Colombian Agricultural Research Articles

Mapping Bovine Tuberculosis in Colombia, 2001-2019.

Bovine tuberculosis is a zoonotic disease of significant impact, particularly in countries where a pastoral economy is predominant. Despite its importance, few studies have analysed the disease's behaviour in Colombia, and none have developed maps using geographic information systems (GIS) to characterise it; as such, we developed this study to describe the temporal-spatial distribution of bovine tuberculosis in Colombia over a period of 19 years. A retrospective cross-sectional descriptive study, based on reports by the Colombian Agricultural Institute (ICA), surveillance of tuberculosis on cattle farms in Colombia from 2001 to 2019 was carried out. The data were converted into databases using Microsoft Access 365®, and multiple epidemiological maps were generated with the QGIS® version 3.36 software coupled to shape files of all the country's departments. During the study period, 5273 bovine tuberculosis cases were identified in multiple different departments of Colombia (with a mean of 278 cases/year). Regarding its temporal distribution, the number of cases varied from a maximum of 903 cases (17.12% of the total) in 2015 to a minimum of 0 between 2001 and 2004 and between 2017 and 2019 (between 2005 and 2016, the minimum was 46 cases, 0.87%). GIS are essential for understanding the temporospatial behaviour of zoonotic diseases in Colombia, as is the case for bovine tuberculosis, with its potential implications for the Human and One Health approaches.

Livestock and environmental characterization of Colombian municipalities: study of vesicular stomatitis.

Amid the surge in data volume generated across various fields of knowledge, there is an increasing necessity for advanced analytical methodologies to effectively process and utilize this information. Particularly in the field of animal health, this approach is pivotal for enhancing disease understanding, surveillance, and management. The main objective of the study was to conduct a comprehensive livestock and environmental characterization of Colombian municipalities and examine their relationship with the distribution of vesicular stomatitis (VS). Utilizing satellite imagery to delineate climatic and land use profiles, along with data from the Colombian Agricultural Institute (ICA) concerning animal populations and their movements, the research employed Principal Component Analysis (PCA) to explore the correlation between environmental and livestock-related variables. Additionally, municipalities were grouped through a Hierarchical Clustering process. The assessment of risk associated with VS was carried out using a Generalized Linear Model. This process resulted in the formation of four distinct clusters: three primarily characterized by climatic attributes and one predominantly defined by livestock characteristics. Cluster 1, identified as "Andino" due to its climatic and environmental features, exhibited the highest odds ratio for VS occurrence. The adopted methodology not only provides a deeper understanding of the local population and its context, but also offers valuable insights for enhancing disease surveillance and control programs.

GENETIC DIFFERENTIATION OF CULTIVATED CITRUS FRUITS (Citrus spp.) IN COLOMBIA USING SSR MOLECULAR MARKERS

Citrus is the second most important fruit crop in Colombia after bananas, with production taking place in 26 of the country’s 32 departments. Oranges, sour limes, and mandarins are the most economically important crops in terms of area planted and production. Microsatellites were used to assess the genetic differentiation of oranges, mandarins, tangelos, grapefruits, and acid limes from the Colombian Agricultural Research Corporation AGROSAVIA germplasm bank and collection of micro-grafted plants at Palmira Research Center in Colombia. A total of 121 samples from eight citrus groups were analyzed with 30 fluoromarked simple sequence repeats (SSR) microsatellites. The mean expected heterozygosity and mean observed heterozygosity were 0.58 and 0.57, respectively, and the coefficient of genetic differentiation was 0.558, confirming very high genetic differentiation among the citrus groups evaluated. Microsatellites mCrCIR01B02, AMB5, Ci01C09, mCrCIR08B08, and Ci01C07 were the most informative, presenting a high number of alleles and polymorphic loci percentages of more than 45 %; in addition, they allowed the identification of unique alleles, which can be used to establish the genetic fingerprint of citrus. Genetic differentiation was achieved for seven out of the eight groups evaluated. The SSRs used failed to differentiate the orange groups, possibly due to genetic origin; for this group, other molecular markers are recommended.

