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Changes in vegetation and land use alter the biogeochemical cycles of soil C and N, as a result of agricultural practices that alter soil quality and function. Adopting sustainable agricultural practices improves soil health by increasing its capacity to store C in the long term. The objective of this study was to evaluate the content and stocks of C and N and the C:N ratio, under different land uses in an Andosol. Four composite soil samples were collected in a pine-oak forest, conventional avocado, organic avocado and organic macadamia soil uses at 0-20 and 20-40 cm soil depths (n=32). The total C content was determined by the Walkley and Black method (Woerner, 1989), the total N by the Kjeldahl method with the Velp Scientifica's UDK159 model equipment (Bremner and Mulvaney 1982). In order to detect significant differences, a two factor analysis of variance (ANOVA) was applied C (%), N (%), SOC (Mg ha-1 ), Nt (Mg ha-1 ) and C:N ratio variables. When applied, a Tukey comparison of means (p≤0.05) was performed. The results indicate that conventional avocado land use presented the highest C and N content at both soil depths (C: 9.22 and 7.32%, N: 0.70 and 0.40%), while the C:N ratio was higher in the forest land use in the first depth (14.5) and higher in the organic avocado land use in the second soil depth (25.8). The stock of SOC varied from 65.27 to 267.30 (Mg ha-1 ) and the Nitrogen from 4.61 to 14.61 (Mg ha-1 ). The C:N ratio showed significant variations between land uses, specifically in the first depth it ranged from 10.33 (O. Macadamia) to 14.51 (Forest), while in the second depth it varied from 13.09 (Conventional) to 25.83 (O avocado). The pine-oak forest, organic avocado and organic macadamia systems, with the smallest reseivors, were statistically similar only in C content, while the conventional system, with the largest stocks, was differente in C and N content. The change in land use from forest to agricultural caused a significant effect on the carbon and nitrogen content and the stocks in the Andosol soil, which may be attributes to the different agricultural applied practices such as pruning, pesticides and fertilization used in the organic and conventional regimes, respectively. The C:N ratio indicates that mineralization rates decrease as depth increases because the quantity and quality of soil organic matter also decreases. Specifically, the conventional avocado practice compared to organic avocado and macadamia practices maximized crop yields. [ABSTRACT FROM AUTHOR]

Copyright of Revista Chapingo Serie Horticultura is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Elsinoe perseae (= Sphaceloma perseae) is the causal agent of the Mancha purpura or scab in avocado (Persea americana). In this study, the pathogenicity and virulence of E. perseae isolates from different agroecological producing areas of Michoacán, Mexico will be reduced. For this, nursery plants with avocado fruits of Flor de María and Méndez varieties were used. On the other hand, the in vitro sensitivity of chemical fungicides (azoxystrobin, thiabendazole, pyraclostrobin, cyprodinil + fludioxonil and azoxystrobin + propiconazole) and authorized for use in orchards with organic management (copper sulfate, copper gluconate, copper oxychloride and the plant extract Larrea tridentata). The observed symptoms of Mancha purpura in the inoculated fruits were corroborated with those described for E. perseae in avocado. Inoculated fruits Flor de María variety shows the highest susceptibility to the pathogen. The isolates of E. perseae presented different degrees of virulence. The isolates showed different in vitro sensitivity values to the fungicides evaluated in the experiment. The pathogen showed the most sensitivity in vitro to chemical fungicides: thiabendazole and azoxystrobin + propiconazole (100% inhibition), and to those authorized in orchards with organic management: L. tridentata and copper oxychloride (on average 58% inhibition). [ABSTRACT FROM AUTHOR]

Mexico is the main producer and exporter of avocado (Persea americana) in the world; however, pests and diseases are limiting factors for production. One of the diseases of great economic importance is avocado scab, which is characterized by causing corky-looking lesions on the epicarp of the fruits, which decreases quality and price by up to 60%. In this study, a sampling was carried out aimed at avocado fruits with damage in the epicarp with a corky appearance, these commonly known in the field as "scab" and "purple spot". For molecular and phylogenetic identification, a combination of techniques with morphological keys and molecular markers (ITS1/ITS4, ITS5/ITS4, FE-1a/EF-1a, Sph1 F/Sph1R) was used. Pathogenicity tests were also carried out on fruits in plants of Hass, Flor de María and Méndez varieties. Through morphological analysis, fungi of the genera Colletotrichum, Pestalotiopsis and Elsinoe were identified. Molecular identification and phylogenetic analysis confirmed the presence of the species Colletotrichum gloeosporioides and Elsinoe perseae. C. gloeosporioides reproduced symptoms similar to the avocado scab disease. With the strain identified as E. perseae, the symptom known in the field as purple spot was confirmed, while Pestalotiopsis sp. caused descending necrosis. [ABSTRACT FROM AUTHOR]

The redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), vectors the mycopathogen that causes laurel wilt, a lethal vascular disease of trees in the Lauraceae. Since being detected in Georgia, USA in 2002, this invasive pest has become established in 11 additional states.With continued spread, X. glabratus will likely enter Mexico. In advance of this event, this study was initiated to assess the risk posed to eight native laurels and Hass avocados, the predominant cultivar grown in Mexico.Wood bolts from each species were used in (a) field tests to determine the relative attraction of female X. glabratus, (b) laboratory bioassays to evaluate boring preferences, and (c) GC–MS analyses to identify host kairomones. For comparison, tests included control bolt treatments consisting of silkbay (an attractive U.S. laurel) and Simmonds avocado (a Florida cultivar susceptible to laurel wilt).Hass avocado and two native laurels (Persea schiedeana and Ocotea heribertoi vel aff.) were highly attractive to females and elicited strong boring responses. These species were high in sesquiterpene hydrocarbons, including α‐copaene and α‐cubebene.Results of this study suggest that X. glabratus could become a serious agricultural and forest pest upon incursion into Mexico, with severe economic and ecological impacts. [ABSTRACT FROM AUTHOR]

Mexico is the world's leading producer and exporter of avocado (Persea americana Miller). There are few studies on soil microorganisms associated with this crop, which are important to establish the role they can play in the production system and their use in different areas of interest. In this re-search, the biodiversity of cultivable micromycetes in the soil of five avocado orchards located in two municipalities of the state of Nuevo León was determined. The isolates obtained were grouped into morphotypes and identified to genus level or grouped by common morphological characteristics. Shannon-Wiener, Simpson, and Margalef diversity indices were determined for morphotypes, as well as for and genera and groups of micromycetes with common characteristics in each orchard. The Hutcheson's test (p= 0.05) was performed to determine significant differences between Shannon-Wiener diversity index of genera and micromycetes with common characteristics between orchards. A total of 518 isolates were obtained and classified into 291 morphotypes that were grouped into 44 genera and 7 groups with common characteristics. Hutcheson's test showed that the Shannon-Wiener index of genera and groups of a single orchard is different to the others. The sterile mycelium group was the most abundant in four of the five orchards. Genera reported as phytopathogens (Fusarium, Verticillium), entomopathogens (Beauveria, Paecilomyces, Metarhizium) and mycoparasites (Trichoderma, Gliocladium) were identified. In addition, 28 new genera associated with avocado orchard soil are reported in this research. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The widespread Scolytinae and Platypodinae beetles are capable to colonize a broad range of host plants and several species are considered serious pests in agri-forest environments. In this work, we report the abundance and seasonal variation of scolytine and platypodine beetles associated to a Hass avocado orchard in West-central Mexico. During 2018 and 2019, specimens were captured using bottle traps baited with ethyl alcohol. We tested whether the climatic conditions explain the abundance and species richness. A total of 3,548 specimens from 30 species and 13 genera were collected. Thirteen species are new records for Nayarit State. The most abundant species were Corthylocurus aguacatensis (Schedl 1940), Xyleborus volvulus (Fabricius 1775) and Xyleborus affinis (Eichhoff 1868), these Scolytinae representing 54% of total collected. Abundance and species richness peaked during the fall season (from October to December). Differential responses to temperature and humidity across the temporal scale was found between species. Temperatures below 30 ° but above 26 ° C, and relative humidity (70 to 85%) favored the highest abundance and species richness of most Scolytinae (e.g. C. aguacatensis, Corthylus papulans and X. affinis). Thus, for sustainable management of these pest species we suggest regularly monitoring them in the avocado plantations from Nayarit and other producing states in Mexico. [ABSTRACT FROM AUTHOR]

