ASSESSMENT OF PEANUT LEAF-SPOT DISEASE-CONTROL GUIDELINES USING CLIMATOLOGICAL DATA

Early leaf spot, caused by Cercospora arachidicola, and late leaf spot , caused by Cercosporidium personatum, can be controlled by foliar fun gicides. Extension recommendations in South Carolina suggest planting peanuts between 15 April and 15 May. The recommended starting date to initiate 10- to 14-day fungicide spray schedules to control leaf spot is 15 June. The 1980-1990 climatological data for Sumter, Florence, an d Blackville, South Carolina, were used to simulate calendar spray sch edules and a method for spray timing developed at Auburn University (A UPNUT) that used observed and forecast rainfall, This simulation showe d that adoption of AUPNUT scheduling in South Carolina could result in less foliar fungicide usage than the 10- and 14-day calendar-based sp ray schedules. The study showed: (i) the number of AUPNUT sprays depen ded on location in the state; (ii) the AUPNUT schedule added one appli cation prior to 15 June on early-planted fields but averaged less than one additional spray per year for later plantings when compared to a 14-day calendar-based schedule that started on 15 June; (iii) at least one spray per year can be saved regardless of planting time, and up t o five sprays can be saved depending on the distribution of days with rain; and (iv) a simulation using historical weather data can demonstr ate potential savings associated with adoption of new application sche dules.