Mango (Mangifera indica L) is one of the most important cash crops of northern Peru. Since 2003, adult mango trees (cvs. Criollo and Kent) located in Piura Province developed symptoms of dieback characterized by the death of twigs and branches in the tree canopy. Additional disease symptoms involved darkened, elongated lesions on the peduncle, causing an early maturation of the fruit, and in advanced symptoms, stem-end rot of fruits. Symptoms were frequent in the spring months (September to November) when the lesions expand rapidly. Diseased tissues from branches and fruits were collected and small pieces of necrotic tissues were surface disinfected and plated onto potato dextrose agar (PDA) with 0.5 g L–1 streptomycin sulfate. Plates were incubated at 25°C in the dark. All affected tissues consistently developed colonies with a white mycelium, moderately dense, and becoming olivaceous gray after 5 to 6 days. Pycnidia were produced on sterile mango twigs placed on the surface of potato carrot agar (PCA) after 10 days. Conidia were hyaline, guttulate, aseptate, measuring (15-) 18.5 (-22.5) × (4-) 5.2 (-7.5) μm. Conidia became olivaceous and developed one or two septa before germination. Isolates were identified as Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers, & A.J.L. Phillips (1). DNA sequences of the rDNA internal transcribed spacer region (ITS) and part of the translation elongation factor 1-alpha (EF1-α) genes were used to confirm the identification through BLAST searches in GenBank (ITS: 99% identity to Accession No. EU080928; EF1-α: 98% identity to Accession No. AY343367). Representative sequences of the studied DNA regions were deposited at GenBank (ITS: Accession No. FJ528596; EF1-α: Accession No. FJ528597). Pathogenicity tests were conducted on 18-month-old potted mango plants cv. Kent with two N. parvum strains (A4 and A5). A mycelial plug (3 cm in diameter) taken from the margin of an actively growing colony of each isolate was put in a wound made with a cork borer of the same diameter on the stem of each plant. Inoculation wounds were wrapped with Parafilm. Controls were inoculated with sterile PDA plugs. Ten replicates for each isolate were used with an equal number of control plants. Plants were maintained in a greenhouse with a temperature range of 22 to 28°C. After 4 weeks, mango plants showed necrotic stem lesions originating from the inoculation point affecting also the branches of the inoculated plants. No differences in lesion area between strains were obtained. No lesions developed in the control plants. Reisolations from necrotic tissues were successful and both isolates were morphologically identical to those used for inoculations. N. parvum was isolated from all symptomatic trees in all surveyed areas. This pathogen has already been reported on mango (2) and currently represents a serious problem in the mango-producing areas of Peru. To our knowledge, this is the first report of N. parvum affecting mango in Peru. References: (1) P. W. Crous et al. Stud. Mycol. 55:235, 2006. (2) B. Slippers et al. Mycologia 97:99, 2005.
<p><strong>Background:</strong> <em>Phaeoacremonium parasiticum</em> is a frequently species associated with "Petri's disease" in young plants of grapevine in Peru. One of the main limitations is the use of fungicides and the limited molecules for its control. In this scenario, biological control is an important alternative to integrate in the management of grapevine diseases. <strong>Objective:</strong> The objective of the research was to evaluate the <em>in vivo</em> efficacy of native antagonists to <em>P. parasiticum</em> and their growth promoting effect on grapevine. <strong>Methodology:</strong> Plant material from mother plants (R-110) underwent thermotherapy (52.5°C for 30 min). Subsequently, the antagonists (bacteria and fungi) were inoculated by partial immersion at a concentration of 1x10<sup>6</sup> cfu ml<sup>-1</sup> (Colony forming units) for 3 h; 30 days later, <em>P. parasiticum</em> was inoculated, measuring shoot length before inoculation (SLBI). Seventy days after inoculation (DAI), shoot length (SL), length of necrotic stria (LNS), root dry weight (RDW) and root fresh weight (RFW) were measured.<strong> </strong><strong>Results:</strong> Isolate Tr-5 (<em>Trichoderma</em> spp.) increased SLBI by 68%. <em>Bacillus</em> spp. (Bac-1, Bac-2), <em>Trichoderma</em> spp. (Tr-5) and <em>T. harzianum</em> (T-22) increase >40% SL 70 DDI. Tr-6 (<em>Trichoderma</em> spp.), T-22 and Act-2 (Actinomycete) reduce >50% LNS. <em>Bacillus</em> spp. (Bac-2: Bac-3) significantly increase RFW (59.29%: 49.39%) and RDW (60.41%: 55.08%). <strong>Implications:</strong> Biological control with native antagonists reduces the development of Petri disease and promotes grapevine growth<strong>.</strong> <strong>Conclusions:</strong> The native antagonists show growth-promoting effect and control of LEN caused by <em>P. parasiticum</em> at the nursery stage.</p>
Los abonos orgánicos son una alternativa sostenible con el agroecosistema frente a los fertilizantes convencionales causantes de la contaminación de los recursos naturales. El objetivo fue determinar la eficacia de los microorganismos eficientes nativos (MEN) y de compost sobre el rendimiento y rentabilidad en el cultivo de quinua variedad INIA 415-Pasankalla en tres pisos altitudinales (Faical 1935 m de altitud, Lagunas Amarillas 2328 m de altitud. y Cascapampa 2995 m de altitud). Se evaluaron cinco tratamientos: T0 (testigo), T1 (MEN 2.5%), T2 (MEN 5.0%), T3 (MEN 2.5%+0.9 kg compost m-1) y T4 (MEN 5.0%+1.8 kg compost m-1), evaluando: AP (altura de planta), RHa (rendimiento hectárea-1), RPa (rendimiento planta-1), PP (peso de panoja), PMG (peso de mil granos) y DT (diámetro de tallo). Además, se analizó el beneficio/costo por tratamiento. Se realizó un análisis de componentes principales ACP, una comparación triple de ANOVA y un análisis de correlación. Con el ACP se obtuvo dos componentes (C1 y C2) explicando el 97.20% de la variabilidad del estudio. El Componente 1 (78.46%) explica la mayor variabilidad y agrupó variables: G-I (AP, DT), G-II (RHa, Rpa, PP). Los tratamientos T4 y T3 presentaron los mejores resultados en relación a la altitud: Lagunas Amarillas-T4 con G-I y Cascapampa-T4 con G-II presentaron los mayores valores del estudio. No obstante, Cascapampa-T2 fue el más rentable (b/c= 5.68). La mezcla combinada de los insumos orgánicos elaborados a partir de materias primas locales y aplicados en forma foliar y suelos presentes en T4, mejoró los rendimientos y la rentabilidad del cultivo de quinua en relación a la altitud.
<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>
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