Avocado Crops Research Articles

A brief reflection on the banana and avocado crops in Tanzania

A brief reflection on the banana and avocado crops in Tanzania

Pest categorisation of the avocado sunblotch viroid.

The EFSA Panel on Plant Health conducted a pest categorisation of the avocado sunblotch viroid (ASBVd) for the EU. The identity of ASBVd, a member of the genus Avsunviroid (family Avsunviroidae) is clearly defined and detection and identification methods are available. The pathogen is not included in the EU Commission Implementing Regulation 2019/2072. ASBVd has been reported in Australia, Ghana, Guatemala, Israel, Mexico, Peru, South Africa, USA (California, Florida) and Venezuela. In the EU, it has been reported in Greece (Crete Island) and Spain. The pathogen could establish in the EU wherever avocado (Persea americana) is grown. The only known natural host of ASBVd is avocado to which it causes the severe 'avocado sunblotch' disease, characterised by white, yellow, red or necrotic depressed areas or scars on the fruit surface, bleached veins and petioles of the leaf, and rectangular cracking patterns in the bark of the old branches. Fruit yield and quality are severely diminished. ASBVd infects under experimental conditions a few more species in the family Lauraceae. The viroid is naturally transmitted at an extremely high rate by seeds (up to 100% in asymptomatically infected trees), but with a low efficiency by pollen (only to the produced seeds), and possibly through root grafts. Plants for planting, including seeds, and fresh avocado fruits were identified as the most relevant pathways for further entry of ASBVd into the EU. Avocado crops are cultivated in southern EU countries. Should the pest further enter and establish in the EU, impact on the production of avocado is expected. Phytosanitary measures are available to prevent entry and spread of the viroid in the EU. ASBVd fulfils the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.

Wild Floral Visitors Are More Important Than Honeybees as Pollinators of Avocado Crops

Wild insects provide pollination services in agroecosystems. Avocado is an economically important crop grown in the Chilean Mediterranean climate region and exported worldwide. Avocado pollination is managed using honeybee hives, while the role of wild insects as pollinators remains poorly known. We quantified the relative contributions of wild floral visitors and honeybees to the fruit set of avocados in two contrasting seasons (2015 and 2016) in Central Chile. Observations were made in 60 trees grown nearby (~300 m) to remnant patches of native sclerophyll vegetation. We found that honeybees and wild insects accounted for 48.6% and 51.4% of total floral visitation, respectively, with a 68% taxonomic similarity of floral visitors between seasons. The presence of honeybees significantly modulated the floral visitor composition and modified plant-pollination network parameters, which resulted in the biotic homogenization of the interaction network, through the increase of shared tree–floral visitor interactions, to the detriment of exclusive interactions. Finally, wild insects were more effective than honeybees in pollinating avocado trees and their contribution was greatest during the dry year. Thus, honeybees alone cannot be relied upon to deliver maximum pollination. We highlight ecological intensification practices to encourage wild insect visits and avoid native vegetation replacement with orchards. Therefore, we emphasize that future ecological intensification research should address agricultural practices to promote wild insects and evaluate the role of native vegetation as wild pollinator habitat in agricultural landscapes.

Introduction of Avocado (Persia americana) Fruits in Eastern Himalaya of India: A Review

Avocado (Persia americana) or locally called Phamfal is a subtropical, dicotyledonous, evergreen tree belonging to the family Lauraceae. The avocado tree is originated from a broad geographical area stretching from the eastern and central highlands of Mexico through Guatemala to the Pacific coast of Central America. Avocado is a fruit, produced from tropical trees characterized by a pear shape and blackish green in colour with high nutritional value and creamy texture. Avocado crop can be used in several ways i.e for processed products, exportation and oil extraction, pharmaceutical and cosmetic industries as a raw material thereby generating high value added products.High demand for information on avocado indicates that there is considerable interest in this crop in various parts of India as well as Eastern India. Moreover, avocado can be grown in Darjeeling hilly region and adjoining states of India as the soil and climatic condition is favourable for their growth and development. However, in this region avocado cultivation is very negligible in homestead garden, small and marginal orchard due to lack of scientific knowledge of farmers. So that in this context to identify and conservation of wild and farmers cultivated species of avocado is the major concern for all avocado growers and scientist.

