Journal articles on the topic 'Avocado orchard soils'
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Merrington, G., S. L. Rogers, and L. Van Zwieten. "The potential impact of long-term copper fungicide usage on soil microbial biomass and microbial activity in an avocado orchard." Soil Research 40, no. 5 (2002): 749. http://dx.doi.org/10.1071/sr01084.
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The impact of copper-based fungicides on soil microbial function in an avocado orchard was assessed. Copper (Cu) residues (280 and 340 mg/kg, respectively) in surface soils (0-2 cm) of an established avocado orchard were shown to be significantly (n = 6, P ≤ 0.05) greater than a nearby reference site under natural vegetation (13 mg/kg). The bioavailable fraction of Cu in these soils was also shown to be significantly greater (2.15 and 1.29 mg/kg, c. pCu2+ 8.64) than in the reference site (0.71 mg/kg, c. pCu2+ 9.2), as measured by ion-selective electrode in CaCl2 extraction. Similar trends were observed for the 2-10 cm soil profile. Data suggest that the Cu residues are responsible for significant reductions in biomass carbon (Cmic) even though the orchard soils had similar or elevated levels of total organic carbon (Corg). The Cmic : Corg ratio was significantly lower in all of the Cu contaminated soils, and a significant correlation was observed between CaCl2-extractable Cu in the surface soils and Cmic (n = 16, r2 = 0.68, P b 0.01). Soil respiration in surface soils from the orchard were elevated (6.04 and 5.57 mg CO2-C/kg.day) compared with the reference soil (3.04 mg CO2-C/kg.day), and the metabolic quotient (qCO2) was also significantly greater.
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Arima, Eugenio Y., Audrey Denvir, Kenneth R. Young, Antonio González-Rodríguez, and Felipe García-Oliva. "Modelling avocado-driven deforestation in Michoacán, Mexico." Environmental Research Letters 17, no. 3 (February 23, 2022): 034015. http://dx.doi.org/10.1088/1748-9326/ac5419.
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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 (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.
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Haas, Jerry H., and John A. Menge. "VA-mycorrhizal fungi and soil characteristics in avocado (Persea americana Mill.) orchard soils." Plant and Soil 127, no. 2 (October 1990): 207–12. http://dx.doi.org/10.1007/bf00014427.
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Tsanis, Ioannis K., Konstantinos D. Seiradakis, Sofia Sarchani, Ioanna S. Panagea, Dimitrios D. Alexakis, and Aristeidis G. Koutroulis. "The Impact of Soil-Improving Cropping Practices on Erosion Rates: A Stakeholder-Oriented Field Experiment Assessment." Land 10, no. 9 (September 12, 2021): 964. http://dx.doi.org/10.3390/land10090964.
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The risk of erosion is particularly high in Mediterranean areas, especially in areas that are subject to a not so effective agricultural management–or with some omissions–, land abandonment or wildfires. Soils on Crete are under imminent threat of desertification, characterized by loss of vegetation, water erosion, and subsequently, loss of soil. Several large-scale studies have estimated average soil erosion on the island between 6 and 8 Mg/ha/year, but more localized investigations assess soil losses one order of magnitude higher. An experiment initiated in 2017, under the framework of the SoilCare H2020 EU project, aimed to evaluate the effect of different management practices on the soil erosion. The experiment was set up in control versus treatment experimental design including different sets of treatments, targeting the most important cultivations on Crete (olive orchards, vineyards, fruit orchards). The minimum-to-no tillage practice was adopted as an erosion mitigation practice for the olive orchard study site, while for the vineyard site, the cover crop practice was used. For the fruit orchard field, the crop-type change procedure (orange to avocado) was used. The experiment demonstrated that soil-improving cropping techniques have an important impact on soil erosion, and as a result, on soil water conservation that is of primary importance, especially for the Mediterranean dry regions. The demonstration of the findings is of practical use to most stakeholders, especially those that live and work with the local land.
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Reyes-Martín, Marino Pedro, Irene Ortiz-Bernad, Antonio M. Lallena, Layla M. San-Emeterio, M. Lourdes Martínez-Cartas, and Emilia Fernández Ondoño. "Reuse of Pruning Waste from Subtropical Fruit Trees and Urban Gardens as a Source of Nutrients: Changes in the Physical, Chemical, and Biological Properties of the Soil." Applied Sciences 12, no. 1 (December 25, 2021): 193. http://dx.doi.org/10.3390/app12010193.
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A field experiment was conducted on the Andalusian coast (Granada, Southern Spain) to study the time course of nutrient release into the soil after the addition of bagged pruning waste from subtropical orchard trees (avocado, cherimoya, and mango) and urban garden waste over three two-year periods. N, P, and K concentrations were greater in the garden waste, whilst avocado and cherimoya pruning waste registered the highest values for Mg. In general, micronutrient contents were low in all waste, especially Cu. Macronutrient release followed a three-phase dynamic: fast initial release, intermediate stabilization, and final increase. Garden waste showed a similar time course in all three trees and released greater concentrations of K and P. The annual decomposition rate factor k was negative for N and Ca in the avocado tree, indicating strong biological activity in this plot. Avocado, cherimoya, and garden waste showed a good microbial degradation, improving soil quality by increasing carbon and nitrogen contents as well as soil microbial activity. As for the mango tree, its special microclimatic conditions appeared to favor waste photodegradation, thus eliminating nutrients that were not incorporated into the soil. Soil enzymatic activities increased in the avocado and cherimoya trees with the addition of all waste. In the mango tree, only an increase in urease was detected after the addition of garden waste. Our results suggest that the time course of organic waste in different subtropical trees grown on similar soils is significantly conditioned by the microclimatic characteristics.
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Van Zwieten, Lukas, Josh Rust, Tim Kingston, Graham Merrington, and Steven Morris. "Influence of copper fungicide residues on occurrence of earthworms in avocado orchard soils." Science of The Total Environment 329, no. 1-3 (August 2004): 29–41. http://dx.doi.org/10.1016/j.scitotenv.2004.02.014.
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Crowley, David E., Woody Smith, Ben Faber, and John A. Manthey. "Zinc Fertilization of Avocado Trees." HortScience 31, no. 2 (April 1996): 224–29. http://dx.doi.org/10.21273/hortsci.31.2.224.
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Methods for Zn fertilization of `Hass' avocado (Persea americana Mill.) trees were evaluated in a 2-year field experiment on a commercial orchard located on a calcareous soil (pH 7.8) in Ventura County, Calif. The fertilization methods included soil- or irrigation-applied ZnSO4; irrigation-applied Zn chelate (Zn-EDTA); trunk injection of Zn(NO3)2, and foliar applications of ZnSO4, ZnO, or Zn metalosate. Other experiments evaluated the influence of various surfactants on the Zn contents of leaves treated with foliar-applied materials and on the retention and translocation of radiolabeled 65ZnSO4 and 65Zn metalosate after application to the leaf surface. In the field experiment, tree responses to fertilization with soil-applied materials were affected significantly by their initial status, such that only trees having <50 μg·g–1 had significant increases in foliar Zn contents after fertilization. Among the three soil and irrigation treatments, ZnSO4 applied at 3.2 kg ZnSO4 per tree either as a quarterly irrigation or annually as a soil application was the most effective and increased leaf tissue Zn concentrations to 75 and 90 μg·g–1, respectively. Foliar-applied ZnSO4, ZnO, and Zn metalosate with Zn at 5.4, 0.8, and 0.9 g·liter–1, respectively, also resulted in increased leaf Zn concentrations. However, experiments with 65Zn applied to leaves of greenhouse seedlings showed that <1% of Zn applied as ZnSO4 or Zn metalosate was actually taken up by the leaf tissue and that there was little translocation of Zn into leaf parenchyma tissue adjacent to the application spots or into the leaves above or below the treated leaves. Given these problems with foliar Zn, fertilization using soil- or irrigation-applied ZnSO4 may provide the most reliable method for correction of Zn deficiency in avocado on calcareous soils.
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Nuñez-Elisea, R., B. Schaffer, M. Zekri, S. K. O'Hair, and J. H. Crane. "533 Monitoring Soil Water Content in Tropical Fruit Orchards in Southern Florida with Multi-sensor Capacitance Probes and Tensiometers." HortScience 35, no. 3 (June 2000): 487C—487. http://dx.doi.org/10.21273/hortsci.35.3.487c.
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Tropical fruit trees in southern Florida are grown in porous, oolitic limestone soil that has very low organic matter content and water-holding capacity. Thus, trees require frequent irrigation during dry periods. In these soils, a quantitative basis for monitoring soil water content to determine when and how much to irrigate has been lacking. Multi-sensor capacitance probes (EnviroSCAN™, Sentek, Australia) were installed in commercial carambola, lime, and avocado orchards to continuously monitor changes in soil water content at depths of 10, 20, 30, and 50 cm. Eight probes were installed per orchard. Volumetric soil water content was recorded at 15-min intervals with a solar-powered datalogger. Results were downloaded to a laptop computer twice a week. Monitoring the rate of soil water depletion (evapotranspiration) allowed irrigation before the onset of water stress. The time at which soil reached field capacity could be determined after each irrigation (or rain) event. Soil water tension was recorded periodically using low-tension (0–40 cbars) tensiometers placed adjacent to selected capacitance probes at 10- and 30-cm depths. Soil water tension was better correlated with volumetric soil water content at a 10-cm depth than at 30-cm depth. Using multi-sensor capacitance probes is a highly accurate, although relatively expensive, method of monitoring soil water content for scheduling irrigation in tropical fruit orchards. Whereas tensiometers require periodic maintenance, the multi-sensor capacitance probe system has been virtually maintenance free. The correlation between soil water content and soil water tension obtained in situ indicates that tensiometers are a less precise, but considerably cheaper, alternative for scheduling irrigation in tropical fruit orchards in southern Florida.
