<p><strong>Background:</strong> Biocontrol of grapevine trunk diseases (GTDs) is a friendly alternative to chemical control that cause resistance and contamination of the ecosystems. <strong>Objective:</strong> isolate native grapevine root and rhizosphere microorganisms with biocontrol potential of grapevine trunk fungi diseases. <strong>Methodology:</strong> The competition for substrate (CS) was studied with the Bell´s scale, contact time (CT) between the antagonist-pathogen (days) and the growth inhibition percentage (GIP). <strong>Results:</strong> Seven <em>Trichoderma</em> strains were isolated (from roots: Tr-1, Tr-2, Tr-3, Tr-6; and from rhizosphere: Tr-4, Tr-5 Tr-7); six <em>Bacillus </em>spp. (from roots: Bac-4, Bac-5, Bac-6; and from rhizosphere: Bac-1, Bac-2, Bac-3); and two <em>Streptomyces</em> sp. (Act-1, Act-2). The CS results evaluated with the Bell scale showed Tr-1, Tr-7, T.atv (<em>Trichoderma atroviride</em>)<em> </em>and T-22 (<em>Trichoderma harzianum</em>) were placed in class 1 against <em>Lasiodiplodia theobromae</em> and, all isolates were placed in class 1 against <em>Campylocarpon pseudofasciculare</em> and <em>Phaeoacremonium</em><em> parasiticum</em>. The CT of <em>Trichoderma</em> was 2 days (<em>L. theobromae</em>) and 3 days (<em>C. pseudofasciculare</em> and <em>P.</em><em> parasiticum</em>). In the antibiosis test, Tr-5 (<em>Trichoderma</em>) and Bac-3 (<em>Bacillus</em>) had the highest GIP values (>50%) against the different evaluated pathogens. The isolate Act-2 (<em>Streptomyces</em> sp.) presented a GIP, >70% (<em>L. theobromae</em>), and >40% (<em>C.</em> pseudofasciculare) and >30% (<em>P.</em><em> parasiticum</em>). <strong>Implications:</strong> The use of biological control in the management of grapevine trunk diseases is an effective tool, and can be integrated into an integrated management strategy for these pathologies. <strong>Conclusions:</strong> The native isolates Bac-3 (<em>Bacillus </em>spp.), Tr-5 (<em>Trichoderma</em> spp.), Act-2 (<em>Streptomyces</em> sp.) demonstrated <em>in vitro</em> control against the pathogens <em>L. theobromae</em>, <em>C. pseudofasciculare</em> and <em>P. parasiticum</em>, pathogens associated to grapevine trunk diseases.</p>
<p><strong>Background: </strong>Peru has become the leading exporter of table grapes focusing its production in the Piura and Ica regions. However, most of the young vineyards (<5 years) in the Piura region have been showing symptoms of Petri's disease. <strong>Objective</strong>: To isolate, identify and pathogenicity evaluation of fungi associated with Petri disease. <strong>Methodology:</strong> Isolates were obtained from necrotic streaks in vascular bundles in plants with symptoms of the Petri disease. Identification was performed with the keys proposed by Mostert, by means of macro and microscopic observations. Pathogenicity tests were also performed by measuring the advancement of the length of the necrotic streak (LNE). <strong>Results:</strong> By their cultural and microscopic characteristics, the following were identified: <em>Phaeoacremonium</em> spp, <em>P. krajdenii</em>, <em>P. inflatipes</em>, <em>P. parasiticum</em> and <em>Phaeomoniella chlamydospora</em>. All the selected isolates were pathogenic in pathogenicity tests 75 days post inoculation (DPI), being the <em>Phaeoacremonium</em> species the ones that presented higher LNE compared to <em>Pa. chlamydospora</em>, which demonstrates their capacity for colonization of vascular bundles and wood degradation. <strong>Implications:</strong> The pathogens Phaeoacremonium spp, <em>P. krajdenii</em>, <em>P. inflatipes</em>, <em>P. parasiticum</em> and <em>Phaeomoniella chlamydospora</em> are related to Petri's disease in the Piura-Peru region. <strong>Conclusion:</strong> <em>Phaeoacremonium</em> species showed higher pathogenicity than <em>Pa. chlamydospora</em> 75 DPI. Also, <em>P. inflatipes</em> was morphologically identified in the Piura region requiring molecular identification for corroboration.</p>
The banana Musaspp. (Musaceae) is a tropical perennial crop of major consumption in the world, the main producing regions are; Asia (54.1%), America (25.5%), Africa (18.4%). In Peru, Piura accounts for 72% of the country's total volume of organic banana exports. In recent years in Peru and in other producing areas of the world, symptoms of necrosis in the vascular bundles of the pseudostem have been occurring, causing the early death of plants in production. The objective of this study was to identify the main fungal pathogens associated with vascular necrosis of banana. The fungi isolated from the pseudostem, rhizome and roots were identified using taxonomic keys. The external symptoms of the disease were yellowing and necrosis of the leaves from the edge towards the midrib, collapse of the petiole and death of the plant. The internal symptoms were necrosis of the vascular bundles and internal necrotic lesions in the rhizome and roots. The fungal isolates were identified by their morphometric characteristics as Fusarium oxysporum, F.verticillioidesand F.solani. For the control of this disease, it is recommended to implement an integrated management plan.
Etiología de la muerte regresiva por Phytophthora palmivora en el cultivo de cacao (Theobroma cacao L.) Etiology of regressive dieback by Phytophthora palmivora in the crop of cocoa (Theobroma cacao L.
Organic banana (Musa sp.) is one of the most important export crops in Peru, especially in the Department of Piura. The cultivation of the crop is mainly affected by biotic factors, resulting in important economic losses. The aim of this research was to characterize the causal agent of banana bacteriosis disease in Piura. Bacterial isolates were extracted from rhizome and pseudostem samples of organic bananas with typical symptoms of soft rot from different banana growing areas of Piura. Sixty colonies were obtained, while 10 isolates were selected for presenting cultural and morphological characteristics similar to those of Pectobacterium (01MB, 04MB, 05MB, 06MB and 10MB) and Dickeya (02MB, 03MB, 08MB, 07MB and 09MB); different biochemical and molecular tests were conducted. The pathogenicity of the isolates was confirmed by in vitro and in vivo inoculation of rhizome pieces and pseudostems from cultivated plants. The 10 isolates were gram negative and with perimeter flagella. The biochemical tests showed that all the isolates were positive on nutrient agar medium, Mac Conkey, catalase, gelatin hydrolysis and growth at 37°C, whereas they were negative on King's B medium, nitrate reductase and oxidase tests. Isolates 02MB, 03MB, 08MB, 07MB and 09MB also tested positive for erythromycin and indole, while isolates 01MB, 04MB, 05MB, 06MB and 10MB were positive for CVP (Crystal violet pectate). Molecular identification and phylogenetic analysis confirmed that isolates 01MB, 04MB, 05MB and 10MB corresponded to Pectobacterium carotovorum subsp. carotovorum; isolates 03MB and 08MB corresponded to Dickeya chrysanthemi; and 02MB and 07MB corresponded to Dickeya paradisiaca and Klebsiella variicola, respectively. It was concluded that rhizome and pseudostem wet rot of banana grown organically in Piura is caused by the bacterial complex formed by P. carotovorum subsp. carotovorum, D. chrysanthemi, D. paradisiaca and K. variicola. This is valuable information for the implementation of appropriate disease management practices in the area.
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