Effect of fungicides on anthracnose (Colletotrichum fragariae Brooks) on strawberry plants [Fragaria × ananassa (Duchesne ex Weston) Duchesne ex Rozier]

Abstract

High profitability and adaptability that presents strawberry production in Paraguay are affected negatively by the continuous increase of incidence of anthracnose. In order to select a fungicide that effectively controls the disease, it was assessed the effect of the products; for that, two experiments were conducted, in laboratory and greenhouse in the College of Agricultural Sciences of the National University of Asuncion. On in vitro experiment, it was determined the percentage of mycelium inhibition, there was established 22 treatments and eight replications, which consisted of different fungicides and a control; the experimental unit was composed by one Petri plate. On in vivo experiment, it was determined the incidence, severity, intensity of damage, chlorophyll content and NDVI; 13 treatments and five replications were composed by the different fungicides and the control; the experimental unit consisted of three strawberry’s plants. The completely randomized design was used for both experiments. The data obtained was submitted to variance analysis and Test of Tukey 5%. In vitro results indicated Colletotrichum fragariae was inhibited completely by the triazoles, strobilurins, in mixtures; and mancozeb. During in vivo trials, the products Mancozeb, Tebuconazole+Trifloxystrobin, Trifloxystrobin+Cyproconazole and Azoxystrobin+Propiconazole+Difenoconazole presented moderate incidence and reduced 51-63% of severity and 60-77% of intensity of damage of anthracnose. The strawberry plants treated with Tebuconazole+Trifloxystrobin resulted in a major chlorophyll content.