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Kuwano, Biana Harumi, Adriana Knob, Dáfila Santos Lima Fagotti, Nagib Jorge Melém Júnior, Leandro Godoy, Raquel Cátia Diehl, Cristina Célia Krawulski, et al. "Soil quality indicators in a rhodic kandiudult under different uses in northern Parana, Brazil." Revista Brasileira de Ciência do Solo 38, no. 1 (February 2014): 50–59. http://dx.doi.org/10.1590/s0100-06832014000100005.
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Sustainable use of soil, maintaining or improving its quality, is one of the goals of diversification in farmlands. From this point of view, bioindicators associated with C, N and P cycling can be used in assessments of land-use effects on soil quality. The aim of this study was to investigate chemical, microbiological and biochemical properties of soil associated with C, N and P under different land uses in a farm property with diversified activity in northern Parana, Brazil. Seven areas under different land uses were assessed: fragment of native Atlantic Forest; growing of peach-palm (Bactrys gasipaes); sugarcane ratoon (Saccharum officinarum) recently harvested, under renewal; growing of coffee (Coffea arabica) intercropped with tree species; recent reforestation (1 year) with native tree species, previously under annual crops; annual crops under no-tillage, rye (Cecale cereale); secondary forest, regenerated after abandonment (for 20 years) of an avocado (Persea americana) orchard. The soil under coffee, recent reforestation and secondary forest showed higher concentrations of organic carbon, but microbial biomass and enzyme activities were higher in soils under native forest and secondary forest, which also showed the lowest metabolic coefficient, followed by the peach-palm area. The lowest content of water-dispersible clay was found in the soil under native forest, differing from soils under sugarcane and secondary forest. Soil cover and soil use affected total organic C contents and soil enzyme and microbial activities, such that more intensive agricultural uses had deeper impacts on the indicators assessed. Calculation of the mean soil quality index showed that the secondary forest was closest to the fragment of native forest, followed by the peach-palm area, coffee-growing area, annual crop area, the area of recent reforestation and the sugarcane ratoon area.
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Marques, J. R., P. J. Hofman, and A. H. Wearing. "Between-tree variation in fruit quality and fruit mineral concentrations of Hass avocados." Australian Journal of Experimental Agriculture 46, no. 9 (2006): 1195. http://dx.doi.org/10.1071/ea04051.
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Inconsistent internal fruit quality in Hass avocados affects consumer confidence. To determine the influence of individual trees on fruit quality, Hass avocado fruit were harvested from adjacent trees of similar external appearance in 3 commercial orchards in 1998 and 1 orchard in 1999. The trees in each orchard were grown with similar commercial practices and in similar soil types. Within each location, there were significant (P<0.05) differences in the mean ripe fruit quality between trees with respect to fruit body rot severity (mainly anthracnose) with and without cold storage, internal disorders severity due to diffuse discolouration and vascular browning (after cold storage), days to ripen, percentage dry matter, and the percentage of the skin area with purple-black colour when ripe. These effects were also noted in the same orchard in 1999. There were significant (P<0.05) differences in fruit flesh calcium, magnesium, potassium, boron and zinc concentrations between trees. Significant (P<0.05) correlations were observed between average fruit mineral concentrations in each tree (particularly calcium, magnesium and potassium) and body rot severity, percentage dry matter and fruit mass. There was little conclusive evidence that characteristics such as the growth of the non-suberised roots or the degree of scion under- or overgrowth was involved in these tree effects; however, differences between trees with respect to other rootstock characteristics may be involved. The inconsistency of the correlations across sites and years suggested that other factors apart from tree influences could also affect the relationship between fruit minerals and fruit quality.
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Tirado-Corbalá, Rebecca, Elvin Román-Paoli, and Jonathan Muñoz-Barreto. "Fertilization and precise irrigation scheduling for mature avocado." Journal of Agriculture of the University of Puerto Rico 105, no. 1 (January 1, 2021): 73–88. http://dx.doi.org/10.46429/jaupr.v105i1.19637.
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Irrigation scheduling (IS) and fertilization are among the most important practices in the production of horticultural crops because they affect fruit quality and quantity directly. Thus, a 15-year-old avocado orchard (cv. ‘Simmonds’) was used to determine precise IS, based on monitoring soil moisture content (SMC), remote sensing technologies [Unmanned Aerial Vehicle (UAV)] under two fertilization levels using granular formulation 15-3-19. In October 2015, all trees were pruned (topped and hedged) to 3.05 m height and 2.44 m diameter. In December 2015, soil moisture (SM) sensors were installed at five (10, 30, 50, 70 and 90 cm) soil depths in six locations. Trees received two fertilizer treatments: F1-9.06 kg and F2-12.07 kg of 15-3-19/tree/year every three months. Precipitation and SM data were recorded daily for 21 months; SM data was corrected with a quadratic equation (y = -4.1881x2 + 3.6886x - 0.3083) generated specifically for the Coto soil series (Typic Hapludox). The SM values recorded were always greater than 41%, indicating that the avocado orchard was growing under water saturation conditions; thus, micro-irrigation was not needed. The UAV data at 5, 13 and 20 months after pruning (MAP) showed quick closure of the avocado canopy; acquiring a denser and more cylindrical shape (from 17.6 ± 2.65 m2 to 52.7 ± 6.10 m2), regardless of fertilizer level. Based on correlation of UAV and manual results, F2-treated trees indicated stronger correlation at 13 and 20 MAP (R2 >0.75) than F1-trees. Yield production (110 avocados per tree = 13,200 per hectare) and leaf nutrient content did not differ significantly with fertilizer level. For commercial avocado farmers the use of SMC sensors and UAV technology could be an advantage, albeit an expensive one. Soil moisture content sensors have been shown to be very effective in irrigation water conservation. In terms of fertilization, the results suggest not using more than 9.06 kg of 15-3-19/tree/year as this amount seems enough to satisfy avocado requirements, under the experiment’s conditions. Future evaluations will determine if it is possible to use less fertilizer and still maintain an optimal avocado production.
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Huett, D. O. "Macadamia physiology review: a canopy light response study and literature review." Australian Journal of Agricultural Research 55, no. 6 (2004): 609. http://dx.doi.org/10.1071/ar03180.
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The management of mature macadamia orchards has evolved largely through the need to control inter-row crowding to maintain machinery access. The current study was undertaken to identify physiological constraints to production and priorities for future research and development. The two components of the study were a preliminary field study to determine the impact of current pruning and hedging management strategies on canopy photosynthetic performance and a literature review to identify physiological issues affecting orchard productivity. The field photosynthesis study demonstrated that emerging flush leaves have a negative light saturation net assimilation rate (Amax) that increases to that of mature leaves (Amax 8–10 µmol CO2/m2.s) over 28 days. Leaf age has no effect on Amax of light-adapted leaves. Shade-adapted macadamia leaves cannot attain the photosynthetic capacity of light-adapted leaves. This means that a late hedging strategy to remove around 1 m of canopy from the side of trees to improve orchard access reduces the photosynthetic capacity of the orchard until sufficient flushing occurs to restore the canopy. The literature review focussed on light interception and distribution, photosynthesis, carbohydrate and nitrogen cycling, environmental response, flowering and fruit set, nut abscission, canopy management, and nutrition and disease control. Light interception modelling work, which has been widely adopted for deciduous temperate fruit crops, has immediate application to macadamia production and can explain many of the yield responses recorded by macadamias to canopy management. Macadamia yields appear to increase up to about 96% light interception. Variation in light distribution within canopies that affects the yield and quality of temperate crops is also a present problem with macadamias. It leads to uneven distribution of leaf and fruit throughout the canopy and to a heavily shaded void developing in the middle of trees. The relationship between irradiance, leaf photosynthetic capacity and longevity, flushing, flowering, and fruit set is poorly understood. No information is available on the training of young trees to improve light distribution and canopy photosynthetic efficiency. The current practice of light annual hedging of mature macadamias appears to restrict the production of fruiting wood. Earlier nut abscission can be achieved by the use of ethephon, which offers greater flexibility in the timing of hedging. Research work is required on the effects of timing, frequency and severity of hedging on fruiting wood production, flowering, and fruit set of macadamias. Information on the need to supplement mechanical hedging with manual pruning to improve light distribution throughout canopies is also required. The cyclical and highly variable nature of macadamia yields needs to be further analysed to determine whether a consistent pattern exists and whether environmental factors are an influence. A simple measure of the storage levels of the major assimilates, carbohydrates and nitrogen compounds, is unlikely to predict cyclical yield patterns because both are continually cycled within the tree and it appears that, from comprehensive studies on another evergreen fruit crop, avocado, the major supply of carbohydrate during the fruit-filling stage is from current photosynthesis. Several studies have failed to demonstrate irrigation responses by field-grown macadamias. The cyclical and variable yield of macadamias demonstrates that yield responses from field experiments cannot be expected in less than 5 years, even assuming adequate plot size, buffering, and replication. On the drier sites with light-textured soils in south-eastern Queensland, yield responses could be expected. Following the success of temperate fruit tree crop breeding programs and trends with other evergreen tree crops, macadamia breeding needs to focus on dwarfing clonal rootstocks that provide uniformity, and vigour control to improve cropping efficiency, to reduce canopy management costs and to minimise the reduction in yield following tree topping.
