Effect of Fungicide Applications on Plant Health in Louisiana Grain Sorghum.

Based on recommendations from fungicide manufacturers, producers are applying fungicides to grain sorghum to enhance plant health and to increase yields, even in the absence of foliar disease symptoms.  To address this practice, two foliar fungicide trials were conducted in Louisiana.  The objective of these two studies was to determine if there was a yield increase or economic benfit of applying a fungicide to grain sorghum in the absence of disease pressure.  Foliar fungicide applications were made when grain sorghum reached 25% bloom.  Fungicides evaluated in these studies included Headline® (pyraclostrobin), Quadris® (azoxystrobin), and Topguard® (flutriafol).  Beginning at 25% bloom, leaf temperatures and chlorophyll measurements were taken to determine if there were differences between the fungicide treatments.  These measurements were taken on a weekly basis until grain sorghum reached physiological maturity.  At harvest, percent lodging, percent grain moisture, bushel weight, and grain yield were measured.  Following harvest, grain samples were evaluated to see if differences in surface grain mold, total nitrogen, and percent protein in the seed were evident.