High mountain agriculture in Colombia: opportunities for conversion to sustainability

This review article presents a socioecological analysis based on current literature to provide elements to enrich the currentdebate on the transition to sustainability proposed in Law 1930 of 2018. to achieve this objective, a review of currentregulations and commitments of Colombia for sustainable agriculture is made, Afterwards, a review of high mountainecosystems and their importance with emphasis on agricultural and livestock activities is included. Subsequently, adescription of the different schools of agriculture present in high mountain ecosystems is included. Finally, a reflection ismade regarding the progress and challenges to achieve the transition of agricultural activities towards sustainability inmoorland ecosystems. It is concluded that, although there are advances in the political-institutional and socio-ecologicalframework, it is imperative to focus on all the actors of the Colombian agri-food system and make timely progress in therecognition and valuation of the contributions that the different schools of agriculture make to sustainability, usingcriteria that are proposed based on the dimensions of sustainability. Not including these elements in the debate turns thetransition into a sophism that will perpetuate socio-ecological conflicts in the territories.

Calibration and Implementation of a Dynamic Energy Balance Model to Estimate the Temperature in a Plastic-Covered Colombian Greenhouse

Modeling and simulation have become fundamental tools for the microclimatic analysis of greenhouses under various climatic conditions. These models allow precise control of the climate inside the structures and the optimization of their performance under any situation. In Colombia, the availability of energy balance models adapted to local greenhouses and their climate is limited, which affects the decision-making of both technical advisors and growers. This study focused on calibrating and evaluating a dynamic energy balance model to predict the thermal behavior of an innovative type of plastic-covered greenhouse designed for the Bogotá savanna. The selected model considers fundamental heat and mass transfer processes, incorporating parameters that depend on the architecture of the structure and local climatic conditions, making it suitable for protected agriculture in Colombia. The results of the post-calibration evaluation showed that the model is highly accurate, with a temperature prediction efficiency close to 86%. This ensures that the model can accurately predict the thermal behavior of the greenhouse being evaluated. It is important to note that the model can also anticipate phenomena characteristics of Colombian greenhouses, such as thermal inversion. This advance has become a valuable tool for decision-making in protected agriculture in the region.

Identificación molecular y prevalencia de contaminantes fúngicos en semillas de cultivos semestrales

Seed quality is affected by fungal contamination. These cause abortion, rot, or necrosis of the seed, as well as seedling damage that results in the development of diseases in later stages of growth. Their identification and characterization are essential to establish appropriate management. The objective of this work was to identify and determine the prevalence of fungal contaminants present in the seed of thirteen plant varieties of rice, soybean, corn, and forage sweet sorghum produced in the municipality of El Espinal, Tolima, Colombia. This research was carried out at the Tibaitatá Research Center of the Colombian Agricultural Research Corporation AGROSAVIA (Cundinamarca, Colombia) during the second semester of 2021. By means of a blotter test, fungal contaminants and their prevalence in germinated and non-germinated seeds were identified. A total of 65 fungal isolates were obtained, which were grouped into twenty-eight molecularly identified morphotypes (44 soybean, 5 rice, 7 sorghum and 9 corn). The genera Diaporthe and Fusarium were the ones with the highest total prevalence and in ungerminated seeds. The fungi found include possible pathogens such as Fusarium spp, Curvularia spp and Diaporthe spp. and saprophytic fungi such as Penicillium spp and Aspergillus spp. The isolates of Fusarium equiseti and Diaporthe sp. in soybean seed, Curvularia penniseti in rice seed, Diaporthe melonis in sorghum seed and Fusarium verticillioides in corn seed can be considered as potential seed-borne pathogens that caused a negative effect on germination capacity.

How the visit of pedologist Hans Jenny to Colombia (1946–1947) contributed to the theory of soil-forming factors