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Sáenz-Ceja, Jesús Eduardo, and Diego Rafael Pérez-Salicrup. "Avocado Cover Expansion in the Monarch Butterfly Biosphere Reserve, Central Mexico." Conservation 1, no. 4 (October 25, 2021): 299–310. http://dx.doi.org/10.3390/conservation1040023.
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Avocado cultivation has reduced the extent of forest ecosystems in central Mexico, even in natural protected areas such as the Monarch Butterfly Biosphere Reserve (MBBR) where information on the extent and expansion dynamics of avocado cover is scant. This study aimed to identify avocado plantations within the MBBR through photo interpretation for the 2006–2018 period. Change rates of the avocado cover extent were calculated for the northern, central, and southern zones of the MBBR, and topographic attributes such as elevation, soil type, slope, and slope aspect were identified. A total extent of 958 ha is covered by avocado plantations within the MBBR. The southern zone hosted the largest area under avocado cultivation (570 ha), but the northern zone had the highest change rate between 2006 and 2018 (422%). Most avocado orchards have been established mainly in Acrisol soils, south-facing slopes, on steep hillsides, and in elevations between 2050 and 2800 m. The conversion from traditional agricultural lands has been the main mechanism for the establishment of avocado orchards. However, 40 ha under avocado cultivation derived from deforestation, mainly in the central zone. The expansion of avocado plantations could trigger environmental impacts, even threatening the overwintering habitat and the migratory phenomenon of the monarch butterflies.
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Haberman, Amnon, Leah Tsror (Lahkim), Silit Lazare, Marina Hazanovsky, Sara Lebiush, Isaac Zipori, Amnon Busatn, Eli Simenski, and Arnon Dag. "Management of Verticillium Wilt of Avocado Using Tolerant Rootstocks." Plants 9, no. 4 (April 20, 2020): 531. http://dx.doi.org/10.3390/plants9040531.
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The global avocado industry is growing, and farmers are seeking to expand their plantations. However, many lands suitable for avocado planting were previously cultivated with hosts of the soil-borne fungal pathogen Verticillium dahliae, which is the causal agent of Verticillium wilt (VW). VW can seriously impair avocado orchards, and therefore, planting on infested soil is not recommended. The use of different rootstock types allows avocado cultivation in various regions with diverse biotic and abiotic constraints. Hence, we tested whether genetic variance among rootstocks may also be used to manage avocado VW. Six hundred trees, mostly Hass and some Ettinger, grafted on 23 selected rootstocks were evaluated for five years in a highly V. dahliae-inoculated plot for VW symptoms, fungal infection, and productivity. The selected rootstocks displayed a significant variation related to VW tolerance, and productive avocado rootstocks with potential VW tolerance were identified. Moreover, the rootstock productivity appears to correlate negatively to the susceptibility level. In conclusion, planting susceptible rootstocks (e.g., VC66, VC152, and VC26) in infested soil increases the likelihood of massive tree loss and low productivity. Whereas, tolerant rootstocks (e.g., VC804 and Dusa) may restrict VW and enable avocado cultivation on infested soils.
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Rodríguez-Padrón, Cristina, Ana Rodríguez, and Felipe Siverio. "Survey in Nurseries and Irrigation Water Reservoirs as Sources of Oomycetes Found in Avocado Orchards in the Canary Islands." Plant Disease 103, no. 6 (June 2019): 1264–74. http://dx.doi.org/10.1094/pdis-08-18-1412-re.
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Nursery stocks and irrigation water are important sources of Phytophthora spp. In this study, 20 irrigation water reservoirs and 10 avocado nurseries were surveyed in the Canary Islands between 2013 and 2015 to investigate their potential role in disseminating pathogenic species in avocado orchards. Phytophthora multivora was isolated from one of the irrigation reservoirs, whereas, in two surveys conducted in nurseries, Phytophthora cinnamomi, the primary pathogen in avocado, was detected in addition to other Phytophthora species (P. lacustris, P. multivora, P. nicotianae, P. niederhauserii, and P. palmivora) and Phytopythium vexans. The species recovered from nurseries were isolated mostly from propagated plants but also from nursery irrigation water, soil used for substrate preparation, and soil samples collected in orchards that supply seeds for seedling propagation. Species recovered from nurseries correlated with those found in avocado orchards in a previous study, except for P. lacustris, suggesting that nurseries could be involved in their dissemination in avocado orchards. The improved sanitary status of nurseries resulted in reduced incidence in the second survey, indicating the importance of nursery monitoring to reduce infestations.
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López-López, María Estela, Carmen Lizette Del-Toro-Sánchez, Melesio Gutiérrez-Lomelí, Salvador Ochoa-Ascencio, José Antonio Aguilar-López, Miguel Angel Robles-García, Maribel Plascencia-Jatomea, et al. "Isolation and Characterization of Trichoderma spp. for Antagonistic Activity against Avocado (Persea americana Mill) Fruit Pathogens." Horticulturae 8, no. 8 (August 9, 2022): 714. http://dx.doi.org/10.3390/horticulturae8080714.
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In this research, we aimed to isolate and identify native strains of Trichoderma spp. with potential activity against avocado pathogens (Neofusicoccum parvum, Colletotrichum gloeosporioides, Diaporthe sp., and Phomopsis perseae). Strains of Trichoderma spp. were isolated from roots and soil obtained from avocado orchards from different regions of Mexico. Twenty-five Trichoderma spp. strains were isolated, of which six (TSMICH7, TSMICH8, TRMICH9, TSMICH10, TSMICH15, and TRJAL25) showed greater antagonistic capacity in vitro (>80%) against avocado pathogens. After 96 h, the antagonistic strain undergoes a thickening of hyphae, while the phytopathogen tends to thin, except for Diaporthe sp., which tends to thicken. The characterization of these strains was carried out through morphological observations and the amplification and sequencing of rDNA fragments (ITS regions), as well as the translation elongation factor 1-alpha (Tef 1-α), achieving the identification of Trichoderma harzianum. However, in the in vivo evaluation (applying directly to the avocado fruit), the TSMICH7 strain maintained considerably high effectiveness (>90%) against the four phytopathogens tested, mainly with P. perseae, N. parvum, and Diaporthe sp., increasing the activity of glucanases and chitinases. Therefore, T. harzianum could be used as a biological control agent to inhibit post-harvest pathogens in avocados, thus avoiding significant losses of this fruit of international importance.
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Paranychianakis, Nikolaos V., Giorgos Giannakis, Daniel Moraetis, Vasileios A. Tzanakakis, and Nikolaos P. Nikolaidis. "Crop Litter Has a Strong Effect on Soil Organic Matter Sequestration in Semi-Arid Environments." Sustainability 13, no. 23 (November 30, 2021): 13278. http://dx.doi.org/10.3390/su132313278.
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The agricultural soils in the Mediterranean are characterized by low stocks of soil organic matter (SOM) because of the intensive management practices and constraints on litter inputs to the soil imposed by environmental conditions (low precipitation, high evapotranspiration). To date, several studies have provided evidence for a low potential of Mediterranean agroecosystems, especially on its southern part, to store C, even under soil conservation practices (e.g., non-tillage), questioning the capacity of commonly applied practices to restore soil health, mitigate climate change and improve resilience of agroecosystems to climate extremes. Using paired orchards of avocado and olive trees, we show that soils in the South Mediterranean have a high potential for C storage that depends strongly on crop type and soil properties. Soils planted with avocado trees showed higher SOM contents compared to olive trees mainly in the upper soil layer (0–10 cm) which were linked to higher inputs and litter chemistry. Our findings enable us to re-define achievable thresholds of SOC (≈8%) in Southern Mediterranean soils to store C, to quantify the effect of different cropping systems, and the period required to reach this potential and how this potential is affected by soil properties. Thus, the findings have profound implications for the design of soil conservation practices compatible with Mediterranean conditions and developing initiatives describing achievable targets of SOM restoration depending on soil properties and cropping systems.
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Silva, Simone Rodrigues da, Tatiana Eugenia Cantuarias-Avilés, Bruno Chiavelli, Michael Aleixo Martins, and Michelle Souza Oliveira. "Phenological models for implementing management practices in rain-fed avocado orchards1." Pesquisa Agropecuária Tropical 47, no. 3 (September 2017): 321–27. http://dx.doi.org/10.1590/1983-40632016v4747140.
