Luis Armando Alvarez

Severe decline and death of young table grapevines (1 to 2 years old) have been observed recurrently in commercial vineyards in Peru since 2022. Affected plants developed rapid shoot wilting associated with extensive necrotic lesions at the rootstock collar below the graft union, leading to plant death within days of symptom onset. A Cylindrocarpon-like fungus was consistently isolated from symptomatic collar tissues. Morphological characterization, cardinal temperature assays, and phylogenetic analyses based on the internal transcribed spacer (ITS) region and histone H3 (his3) gene identified the pathogen as a member of the genus Pleiocarpon. Bayesian inference of concatenated sequences resolved the Peruvian isolates as a lineage sister to P. strelitziae (posterior probability = 1.00). Greenhouse pathogenicity tests with two representative isolates on cv. Red Globe grafted onto Salt Creek rootstock reproduced collar lesions and shoot wilting, fulfilling Koch’s postulates. Optimal mycelial growth was estimated at 28.7–29.3 °C, with maximum colony growth recorded at 30 °C, consistent with the warm conditions that prevail during vineyard establishment in coastal Peru. Designated here as collar rot, the syndrome represents an atypically severe form of black foot disease, characterized by extensive belowground collar necrosis and rapid vine collapse soon after planting. Its recurrence across regions and seasons, together with the near-exclusive deployment of a single rootstock (Salt Creek), indicates that Pleiocarpon-associated collar rot is an emerging threat to young table grape plantings in Peru, underscoring the need for early diagnosis, pathogen-free nursery material, and preventive management during vineyard establishment.

Severe decline and death of young table grape vines (1 to 2 years old) have been observed recurrently in commercial vineyards in Peru since 2022. Affected plants developed rapid shoot wilting associated with extensive necrotic lesions at the rootstock collar below the graft union, leading to plant death within days of symptom onset. A Cylindrocarpon-like fungus was consistently isolated from symptomatic collar tissues. Morphological characterization, cardinal temperature assays, and phylogenetic analyses based on the internal transcribed spacer region (ITS) and histone H3 (his3) gene identified the pathogen as a member of the genus Pleiocarpon. Bayesian inference of concatenated sequences resolved the Peruvian isolates as a distinct lineage sister to P. strelitziae (posterior probability = 1.00). Greenhouse pathogenicity tests with two representative isolates on cv. Red Globe grafted onto Salt Creek rootstock reproduced collar lesions and shoot wilting, fulfilling Koch's postulates. Optimal mycelial growth occurred between 25.7 to 26.1°C, and maximum experimental growth was observed between 28.8 to 31.5°C, consistent with warm conditions during vineyard establishment in coastal Peru. The disease, designated here as collar rot of grapevine, is pathologically distinct from classical black-foot disease due to its extensive belowground collar necrosis and rapid vine collapse. Recurrent outbreaks and the near-exclusive use of the susceptible Salt Creek rootstock indicate that Pleiocarpon-associated collar rot is an emerging threat to table grape production in Peru.

This study aimed to isolate and characterize native Trichoderma species from soils with low anthropogenic activity in the central Peruvian rainforest and evaluate their antagonistic mechanisms against Botrytis cinerea, the causal agent of gray mold and a model polyphagous pathogen. Twenty Trichoderma isolates were evaluated using inhibition assays, a quantitative assessment of mycoparasitism, and endophytic colonization tests in Capsicum baccatum. Ten isolates with promising antifungal activity were identified at the molecular level, revealing T. azadirachtae and T. anisohamatum as the first reports for Peru. Several strains showed a remarkable capacity for root colonization, and in vitro antagonistic activity reached maximum values of approximately 65%. These findings highlight the functional and phylogenetic diversity of Trichoderma strains from Peruvian rainforest soils and support their potential as sustainable biocontrol agents against B. cinerea.