When the Swiss pedologist Hans Jenny wrote his 1941 treatise Factors of Soil Formation: A System of Quantitative Pedology, knowledge of tropical soils was very limited. This treatise, which explains the theory of soil genesis in detail and provides a basis for taxonomic classification, hardly used case studies from the tropics for generalization of the theory. Yet, a careful reading of the five articles published using the fieldwork data from Colombia (1946–1947), revealed how Jenny was able to test his theories in a tropical environment. Meanwhile, under the influence of Jenny, new knowledge and awareness of natural processes involved in the formation and evolution of soils was introduced in Colombia. Jenny’s visit had an important impact not only on soil research but also on human resource training and soil management in the country. In this article we review the context of his visit, the importance of Jenny’s research on soils of Equatorial Colombia (published in five articles, three of them are translations also published in Spanish), and its impact at a global level. Hans Jenny’s visit to Colombia was rewarding for both parties. On one hand, close contact with Jenny strengthened research in soil science applied to agriculture in Colombia (mainly coffee and sugarcane crops), and reinforced institutions such as Laboratorio Químico Nacional, Federación Nacional de Cafeteros and Facultad Nacional de Agronomía. Colombia; on the other hand, it provided a unique opportunity to compare and contextualize preconceived ideas from his theoretical models in the humid tropics. Hans Jenny is known by soil science experts especially for his theory of soil formation. However, the circumstances of his visit to Colombia and its effects on soil science have not received sufficient recognition. Research and field work in the tropics went beyond being important complements to his pedological theories. They improved the understanding of the increasing complexity of climate influence on soil formation at low latitudes.

Genetically modified agriculture. A bioethical evaluation of a case from Colombian

<p>Transgenic technology promises to eradicate hunger and poverty worldwide, among other sustainable development goals, and as a result, its acceptance is increasing. However, there are perspectives that highlight the challenges raised by such expansion. This paper is a reflection on a study effort on the bioethical consequences of using transgenic technology in agriculture in Colombia. The goal is to prove that this adoption poses a bioethical danger. The paper, on the one hand, addresses the problem that arises from confronting arguments for and against the adoption of this technology, while also noting the absolute importance of the economic aspect in the provision of genetically modified organisms (GMOs) and the general difficulties of Colombian national regulations regarding GMO control and surveillance. Finally, it discusses the bioethical implications of adoption, beginning with the illusion of a transformational technology and progressing via the political will of the government to its eventual delivery to consumers.</p>

Mapping the Spatiotemporal Distribution of Bovine Rabies in Colombia, 2005-2019.

Introduction: Rabies is caused by a virus belonging to the genus Lyssavirus and family Rhabdoviridae, which can infect any mammal including humans. Hematophagous, fructivorous, and insectivorous bats have become the main reservoir of sylvatic rabies in Latin America. In the sylvatic cycle, hematophagous bats are usually the main reservoir. In contrast, dogs and cats fulfil this critical role in the urban cycle. However, in rural areas, the most affected animals are bovines. They show clinical signs such as behavioural changes, hypersalivation, muscle tremors, spasms caused by extensive damage to the central nervous system, and death from respiratory paralysis. Objective: To describe the spatiotemporal distribution of bovine rabies in Colombia from 2005 to 2019. Methods: Retrospective cross-sectional descriptive observational study, based on the monthly reports of the Colombian Agricultural Institute (ICA) on the surveillance of bovine rabies in Colombia from 2005 to 2019, retrieved from its official website. The data were converted to databases in Microsoft Access 365®. Multiple epidemiological maps were developed with the GIS software Kosmo RC1® 3.0 coupled to the shape files (.shp) of all the country’s municipalities. Results: During the study period, 4888 cases of rabies were confirmed in cattle, ranging from a peak of 542 cases (11.1%) in 2014 to 43 in 2019 (0.88%). From 2014 to 2019, there has been a significant reduction in the annual national number of cases (r2 = 0.9509, p < 0.05). In 2019, 32.6% of the cases occurred in January, and 48.8% occurred in the department of Sucre. In 2009, the maximum number of spatial clusters (13) occurred in the Orinoquia region, where other clusters were also identified in 2005, 2006 and 2008. In 2018, 98 outbreaks were identified that led to the death of cattle and other animals, 28.6% of them in the department of Sucre. In the first half of 2019, of 38 outbreaks, 55.2% were identified in Sucre. Conclusions: It is necessary to review the current national program for the prevention and control of rabies in cattle, incorporating concepts from the ecology of bats, as well as the prediction of contagion waves of geographical and temporal spread in the context of the OneHealth Approach. Sylvatic rabies remains a threat in Colombia that requires further study.