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ABSTRACT Only a few phenological models have been formulated for rain-fed avocados in warm subhumid environments, and none of them have suggested crop management strategies for improving the trees performance in such conditions. The occurrence and intensity of major phenological events were assessed in 'Hass' and 'Margarida' avocado trees, in order to properly schedule the main crop practices for optimum management of rain-fed orchards in warm subhumid growing environments. Shoot growth, root density, number of open flowers, fruit set and fruit dropping rate were evaluated. For both cultivars, two shoot flushes were observed in September-October (spring) and January-February (summer), while a maximum feeder root growth took place in late August, coinciding with flowering. Two other minor root growth flushes occurred after the onset of summer rains. Both cultivars had only one flowering period, followed by an intense fruitlet dropping. A second minor fruit dropping wave occurred in February (mid-summer), for both cultivars. By determining the extent of each phenological phase in both avocado cultivars, it is possible to schedule applications of fertilizer, mulch and soil amendments, during the root growth flushes, as well as foliar sprays during shoot flushes, in order to maintain an adequate nutritional and sanitary status.
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Downer, Jim, Ben Faber, and John Menge. "Factors Affecting Root Rot Control in Mulched Avocado Orchards." HortTechnology 12, no. 4 (January 2002): 601–5. http://dx.doi.org/10.21273/horttech.12.4.601.
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Mulches can exert positive (disease controlling) or negative (disease enhancing) potential when applied to young avocado (Persea americana) trees. Regulation of root disease in avocado is a complicated process that is affected by host resistance, inoculum density, temperature, soil salinity and soil water potential. There are short-term immediate effects from mulching and subtle long-term effects that regulate disease caused by the root rot pathogen Phytophthora cinnamomi. Short-term effects include increased soil moisture and soil temperature moderation. Long-term effects include increases of: soil mineral nutrients, soil aggregation and drainage; microbial activity; and cellulase enzyme activities. Biological control of Phytophthora in mulched soil is partially regulated by cellulase enzyme activities. This soil enzyme concept of biological control is discussed in regard to the classical Ashburner method of biological control.
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Mohale, P. M., A. Manyevere, C. Parwada, and M. G. Zerizghy. "Effect of eucalyptus wood-based compost application rates on soil chemical properties in semi-organic avocado plantations, Limpopo province, South Africa." PLOS ONE 18, no. 2 (February 7, 2023): e0265728. http://dx.doi.org/10.1371/journal.pone.0265728.
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Mixing different types of organic matters to form a compound compost can be useful in both short-and long-term improvement of soil chemical properties. However, effects of such composts on soil chemical properties are unknown. A 3-year field study was done to determine the effects of eucalyptus wood-based compost on selected chemical properties of soils at Mooketsi and Politsi avocado orchards, Limpopo Province, South Africa. The study was laid as a repeated measures design with 4 compost treatments at 0, 5, 10, and 15 t ha-1 year-1 with three replicates. Soil pH, EC, organic carbon, active carbon, soil NO3-N, NH4-N, PMN, P K, Ca, Mg, Na Mn, Cu, Zn, and Fe were measured annually at the two orchards after applying compost at the different rates. The eucalyptus wood-based compost significantly (p<0.05) altered the composition of the measured chemical properties at both orchards. The values of the soil chemical properties increased cumulatively with compost quantity and time. This trend was consistent at both orchards. Significantly (p<0.05) highest and lowest values of the soil chemical properties were recorded at 15t ha-1 and 0t ha-1 in 2018 respectively but with no significant (p>0.05) differences between 10t ha-1 and 15t ha-1 compost application rates the entire study period. Eucalyptus wood-based compost raised values of the soil chemical properties at ≥10t ha-1 application rates. It is recommended to apply the eucalyptus wood-based compost ≥10t ha-1 at both orchards, nevertheless, other factors governing organic matter decomposition such as soil temperature were not measured hence further studies are necessary.
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Everett, K. R., H. A. Pak, I. P. S. Pushparajah, J. T. Taylor, M. S. Astill, and D. B. King. "Field evaluation of fungicides to control postharvest rots of avocados in New Zealand." New Zealand Plant Protection 64 (January 8, 2011): 112–18. http://dx.doi.org/10.30843/nzpp.2011.64.5971.
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Copper is the only fungicide currently registered for use on avocado orchards for controlling fruit rots that are expressed postharvest Two additional fungicides that performed well in previous tests were evaluated as spray applications to 12 orchards four in each of the three major avocado growing regions of New Zealand (North of Kaitaia Whangarei and Bay of Plenty) Pyraclostrobin/boscalid and fluazinam were at least as effective as copper in controlling avocado rots and are suitable alternatives to copper Fluazinam should be applied in winter because in combination with the additive di1pmethene it damaged leaves during the spring flush Pyraclostrobin/boscalid would need to be used judiciously to prevent build up of resistance in fungal populations Copper could still be applied but in combination with these fungicides thus reducing the numbers of applications of copper and therefore the risk of copper accumulation in soil
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Atucha, Amaya, Ian A. Merwin, Michael G. Brown, Francisco Gardiazabal, Francisco Mena, Cecilia Adriazola, Marc Goebel, and Taryn Bauerle. "Root distribution and demography in an avocado (Persea americana) orchard under groundcover management systems." Functional Plant Biology 40, no. 5 (2013): 507. http://dx.doi.org/10.1071/fp12317.
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The effect of groundcover management systems on root demography and distribution of newly planted avocado (Persea americana Mill) trees was examined using minirhizotron techniques. We evaluated three groundcover systems: (1) bare soil (BS), pre- and post-emergence herbicides; (2) vegetation strip (VS), post-emergence herbicide applied in a 1-m wide strip centred on the tree row plus a groundcover mixture seeded between tree rows; and (3) complete groundcover (GC), covering the entire surface of the plots. Root production was higher in the non-bearing year (2009–10) than in the bearing year (2010–11). Trees in the BS plots had more roots of bigger diameter in the top 30 cm of soil and trees in VS and GC plots had more roots in the 30–60 cm depth and of smaller diameter. Lifespan of spring-born roots were 61 and 59% greater than those born during autumn and summer, respectively and soil depth and root diameter were positively correlated with root longevity. Lifespan of thinner roots (<0.2 mm) in the BS and VS plots were 49 and 33% greater than GC respectively. Avocado trees grown in contrasting condition compared with their native habitat show high morphological root plasticity, in response to resource and non-resource competition when grown in mixed stands.
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Casanova, Manuel, Berthin Ticona, Osvaldo Salazar, Eduardo Gratacós, Marco Pfeiffer, Gonzalo Ávila, Yasna Tapia, Oscar Seguel, and Carlo Sabaini. "Physical assessment of a Mollisol under agroecological managements at Quillota valley. Mediterranean Central Chile." International Journal of Agriculture and Natural Resources 47, no. 3 (December 2020): 261–79. http://dx.doi.org/10.7764/ijanr.v47i3.2290.
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A number of agroecological practices have been proposed for assessing soil quality. Several physical soil properties have been shown to be important for determining soil quality by using the sustainability index (SI) and the cumulative rating approach. The main aim of the study was to determine the effects of different agroecological managements on the physical properties of a Mollisol in the Mediterranean central Chile. In addition, some physical properties were selected to compare the soil quality among different agroecological management practices and highly mechanized intensive systems by using the SI and cumulative rating approaches. An experimental field was defined in an area of 3.5 ha in 2014. Four sites with different agroecological practices were selected in 2019 to assess soil physical properties: rainfed Mediterranean annual prairie - no tillage (1-S), irrigated perennial prairie with deep-root species - no tillage (2-N), irrigated annual and perennial prairie - conventional tillage (4-S), irrigated vegetables and flowers - minimum tillage (4-N); an avocado orchard with traditional management was used as the control. Soil organic carbon and the following soil physical properties were selected to assess SI and CR: bulk density, total porosity, void ratio, air capacity, fast-drainage pores, relative field capacity, hydraulic conductivity, structural stability index and unavailable water pores. The applicability of the selected physical indicators to the SIs of agroecological management practices compared with the control was demonstrated. The cumulative rating index (CR) for each land use showed that all agroecological practices constituted sustainable soil management (25≤CR<30), whereas the avocado orchard showed the least sustainable management (30≤CR<40), and a change in soil use is recommended.
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López-Herrera, C. J., R. M. Pérez-Jiménez, T. Zea-Bonilla, M. J. Basallote-Ureba, and J. M. Melero-Vara. "Soil Solarization in Established Avocado Trees for Control of Dematophora necatrix." Plant Disease 82, no. 10 (October 1998): 1088–92. http://dx.doi.org/10.1094/pdis.1998.82.10.1088.
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Four field experiments on the control of Dematophora necatrix in avocado orchards affected by white root rot were conducted in the Mediterranean coastal area of southern Spain during 1991 to 1994. In the unshaded locations of solarized plots, the maximal temperatures were 35 to 42°C, depending upon the year and soil depth (15 to 60 cm). Temperature increases attributable to soil solarization ranged between 4 and 8°C in unshaded areas, whereas for shaded areas they were approximately 4°C. Inoculum recovery was decreased in root samples buried at 15 to 30 cm in unshaded locations of both solarized and unsolarized plots after 3 to 5 weeks, whereas 4 to 8 weeks of solarization were required for the elimination of the pathogen buried at depths of 45 to 60 cm. In contrast, inoculum recovery ranged from 30 to 60% for samples in shaded locations of unsolarized plots. D. necatrix was not recovered from roots of infected trees in solarized plots sampled 9 months after solarization, whereas recovery from roots in unsolarized plots was similar to levels before solarization. Soil solarization in established orchards was successful in reducing viability of inoculum buried in soil and eliminated inoculum in infected roots of live trees.