Natural occurrence of Metarhizium in agricultural avocado soils (Persea americana Mill.) in Colima, Mexico

Avocado (Persea americana Mill.) has become one of the most important fruits in the world, being Mexico the main producer and exporter worldwide, it has led to an accelerated growth in the establishment of monoculture avocado plantations, promoting the increase of insect and mite pests, which has led to the need for biological control strategies for integrated pest management. The objective of this study was to isolate entomopathogenic fungi from the soil of a conventional avocado orchard and identify them by translation elongation factor 1-α (5’TEF). During the sampling, a total of 34 isolates were obtained, belonging to the genus Metarhizium, 23 isolates identified as Metarhizium robertsii and 11 as Metarhizium guizhouense. These results show the low diversity of entomopathogenic fungi species associated with the rhizosphere of the avocado crop and suggest that their occurrence could be associated with their ability to survive agronomic practices that induce their endophytic activity. It is necessary to understand the role of Metarhizium in the rhizosphere, this will allow the development of biological control programs specific for each crop, and thus guarantee its success in pest control.

Fungal Pathogens Associated with Aerial Symptoms of Avocado (Persea americana Mill.) in Tenerife (Canary Islands, Spain) Focused on Species of the Family Botryosphaeriaceae.

Fungi of the family Botryosphaeriaceae are considered responsible for various symptoms in avocado such as dieback, external necrosis of branches and inflorescences, cankers on branches and trunks, or stem-end rot of fruits. In recent years, these problems are becoming more frequent in avocado orchards in the Canary Islands (Spain). This work includes the characterization of fungal species involved in these diseases, which were isolated from avocado crops in Tenerife Island between 2018 and 2022. A total of 158 vegetal samples were collected, from which 297 fungal isolates were culture-isolated. Fifty-two of them were selected according to their morphological features as representative isolates of Botryosphaeriaceae, and their molecular characterization was carried out, sequencing the ITS1-2 region as well as the β-tubulin and the elongation factor 1-alpha genes. Five species of Botryosphaeriaceae were isolated, including Neofusicoccum australe, N. cryptoaustrale/stellenboschiana, N. luteum, N. parvum, and Lasiodiplodia brasiliensis. This is the first time that L. brasiliensis has been associated with avocado dieback and that N. cryptoaustrale/stellenboschiana has been cited in avocado causing symptoms of dieback and stem-end rot. However, it was not possible to assign our isolates unequivocally to N. cryptoaustrale or N. stellenboschiana even additionally using the rpb2 marker for their molecular characterization. Botryosphaeriaceae family seem to be involved in avocado dieback, in the premature fall of fruits during their development in the field and in post-harvest damage in Tenerife, but further studies are needed to clarify the fungal pathogens associated with symptoms in relation to phenological plant growth stages or less frequently observed.

Economic Impact of the Persea Mite in Spanish Avocado Crops

The Persea mite, Oligonychus perseae Tuttle, Baker & Abbatiello (Acari: Tetranychidae), is an economically important foliar pest of avocados in Spain. The effects of this mite on the foliar damage, production losses and economic impact were assessed in two avocado, cv. Hass, orchards located in the main growing areas of Spain (Northern Tenerife and Málaga) for 3 and 5 consecutive years, respectively. The economic injury level (EIL) for the optimization of the use of acaricides to control this mite was also established, considering three spraying strategies: (i) mite-free treatment (<50 mites per leaf), (ii) conventional treatment (50–150 mites per leaf), and (iii) control treatment (the absence of spraying). Persea mite populations were sampled fortnightly and foliar damage was estimated. At the end of each season, fruits were harvested, weighed and production losses were quantified. The cumulate mite-days (CMDs) had a significant effect on the percentage of leaf area damaged (PLAD) and yield reduction. High numbers of the Persea mite caused extensive damage to leaves, so a loss in tree yield was evident. However, for the middle population level, there was no evidence of yield losses. The quantitative EIL was estimated at a PLAD of 17%, equivalent to a CMDs of 178 mites per leaf, which is the amount of damage that should not be exceeded. In Northern Tenerife, with a mild climate, the Persea mite can reach significant populations that are maintained throughout the months. In avocado orchards in Málaga, the summer is hotter and drier, so the presence of the mite exists for a shorter duration in the seasons, with less damage to the leaves. In Tenerife, yield loss can be compensated by chemical treatments that permit pest control.