Evaluation of a Colombian oregano oil (Lippia origanoides Kunth) and a novel yeast product from Pichia guilliermondii, alone or in combination, on rumen fermentation, methanogenesis and the microbiome in the rumen simulation technique

In this study, Lippia origanoides Kunth, native to the Alto Patía region in Southwest Colombia, and Pichia guilliermondii LV196, an inactivated yeast from the germplasm bank of Agrosavia (Colombian Agricultural Research Corporation), alone or combined, were tested for their long-term effect on rumen fermentation and methanogenesis whilst also characterising their effect on bacterial and methanogen communities. Whereas essential oils act through selective inhibition of microbial groups, yeasts are thought to work through the selective stimulation of key microbes in the rumen. We hypothesized that yeast supplementation could modulate the antimicrobial effect of a high thymol-containing oregano oil, allowing a more efficient feed utilization whilst decreasing methane production. When added to a rumen simulating fermentor (RUSITEC), L. origanoides Kunth at 132 µL/d had a detrimental effect on rumen fermentation which was accompanied by a reduction in the relative abundance of protozoa and fungi and a profound impact on the bacterial and archaeal communities. P. guilliermondii LV196 at 0.5 g/L, however, had no effect on fermentation parameters or nutrient utilization, and neither changes in microbial abundances or in the structure of bacterial and archaeal communities were observed. P. guilliermondii LV196 did not stimulate microbial numbers nor activity and, consequently we could not test whether it could have counterbalanced the antimicrobial effect of the essential oil. Future studies need to both investigate lower levels of essential oil addition, but also to re-examine the effects of P. guillermondii in the rumen and/or to replace it with other yeast of known biological activity when combined with oils extracted from L. origanoides Kunth.

Blackberry (Rubus glaucus Benth.) fertilized with nitrogen, phosphorus, potassium and calcium: Effect on anthracnose under controlled conditions

In order to seek management alternatives for anthracnose caused by the fungus Colletotrichum gloeosporioides in blackberry (Rubus glaucus Benth.), at the Tibaitatá Research Center of the Colombian Agricultural Research Corporation AGROSAVIA (formerly CORPOICA), an experiment was conducted to evaluate the effect of the application of the major elements nitrogen (N), phosphorus (P), potassium (K) and calcium (Ca) on infections of the fungus C. gloeosporioides strain-52. For this purpose, a randomized complete block design was used with an arrangement of treatments in an orthogonal central composite design. To evaluate the relationship of fertilization levels and disease severity, an artificial inoculation was made on thorny blackberry stems using 0.5 cm mycelial discs at a concentration of 9.53 × 104 conidia. Observations consisted of: disease severity (S), incubation period (IP) and rate of development (r). Data analysis was done by the cluster method on the severity variable, a Pearson correlation analysis between variables, as well as a regression to estimate the effect of nutrients applied on the severity of C. gloeosporioides strain-52. The treatments were concentrated in four groups with the ranges (in parentheses) S (15.9% and 91.8%), PI (9 and 15.3) and Tr (0.0254 and 0.0468). A positive and significant correlation was observed between S and r (P &lt; 0.001) and a negative correlation between PI with S and r (P &lt; 0.001). By means of regression analysis, a linear model was generated that showed a reduction in disease severity with increasing N dose and an increase with the levels of P and Ca applied.

Modeling and simulation of an improvement proposal through the method mechanized transplanting

Rice agriculture in Colombia has high costs and low profitability, compared to rice agriculture in leading countries that are supported in different ways by their governments worldwide. Part of these high costs is due to the deficient technification of the processes, the absence of standardized procedures and the farmers’ lack of resources. This article develops modeling and simulation of the implementation of the indirect seeding method by mechanized transplanting; these results are obtained through the study and definition of technologies for the cultivation method, the description of the process, machinery, equipment, and inputs, which determined the necessary capacity of the production plant through modeling and simulation in software Flexsim. Rice cultivation is one of the main incomes of countries with high population density and poor economy, alternatives and improvement actions are of great importance for the growth of the sector. As a result, there is evidence of improved crop productivity, better water consumption efficiencies by physical analysis (comparison of traditional and technician water consumption) and the necessary capacity of a production plant from harvesting to final packaging.