Los hongos endófitos son organismos que pueden promover crecimiento y resistencia a estreses abióticos en las plantas. El objetivo de este estudio fue evaluar el efecto de diversos hongos endófitos sobre el crecimiento vegetativo del portainjerto de vid ‘Salt Creek’ a nivel de vivero. Se emplearon 14 cepas de los hongos más un testigo no inoculado, para constituir un ensayo con 15 tratamientos y 4 repeticiones mediante un diseño completamente al azar. Las cepas fueron inoculadas cada 15 días en las plantas con una concentración de 1×106 ufc·g-1 de sustrato y luego de 105 días se realizaron las mediciones del crecimiento. Los resultados indicaron que la cepa de Aspergillus niger superó a la gran mayoría de las cepas, excepto a Trichoderma inhamatum y Cladosporium halotolerans, con las cuales compartió significancia estadística en las variables de longitud y diámetro de los brotes, longitud de la raíz, y biomasa aérea, y con T. asperellum y Penicillium steckii en la variable biomasa total. En la biomasa radical los mayores promedios lo presentaron dos cepas de T. asperellum. Se concluye que las cepas de A. niger, T. inhamatum y C. halotolerans son las que mejor promueven el crecimiento vegetativo del portainjerto de vid en sus etapas iniciales, a la vez que demuestran muy buen potencial para su aplicación en los cultivos para una agricultura sostenible.

El limón sutil es un cultivo de alta demanda e importancia en el desarrollo socioeconómico en Perú, empleándose mayormente fertilizantes inorgánicos que generan incrementos constantes en los costos de producción, siendo necesario el uso de alternativas orgánicas e inocuas para su producción. El objetivo fue evaluar el efecto de diferentes dosis de biol o biofertilizante, y su correlación en los parámetros productivos y de calidad en el cultivo de limón sutil. Se evaluaron cuatro tratamientos: T0 (testigo: manejo convencional), T1 (Biol 10%), T2 (Biol 20%) y T3 (Biol 30%) aplicados cada 15 días, evaluando los siguientes parámetros: 1) productivos: diámetro del fruto (DF), grosor de cáscara (GC), peso del fruto (PF), rendimiento por ha (RHa) y 2) calidad: acidez (AD), porcentaje de sólidos solubles (PSS), pH, zumo o jugo de limón (ZL). Se realizó análisis de correlación, análisis de componentes principales-ACP, un ANOVA, y se analizó la relación Beneficio/Costo. En el ACP se obtuvo dos componentes: C1 (71.40%) y C2 (11.80%) explicando el 83.20% de la variabilidad. El C1 explica la mayor variabilidad y agrupó variables: G-I (ZL, AD), G-II (DF, GC, PSS) y GIII (PF, RHa). Los tratamientos con Biol 10%, 20%, 30% en ZL, AD (G-I) presentaron los mejores resultados (P < 0.05); el T2 presentó los mayores valores de PF y RHa, y fue el tratamiento más rentable (B/C=3.84). El Biofertilizante es una alternativa para reducir el uso de fertilizantes sintéticos y los costos de producción. El biofertilizante al 20% resultó más rentable y mejoró variables evaluadas.

Background: Peru is considered the third largest exporter of mango in the world and Piura is the first mango producing region representing 68% of the national production; however, the fungus Lasiodiplodia theobromae has been associated with dieback and the presence of cankers in mango cultivation, reducing fruit production and quality. Objective: To evaluate sustainable alternatives for in vitro and in vivo control of L. theobromae in mango, using products based on copper sulfate pentahydrate and a liquid biofertilizer. Methodology: Treatments were applied: T0 (Control), T1 (Vacun-Q organic 0.35 mL100 mL-1), T2 (Vacun-Q organic 0.175 mL 100 mL-1), T3 (Phyton 27® 0.35 mL100 mL-1), T4 (Phyton 27® 0.175 mL100 mL-1), T5 (Biol 10%) and T6 (Biol 20%). Radial growth and mycelial growth inhibition percentage (GIP) of the pathogen were evaluated in the in vitro phase with poisoned media, and necrotic area progression was assessed in the in vivo phase on mango leaves. Results: At 72 h after inoculation, treatments T3, T5 and T6 showed the lowest radial growth of L. theobromae, statistically equal to each other and inferior to the control that completed its development in the Petri dish; likewise, they showed 100% GIP. Five days after inoculation of mango leaves, T5 and T6 presented the smallest necrotic areas with 1.44 cm2 and 1.61 cm2 respectively, followed by T4 with 1.64 cm2 and T2 with 1.69 cm2 compared to the control with 2.05 cm2. Implications: In view of the constant restrictions of active molecules, sustainable and innocuous alternatives for humans and the environment are sought for the control of L. theobromae. Conclusion: Treatments T5 and T6 based on liquid biofertilizers showed to be effective in the in vitro and in vivo control of L. theobromae.