Water footprint of representative agricultural crops on volcanic islands: the case of the Canary Islands

Abstract The Canary Islands are a Spanish archipelago, where the greatest water demand comes from agriculture. Being an outermost European region that receives a large number of tourists per year, the need for greater food sovereignty becomes more important. It is vital to undertake studies on the water footprint (WF) of the main crops, in order to identify the irrigation practices of local farmers and establish recommendations for water saving through improvement of these practices. The results of this study show that the average WF for bananas in the Canary Islands is 340.80 m3 t−1 ± 34.07 and for avocadoes is 1741.94 m3 t−1 ± 286.16. The WF models proposed can explain 92 and 86% of the total variance of the WF for banana and avocado crops, respectively. The WF of both crops can be reduced, and this work can be a starting point for improvement. Farmers will face a change in temperature and water availability due to climate change; useful water saving strategies for local farmers can now be made based on estimation of the WF with yield and net needs data.

Potential of Time-Series Sentinel 2 Data for Monitoring Avocado Crop Phenology

The ability to accurately and systematically monitor avocado crop phenology offers significant benefits for the optimization of farm management activities, improvement of crop productivity, yield estimation, and evaluation crops’ resilience to extreme weather conditions and future climate change. In this study, Sentinel-2-derived enhanced vegetation indices (EVIs) from 2017 to 2021 were used to retrieve canopy reflectance information that coincided with crop phenological stages, such as flowering (F), vegetative growth (V), fruit maturity (M), and harvest (H), in commercial avocado orchards in Bundaberg, Queensland and Renmark, South Australia. Tukey’s honestly significant difference (Tukey-HSD) test after one-way analysis of variance (ANOVA) with EVI metrics (EVImean and EVIslope) showed statistically significant differences between the four phenological stages. From a Pearson correlation analysis, a distinctive seasonal trend of EVIs was observed (R = 0.68 to 0.95 for Bundaberg and R = 0.8 to 0.96 for Renmark) in all 5 years, with the peak EVIs being observed at the M stage and the trough being observed at the F stage. However, a Tukey-HSD test showed significant variability in mean EVI values between seasons for both the Bundaberg and Renmark farms. The variability of the mean EVIs between the two farms was also evident with a p-value < 0.001. This novel study highlights the applicability of remote sensing for the monitoring of avocado phenological stages retrospectively and near-real time. This information not only supports the ‘benchmarking’ of seasonal orchard performance to identify potential impacts of seasonal weather variation and pest and disease incursions, but when seasonal growth profiles are aligned with the corresponding annual production, it can also be used to develop phenology-based yield prediction models.

Oligonychus perseae Tuttle, Baker & Abbatiello (Acari: Tetranychidae) population dynamics and associated phytoseiid mites (Acari: Phytoseiidae) in avocado orchards in the Canary Islands (Spain)

ABSTRACT The Persea mite, Oligonychus perseae, was identified for the first time in the Canary Islands (Spain) in 2006 becoming a major pest in avocado crops. This study analyses seasonal trends of Persea mite and phytoseiid predatory mites. The study aims to gain a better understanding of pest-predator dynamics and assess which predators have potential as biological control agents. In addition, predatory mites present in resident wild ground cover were studied with a view to promoting biological control. Results showed that Persea mite was present year-round with one or two peaks from April to July. The incidence of O. perseae varied depending on the avocado production area, but in all of them, it exceeded the density of 100 mites/leaf, established as the action threshold. Phytoseiids were more abundant on the trees in late winter, spring and early summer. Euseius stipulatus, Neoseiulus californicus and E. scutalis represented almost 96.5% of phytoseiids collected in commercial avocado orchards. They were also the most abundant species in the untreated study site. Resident wild ground cover associated with commercial avocado orchards was composed of 45 plant species belonging to 22 families, with Urticaceae and Asteraceae harbouring the highest richness in phytoseiid species.

