Evaluation of Peanut Agrochemical Efficacy in Situations where Spray Solution Application is Delayed

Abstract

ABSTRACT The effect of delayed application of spray solutions is poorly understood with respect to efficacy of fungicides, insecticides, inoculants, and plant growth regulators commonly used in peanut (Arachis hypogaea L.). Research was conducted in North Carolina during 2009 and 2010 to determine if tobacco thrips (Frankliniella fusca Hinds) control by acephate; early leaf spot (caused by Cercospora arachidicola Hori) and late leaf spot (caused by Cercosporidium personatum Berk. and Curt.) control by chlorothalonil, prothioconazole plus tebuconazole, pyraclostrobin, and tebuconazole; Sclerotinia blight (caused by Sclerotinia minor Jagger) control by boscalid and fluazinam; and improvement in row visibility by prohexadione calcium were affected by the time interval between solution preparation and application. Performance of the inoculant Bradyrhizobium was also compared when prepared in 25 different sources of water when application was delayed after preparation of solutions. Agrochemicals and prohexadione calcium solutions were prepared the d of application or 3, 6, and 9 d prior to application with all solutions applied on the same d. Similarly, inoculant solutions were prepared the d of application or 4 and 8 d prior to application and applied on the same d. Performance of fungicides, insecticides, inoculant, and prohexadione calcium was not reduced in most instances when left in spray solution up to 8 or 9 d. The magnitude of difference in efficacy was minor when differences were observed.