Avocado Crops Research Articles

Implications of the foliar phytochemical diversity of the avocado crop Persea americana cv. Hass in its susceptibility to pests and pathogens.

Phytochemical diversity (PD) can be considered as a defensive trait; it can operate through single plant secondary metabolites or usually as complex mixtures of them. We tested the more diversity-better defense hypothesis correlating the leaf plant secondary metabolites (PSMs) with the incidence of plant enemies on Hass avocado trees. We expected a negative correlation between the occurrence of plant enemies and PD metrics. Also, as intraspecific PSMs polymorphisms in plant populations are common, we studied the incidence of plant enemies on Hass avocado trees representing chemical variants (chemotypes). We expected a differential incidence of plant enemies among trees grouped by their mono and sesquiterpene + phenylpropanoid chemotypes. We analyzed foliar hexane extracts from 236 trees in 17 orchards by gas chromatography and for the incidence of red mite, thrips, whitefly, avocado branch borer, fruit rot, scab, and peduncle collar blight. The predicted negative correlation between the plant enemies’ incidence and the phytochemical metrics did not occur. To determine the relationship between enemy incidence and chemotypes we grouped the trees by cluster analysis using a matrix of PSMs in each tree. Most trees were grouped under four out of 23 chemotypes. Branch borers attacked trees of low-frequency chemotypes more frequently than trees with common chemotypes. The incidence of five plant enemies was different among the predominant chemotypes. The hypothesis of more diversity-better defense was not supported by the correlations between the phytochemical diversity and the incidence of pests and pathogens in Hass avocado orchards. Based on our results, we hypothesize that phytochemical diversity function as a defensive trait relies more on differentiation among individuals in a population than on the sole increase of chemical diversity. Also, the differential incidence of pests and pathogens on trees classified by their foliar chemotypes implies that these susceptibility or resistance markers represent potential useful tools for Hass avocado orchard pest management.

Avocado cv. Hass Needs Water Irrigation in Tropical Precipitation Regime: Evidence from Colombia

The primary natural source of water for the Hass avocado crop in the tropics is precipitation. However, this is insufficient to provide most crops’ water requirements due to the spatial and temporal variability. This study aims to demonstrate that Hass avocado requires irrigation in Colombia, and this is done by analyzing the dynamics of local precipitation regimes and the influence of Intertropical Convergence Zone phenomena (ITCZ) on the irrigation requirement (IR). This study was carried out in Colombia’s current and potential Hass avocado production zones (PPA) by computing and mapping the monthly IR, and classifying months found to be in deficit and excess. The influence of ITCZ on IR by performing a metric relevance analysis on weights of optimized Artificial Neural Networks was computed. The water deficit map illustrates a 99.8% of PPA requires water irrigation at least one month a year. The movement of ITCZ toward latitudes far to those where PPA is located between May to September decreases precipitation and consequently increases the IR area of Hass avocado. Water deficit visualization maps could become a novel and powerful tool for Colombian farmers when scheduling irrigation in those months and periods identified in these maps.

Edaphic factors associated with the development of avocado wilt complex and implementation of a GIS tool for risk visualization

Avocado wilt complex (AWC) is an important disease and disorder of the avocado crop. It is associated with different causal agents that induce similar disease symptoms of expression, with Phytophthora cinnamomi, Verticillium sp., and abiotic hypoxia-anoxia being the most important ones under tropical conditions. The objectives of this work were to identify the edaphic variables associated with AWC foci and develop a GIS tool for the prevention of this disease. Microbiological, topographic, physical and chemical soil properties were performed, and AWC incidence and severity were estimated in plots planted with avocado. The effect of each of the soil properties on AWC was determined using a generalized additive model. Additionally, three categories of crop management were proposed and a GIS tool was designed to determine the risk of AWC presence. Diseased plants with AWC were more frequently found (P<0.001) in flatter areas. Sulfur content in the soil (P<0.001, -0.09), infiltration (P<0.001, -1.7), hydraulic conductivity (P<0.001, -0.7), microbial diversity (P<0.001, -0.85), fungi (P<0.001, -9.58) and bacteria (P<0.001, -3.51) populations in the soil were negatively correlated with AWC development. On the other hand, copper (P<0.001, +0.65), high clay content in soil (P<0.001, +9.91), and moisture retention capacity (P<0.001, +3.29) were positively correlated with AWC development. The obtained results may be used as technical parameters for the selection of the most suitable areas for the establishment of avocado crops based on the elimination of areas that may favor AWC and that can be easily visualized under a GIS tool.