Elicitor Activity of Curdlan and Its Potential Application in Protection of Hass Avocado Plants against Phytophthora cinnamomi Rands

Phytophthora cinnamomi causes one of the most important diseases in avocado crop and its chemical management represents 25% of the production cost per year. Induction of plant defense responses by elicitors is a promising strategy that is compatible with sustainable agriculture. This study aimed to evaluate the effect of curdlan application on the induction of defense responses in avocado plants against P. cinnamomi. The trials were conducted under greenhouse conditions, and curdlan leaf spraying was performed one day before the inoculation of the pathogen. The results showed that the application of elicitor significantly increased the protection of avocado plants against P. cinnamomi, decreasing the injury and wilting. The Curd + Phy treatment improved the defenses of plants by increasing the enzymes peroxidase (POD) and polyphenol oxidase (PPO) in the first 3 h after inoculation and increasing the enzymes superoxide dismutase (SOD) and phenylalanine ammonium lyase (PAL) 144 h after inoculation (p < 0.05). Also, chlorophyll and carotenoid content increased or remained stable in Curd + Phy treatment. Therefore, these results suggest that curdlan increases the protection against P. cinnamomi and its protection could be due to an increase in the activity of the enzymes related to the phenylpropanoid pathway as well as the effect on chlorophyll and carotenoids.

Environmental life cycle assessment (E-LCA) and social impact assessment (SIA) of small-scale biorefineries implemented in rural zones: the avocado (Persea Americana var. Americana) case in Colombia.

The objective of this study is to compare the environmental and social performance of two small-scale avocado biorefineries implanted in a rural zone in the North of Colombia. Two small-scale biorefineries were proposed. Small-B1 addressed to produce avocado oil and animal feed, and Small-B2 focused on the guacamole production. The environmental analysis was done by applying the life cycle assessment methodology. Then, agronomic information and process simulation were required to complete the analysis. Moreover, the water footprint of the avocado crops was estimated. Both biorefineries were compared with the direct avocados production and commercialization. The social assessment was achieved by the estimation of quantitative indicators related to wages, jobs, and working hours. The agricultural carbon and water footprints of the creole avocado crop were 0.59kg CO2-eq/kg and 2.13 m3/kg. In the same way, Small-B1 and Small-B2 obtained a carbon and water footprints of 8.99kg CO2-eq/kg and 6.63 m3/kg and 0.72kg CO2-eq/kg and 1.38 m3/kg, respectively. The hotspots of the creole avocado crop are related to the use of fertilizers and fungicides. Then, new strategies should be implemented to reduce the farmer's dependency. The social analysis exhibit a high resilience of the Small-B1 biorefinery since a salary increase to worker about 50% can be proposed. In addition, the installation of this biorefinery can create more than ten jobs. A disjunction was found between the economic, environmental, and social analyses. Thus, the need to establish a multidimensional strategy to design sustainable biorefineries is presented.

Oribatid mites in agricultural and natural soils: a case study of vertical distribution

The vertical distribution of oribatid mites was evaluated in a natural soil (pine-oak forest) in the municipality of San Juan Nuevo and an agricultural soil (avocado crop) in the municipality of Uruapan in Michoacán, Mexico. Samples were taken in seven layers distributed in a 100 cm deep trench. A total of 466 oribatid mites/cm3, representing 37 species of 29 genera were identified. In both sites, the highest abundance and biodiversity were found in the top 5 cm layer. Nothrus anauniensis Canestrini & Fanzago, 1877 (Nothridae), Ramusella (Insculptoppia) merimna Balogh & Mahunka, 1977 (Oppiidae), Allogalumna (Acrogalumna) sp. 1 (Galumnidae) and Scheloribates sp. 2 (Scheloribatidae) were found at the greatest depths (10–25 cm in natural soil and 25–50 cm in agricultural soil).