Avocado fruits (Persea americana), native to Central America and Mexico, are highly nutritious and grown widely in tropical and subtropical regions. They are rich in fatty acids and other bioactive compounds such as vitamin E, carotenoids and phenolic compounds. Recently, avocado cultivars grown in Vietnam have gained more interest due to their value. This study aimed to investigate variations in lipid contents and bioactive compounds among avocado cultivars grown in Vietnam. Avocado fruits were harvested at mature green and transferred to the laboratory and stored at room temperature for ripening. Lipid content was measured by extraction with hexane. Phenolic content, antioxidant activity and carotenoid content were determined using the Folin-Ciocalteu, DPPH and spectral methods, respectively. The results showed that the lipid content varied from 35.41% for Sap bong cultivar to 61.40% for 034 cultivar. Booth 3 cultivar showed the highest total phenolic content (6.46 mg GAE/g DW), while this value is the lowest for HAC cultivar (2.67 mg GAE/g DW). Flavonoid content also significantly varied between cultivars from 0.70 to 2.01 mg catechin/g DW. Carotenoid content ranged from 38.55 µg/g for HAC to 226.77 µg/g for Nam long. Variations in chlorophyll a and chlorophyll b contents were also observed. Chlorophyll a and chlorophyll b contents varied from 127.60 to 316.30 µg/g and 46.83 to 223.81 µg/g, respectively. Significant variations in the lipid content and the bioactive compounds between the avocado cultivars provide information to select high quality avocado fruits for commercial purposes. [ABSTRACT FROM AUTHOR]

The natural enemies of the avocado stem weevil, (Copturus aguacatae Kissinger) (Coleoptera: Curculionidae), in the state of Nayarit, Mexico, were identified. Branch samples were taken biweekly during Feb–Dec 2015 in avocado orchards located in Tepic and Xalisco. The branches with C. aguacatae larvae were placed in cages and checked weekly until parasitoids or adult borers emerged. Eleven species of parasitic Hymenoptera were found; particularly abundant was Heterospilus bruchi (Viereck) (Braconidae). In addition, three species of entomopathogenic fungi (Metarhizium pingshaense, Metarhizium anisopliae and Beauveria bassiana) were identified associated with avocado stem weevil in Nayarit. [ABSTRACT FROM AUTHOR]

Mexico is the main avocado (Persea americana Mill.) producer in the world; however, this fruit is susceptible to phytopathogenic fungi that reduce quality during postharvest. Therefore, the timely identification of these organisms using non-invasive tools, such as artificial intelligence analysis, is of interest to reduce economic losses. The objective of this study was to implement a machine learning model with a database of digital images of fruits collected in the field, by creating a convolutional neural network (CNN) classifier, training and validating it to identify healthy avocado cv. Fuerte fruits and fruits infected with scab (Sphaceloma perseae Jenkins) or anthracnose (Colletotrichum spp.) from the production area in the State of Morelos, Mexico. Healthy avocado fruits were collected in the field, as well as fruits with the scab and anthracnose from different orchards to generate a set of 569 digital images. Transformations of these increased the dataset to 3983 images. The CNN model was trained with a random partition of 80% of the images and validated for prediction with the remaining 20%. CNN achieved an overall correct classification accuracy of 80% with the validation set. In addition, the classifier was evaluated with a test set of 100 images not included in the original set and achieved an overall correct classification accuracy of 87%. The CNN deep learning classifier implemented in this study represents the feasible use of artificial intelligence for application in avocado disease identification from digital images at the postharvest stage. [ABSTRACT FROM AUTHOR]

