Is Early Season Whorl-Stage Application of Acaricide a Viable Practice for Managing Spider Mites in Maize?
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Banks grass mite, Oligonychus pratensis (Banks), and twospotted spider mite, Tetranychus urticae Koch, are major pests of maize, Zea mays L., throughout the Great Plains states. Acaricides are primarily applied at late-vegetative to posttassel growth stages, but producers and crop consultants sometimes apply acaricides when maize is at the V3-V5 growth stages. This study investigated whether or not early applications of acaricides or applications at V9-V11 growth stages would be sound practices for managing spider mites. Studies from 2010 to 2012 used Comite II (propargite) at 4.76 liters/ha, Oberon 4SC (spiromesifen) at 0.53 liters/ha, and Onager (hexythiazox) at 1.05 liters/ha at the designated growth stages. In two of the three years, spider mites in the nontreated check or treated plots never developed to damaging numbers when acaricides were applied at the very early V3-V5 or the late V9-V11 growth stages. The spider mites were suppressed naturally by predators during the 2 years. In 2011 when spider mites increased to damaging levels, applications of acaricides were equally effective in suppressing mites at both maize growth stages. However, the acaricides did not prevent spider mites from damaging maize when compared to the nontreated check. Inability to predict if early season spider mites will develop into damaging infestations makes early whorl-stage applications unreliable and costly.
author list (cited authors)
Bynum, E. D., Nino, E., Vandiver, M., & Porter, P.
complete list of authors
Bynum, Edsel D||Nino, Emilio||Vandiver, Monti||Porter, Pat