Honey-Guacamole: Assessment of pollination environmental service in avocado production in Michoacan, Mexico

The effects of the pollination service provided by the natural areas adjacent to avocado crop areas in Michoacan, Mexico, were estimated. The effect is estimated by measuring the change in avocado crop productivity as the abundance of pollinators coming from neighboring natural areas changes. Pollinators’ abundance is approximated through an index estimated with the InVEST system whose parameters were adapted for the region under study. The change in productivity is extended to an economic value to provide an economic estimate of the environmental service. The results show that, in an area where the abundance of domesticated and wild pollinators is close to the mean, the harvested volume of avocado is 28% (+/- 23%) greater. Moreover, they show that this effect is only present when both wild and domesticated pollinators are available. Finally, some model limitations and public policy implications are provided.

Report of Astaena pygidialis Kirsch (Coleoptera: Scarabaeidae), the Main Chafer Beetle Causing Damage to Avocado Fruit and Young Leaves in Antioquia Department, Colombia

Scarab beetles (Coleoptera: Scarabaeidae) are one of the most limiting pests of avocado in Antioquia Department, Colombia. The establishment of management strategies to control these beetles has been difficult because the species causing damage to avocado fruit and young leaves have not been identified. Selected commercial avocado fields were surveyed at different times of d for scarab beetle adults affecting small fruit and young leaves, as well as other plant structures such as flowers, tender buds, stems, and mature leaves. Additionally, ultraviolet light traps were placed at each field to quantify the species captured. After direct scouting of avocado trees, the only scarab beetle species detected causing damage to fruit and young leaves at all sampling sites was Astaena pygidialis Kirsch (Coleoptera: Melolonthinae). Adults were observed chewing the green skin of small fruit causing striations on the fruit and skeletonization of young leaves by chewing the leaf tissue between veins on the upper surface. Other species observed include Anomala cincta Say (Coleoptera: Rutelinae), Charioderma xylina Blanchard, and Strigoderma sp. (all Coleoptera: Rutelinae) associated with flowers, Isonychus sp. (Coleoptera: Melolonthinae) with flower buds, Cyclocephala fulgurata Burmeister (Coleoptera: Dynastinae) with tender buds, stems and flowers, and Astaena valida Burmeister and Plectris pavida (Burmeister) (both Coleoptera: Melolonthinae) with mature leaves. The species detected through scouting also were captured with light traps. The dominant species captured with light traps was Phyllophaga obsoleta (Blanchard) (Coleoptera: Melolonthinae), which was not observed causing damage to avocado fruit or young leaves. Correct identification of the species is the key to establish adequate sampling and management strategies for these scarab beetles in avocado crops.

Abundance and community composition of flower visiting insects of avocado (Persea americana Mill) in the East African region