Insect pollination increases the yield and quality of many crops and therefore, understanding the role of insect pollinators in crop production is necessary to sustainably increase yields. Avocado Persea americana benefits from insect pollination, however, a better understanding of the role of pollinators and their contribution to the production of this globally important crop is needed. In this study, we carried out a systematic literature review and meta‐analysis of studies investigating the pollination ecology of avocado to answer the following questions: (a) Are there any research gaps in terms of geographic location or scientific focus? (b) What is the effect of insect pollinators on avocado pollination and production? (c) Which pollinators are the most abundant and effective and how does this vary across location? (d) How can insect pollination be improved for higher yields? (e) What are the current evidence gaps and what should be the focus of future research? Research from many regions of the globe has been published, however, results showed that there is limited information from key avocado producing countries such as Mexico and the Dominican Republic. In most studies, insects were shown to contribute greatly to pollination, fruit set and yield. Honeybees Apis mellifera were important pollinators in many regions due to their efficiency and high abundance, however, many wild pollinators also visited avocado flowers and were the most frequent visitors in over 50% of studies. This study also highlighted the effectiveness of stingless bees (Meliponini) and blow flies (Calliphoridae) as avocado pollinators although, for the majority of flower visitors, there is a lack of data on pollinator efficiency. For optimal yields, growers should ensure a sufficient abundance of pollinators in their orchards either through increasing honeybee hive density or, for a more sustainable approach, by managing wild pollinators through practices that protect or promote natural habitat. [ABSTRACT FROM AUTHOR]

Oligonychus punicae (Hirst) (Trombidiformes: Tetranychidae) is a common pest in Mexican avocado orchards. Neoseiulus californicus (McGregor) (Mesostigmata: Phytoseiidae) is frequently found associated with avocado orchards in Mexico and may be an important aid for controlling O. punicae. Given the lack of information in the scientific literature, this study evaluated the predation and oviposition of N. californicus when fed O. punicae at different developmental stages in a no-choice experiment. We also assessed fluctuations in the population size of O. punicae and N. californicus in commercial avocado orchards; correlations among mite density and air temperature, humidity, and precipitation in commercial avocado orchards; and the correlations between prey and predator populations. The no-choice test revealed that N. californicus adult females fed on O. punicae of all developmental stages, with higher levels of predation being recorded for eggs, followed by larvae. The highest oviposition values of N. californicus females were observed when females were fed O. punicae eggs. In orchards, the populations of both mites increased between February and June. The populations peaked during the warmest months of the year, with O. punicae populations peaking between June and July and N. californicus peaking in August. In addition, the population size of N. californicus was significantly and positively correlated with rainfall, air temperature, and the population densities of O. punicae. Meanwhile, O. punicae population size was positively correlated with air temperature, and the population of its predator N. californicus. [ABSTRACT FROM AUTHOR]

Analysis of potential areas for crop establishment is necessary for sustainable agricultural planning, conservation of natural ecosystems, and achievement of food security's current global objective. This study aims to model the current potential distribution of the optimal areas for Hass avocado crop in Mexico, along with the likely impact of climate change on the crops and the surrounding mountain ecosystems in the state of Michoacán, the principal producer. The maximum entropy approach was used to model the current and future potential distribution of the avocado using points of presence of avocado cultivation in Mexico and climatic variables under 10 global climate models (GCMs) and three representative concentration pathways (RCPs) from the IPCC. We estimated a current potential area for the establishment of Hass avocado crops in Mexico of 54 597km², associated with the temperate forests of the Transversal Volcanic Belt and the Sierra Madre del Sur. The loss of area for the establishment of avocado crops in Mexico was 31.1% under the most optimistic scenario, RCP 2.6, whereas 43.0% would be lost under the most pessimistic scenario, RCP 8.5. Currently, the potential distribution for the establishment of Hass avocado crops in the state of Michoacán is 22 561km². Given optimistic scenarios RCP2.6 andRCP8.5 of climate change by 2050, temperate forests mountain would represent 59 and 72.3%, respectively, of the potential area for establishing avocado in the state. Commercial pressure and climate change can lead to forest mountain ecosystem deforestation to establish new avocado crops and exacerbate water resource scarcity problems, jeopardising the entire production system's sustainability. Territorial planning should prioritise conservation policies to avoid land-use change and establish strategies to maintain avocado crop sustainability in the long-term under climate change scenarios. [ABSTRACT FROM AUTHOR]

