Tuesday, November 14, 2006

Effects of Foliar Fungicides on Mid-South Field Corn Production.

Jason Kelley1, Richard Cartwright1, Steven Sheets1, and David TeBeest2. (1) Univ of Arkansas Cooperative Extension Service, PO Box 391, Little Rock, AR 72203, (2) Univ of Arkansas, PTSC 217, Fayetteville, AR 72701

Field experiments were conducted on producer's fields in Southwest, North-Central, and East Arkansas to evaluate the effect of a single preventative foliar fungicide application to two high yielding glyphosate resistant hybrids with varying foliar disease resistance (Dekalb 69-71 and Pioneer 31G96).  Crop rotations of corn after corn and corn after soybeans were evaluated at each location.   Preventative foliar fungicide treatments of Quilt at 14 fl oz/acre were applied near silking and brown silk using a modified Co2 backpack sprayer.  Foliar diseases did not develop in any of these experiments and Quilt applications had no impact on corn yield.  Three application timing experiments were conducted on the Pioneer 31G96 (RR + Herculex) hybrid.  Experiments were located in Southwest Arkansas near Foreman and at the Cotton Branch Research Station near Marianna in Eastern Arkansas.  At Marianna, a typical planting date (April 12) and a late planting date (May 26) were evaluated.  Quilt was applied at 14 fl oz/acre to corn from 40 inches tall to near black layer (depending on location)  Foliar diseases were not present in experiments at Foreman or the early planted experiment at Marianna.  However, in the late planted (May 26) corn experiment, Southern rust was found late in the season at high levels.  Quilt applications made prior to silking provided little or no control of southern rust.  Quilt treatments applied after silking and particularly near brown silk provided the highest level of control.  Corn yields however were not increased with any of the Quilt applications due to the late occurrence of the disease in the growing season.  Visually the later Quilt applications maintained plant greenness, which may reduce plant lodging.   Plant lodging was high for all treatments due to a thunderstorm which resulted in approximately 30% plant lodging across the experiment.