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McDonald, V., E. Pond, M. Crowley, B. McKee, and J. Menge (Emeritus). "Selection for and evaluation of an avocado orchard soil microbially suppressive to Phytophthora cinnamomi." Plant and Soil 299, no. 1-2 (September 2, 2007): 17–28. http://dx.doi.org/10.1007/s11104-007-9340-3.
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Oster, James D., D. E. Stottlmyer, and M. L. Arpaia. "Salinity and Water Effects on ‘Hass’ Avocado Yields." Journal of the American Society for Horticultural Science 132, no. 2 (March 2007): 253–61. http://dx.doi.org/10.21273/jashs.132.2.253.
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A field experiment was conducted between 1992 and 1997 in a commercial orchard of mature ‘Hass’ avocados on Mexican seedling rootstock (Persea americana Mill.) to determine how yield was influenced by the amount of irrigation water applied and the frequency of application. Three amounts of water (targeted at 90%, 110%, and 130% of estimated crop evapotranspiration) were applied at three frequencies (one, twice, and seven times per week) with microsprinklers located beneath the tree canopy. The site was set up as a randomized complete block design with six blocks, each including one replicate of all irrigation treatments. One or two trees located at the center of the replicates were used to measure yields and tree size, and as the locations where samples of soil and soil water were obtained for analysis from beneath the tree canopy. The average electrical conductivity and chloride concentration of the irrigation water, corrected for rain, were 0.7 dS·m−1 and 1.8 mmol·L−1, respectively. From May 1994 to Nov. 1996, salinity of the saturated-paste extracts of soil samples obtained in the 0- to 120-cm depth interval averaged ≈2 dS·m−1 for all irrigation treatments. Irrigation treatments also had little influence on the maximum soil-water salinity, ≈4 dS·m−1, in and below the lower portion of the root zone. Consequently, irrigation treatments had little influence on the fraction of applied water that was not used by the crop, the leaching fraction. Chloride concentrations in leaves were affected by applied water but did not attain levels that are associated with leaf injury. Trees irrigated seven times per week had lower yields than trees that received less frequent irrigation. During the last 2 years of the experiment, when yields no longer increased with time, the yields for treatments irrigated once and twice per week increased with increasing amounts of applied water. We were able to explain the influence of both amount of applied water and soil salinity on avocado yields and leaching fraction using production function concepts. Yields increased with increasing amounts of applied water because of increased water availability for crop use before a soil-water salinity of ≈4 dS·m−1 restricted water uptake. The threshold salinity above which yield decline occurred was determined to be 0.57 dS·m−1 and yield declined by 65% per unit of salinity above the threshold. Our results suggest that maximum yields of ‘Hass’ avocado on Mexican seedling rootstock are not achievable when the average annual salinity of irrigation water, including rainfall, is greater than ≈0.6 dS·m−1.
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Guillermo, Moreno-Ortega, Zumaquero Adela, Matas Antonio, Nicholas A. Olivier, van den Berg Noëlani, Elena Palomo-Ríos, Martínez-Ferri Elsa, and Pliego Clara. "Physiological and Molecular Responses of ‘Dusa’ Avocado Rootstock to Water Stress: Insights for Drought Adaptation." Plants 10, no. 10 (September 30, 2021): 2077. http://dx.doi.org/10.3390/plants10102077.
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Avocado consumption is increasing year by year, and its cultivation has spread to many countries with low water availability, which threatens the sustainability and profitability of avocado orchards. However, to date, there is not much information on the behavior of commercial avocado rootstocks against drought. The aim of this research was to evaluate the physiological and molecular responses of ‘Dusa’ avocado rootstock to different levels of water stress. Plants were deficit irrigated until soil water content reached 50% (mild-WS) and 25% (severe-WS) of field capacity. Leaf water potential (Ψw), net CO2 assimilation rates (AN), transpiration rate (E), stomatal conductance (gs), and plant transpiration rates significantly decreased under both WS treatments, reaching significantly lower values in severe-WS plants. After rewatering, mild- and severe-WS plants showed a fast recovery in most physiological parameters measured. To analyze root response to different levels of drought stress, a cDNA avocado stress microarray was carried out. Plants showed a wide transcriptome response linked to the higher degree of water stress, and functional enrichment of differentially expressed genes (DEGs) revealed abundance of common sequences associated with water stress, as well as specific categories for mild-WS and severe-WS. DEGs previously linked to drought tolerance showed overexpression under both water stress levels, i.e., several transcription factors, genes related to abscisic acid (ABA) response, redox homeostasis, osmoprotection, and cell-wall organization. Taken altogether, physiological and molecular data highlight the good performance of ‘Dusa’ rootstock under low-water-availability conditions, although further water stress experiments must be carried out under field conditions.
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Núñez-Elisea, Roberto, Bruce Schaffer, Mongi Zekri, Stephen K. O'Hair, and Jonathan H. Crane. "In Situ Soil-water Characteristic Curves for Tropical Fruit Orchards in Trenched Calcareous Soil." HortTechnology 11, no. 1 (January 2001): 65–69. http://dx.doi.org/10.21273/horttech.11.1.65.
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Most tropical fruit trees in southern Florida are grown in calcareous gravelly soil that is mechanically trenched to a depth of about 50 cm (about 20 inches). Fruit trees are often planted at the intersections of perpendicular trenches to provide space for root development. Tree root systems are concentrated in the top 10 to 20 cm (about 4 to 8 inches) of soil. Extreme soil rockiness has made it difficult to obtain consistent and reliable measurements of soil water status and to collect soil samples for constructing soil-water characteristic curves in the laboratory. Multisensor capacitance probes andlow-tension [0 to 40 kPa (centibars) (0 to 5.8 lb/inch2)] tensiometers were installed adjacent to star fruit (Averrhoa carambola L.) and avocado (Persea americana Mill.) trees in trenches to simultaneously measure volumetric soil water content and soil matric potential in situ. Capacitance probes consisted of four sensors centered at depths of 10, 20, 30, and 50 cm (3.9, 7.9, 11.8, and 19.7 inches). Tensiometers were installed at 10- and 30-cm depths, adjacent to the 10- and 30-cm deep capacitance sensors. Measurements obtained with both instruments were used to generate in situ soil-water characteristic curves. Rock fragments were more abundant at 30 cm than at 10 cm (71% to 73% versus 26% to 38% of bulk soil volume, respectively) soil depth, which limited the precision of tensiometers at the greater depth. In situ soil water characteristic curves for the 10-cm soil depth can be used to determine parameters needed for irrigation scheduling by techniques such as the water budget method.
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Youlton, Cristian, Paulina Espejo, Jaime Biggs, Marcela Norambuena, Marco Cisternas, Alexander Neaman, and Eduardo Salgado. "Quantification and control of runoff and soil erosion on avocado orchards on ridges along steep-hillslopes." Ciencia e investigación agraria 37, no. 3 (December 2010): 113–23. http://dx.doi.org/10.4067/s0718-16202010000300010.
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Zekri, Mongi, Bruce Schaffer, Stephen K. O'Hair, Roberto Nunez-Elisea, and Jonathan H. Crane. "Evapotranspiration Measurement and Irrigation Scheduling for Several Tropical Fruit Crops Using the EnviroScan System." HortScience 33, no. 3 (June 1998): 549f—550. http://dx.doi.org/10.21273/hortsci.33.3.549f.
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In southern Florida, most tropical fruit crops between Biscayne and Everglades National Parks are irrigated at rates and frequencies based on experience and observations of tree growth and fruit yield rather than on reliable quantitative information of actual water use. This approach suggests that irrigation rates may be excessive and could lead to leaching of agricultural chemicals into the groundwater in this environmentally sensitive area. Therefore, a study is being conducted to increase water use efficiency and optimize irrigation by accurately scheduling irrigation using a very effective management tool (EnviroScan, Sentek Environmental Innovations, Pty., Kent, Australia) that continuously monitors soil water content with highly accurate capacitance multi-sensor probes installed at several depths within the soil profile. The system measures crop water use by monitoring soil water depletion rates and allows the maintenance of soil water content within the optimum range (below field capacity and well above the onset of plant water stress). The study is being conducted in growers' orchards with three tropical fruit crops (avocado, carambola, and `Tahiti' lime) to facilitate rapid adoption and utilization of research results.
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Arjona-López, Juan M., Nieves Capote, and Carlos J. López-Herrera. "Improved real-time PCR protocol for the accurate detection and quantification of Rosellinia necatrix in avocado orchards." Plant and Soil 443, no. 1-2 (July 25, 2019): 605–12. http://dx.doi.org/10.1007/s11104-019-04215-6.
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Atucha, Amaya, Ian A. Merwin, Michael G. Brown, Francisco Gardiazabal, Francisco Mena, Cecilia Adriazola, and Johannes Lehmann. "Soil erosion, runoff and nutrient losses in an avocado (Persea americana Mill) hillside orchard under different groundcover management systems." Plant and Soil 368, no. 1-2 (November 17, 2012): 393–406. http://dx.doi.org/10.1007/s11104-012-1520-0.
