Diversidad genética de Lasiodiplodia theobromae (Pat.) Griffon & Maubl. en pitahaya y sensibilidad a fungicidas de diferentes modos de acción.

Abstract

The aim of this study was to determine the genetic diversity and in vitro sensitivity of Lasiodiplodia theobromae to fungicides of different modes of action; for diversity, the extraction of DNA from 7 strains of Lasiodiplodia theobromae was carried out through the use of the Wizard Kit and consequently PCR was performed, using Go-Taq Hot Star Master Mix as enzyme with the appropriate thermal profile for RAPDs primers and electrophoresis of 14 strains separating them into two sets A and B; on the other hand, for sensitivity, seven active principles were used: thiabendazole, tebuconazole, pyraclostrobin, cyprodinil, copper sulfate pentahydrate, difenoconazole and thiophanate methyl. These were applied to 7 strains of L. theobromae from different localities in the province of Pichincha. The stock solution of the fungicides was prepared, serial dilutions of 0.1, 1, 10 and 100ppm were made, the PDA medium was poisoned and dispensed in Petri dishes with 3 replicates for each concentration, 2 mycelium discs were sown and growth was evaluated. For statistical analysis, the R Studio program was used to perform the richness analysis and determine the MCT and DE50 for each active principle. The results obtained were: Bonanza obtained in set A(3.38-2.52) and set B(2.50-3.38), thiabendazole(DE50:0.54-3.72ppm), tebuconazole(DE50:0.04-0.35ppm), cyprodinil(DE50: 0.62-5.03ppm), pyraclostrobin(DE50:0.43-14.73ppm), copper sulfate pentahydrate(DE50:1.60-4.05ppm), difenoconazole(DE50: 0.07-16.65ppm) and thiophanate methyl(DE50: 0.54-3.72ppm). It was concluded that the Bonanza locality was the one that presented the highest number of multilocus genotypes in all the sets, being the most diverse; in relation to the sensitivity, the efficient active principles on the MCT of L. theobromae were: tebuconazole, thiabendazole and thiophanate methyl, therefore, it was recommended to use more isolates and other products in other work.