An interactive panel for monitoring the spread of bovine tuberculosis and brucellosis in colombia

Aims &amp; objectives: Bovine tuberculosis (BTB) and brucellosis are communicable diseases that require epidemiological surveillance in real-time as a key strategy to control and eradicate outbreaks. Thus, our purpose was to design an epidemiological tool to monitor BTB and brucellosis in Colombia. Methods: We collected the epidemiological data from the epidemiological bulletins of the Colombian Agricultural and Livestock Institute (ICA) between 2004-2019. Data analysis was conducted using multiple correspondence analysis (MCA) and a Chi-square test in Factominer and Factoextra packages executed in the R software (v3.6). We designed a user-friendly dashboard with epidemiological information using the ArcGIS platform coupled with the Esri's Map-Viewer tool. Results: Our final dataset included 529 BTB and 739 brucellosis cases reported in Colombia for 15 years. The variables location and case number for both diseases were significantly associated. Our tool's analysis showed that Cundinamarca and Valle del Cauca provinces have been epidemic areas for bovine BTB and brucellosis, respectively (p-value &lt;0.001). Furthermore, increased case detection was reported in 2012 for bovine BTB and brucellosis (p-value &lt;0.001) during 2019. We implemented a user-friendly dashboard for the mapping of both diseases during the observation period to focus on program control actions. Conclusions: We expect that our GIS-based tool will support disease control strategies, tracking disease hotspots, and identify trends over time to provide useful information for animal health authorities tailoring new strategies for control programs. Dashboard availability: https://arcg.is/1uvSLv

Law of Origin Integrator of Premodern - Modern Production Practices in Kankuamo Territory of Colombia

Abstract The Kankuamo people from Sierra Nevada of Santa Marta [SNSM], Colombia, are undergoing a process of recovering their local knowledge and self-determination as an indigenous people; however, exogenous information affects their decisions and contributes to their acculturation. In this contr nnovative ones recommended by the Colombian Agricultural Research Corporation [AGROSAVIA]. This study seeks to contribute to the construction of a Hybrid Methodology that integrates the two positions by identifying emerging points of intersection in social, cultural, agro-environmental, political, and economic activities in its territory. It concludes on the need to align technological innovation strategies with the “Law of Origin” that governs the life of its people in the search for “good living”, to adopt them without detriment to their autonomy and cosmogony.

Compatibility of Ancestral and Innovative Agricultural Practices in the Kankuamo People of Colombia

Abstract The agricultural practices of the ancestral Latin American peoples hardly lead to optimal productivity integrated with adequate management of resources. This work evaluates the compatibility between the ancestral practices of the Kankuamo community in the vulnerable ecosystem Sierra Nevada de Santa Marta, Colombia, and innovative practices by the [AGROSAVIA] Colombian Agricultural Research Corporation, in biofortified beans of high nutritional value in the face of malnutrition and scarcity of the community’s own food. Methodologically, surveys were carried out that identify sustainability tracers and microbiological analysis of soils and the association among the variables evaluated. The results identify the incidence of education, health, self-care, gender and food supply in this vulnerability, verify the exclusion of agrochemicals in production, and show the need for a strategy of technological adoption with a differential approach.

Use of Biochar in agriculture.

The objective of this review is to show in a general way how biochar (BC) can be obtained and its effects on the physicochemical properties of soils and physiological behavior of cultivated plants. BC is a product rich in carbon that comes from the pyrolysis of biomass, generally of vegetable origin. BC is obtained by the decomposition of organic matter exposed to temperatures between 200-900 ºC in an atmosphere with low oxygen availability (pyrolysis), which can be slow, intermediate or fast. Depending on the biomass and the temperature used in its production, BC can contain high levels of elements such as carbon, nitrogen, oxygen, hydrogen, sulfur, among others. The main sources to produce biochar are forest, agroindustrial and manure residues. BC quality and physical-chemical characteristics will depend not only on the type of waste or plant material for production, but also on the plant photosynthetic apparatus. The high carbon contents present in organic matter, which are more resistant to biological and chemical decomposition, are stabilized by the pyrolysis process. When incorporated into the soil, BC remains stable for longer periods of time and is not volatilized into the atmosphere; this allows BC to be considered as an important compound for the mitigation of the impacts of polluting substances. Additionally, it has been found that BC application improves the physicochemical characteristics of the soil, including fertility. This improvement generates positive responses in the physiological behavior of cultivated plants such as the increase of germination, accumulation of dry matter, photosynthetic rate, yield and quality of the harvested organ. BC use opens important doors for the sustainable management of agriculture in Colombia. It can be considered in production systems exposed to heavy metals such as vegetables and perennial species, in order to reduce the impact of these substances on human health.