Copyright of Revista Ciencia y Tecnología Agropecuaria is the property of Agrosavia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Chapingo Serie Horticultura is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Colletotrichum species cause anthracnose disease in tropical and subtropical fruit crops worldwide. Mexico is the main producer and exporter of avocado (Persea americana) globally and has yearly outbreaks of anthracnose on this crop. However, which specific Colletotrichum spp. cause these outbreaks in avocado‐producing regions remain uncertain; thus, the objective of the present study was to identify the species responsible. A survey performed in six production regions of Mexico yielded 232 isolates, from which a subset of 104 strains was selected based on morphological characteristics and origin. This subset was sequenced and haplotypes were analysed in the gapdh partial gene. Finally, 31 strains were identified through multilocus phylogenetic analyses using the sequences of the internal transcribed spacer region and six loci. This study revealed the presence of two species previously reported in Mexico (C. karsti and C. godetiae), three novel records in Mexico (C. siamense, C. fioriniae, and C. cigarro), four novel records on avocado (C. chrysophilum, C. jiangxiense, C. tropicale, and C. nymphaeae), and two novel lineages (Colletotrichum sp. 1 and Colletotrichum sp. 2). C. siamense was the most prevalent, while the species reported for the first time on avocado, including the novel lineages, were the least prevalent. C. karsti was the most widespread (four regions), followed by C. siamense, C. jiangxiense, and C. chrysophilum (three regions). Pathogenicity tests showed that all species caused anthracnose on avocado fruit. These findings will be useful for improving the management of avocado anthracnose outbreaks in Mexico. [ABSTRACT FROM AUTHOR]

The present study contributes to the knowledge of the spatial distribution of anthracnose (Colletotrichum gloeosporioides) in avocado orchards in the State of Mexico. The study was carried out in the municipalities of Coatepec Harinas, Tenancingo, Donato Guerra and Temascaltepec. Geostatistical methods were used to determine the spatial distribution of anthracnose. Samples were conducted biweekly during the months of July to December 2018. By randomly selecting 200 trees per municipality, they were geographically geo-referenced using a Trimble eTrex model navigator. The spatial distribution of anthracnose in avocado cultivation showed differences in each of the municipalities evaluated, adjusting to different geostatistical models (Gaussian, spherical and exponential), which were validated by the cross-validation method. The spatial distribution of anthracnose was obtained with maps drawn up through ordinary krigeado. These maps revealed that the municipality of Tenancingo had the highest anthracnose density, compared to the municipalities of Coatepec Harinas, Temascaltepec and Donato Guerra. The spatial distribution of anthracnose in the four municipalities presented aggregation and localized sources of infection. This study concludes that geostatistical methods are an alternative to improve disease management programs such as anthracnose and help to adequately conduct control. [ABSTRACT FROM AUTHOR]

The most important agricultural activity in Michoacán, Mexico, is avocado farming, which represents revenues of $30 265 787.40 pesos per year. The crop is extensive and based on conventional agricultural practices that affect the physical, chemical and biological properties of the soil. The objective of this study was to determine the diversity of species of arbuscular mycorrhizal fungi (AMF) in avocado orchards. Soil samples were collected in avocado orchards during the rainy season (August 2016). Soil samples (three subsamples per orchard) were taken from the upper horizon to 30 cm deep. In the laboratory, the spores were isolated from dry soil samples and morphologically identified. 15 morphic species AMF classified into eight genera and four families were recorded and described. 78.5% of the species belong to the families Glomeraceae and Diversisporaceae; the rest to Claroideoglomeraceae and Acaulosporaceae; the species Sclerocystis sinuosa, S. rubiformis, Funneliformis geosporum, F. mosseae, Acaulospora scrobiculata, Diversispora spurca and Entrophospora infrequens, previously reported in avocado cultures, were identified, while Glomus citrícola, G. macrocarpum, Septoglomus constrictum and Claroideoglomus claroideum, were identified. report for the first time in avocado. The presence of D. aurantia and Tricispora nevadensis is recorded for the first time in Mexico. Therefore, currently there is a great diversity of AMF in avocado orchards of Uruapan that must be conserved. [ABSTRACT FROM AUTHOR]