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Baram, Shahar, Asher Bar-Tal, Alon Gal, Shmulik P. Friedman, and David Russo. "The effect of static chamber base on N2O flux in drip irrigation." Biogeosciences 19, no. 15 (August 9, 2022): 3699–711. http://dx.doi.org/10.5194/bg-19-3699-2022.
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Abstract. Static chambers are commonly used to provide in situ quantification of nitrous oxide (N2O) fluxes. Despite their benefits, when left in the field, the physicochemical conditions inside the chamber's base may differ from the ambient, especially in drip-irrigated systems. This research aimed to study the effects of static chamber bases on water and N distribution and the subsequent impact on N2O fluxes. N2O emissions were measured in a drip-irrigated avocado orchard for 2 years, using bases with a dripper at their center (In) and bases installed adjacent to the dripper (adjacent). During the irrigation and fertigation season, the measured N2OIn fluxes were greater than the N2OAdjacent fluxes (0.015 ± 0.003 vs. 0.006 ± 0.001 g m−2 d−1). By contrast, during the winter, when the orchard is not irrigated or fertilized, insignificant differences were observed between the measured N2OAdjecent and N2OIn fluxes. Three-dimensional simulations of water flow, N transport, and N transformations showed two opposing phenomena: (a) increased water contents, N concentrations, and downward flushing when the dripper is placed inside the base, and (b) hampering of the lateral distribution of water and solutes into the most bio-active part of the soil inside the base when the base is placed adjacent to the dripper. It also showed that both “In” and “adjacent” practices underestimate the “true” cumulative flux from a dripper with no base by ∼ 25 % and ∼ 50 %, respectively. A nomogram in a non-dimensional form corresponding to all soil textures, emitter spacings, and discharge rates was developed to determine the optimal diameter of an equivalent cylindrical base to be used along a single dripline. Further studies under variable conditions (soil types, wetting patterns, nutrient availabilities), rather than a single study, are needed to test the constructiveness of the suggested methodologies.
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Yalin, D., A. Eshel, A. Schwartz, J. Tarchitzky, and M. Shenker. "How does irrigation with treated wastewater affect soil oxygen dynamics in avocado (Persea americana) orchards planted in clayey soils and implications to plant Na homeostasis." Acta Horticulturae, no. 1333 (January 2022): 93–98. http://dx.doi.org/10.17660/actahortic.2022.1333.13.
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Bravo-Espinosa, M., M. E. Mendoza, T. CarlóN Allende, L. Medina, J. T. Sáenz-Reyes, and R. Páez. "EFFECTS OF CONVERTING FOREST TO AVOCADO ORCHARDS ON TOPSOIL PROPERTIES IN THE TRANS-MEXICAN VOLCANIC SYSTEM, MEXICO." Land Degradation & Development 25, no. 5 (May 16, 2012): 452–67. http://dx.doi.org/10.1002/ldr.2163.
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Sawant, Shailesh S., Eu Ddeum Choi, Janghoon Song, and Ho-Jin Seo. "Current Status and Future Prospects of White Root Rot Management in Pear Orchards: A Review." Research in Plant Disease 27, no. 3 (September 30, 2021): 91–98. http://dx.doi.org/10.5423/rpd.2021.27.3.91.
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The current social demand for organic, sustainable, and eco-friendly approaches for farming, while ensuring the health and productivity of crops is increasing rapidly. Biocontrol agents are applied to crops to ensure biological control of plant pathogens. Research on the biological control of white root rot disease caused by a soil-borne pathogen, Rosellinia necatrix, is limited in pears compared to that in apple and avocado. This pathogenic fungus has an extensive host range, and symptoms of this disease include rotting of roots, yellowing and falling of leaves, wilting, and finally tree death. The severity of the disease caused by R. necatrix , makes it the most harmful fungal pathogen infecting the economical fruit tree species, such as pears, and is one of the main limiting factors in pear farming, with devastating effects on plant health and yield. In addition to agronomic and cultural practices, growers use chemical treatments to control the disease. However, rising public concern about environmental pollution and harmful effects of chemicals in humans and animals has facilitated the search for novel and environmentally friendly disease control methods. This review will briefly summarize the current status of biocontrol agents, ecofriendly methods, and possible approaches to control disease in pear orchards.
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Severino, Francisco José, and Pedro Jacob Christoffoleti. "Weed supression by smother crops and selective herbicides." Scientia Agricola 61, no. 1 (February 2004): 21–26. http://dx.doi.org/10.1590/s0103-90162004000100004.
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Using a smother crop is thought to suppress weed density and to add other beneficial effects in sustainable agricultural systems. Weed suppression ought to be considered an essential component of integrated weed management. However, very little is known about the effects of green manure plants on weeds. This study evaluated the influence of three green manure species on weed suppression and selectivity of herbicides. A field experiment was designed to determine the effect of the green manure species Crotalaria juncea, Arachis pintoi and pigeon pea on the weeds Brachiaria decumbens, guineagrass and hairy beggarticks, and on the natural weed infestation in the inter rows area of an avocado orchard. The weed species were suppressed differently by each green manure species. Soil samples collected from the field experiment presented a residual effect, of at least 30 d, in suppressing weed seed bank recruitment; this residual effect was caused by the residues of the green manure present in the soil. When the green manure was incorporated into the top 5 cm of soil or left on the surface, in a greenhouse experiment, the emergence of weed seeds was significantly inhibited, depending on the species, and on the amount and depth of green manure incorporation. Greenhouse experiments indicate that pre-emergence herbicides cause lower phytotoxicity than post-emergence Arachis pintoi. Smother crops using green manure species, when well established in an area, provide additional weed control to the cropping system and are effective and valuable tools in integrated weed management.
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Zea-Bonilla, T., M. A. González-Sánchez, P. M. Martín-Sánchez, and R. M. Pérez-Jiménez. "Avocado Dieback Caused by Neofusicoccum parvum in the Andalucia Region, Spain." Plant Disease 91, no. 8 (August 2007): 1052. http://dx.doi.org/10.1094/pdis-91-8-1052b.
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From 2002 to 2006, adult avocado trees, Persea americana Miller cv. Hass, located in the subtropical-fruit-producing area of Andalucia (southern Spain) developed symptoms of dieback characterized by death of twigs and branches in the tree canopy. Sections of surface-disinfested, necrotic branch tissues were plated on Difco potato dextrose agar (PDA) (Sparks, NV) and a Neofusicoccum-like fungus was isolated. On PDA, the isolates had white, appressed mycelium that turned dull gray as the colony aged, although conidia were not formed. Abundant pycnidia and conidia developed when isolates were cultured on 2% water agar with sterilized pine needles as substratum at 25°C under near-UV light for 2 weeks. Conidia were hyaline, unicellular, ellipsoid with an obtuse apex and subtruncate base, averaged 16.2 μm long by 5.8 μm wide and ranged from 12.0 to 20.0 by 4.0 to 8.0 μm, and becoming brown with one or two septa with age. Sequenced rDNA fragments (ITS1, 5.8S rDNA, and ITS2, amplified with ITS1 and ITS4 primers) of two avocado isolates were 100% homologous with Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers, & A.J.L. Phillips (1) (GenBank Accession Nos. AM410965 and AM410966). Morphological and molecular results confirmed this species as N. parvum, reported as the anamorph of Botryosphaeria parva (1). A pathogenicity test was conducted using two isolates on sets of five 2-year-old avocado plants produced from seeds of cv. Topa-Topa growing in 5-liter pots with soil. Unwounded and wounded plants were used for inoculations. Plants were wounded 2 to 3 cm below the apical tip with a lance (4 mm long and 1 mm deep). For inoculation, 4-mm 2-week-old PDA culture plugs were placed in contact with wounded tissues and covered with Parafilm. Five noninoculated plants treated similarly served as controls. Plants were maintained in the greenhouse with a temperature range of 18 to 26°C, and 1 month later, brown stem lesions, as much as 5 cm, originating from the inoculation site followed by dieback of branches were observed. Reisolations from necrotic branches were successful, and both isolates with identical morphology to those used for inoculations were recovered. Pathogenicity tests of seedlings using the same methods also caused stem lesions on unwounded plants and the pathogen was reisolated. To our knowledge, this is the first report of N. parvum causing dieback of avocado trees in Spain. Previously, B. parva has been reported causing stem-end rot of avocado fruit in New Zealand (2). In Spain, since diseased orchards are increasing rapidly, this pathogen could be efficiently distributed by pruning activities (tools and vegetal debris) as observed with other diseases (3). The presence of N. parvum in this subtropical area presents a serious disease problem not only to avocado but also to mango (Mangifera indica L.), which is another susceptible host (4). References: (1) P. W. Crous et al. Stud. Mycol. 55:235, 2006. (2) W. F. T. Hartill et al. N. Z. J. Crop Hortic. Sci. 30:249. 2002. (3) A. J. L. Phillips. Phytopathol. Mediterr. 41:3, 2002. (4) B. Slippers et al. Mycologia 97:99, 2005.
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Huett, D. O., and J. F. Dirou. "An evaluation of the rationale for fertiliser management of tropical fruit crops." Australian Journal of Experimental Agriculture 40, no. 8 (2000): 1137. http://dx.doi.org/10.1071/ea00047.
