure statement

No potential conflict of interest was reported by the author(s).