70 Mexican race avocado trees ( Persea americana var. drymifolia ) located at different points in the municipalities of Quimixtlán, Puebla (19.254654 LN and −97.133851 LW), Zumpahuacán (18.832133 LN and −99.580109 LW) and Tenancingo in the Estado de México (18.957769 LN and −99.588872 LW) and 35 avocado trees var. ‘Hass’ from Tingambato, Michoacán (19.496635 LN and −101.858034 LW) were sampled and analyzed to detect the Avocado sunblotch viroid (ASBVd) by RT-PCR and Dot-Blot hybridization. Additionally, statistics from 1999 to 2015 of land area planted with avocado in México were analyzed considering 32 Rural Development Districts (RDD) that amount to 90% of avocado planted area and finally, the species distribution model Maxent was applied using 102 sites in 38 avocado producing municipalities amounting to 88% (149,294 ha) of avocado cultivated in México. These considered as risk indicators to the dispersion and establishment of ASBVd. The results indicated that the 70 Mexican race avocado trees from the different States were free of the ASBVd, but 14% incidence of plants infected with ASBVd was detected by RT-PCR and 8% by Dot-Blot hybridization in ‘Hass’ avocado trees from Michoacán. The dynamics of the increase of the growing area in México during the period 2000 to 2015 was heterogeneous since the maximum values occurred in 7 RDD of the states of Michoacán, Jalisco and Nayarit, and 11 municipalities showed a steady increase in the area intended for avocado cultivation. Maxent model produces better results than random predictions, for the Kappa index was greater than 0.74 and the mean of the Area Under the Curve (AUC) presented values of 0.99; additionally, the model represents the actual distribution of avocado var. ‘Hass’ and ‘Hass-Mendez’ in Mexico and corresponds to the physiographic region with the greatest diversification of the Mexican race avocado ( Persea americana var. drymifolia ). [ABSTRACT FROM AUTHOR]

Tamarixia aguacatensis Yefremova, sp. n. (Hymenoptera: Eulophidae: Tetrastichinae) is described from Mexico as a parasitoid of the avocado psyllid, Trioza aguacate Hollis & Martin (Hemiptera: Triozidae). Trioza aguacate is a serious pest of avocado, Persea americana Miller. A key to the species of Tamarixia Mercet in Mexico is given. [ABSTRACT FROM AUTHOR]

Background: Persea americana seeds are widely used in traditional Mexican medicine to treat rheumatism, asthma, infectious processes as well as diarrhea and dysentery caused by intestinal parasites. Methods: The chloroformic and ethanolic extracts of P. americana seeds were prepared by maceration and their amoebicidal, giardicidal and trichomonicidal activity was evaluated. These extracts were also tested against Mycobacterium tuberculosis H37Rv, four mono-resistant and two multidrug resistant strains of M. tuberculosis as well as five non tuberculosis mycobacterium strains by MABA assay. Results: The chloroformic and ethanolic extracts of P. americana seeds showed significant activity against E. histolytica, G. lamblia and T. vaginalis (IC50 <0.634 µg/ml). The chloroformic extract inhibited the growth of M. tuberculosis H37Rv, M. tuberculosis MDR SIN 4 isolate, three M. tuberculosis H37Rv mono-resistant reference strains and four non tuberculosis mycobacteria (M. fortuitum, M. avium, M. smegmatis and M. absessus) showing MIC values ≤50 µg/ml. Contrariwise, the ethanolic extract affected only the growth of two mono-resistant strains of M. tuberculosis H37Rv and M. smegmatis (MIC ≤50 µg/ml). Conclusions: The CHCl3 and EtOH seed extracts from P. americana showed amoebicidal and giardicidal activity. Importantly, the CHCl3 extract inhibited the growth of a MDR M. tuberculosis isolate and three out of four monoresistant reference strains of M. tuberculosis H37Rv, showing a MIC = 50 µg/ml. This extract was also active against the NTM strains, M. fortuitum, M. avium, M. smegmatis and M. abscessus, with MIC values <50 µg/ml. [ABSTRACT FROM AUTHOR]

Copyright of Revista Chapingo Serie Horticultura is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Thirty eight isolates of Phytophthora cinnamomi from five counties in Michoacan, Mexico, were genetically analyzed using amplified fragment length polymorphisms (AFLP) to determine the genetic variability and the existing relationships among the avocado isolates. The amplifications showed 296 bands. A genetic dissimilarity matrix was obtained in this trial by means of the multiple coupling coefficient and the hierarchical grouping method, also called non-weighted average method. The resulting dendogram showed two levels of association. The isolates were classified within two main groups associated with the geographical location from which they were obtained. The analysis and determination of the confidence levels demonstrated that these geographical groups are strong. [ABSTRACT FROM AUTHOR]

