In vitro evaluation of biological fungicides against Curvularia eragrostidis, a phytopathogenic fungus of pineapple crop

Abstract

In vitro effectiveness of two plant extract-based products, System Max® (Mimosa tenuiflora + Quercus robur) and Sedric 4X® (Yucca schidigera); and three biological control agents-based products, BliteFree® (Streptomyces spp.), BioFungus Clean® (Bacillus subtilis + B. thuringiensis + Trichoderma harzianum + T. viride), and Tonka® (Bacillus subtilis + Trichoderma harzianum + Streptomyces lydicus) were evaluated against Curvularia eragrostidis, an associated fungus to leaf spot disease in pineapple (Ananas comosus) plants. The strain was identified by phylogenetic reconstruction using the rDNA ITS1-5.8S-ITS2 sequences as Curvularia eragrostidis. Through a doses response-bioassays f ive concentrations: 0 (control), 0.125, 0.25, 0.5 and 1.0% of each commercial product were tested. Daily mycelial growth (DMG), mycelial growth inhibition (% MGI) and the lethal mean concentration (LC50 ) were calculated. Sedric 4X® showed the highest% MGI (75%) at highest concentration, while Tonka® showed the highest% MGI (65%) at lower concentration, being constant (65.3-66.9%) at all the concentrations tested. The lowers values of EC50 were achieved by Tonka® (0.008%), BliteFree® (0.015%) and BioFungus Clean® (0.017%). In contrast, the highest CE50 were reached by Sedric 4X® (0.260%) and System Max® (3.5%). SystemMax® and Sedric 4X®, showed a positive relation between concentration and% MGI, despite its highest CE50 values. The biofungicides seem to be more effective against C. eragrostidis than plant extracts fungicides.