First Report of Fusarium Wilt Tropical Race 4 in Cavendish Bananas Caused by Fusarium odoratissimum in Colombia

Fusarium wilt of bananas, commonly called Panama disease, is caused by a suite of Fusarium species. Fusarium odoratissimum (previously known as Fusarium oxysporum f.sp. cubense) comprises Tropical Race 4 (TR4) (Maryani et al., 2018), which is highly aggressive on Cavendish bananas as well as many other banana varieties (Ploetz 2015). Since the 1990's TR4 has spread across Asia until it surfaced outside this region in Jordan in 2013 (Garcia-Bastidas et al., 2014). Subsequently, a succession of TR4 incursions in banana-growing regions in Asia, the Middle East, the Indian subcontinent, Africa and even Europe was reported (Zheng et al., 2018). Thus far TR4 was not reported in Latin America. Here, we report the occurrence of TR4 in samples originating from the department of Guajira in the northeast of Colombia, which is one of the leading global banana producing countries (~550.000 ha. banana and plantain production, with 66,000 ha. for export). Typical symptoms, such as wilting and chlorosis of leaves and vascular discoloration, were observed in at least hundred plants in June 2019 in four farms totaling more than 175 ha. This area was placed under quarantine by the Colombian Agricultural Institute (ICA) and a massive eradication effort was started. In total, 22 arbitrarily pseudostem samples were collected from symptomatic Cavendish plants from two farms located 3.8 km apart. These were processed for fungal isolation and characterization as described by Zheng et al. (2018). White fungal colonies developed from surface sterilized (1% NaClO) tissue on potato dextrose agar (PDA). Three single-spore isolates (Col 2, Col 4 and Col 17) that phenotypically resembled F. odoratissimum ( Maryani et al., 2018). Subsequently, these isolates were analyzed using three molecular diagnostics targeting two independent regions of the TR4 genome. The first region was assayed according to Dita et al., (2010) and with the commercial Clear®Detections TR4 kit. The second region was tested with a Loop‐Mediated Isothermal Amplification (LAMP) assay (Ordonez et al., 2019). These tests identified the three isolates as F. odoratissimum TR4 (Figure 1). Further analyses were undertaken by whole-genome sequencing using the Illumina platform (MiSeq Kit V3) and subsequent phylogenetic analyses using the TR4 reference (Foc II5, see PRJNA73539 and PRJNA56513, GenBank) as well as available additional Fusarium spp. (Asai et al., 2019; Ordonez et al., 2015; Maryani et al., 2018; Yun et al., 2019; Zheng et al., 2018). This confirmed that the three Colombian isolates firmly group together with other F. odoratissimum TR4 isolates (Figure 1). Finally, we tested whether the three isolates were able to cause Fusarium wilt in Cavendish. The pathogenicity assays and inoculum production were according to Garcia-Bastidas et al. (2019) and included water controls, a Race 1 isolate, which is not pathogenic on Cavendish, the three Colombian isolates Col 2, Col 4, and Col 17, and the II5 TR4 reference strain. Five plants per isolate were inoculated, all plants inoculated with the Colombian TR4 isolates and the II5 reference showed typical symptoms of Fusarium wilt after four weeks. After six weeks, internal symptoms were recorded (Figure 2), and affected tissue was collected from all plants for re-isolation of the causal fungus. All affected tissues and the re-isolated strains were positive with the aforementioned TR4 diagnostics. No isolates were recovered from water controls or plants inoculated with Race 1, which remained asymptomatic (Figure 2). Taken together, our results confirm the presence of TR4 in Colombia. Despite major efforts currently undertaken to cordon off the affected farms, this is an imminent threat for Colombia and the entire region.

