THE EFFECTS OF CHEMICAL TREATMENT, HARVEST DATE, AND SPECIFIC ISOLATION MEDIA ON THE PEANUT SHELL MYCOBIOTA OF 2 PEANUT CULTIVARS

Peanut (Arachis hypogaea) cultivars Florunner and Southern Runner grow n at two locations near Tifton, Georgia, were either treated with the fungicide flutolanil (Moncut) or nontreated. Comparisons of peanut she ll mycobiota were made for both treatments at two harvest dates. A tot al of 12,744 fungal isolates were cultured from 4,200 shells assayed. Over two-thirds of the isolates were Deuteromycotina. Common form-gene ra isolated were Alternaria, Curvularia, Fusarium, Lasiodiplodia, Nigr ospora, Rhizoctonia, and Rhizopus. Isolations of some genera were sign ificantly different between treatments within a cultivar, and between the two cultivars. However, these differences were of small magnitude and inconsistent across farms, harvest dates, or cultivars. In particu lar, Fusarium, Rhizoctonia, and Nigrospora sphaerica were isolated at significantly different rates from both sites. On Florunner, flutolani l increased total isolations of Fusarium oxysporum, F. solani, and F. equisiti. Also, several Rhizoctonia anastomosis groups (AGs), excludin g R. solani AG-4, could be obtained more readily from Florunner than f rom Southern Runner shells. Mean isolations on three media were signif icantly different. Rhizoctonia spp. were isolated from shells at the s ame frequency with tannic acid-benomyl agar (TABA) (semiselective Basi diomycete medium) and malt extract agar (MEA) media. Fusarium spp. wer e isolated more frequently on malt-salt agar than on MEA and TABA.