Four field trials were carried out in Ribeirão Preto and Pindorama, SP, Brazil (1996 and 1997) to evaluate the efficiency of fungicides in the control of late leaf spot (Cercosporidium personatum) and scab (Sphaceloma arachidis) in peanut (Arachis hypogaea), cultivar Tatu. The treatments consisted of: control, not sprayed; conventional control, with four sprayings of chlorothalonyl at 14-day intervals, starting at 41 to 43 days after planting; monitored control with chlorothalonyl, tebuconazole, difenoconazole and propiconazole, respectively, in the recommended dosages for the peanut crop. Monitoring consisted of doing the first spraying when 5 to 15% of the leaflets were infected by the late leaf spot and, the following sprayings, at a minimum of 14-day intervals between applications, after three days, consecutive or not, in which rain precipitations greater than 2.5 mm were registered, in periods of seven days. Late leaf spot severity was assessed at weekly intervals during the growing season with diagrammatic scales of infected leaf area. Scab severity was evaluated at 84-92 days after planting with a specific scale of notes, ranging from one to four, according to the symptoms exhibited in stems and petioles. The results showed that in the monitored control, where the number of sprayings was reduced to one to three, the triazole fungicides were more efficient than chlorothalonyl, resulting in pod yields close to the treatment where four fixed sprayings were made. Tebuconazole promoted the highest reductions in late leaf spot intensity and, difenoconazole showed outstanding efficiency in the control of scab.