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Sustainable fertiliser management involves maximising production, preventing on-site soil degradation and minimising off-site movement of nutrients. In the past, fertiliser management has been driven by the need to maximise production. Fertiliser costs are generally less than 10% of the variable production costs in horticultural enterprises and this has often led to excessive application of nutrients. Fertiliser experiments have not generally provided calibrated soil or leaf test data because of their short-term nature, the biennial or variable production of many tree crops, their narrow focus and the difficulty in demonstrating yield responses because tree crops have relatively low rates of nutrient removal over long periods of time. Nutrient balance is a basically sound approach to developing fertiliser recommendations and can be easily estimated from crop nutrient removal data. This approach has been used successfully for crops such as low-chill stonefruit (Huett and Stewart 1999) and a simplified approach is presented for passionfruit, mango and avocado based on nutrient uptake by well-managed, mature, productive orchards. Macronutrient removal by a 20 t/ha passionfruit crop was (kg/ha) 55 nitrogen (N), 78 potassium (K), 6 phosphorus (P), 6 sulfur (S), 5 calcium (Ca) and 4 magnesium (Mg). For a 10 t/ha mango crop it was (kg/ha) 11 N, 15 K, 2 P, 1 S, 2 Ca and 2 Mg. For a 10 t/ha avocado crop it was (kg/ha) 41 N, 61 K, 8 P, 4 S, 7 Ca and 8 Mg. Passionfruit, in contrast to tree crops, is generally a 3-year crop and nutrient uptake by developing leaf, vines and roots will inflate nutrient uptake by a factor of 2–3. Nutrient losses due to leaching, runoff and fixation will further inflate fertiliser requirements. However, the inclusion of these additional factors still means that nutrient application rates will be substantially less than current fertiliser recommendations.
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Morianou, Giasemi, Nektarios N. Kourgialas, and George P. Karatzas. "A Review of HYDRUS 2D/3D Applications for Simulations of Water Dynamics, Root Uptake and Solute Transport in Tree Crops under Drip Irrigation." Water 15, no. 4 (February 13, 2023): 741. http://dx.doi.org/10.3390/w15040741.
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Orchards with tree crops are of critical importance to the global economy and to the environment due to their ability to be productive for many years without the need for replanting. They are also better adapted to extreme climatic conditions compared to other crops. However, new challenges are emerging as climate change threatens both tree production and water supply. Drip irrigation (surface and subsurface) is an irrigation method that has the potential to save water and nutrients by placing water directly into the root zone and minimizing evaporation. Many irrigation designs and strategies have been tested to best perform drip irrigation for any given soil, crop and/or climate conditions. The researchers’ need to find the optimal combination of irrigation management and design in the most economical and effortless way led to the use of comprehensive numerical models such as HYDRUS 2D/3D. HYDRUS 2D/3D is a widely used mathematical model for studying vadose zone flow and transport processes. A review of HYDRUS 2D/3D applications for simulations of water dynamics, root uptake and solute transport under drip irrigation in the four most common categories of tree crops (citrus, olive, avocado and deciduous fruit/nuts) is presented in this study. The review promotes a better understanding of the effect of different drip irrigation designs and treatments, as well as the reliability provided by HYDRUS 2D/3D in the evaluation of the above. This manuscript also indicates gaps and future challenges regarding the use of the model in simulations of drip irrigation in tree crops.
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Bekker, Theo F., Nico Labuschagne, Terry Aveling, Thierry Regnier, and Clive Kaiser. "Effects of soil drenching of water-soluble potassium silicate on commercial avocado (Persea americanaMill.) orchard trees infected withPhytophthora cinnamomiRands on root density, canopy health, induction and concentration of phenolic compounds." South African Journal of Plant and Soil 31, no. 2 (April 3, 2014): 101–7. http://dx.doi.org/10.1080/02571862.2014.912687.
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Garbelotto, M., D. Hüberli, and D. Shaw. "First Report on an Infestation of Phytophthora cinnamomi in Natural Oak Woodlands of California and its Differential Impact on Two Native Oak Species." Plant Disease 90, no. 5 (May 2006): 685. http://dx.doi.org/10.1094/pd-90-0685c.
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During an intense survey of natural woodlands around Lake Hodges (33°N, 117°W) in June 2001, symptoms typical of root and collar rot caused by Phytophthora spp. were observed on 27% of 474 coast live oaks (Quercus agrifolia Nee.) and on none of 86 Engelmann oaks (Q. engelmannii Greene), in spite of complete spatial intermixing of the two species. Symptoms on coast live oaks included viscous exudates emerging through intact bark matched by underbark dark lesions with irregular margins. Lesions were delineated by a dark line and present on the root collar or the buttress of symptomatic trees. Crowns of trees with lesions ranged from completely healthy to declining or dead. All symptomatic trees were in proximity of the lake or streams. Phytophthora cinnamomi Rands was isolated from four trees in three distinct sites by plating tissues from lesion margins on PARP selective medium and from four soil samples by using standard pear baiting and plating lesions from pear tissue onto PARP. Identification of the isolates was obtained from microscopic observations and direct sequencing of the internal transcribed spacer region of the rDNA (Genbank Accession Nos. AY302148, MC2 and AY302149, MC3). P. citricola Sawada was also isolated once. Pathogenicity tests were completed to compare the susceptibility of the two species of oaks growing in the Lake Hodges region with P. cinnamomi. Two P. cinnamomi isolates from Lake Hodges (MC2, ATCC MYA-3711; MC3) and one isolate from an avocado orchard in San Diego County (MC6) were used to inoculate separately 10 5-year-old trees each of Q. agrifolia and Q. engelmannii grown in 5-gallon containers. Inoculations were performed in two lath-house experiments during February and September 2002 by placing an 8-mm diameter V8-agar plug from the margin of a P. cinnamomi colony underbark and sealing the wound with Parafilm and grafting wax. Lesion lengths were measured 2 months after inoculation, and the presence of the pathogen confirmed by reisolation on PARP. Mean average, maximum, and minimum temperatures were 14, 19, and 9°C and 21, 24, and 18°C for the February and September inoculations, respectively. The February inoculation resulted in small lesions only on Q. agrifolia (26 ± 15 mm, SD). The September inoculation resulted in 135 ± 68 mm (SD) lesions on Q. agrifolia and 49 ± 35 mm (SD) lesions on Q. engelmannii. Controls did not show any lesions. The length of lesions was significantly different between the two hosts (P < 0.0001) and significant differences were observed among the three isolates (P = 0.0018). Although Q. agrifolia is a known host for P. cinnamomi in California (2,3), to our knowledge, this is the first report of widespread infestation of P. cinnamomi in natural oak woodlands in the western United States. Survey and inoculation results indicated Q. engelmannii to be less susceptible to infection. Inoculation results confirm previous research that cold temperatures are unfavorable to this pathogen and isolates differed in pathogenicity toward Q. agrifolia. Decline of oaks infected by P. cinnamomi was observed only in conjunction with other factors, in particular with the presence of the oak twig girdler, Agrilus angelicus Horn., an insect favored by stress conditions such as drought. Similar effects have been reported for Mediterranean oaks infected by the same pathogen (1). References: (1) C. M. Brasier. Nature 360:539, 1992. (2) P. A. Miller. Western Shade Tree Conf. Proc. 8:39, 1941. (3) S. M. Mircetich et al. Plant Dis. Rep. 61:66, 1977.
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Arima, Eugenio Y., Audrey Denvir, Kenneth R. Young, Antonio González-Rodríguez, and Felipe García-Oliva. "Modelling avocado-driven deforestation in Michoacán, Mexico." Environmental Research Letters, February 9, 2022. http://dx.doi.org/10.1088/1748-9326/ac5370.
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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.
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Leopold, Audrey, Julien Drouin, Elia Drohnu, Hélène Kaplan, Jacques Wamejonengo, and Severine Bouard. "Fire-fallow agriculture as a sustainable cropping system for maintaining organic carbon in Maré Loyalty Island (New Caledonia, southwest Pacific)." Regional Environmental Change 21, no. 4 (October 12, 2021). http://dx.doi.org/10.1007/s10113-021-01814-x.
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AbstractThe Loyalty Islands are part of the French archipelago of New Caledonia in the Southwest Pacific. In these islands, Gibbsic Ferralsols (Humic) are traditionally used for fire-fallow cultivation (FFC) by the Kanak people, but the planting of perennial orchards has been encouraged over the past two decades. The impacts of this policy on soil organic carbon (SOC) are nevertheless unknown, especially in these clay-free soils in which organic matter is the main contributor to soil fertility. SOC and permanganate oxidizable organic carbon (POXC) were studied in the soils of avocado orchards, FFC, and secondary and native forests. Mean SOC stocks are particularly high, ranging between 71.9 and 194.4 MgC ha−1 in an equivalent soil mass of 2000 Mg ha−1, but they are significantly impacted by land use. Avocado farming reduced SOC stocks by about 30% compared to forest soils, even if fields were established on secondary forests that had already experienced SOC losses. In contrast, FFC did not impact them. The POXC content decreased as the degree of soil anthropization increased; however, it was less sensitive than SOC in highlighting the impacts of land use. SOC storage can be achieved through changes in agricultural practices in avocado farming, with support for farmers in transitioning from family farming to perennial cultivation and the policy management of secondary forests designed to enhance the recovery of native forests.