METHODOLOGY FOR AVOCADO (Persea americana Mill.) ORCHARD EVALUATION USING DIFFERENT MEASUREMENT TECHNOLOGIES

Avocado crop (Persea americana Mill.) is of great commercial importance due to its high profitability. However, it is being affected by various diseases and pests that affect yield and reduce fruit quality. The aim of this research was to develop methodologies for the evaluation of avocado plantations using different non-destructive technologies for rapid phenotyping and early detection of the incidence of diseases or damage due to stress in the stem. A plot of 0.7 ha. was evaluated, with a total of 44 individuals using Field-Map technology (dasometric and morphological characterization), RGB-multispectral images from Remotely Piloted Aircraft System (RPAS) (rapid phenotyping), while 15 individuals were evaluated using tomography (assessment of the internal state of the stem). The results with tomography indicated that there is a tree with wood rot of 14% with a lower acoustic speed with respect to the other trees evaluated. A high correlation was observed between the dasometric variables (r-Pearson from 0.63 to 0.98) estimated with Field-Map [crown base height, crown projection (m2 ) and total height] and with RPAS (height, perimeter and area). The vegetation indices do not have a direct correlation with the dasometric variables; five of the indices have a high contribution to variability except for the Normalized Difference Red Edge (NDRE). It can be concluded that the technologies used in this study would help to perform evaluations with a greater number of reliable and precise data with respect to the information obtained in a traditional way, while they can be replicated in commercial plots or research studies of different perennial crops, generating useful information for management decisions and crop evaluation.

Modelling avocado-driven deforestation in Michoacán, Mexico

As demand for avocado climbs, avocado production in Michoacán—Mexico’s biggest avocado growing region—expands into new places. We use a spatial probit model to project the geographic distribution of likely future avocado expansion and analyze those results to determine (a) threats to specific forest types and (b) how the distribution of avocado is shifting spatially under current and future climate scenarios. Our results suggest that avocado expansion in Michoacán is strongly driven by distance to existing agriculture, roads, and localities, as well as the dwindling availability of Andosol soils. As future expansion ensues, it presents risk of forest loss across various forest types, with pine-oak forest, mesophilic montane forest, and oyamel fir forest being of particular concern. Moreover, our results suggest that avocado production will occupy wider ranges in terms of temperature, precipitation, slope steepness and soil. The model predicts that climate change will alter the spatial distribution of avocado plantings, expanding into forest types at lower and at higher elevations. Forest loss threatens ecosystem degradation, and a wider avocado crop production footprint could lead to orchard establishment into dwindling forests that host a high diversity of native oaks and charismatic species, including the monarch butterfly.

Modelling avocado-driven deforestation in Michoacán, Mexico

Abstract As demand for avocado climbs, avocado production in Michoacán - Mexico’s biggest avocado growing region - expands into new places. We use a spatial probit model to project the geographic distribution of likely future avocado expansion and analyze those results to determine (1) threats to specific forest types and (2) how the distribution of avocado is shifting spatially under current and future climate scenarios. Our results suggest that avocado expansion in Michoacán is strongly driven by distance to existing agriculture, roads, and localities, as well as the dwindling availability of Andosol soils. As future expansion ensues, it presents risk of forest loss across various forest types, with pine-oak forest, mesophilic montane forest, and oyamel fir forest being of particular concern. Moreover, our results suggest that avocado production will occupy wider ranges in terms of temperature, precipitation, slope steepness and soil. The model predicts that climate change will alter the spatial distribution of avocado plantings, expanding into forest types at lower and at higher elevations. Forest loss threatens ecosystem degradation, and a wider avocado crop production footprint could lead to orchard establishment into dwindling forests that host a high diversity of native oaks and charismatic species, including the monarch butterfly.

Effect of COVID-19 on the phytosanitary condition and commercialization of avocado in Jalisco

<p>Avocado crop (<em>Persea americana</em>) in Ciudad Guzmán, Jalisco, Mexico, is affected by pests and diseases that have worsened with the COVID-19 (SARS-CoV-2) pandemic. Damage to fruits has increased due to the reduction of the workforce by more than half, which restricts crop sampling and the timely control of pests. Furthermore, the closure of businesses and the consequent lack of agricultural inputs have affected the management and profitability of avocado crop. The restricted access to markets such as Monterrey, Mexico City and Guadalajara has also affected avocado availability.</p>

Analysis of thrips (Thysanoptera: Thripidae) diversity in avocado shows the presence of a new species and limitations of using the COI gene for differentiation of two species