Pollination of avocado flowers is essential for fruit production and is facilitated by various insect taxa. Currently, there is limited information available on the community structure of the pollinators of avocado crops in East Africa. We duly present the distinct groups of insects visiting avocado flowers across two most important avocado producing countries in the East African region. Insects were swept from avocado flowers along transects and sorted by morphological features that classified them into orders, families, and genera. Five common orders were identified, namely: Coleoptera, Diptera, Heteroptera, Hymenoptera, and Lepidoptera. The relative abundance of Hymenoptera and Diptera were highest (49% and 22% respectively) hence we further identified them to the families and genera taxonomic groups. Three Dipteran families were found (Calliphoridae, Muscidae, and Syrphidae) from which we recognized five genera: Chrysomya, Spilogona, Eristalinus, Phytomia and Syritta. Hymenoptera on the other hand were placed into two general groups; bees and wasps. For bees, family Apidae was represented by Apis, Ceratina, Meliponula, and Xylocopa whereas seven diverse wasp families (Braconidae, Philanthidae, Vespidae, Ichneumonidae, Eumeninae, Thynnidae and Pompilidae) were also noted. The occurrence of Coleoptera and Lepidoptera varied across the three orchards while the rest of the orders remained unaffected. We further recorded the insect’s potential pollinator functions and concluded that the main pollinators of avocado flowers in the region are members of Syrphidae and Apidae families. This information serves as a foundation for avocado pollination studies in the East African region that are important for improving pollination services and insect pollinators’ conservation.

Combustion of avocado crop residues: Effect of crop variety and nature of nutrients

The thermal behaviour of avocado crop residues was studied. The seeds and the pruning remains from Hass and Bacon varieties were analysed to know their fuel properties. The influence of the fertiliser nature was also studied thorough the application of cow manure and inorganic products. Thermogravimetric analysis (TGA) was carried out under 10, 20 and 40 °C/min heating rates. Kinetics was also estimated according to the Friedman, Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods. Results indicated the good fuel performance of the samples. Higher heating values (HHV) were higher for pruning remains (19.43 MJ/kg) when compared to seeds (18.74 MJ/kg). Cow manure improved the behaviour of all avocado samples regardless of the varieties. Average action energy was lower for wood (143.89–211.04 kJ/mol) than seeds (174.05–279.99 kJ/mol). Regarding TGA, this analysis showed three different mass loss associated to hemicellulose, cellulose and lignin release. TGA profiles were so different for the analysed biomass sources according to the fertiliser employed. Hence, the heating rate influenced the thermal behaviour of the samples, highlighting the fast release of the SBC and WHM for the 10 and 20 °C/min ramps respectively.

Diseases and disorders associated with different stages of crop development and factors that determine the incidence in Hass avocado crops

Hass avocado production systems in Colombia have increased to become the third largest area planted for fruit production. A number of factors that limit productivity such as diseases have become of high economic importance. The objectives of this study were to identify the causal agents associated with pathologies in Hass avocado crops in different stages of development and to determine main environmental factors associated with their incidence. This work was conducted over a period of eight years (2009-2016), during which plots and nurseries were monitored. Results showed that the most common disease of Hass avocado was avocado wilt complex (AWC) caused mainly by Phytophthora cinnamomi. In addition, it was found that pathogens such as Lasiodiplodia theobromae, Colletotrichum gloeosporioides sensu lato, and Phytophthora palmivora, can affect diverse tissues of avocado plants, appearing in different stages of crop development. Incidence of different pathologies in commercial plots were influenced by technological level, the sampling season (rainy and dry), and environmental and topographical variables such as precipitation, slope and elevation. This work presented a holistic approach for analysis of pathologies in Hass avocado crops, which were determined by the stage of crop development, environmental and topographic variability and the technological level of the productive system.

A new species of Neohydatothrips (Thysanoptera: Thripidae) from India.

With 120 described species (ThripsWiki 2020) Neohydatothrips is the most species-rich genus in the Thripidae subfamily Sericothripinae. Although widely distributed almost 70% of the species are from the New World (Lima Mound 2016), with only seven species recorded from India (Rachana Varatharajan 2017). The biology of most species in the genus remains unknown, but they apparently feed and breed on the leaves and/or flowers of various unrelated plants. A few species are economically important as plant pests as well as virus vectors, such as N. variabilis (Beach) (Zhou Tzanetakis 2013; Lima Mound 2016; Han et al. 2019). N. samayunkur (Kudo) is a pest on flowers and leaves of Tagetes spp. in many countries including India (Nakahara 1999; Bhatti et al. 2003). Even though N. gracilipes (Hood) was described originally as damaging cotton in Mexico, it is associated with weedy species of Sida in several countries including central India (Lima Mound 2016). In southern China, N. flavicingulus Mirab-balou, Tong Yang is reported as damaging leaves of Manglietia fordiana. In California, avocado crops are sometimes damaged by N. burungae (Hood) and this species is also recorded as distorting the young leaves of Passiflora in Colombia (Mound et al. 2019). N. gracilicornis (Williams) is reported as damaging Pinaceae and Betulaceae in Spain and South Italy (Marullo 2009). The purpose of this article is to describe a new species from India that was collected in the flowers of Jasminum sambac (Oleaceae) in Assam, northeastern India. A detailed structural diagnosis of this genus is provided by Masumoto and Okajima (2020).