Socio-economic and technological typology of avocado cv. Hass farms from Antioquia (Colombia)

ABSTRACT: A typology of avocado cv. Hass farms was constructed based on information collected from productive units in Antioquia, Colombia. The study aimed to provide key information about the farms for those involved in the design of programs and public policies directed to growers. The data were scrutinized through Multiple Correspondence Analysis (MCA) and Cluster Analysis. The sample was made up of 214 growers of the crop. Quantitative and qualitative variables were employed for the MCA, which rendered 40 dimensions, out of which 16 accounted for 70% of the total inertia (variance) found in the data. These 16 dimensions were used as input for the Cluster Analysis, which provided the following results: 52%, 32% and 15% of the farms were located in Clusters 1, 2 and 3, respectively. The identified farm types can be associated to peasant (Cluster 1) and commercial (Cluster 3) agricultural schemes, plus a transition between them (Cluster 2). The most discriminating variables regarding such categorization were: farm size, farm registry at ICA (Colombian Agricultural Institute), Avocado cv. Hass yield, labor source, presence of crops other than avocado, existence of formal commercial alliances and technical assistance type. The percentage of farmers belonging to grower organizations was high in the three clusters. Growers in Clusters 3 and 2 had established formal commercial alliances which enabled them to access better sale prices for the crop. A trend towards establishing cv. Hass as a monocrop is observed, which may threaten both crop biodiversity and the food security of peasant growers.

Applied research on dairy cattle feeding systems in Colombian high tropics

Sustainable intensification of dairy production is a strategy to consolidate a competitive sector. However, technologies adoption is limited due to the difficulty to accessing to research results. The objective of this document was to review a compilation of research works carried out mainly by the Colombian Agricultural Research Corporation (Agrosavia) in specialized dairy feeding systems of Colombian high tropics. In soils issue, research has been carried out on soil recovery and grassland renewal. Recently, the growth of grasses has been evaluated under different environmental conditions to generate efficient forage management schemes. In 2018 was registered Altoandina oat to forage use, but, in Colombian high tropic, there is a limited offer to forages due to absence of breeding program and evaluation of germplasm. Integrated management of Collaria scenica has been developed. Characterization and use of tree and shrub species have been carried out to silvopastoral systems (SSPs). In feeding systems, Agrosavia has been working on determining chemical and nutritional compositional of feed resources and design of supplementation schemes to improve animal response. Methane production increases when mature forage species are used, contrary a balanced diet or grazing in SSPs reduces methane emissions. Finally, research developments must incorporate and recognize the production costs of the system to ensure the adoption of technologies.

Estudio poblacional de Steneotarsonemus spinki (Acari: Tarsonemidae) sobre tres variedades de arroz sembradas en diferentes épocas

Entre los factores limitantes para la producción de arroz (Oryza sativa), se encuentran las plagas y enfermedades, responsables del 35 % de las pérdidas económicas y que exigen la adopción de medidas de control adecuadas con el fin de garantizar mejores índices de producción. El ácaro Steneotarsonemus spinki es una de las plagas que en los últimos años ha generado pérdidas en el sector arrocero. El Instituto Colombiano Agropecuario, declaró en 2005 la presencia de la enfermedad conocida como “vaneamiento de la espiga”, la cual afecta la calidad del grano y la productividad del cultivo hasta en un 60 %, generando pérdidas económicas para los agricultores. S. spinki, hace parte del complejo de organismos que causan el vaneamiento. Por lo anterior el objetivo de este trabajo fue evaluar la dinámica poblacional de S. spinki en diferentes épocas de siembra en un centro de investigación de Corpoica en Agustín Codazzi, Cesar, Colombia. Para lo cual, durante 2014 se realizaron siembras cada 20 +/- 3 días, de tres variedades diferentes de arroz, para un total de siete siembras en un diseño de bloques completos al azar en franjas fijas con cuatro repeticiones. A los 60 días después de emergencia de cada siembra, se procedió a tomar cuatro plantas por repetición por variedad en cada muestreo, haciendo cinco muestreos durante la etapa de cultivo. En la unidad de entomología del CI Motilonia se cuantificó el número de ácaros en las vainas de las tres últimas hojas de la macolla central de cada planta. Las poblaciones de S. spinki, superaron los 100 individuos por planta en algunos muestreos, la variedad FED 733 presentó la mayor población del ácaro y la variedad FED 2000 las menores. Según los resultados las poblaciones de S. spinki, aumentan en el segundo semestre del año y en etapas fisiológicas avanzadas del cultivo. Aparentemente las poblaciones del ácaro no influyen sobre los rendimientos de las variedades de arroz evaluadas.