Quantifying the Effect of Pyraclostrobin on Grainfill Period and Kernel Dry Matter Accumulation in Maize

Abstract

Strobilurin fungicides are effective against a wide range of foliar fungal diseases on several crops and may offer additional physiological benefits, including plants staying green longer than normal (the “stay-green effect”). It has been hypothesized that the stay-green effect may extend the grain fill period leading to increased grain yield due to a longer period of dry matter accumulation. We investigated the effect of pyraclostrobin fungicide applied at tasseling on foliar disease suppression, stalk rot severity, the stay-green effect of leaves in the upper canopy, dry matter accumulation, time at physiological maturity, grain yield, and moisture at harvest in maize from 2008 through 2010 in Iowa at six location years. Foliar disease severity was <5% in all location years. Pyraclostrobin-treated plots had a significantly higher area under green leaves incidence curve compared to non-treated maize. Although grain yield and grain moisture at harvest were not different (P > 0.1) between pyraclostrobin-treated and non-treated maize in all location years, treated plots tended to have higher yield and grain moisture. Time at physiological maturity did not differ between pyraclostrobin-treated and non-treated plots (P > 0.1). Although we demonstrated an application of pyraclostrobin to maize delayed senescence of the leaves thus contributing to the stay-green effect, our data did not show grain-fill period extension. Accepted for publication 21 August 2013. Published 24 October 2013.