Yield Loss of Corn to Incremental Defoliation during the Reproductive Stages of Development.

The importance of leaf area to corn for grain production beginning at silking has been documented in past years. However, being able to predict yield loss to defoliators such as foliar plant diseases and insects that progressively increase in severity over time has been difficult to quantify. This study was conducted at the Dean Lee Research and Extension Center located at Alexandria, Louisiana. The objective of this study was to determine the effects of leaf loss at different growth stages throughout the reproductive period of corn development. Two hybrids, differing in maturity were used (Terral Rev 1884AM and Rev 28HR20) in this study. The experimental design was a randomized complete block with four replications in a split-plot arrangement. Plots were four rows by 45 feet in length and were planted on 38-inch row centers. The number of leaves above and below the upper ear leaf were recorded prior to defoliation. Defoliation treatments begin at silking and continued until the dent stage. Ten plants from both rows two and three were defoliated by cutting selected leaves off of the plant at varying stages of development. Some treatments were only defoliated at one growth stage while others were defoliated at multiple growth stages. Plants that were defoliated in each plot were then hand harvested and shelled. Yield was then measured and compared between the different treatments.