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AMINISARTESHNIZI, MEHRNOUSH. "Molecular characters of a bark beetle, Xylosandrus crassiusculus associated with avocado using 28S rDNA from regions of South Africa." Research on Crops VOLUME 23, ISSUE 3 (SEPTEMBER) (August 24, 2022). http://dx.doi.org/10.31830/2454-1761.2022.roc-855.
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South Africa is a significant producer and exporter of avocados in the world. Xylosandrus crassiusculushas was found on mainland Africa for many years but the present study represents the first record of bark beetle in South Africa in Limpopo Province. Its presence infesting important agronomic tree crops such as avocado suggests that it requires further study. Therefore, this molecular study was conducted in 2022 at the University of Limpopo to identify the bark beetle in the South African avocado orchard. The recovered bark beetle was isolated from the bark of avocado in Magoebaskloof region in Limpopo Province. Then its DNA was extracted using the Chelex method, and the phylogenetic position of the beetle was studied using 28S rDNA. The Nblast analysis based on the large subunit ribosomal DNA showed 99% similarity with a population of Xylosandrus crassiusculus from South Africa (MT229960), USA (GU808593), and Taiwan (MT120970). In addition, phylogenetic analysis using the maximum likelihood method as implemented in mega x software was done. The phylogenetic analysis put the South African populations of X. crassiusculus together with other X. crassiusculus with a 100-bootstrap value. In conclusion, the results showed that 28S could detect the X. crassiusculus, and was verified by the molecular method.
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AMINISARTESHNIZI, MEHRNOUSH. "Molecular characters of a bark beetle, Xylosandrus crassiusculus associated with avocado using 28S rDNA from regions of South Africa." Research on Crops VOLUME 23, ISSUE 3 (SEPTEMBER) (August 24, 2022). http://dx.doi.org/10.31830/2348-7542.2022.roc-855.
Full textAbstract:
South Africa is a significant producer and exporter of avocados in the world. Xylosandrus crassiusculushas was found on mainland Africa for many years but the present study represents the first record of bark beetle in South Africa in Limpopo Province. Its presence infesting important agronomic tree crops such as avocado suggests that it requires further study. Therefore, this molecular study was conducted in 2022 at the University of Limpopo to identify the bark beetle in the South African avocado orchard. The recovered bark beetle was isolated from the bark of avocado in Magoebaskloof region in Limpopo Province. Then its DNA was extracted using the Chelex method, and the phylogenetic position of the beetle was studied using 28S rDNA. The Nblast analysis based on the large subunit ribosomal DNA showed 99% similarity with a population of Xylosandrus crassiusculus from South Africa (MT229960), USA (GU808593), and Taiwan (MT120970). In addition, phylogenetic analysis using the maximum likelihood method as implemented in mega x software was done. The phylogenetic analysis put the South African populations of X. crassiusculus together with other X. crassiusculus with a 100-bootstrap value. In conclusion, the results showed that 28S could detect the X. crassiusculus, and was verified by the molecular method.
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Cruz Castillo, Juan Guillermo, Luis Rojas, Alejandro Monterroso-Rivas, and Hector Flores-Magdaleno. "Avocado (Persea americana Mill.) production in Huatusco, Veracruz, Mexico." Agro Productividad, January 17, 2023. http://dx.doi.org/10.32854/agrop.v15i12.2358.
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Objective: To characterize the avocado production system in Huatusco, Veracruz. Design/Methodology/Approach: Interviews based on the snowball method were applied to avocado producers in Huatusco, Veracruz. Meanwhile, fruit and water samples were used to perform a multiresidue analysis of pesticides. Results: The monoculture plantations are rainfed. They have a density of 100-150 trees ha-1. The Hass variety predominates in Andosols, with 5-100% slopes. Most of the producers (92%) carry out conventional management, applying pesticides and chemical fertilizers. Herbicides and brushcutters are used to control weeds. No pesticides were detected in the water samples, while Imidacloprid, Thiabendazole, and alpha-Cypermethrin were identified in a fruit sample, with 0.0038 ± 0.0014 mg/kg, 0.0022 ± 0.0009 mg/kg and 0.0703 ± 0.000 mg /kg concentrations, respectively. These concentrations fall within the limits allowed in Mexico. Study Limitations/Implications: A detailed and frequent sampling of avocado fruits should be carried out to determine pesticide residues. It is also necessary to analyze samples of running water near the orchards to prevent pollution. Findings/Conclusions: The empirical knowledge of the producers about the type of soil is more precise than the scientific classification: they identify five classes of soils beyond Andosols. Additionally, there is a marked inequality in land tenure, since large-scale producers (25% of all producers) own 86% of the established area. Although, in a preliminary sampling, pesticide concentrations did not exceed the limits of residues allowed in the avocado pulp, the number of pesticide applications should be reduced.
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Hartley, Jesse, Juanita Engelbrecht, and Noëlani van den Berg. "Detection and prevalence of Rosellinia necatrix in South African avocado orchards." European Journal of Plant Pathology, June 9, 2022. http://dx.doi.org/10.1007/s10658-022-02532-8.
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AbstractRosellinia necatrix is an ascomycete that causes white root rot (WRR) of several plant host species resulting in economic losses to affected agricultural and forestry industries in various regions. This study aimed to identify and monitor the prevalence of R. necatrix in avocado orchards in South Africa. We used both morphological and molecular methods to isolate and identify R. necatrix from diseased plant material and soil. Results showed that R. necatrix was present on avocado in the Limpopo, Mpumalanga and KwaZulu-Natal provinces. Additionally, a semi-selective medium, containing Rose Bengal, nystatin, cycloheximide, chlorothalonil and 2-phenylphenol, was developed to improve isolation of R. necatrix. We also tested an already established R. necatrix-specific TaqMan qPCR protocol to determine if it can reliably detect the pathogen isolates in planta in the South African samples. Based on our results the technique had a detection rate of 91.3% in artificially infected roots and 100% in artificially inoculated soil. We tested natural infected plant and soil samples and detected R. necatrix in 86% of the plant samples and in 70% of the soil samples. Using a selective medium or an in planta molecular detection method streamlines isolation and detection of R. necatrix, which will help prevent further spread of the pathogen. Moreover, additional information on the prevalence of WRR will create awareness among growers and provide a basis for management of the disease.
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Medina-Urrutia, Victor Manuel, and Jaime Eduardo Reyes-Hernandez. "Características de vigor y susceptibilidad a salinidad de árboles de aguacate en las condiciones subtropicales de Jalisco, Mex." Revista de Invención Técnica, December 31, 2019, 11–16. http://dx.doi.org/10.35429/joti.2019.12.3.11.16.
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Objectives: This work was carried out to determine the tree size and susceptibility to salinity and tristeza of avocado trees on a high density orchard established under subtropical conditions of Sayula Jalisco, with grafted plants introduced from Michoacan. Methodology: Trees of Hass and Mendez varieties grafted on native Mexican monoembryonic rootstocks planted at 5 x 3 m, on a sandy loam soil, pH 7.3, were used. During 5 months 10,500 trees were evaluated to register the size (scale: < 2.0, 2.1-3.5 , and > 3.5 m height) and susceptibility to salinity (scale: 1,3 and 5; 1=no damage, and 5=severe damage on leaves). Contribution: A high variability was observed on size of trees. 20.0 % of trees showed a small size, less than 2 m. 30.0% reached more than 3.5 m height. Salinity expression on leaves was very evident. Most trees showed salinity symptoms with a indices of 3 to 7. Only 28 % of trees were free of salinity. The use of monoembryonic rootstocks and water salinity were the main factors inducing tree avocado variability in this region.
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Prabhakaran, Akila Devi, and Elizabeth Kathryn Dann. "Evaluation of fungicide soil drench treatments to manage black root rot disease of avocado." Plant Disease, April 1, 2022. http://dx.doi.org/10.1094/pdis-02-22-0264-re.
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Four common fungicidal products were evaluated for their effect on symptoms caused by two nectriaceous black root rot fungi, Calonectria ilicicola and Dactylonectria macrodidyma, when applied as pot drenches to avocado (Persea americana) seedlings in the greenhouse. Applications of fludioxonil, thiophanate-methyl + etridiazole, prochloraz, and prochloraz MnCl at 2 and 4 weeks after inoculation with C. ilicicola significantly reduced root necrosis and improved root and aboveground plant biomass, compared with water-treated controls. Fludioxonil reduced necrosis by 60% and had a significantly lower frequency of reisolation of C. ilicicola than the other three fungicide treatments. D. macrodidyma inoculation caused less severe symptoms in seedlings than C. ilicicola despite the longer duration of the trial. Pot drenches with fludioxonil, thiophanate-methyl + etridiazole, and prochloraz MnCl, but not prochloraz alone, significantly reduced root necrosis caused by D. macrodidyma. Prochloraz MnCl was the only fungicide treatment to increase root and plant biomass compared with water-treated controls. Both fludioxonil and prochloraz MnCl reduced the frequency of reisolation of D. macrodidyma from necrotic roots by about 50%, compared with the other fungicides or water controls. The results indicated that drenches with these fungicides may suppress existing low to moderate black root rot infection, allowing new root growth and improved establishment in the orchard. Fungicide drenching must not replace best-practice disease management strategies in nurseries, but may be a useful tool in crisis situations.