Organic fertilizers are a sustainable alternative to conventional fertilizers that cause contamination of natural resources. The objective of this study is to determine the ef ficacy of native microorganisms (ENM) and compost on yield and profitability on the cultivation of quinoa variety INIA 415-Pasankalla in three altitudinal levels (Faical 1935 m altitude, Lagunas Amarillas 2328 m altitude and Cascapampa 2995 m altitude). Five treatments were evaluated: T0 (control), T1 (MEN 2.5%), T2 (MEN 5.0%), T3 (MEN 2.5%+0.9 kg compost m-1) and T4 (MEN 5.0%+1.8 kg compost m-1), considering: PA (plant height), RHa (yield per hectare), RPa (yield plant-1), PP (panicle weight), PMG (thousand kernel weight) and DT (stem diameter). In addition, the benefit/cost per treatment was analyzed. A principal component analysis (PCA), three-way ANOVA comparison and correlation analysis were performed. The PCA yielded two components (C1 and C2) explaining 97.20% of the variability of the study. Component 1 (78.46%) explained the greatest variability and grouped the variables: G-I (AP, DT), G-II (RHa, Rpa, PP). Treatments T4 and T3 showed the best results in relation to altitude: Lagunas Amarillas-T4 with G-I and Cascapampa-T4 with G-II showed the highest study values. However, Cascapampa-T2 was the most profitable (b/c= 5,68). The combined mixture of organic inputs made from local raw materials and applied in foliar form, and the soils present in T4, improved the yields and profitability of the quinoa crop in relation to altitude.

Background: 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. Objective: To isolate, identify and pathogenicity evaluation of fungi associated with Petri disease. Methodology: 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). Results: By their cultural and microscopic characteristics, the following were identified: Phaeoacremonium spp, P. krajdenii, P. inflatipes, P. parasiticum and Phaeomoniella chlamydospora. All the selected isolates were pathogenic in pathogenicity tests 75 days post inoculation (DPI), being the Phaeoacremonium species the ones that presented higher LNE compared to Pa. chlamydospora, which demonstrates their capacity for colonization of vascular bundles and wood degradation. Implications: The pathogens Phaeoacremonium spp, P. krajdenii, P. inflatipes, P. parasiticum and Phaeomoniella chlamydospora are related to Petri's disease in the Piura-Peru region. Conclusion: Phaeoacremonium species showed higher pathogenicity than Pa. chlamydospora 75 DPI. Also, P. inflatipes was morphologically identified in the Piura region requiring molecular identification for corroboration.

Background: Phaeoacremonium parasiticum 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. Objective: The objective of the research was to evaluate the in vivo efficacy of native antagonists to P. parasiticum and their growth promoting effect on grapevine. Methodology: 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 1x106 cfu ml-1 (Colony forming units) for 3 h; 30 days later, P. parasiticum 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. Results: Isolate Tr-5 (Trichoderma spp.) increased SLBI by 68%. Bacillus spp. (Bac-1, Bac-2), Trichoderma spp. (Tr-5) and T. harzianum (T-22) increase >40% SL 70 DDI. Tr-6 (Trichoderma spp.), T-22 and Act-2 (Actinomycete) reduce >50% LNS. Bacillus spp. (Bac-2: Bac-3) significantly increase RFW (59.29%: 49.39%) and RDW (60.41%: 55.08%). Implications: Biological control with native antagonists reduces the development of Petri disease and promotes grapevine growth. Conclusions: The native antagonists show growth-promoting effect and control of LEN caused by P. parasiticum at the nursery stage.