Thrips are important pests of avocados causing damage to the fruits, making themunsuitable for exportation. Many of them are quarantine species and their identification isnecessary. Despite their importance, not many studies describe thrips diversity on avocado,especially in Colombia, partly because identification of some of the species is difficult usingclassical taxonomic keys. In this study, 93 adult thrips specimens were collected on avocadoand adventitious dandelion plants from plantations in the department of Antioquia, Colombia. Morphological characters were used to classify 62 of them and all of them were analyzed by PCR amplification and sequencing of cytochrome c oxidase subunit I (COI) gene and internal transcribed spacer (ITS) region. The species identified by morphological features were Frankliniella gardeniae Moulton, F. gossypiana Hood, F. panamensis Hood, Liothrips perseae Watson, Thrips palmi Karny, T. simplex (Morison), T. trehernei Priesner, Microcephalothrips abdominalis (Crawford DL), and Scirtothrips hansoni Mound & Hoddle (Tubulifera), being F. panamensis, M. abdominalis, and S. hansoni reported for the first time on avocado in Colombia. Thrips simplex and T. trehernei were also found on adventitious dandelion plants, but not on avocado. Phylogenetic analysis of COI and ITS sequences showed that most species, except for F. gardeniae and F. gossypiana were mainly identified with the COI gene. Furthermore, FST values obtained between them suggest no genetic differentiation at COI level. The results obtained here contribute to the knowledge of the diversity of thrips species found on the avocado crop in Colombia and are meaningful for pest management.

Proposal for Integrated Management of Verticillium Wilt Disease in Avocado Cultivar Hass Crops

The area planted with avocado crops in Colombia has been growing rapidly in recent years, especially for export varieties such as Hass. The increase in planted area coincided with increased phytosanitary problems, where pathogens such as fungi of the genus Verticillium spp. are becoming of economic importance. The objective of this study was to evaluate different control strategies for avocado wilt disease caused by Verticillium spp., under in vitro, net house, and field conditions. Strategies tested included fungicides (benomyl, azoxystrobin, captan, and carbendazim), beneficial and antagonistic microorganisms (Trichoderma sp., and Rhizoglomus fasciculatum), and physical and cultural practices such as solarization, drainage and removal of diseased tissues. Treatments T7fi (pruning-solarization-Trichoderma-mycorrhiza-sucrose-organic matter-drainage) and T8fi (fungicide-pruning-solarization-Trichoderma-mycorrhiza-sucrose-organic matter-drainage), showed the greatest reduction in the area under disease progress curve and Verticillium dahliae inoculum in soil and plant tissues under field conditions. Fruit with extra quality increased 120.8% with T7fi and 108% with T8fi, compared to the control with diseased trees. The highest costs were identified for T7fi and T8fi; however, these treatments also showed the best cost/benefit relationship. Integrated approaches as in T7fi and T8fi showed the best results for Verticillium wilt control. As no fungicides of chemical synthesis are included in T7fi (pruning-solarisation-Trichoderma-mycorrhiza-sucrose-organic matter-drainage), it should be preferred to T8fi, which does include them, to avoid their negative impacts on avocado production.

Plant growth-promoting and non-promoting rhizobacteria from avocado trees differentially emit volatiles that influence growth of Arabidopsis thaliana

Microbial volatile organic compounds (mVOCs) play important roles in inter- and intra-kingdom interactions, and they are also important as signal molecules in physiological processes acting either as plant growth-promoting or negatively modulating plant development. We investigated the effects of mVOCs emitted by PGPR vs non-PGPR from avocado trees (Persea americana) on growth of Arabidopsis thaliana seedlings. Chemical diversity of mVOCs was determined by SPME-GC-MS; selected compounds were screened in dose-response experiments in A. thaliana transgenic lines. We found that plant growth parameters were affected depending on inoculum concentration. Twenty-six compounds were identified in PGPR and non-PGPR with eight of them not previously reported. The VOCs signatures were differential between those groups. 4-methyl-2-pentanone, 1-nonanol, 2-phenyl-2-propanol and ethyl isovalerate modified primary root architecture influencing the expression of auxin- and JA-responsive genes, and cell division. Lateral root formation was regulated by 4-methyl-2-pentanone, 3-methyl-1-butanol, 1-nonanol and ethyl isovalerate suggesting a participation via JA signalling. Our study revealed the differential emission of volatiles by PGPR vs non-PGPR from avocado trees and provides a general view about the mechanisms by which those volatiles influence plant growth and development. Rhizobacteria strains and mVOCs here reported are promising for improvement the growth and productivity of avocado crop.