Michoacán and Nayarit are, respectively, the largest and second largest avocado-producing states in Mexico. The main harvest of the 'Hass' avocado in both states is concentrated during November to December, which saturates the market and reduces the price of fruit and grower income. The goal of this research was to manipulate vegetative and reproductive growth of the 'Hass' avocado with properly timed foliar-applied plant bioregulators (PBRs) to shift the date of flowering and harvest to the period before or after the main harvest. Effects of canopy sprays of gibberellic acid (GA3) or prohexadione calcium (a gibberellic acid biosynthesis inhibitor) applied at different stages of tree phenology on inflorescence development, time of anthesis, date of legal maturity for harvest of 'Hass' avocado fruit, yield, and fruit size were quantified. No PBR treatment influenced the time of anthesis. A single or double foliar application of GA3 (50 mg·L-1) ≈4 months (July) before the expected date of main harvest (November) resulted in 'Hass' avocado fruit reaching legal maturity (mesocarp dry matter 21.5% or greater) 24.8 to 28.2 d earlier than those of untreated control trees with no negative effect on yield or fruit size. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the host status in Mexico of commercially cultivated and marketed avocado, Persea americana. (Mill,), 'Hass' to Anastrepha laden (Loew), Anastrepha obliqua (Macquart), Anastrepha serpentina (Wiedemann), and Anastrepha striata (Schiner) (Diptera: Tephritidae). Experiments in Michoacán, Mexico, were carried out in six orchards located at three altitudes above sea level during two times (August-October 2001 and April-June 2002). They included choice ('Hass' avocado plus natural host) and no-choice foraging behavior tests on trees under field cages; no-choice, forced infestation trials on caged, fruit-bearing branches in the field, and with individual fruit under laboratory conditions; infestation trials using 'Hass' avocados left unprotected over 1 and 7 d on the ground of orchards; studies to ascertain depth of oviposition and determine egg hatchability; and experiments to determine susceptibility by using time elapsed since removal of fruit from tree as the experimental variable. We trapped adult Anastrepha (n = 7,936) in all orchards and dissected fruit (n = 7,695) from orchards and packing houses (n = 1,620) in search of eggs or larvae. Most (96.7%) A. ludens, A. obliqua, A. striata, and A. serpentina adults were captured in low-elevation orchards. No eggs or larvae were detected in any of the fruit from foraging behavior studies or dissected fruit from orchards or packing houses. 0f 5,200 mature, intact fruit on trees in the field forcibly exposed to no-choice female oviposition activity (five females/fruit), we only found four fruit infested by A. ludens but no adults emerged. 'Hass' avocados only became marginally susceptible to attack by A. ludens (but not A, obliqua, A. serpentina, and A. striata) 24 h after being removed from the tree. Fruit placed on the ground in orchards (n = 3,600) were occasionally infested by Neosilba batesi (Curran) (Diptera: Lonchaeidae), a decomposes, but not Anastrepha spp. ... [ABSTRACT FROM AUTHOR]

Avocado is a woody perennial fruit crop originating in Central America and Mexico domesticated and cultivated in the Americas since pre-Columbian times, currently cultivated in subtropical, tropical, and Mediterranean climates worldwide, with increasing importance in international trade. Avocado shows an exuberant flower production that, however, results in a very low fruit set reflected in a massive abscission of flowers and fruitlets. Several factors are involved in this behavior, and, in this work, we have focused on pollination limitation. The results obtained show that pollen deposition takes place at the female and male stages during the avocado flowering season and that the percentage of flowers with pollen on the stigma varies along the flowering season, probably due to changes in temperature that affect not only the floral behavior but also pollinator activity. However, no embryo or endosperm development took place when pollination occurred during the male flowering phase. Thus, the low number of pollen grains landing on the stigmas of female stage flowers observed under natural pollination conditions might not be enough to ensure a good yield. The production of an excess of flowers and subsequent flower drop of most of the flowers provides the opportunity of a selective fruitlet drop depending on the genotype of the embryo since fruits derived from outcrossing showed higher chances of reaching maturity. Moreover, an important competition for resources occurs among developing fruits and new vegetative growth, conferring importance to the time of flower fertilization for effective fruit set. [ABSTRACT FROM AUTHOR]