Potential expansion of Hass avocado cultivation under climate change scenarios threatens Mexican mountain ecosystems

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 54 597 km2, 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 22 561 km2. Given optimistic scenarios RCP 2.6 and RCP 8.5 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.

Comportamiento espacial de Hemiberlesia lataniae (Signoret) en aguacate ‘Hass’ en el Estado de México

Introduction: Avocado exports have been affected by the presence of Hemiberlesia lataniae, the main damage is aesthetic and undermines fruit quality. Objective: To determine the spatial distribution of Hemiberlesia lataniae in a ‘Hass’ avocado crop in Estado de Mexico. Methodology: The experiment was developed in three avocado growing areas (Coatepec Harinas, Donato Guerra and Ixtapan del Oro). Sampling was carried out using the quadrat methodology, a total of 400 trees were sampled per zone from August 2019 to July 2020. The trees were divided into three strata (high, medium and low), and a terminal branch from each cardinal point was marked. Each tree was marked and georeferenced with a differential GPS. Results: A total of 24 samples per zone were generated, and all cases had an aggregated spatial behavior of Hemiberlesia lataniae. Semivariograms were fitted to spherical, exponential, and Gaussian models. Limitation of the study: Geostatistics is the only method that provides the exact location of the pest and the sample in density maps. Originality: The present study proposes to implement integrated management strategies to reduce ecological damage, due to indiscriminate use of insecticides, and presence of residues in fruits. Conclusions: The following study allowed us to know the spatial distribution of Hemiberlesia lataniae by means of density maps in three ‘Hass’ avocado producing areas in Estado de Mexico, where an aggregated spatial distribution was observed.

The importance of wild insects in the pollination of avocado crop grown under organic and conventional management practices in central Chile

Several recent studies have highlighted the importance of wild insects in crop pollination. In this study, we performed an exploratory evaluation of the importance of wild insects in the pollination of avocado crop grown under organic and conventional management practices in Quillota, central Chile. The diversity of floral visitors was estimated for each tree. The rate of floral visits by honeybees and wild insects correlated with the number of fruit sets. Regardless of the management practice, on average 34% of the visitors were wild insects. A greater diversity of floral visitors was registered in the organic farm. Finally, fruit set positively correlated with the rate of wild insect visits, especially under conventional management. Our preliminary results highlight the importance of wild insects in the pollination of the avocado crop.

Entoleuca sp. infected by mycoviruses as potential biocontrol agents of avocado white root rot

Rosellinia necatrix Prill. the causal agent of white root rot diseases causes major losses in avocado crops in Spain. To study the biocontrol of this disease, 31 antagonistic isolates were collected from the avocado rhizosphere and identified as Entoleuca sp. Studies were carried out in mycovirus detection, in vitro optimal growth temperature, mycelial compatibility groups of these isolates, and their inhibition of R. necatrix growth. The pathogenicity of these antagonistic isolates and their biocontrol of white root rot on avocado plants were also studied. The presence of mycoviruses was detected in all 31 Entoleuca sp. isolates studied and the optimal growth temperature for almost all the isolates (> 80%) was 25 °C. Dual culture showed different responses, with some isolates compatible and others incompatible with each other, showing inhibition halos and black lines. Twenty-five of the 31 isolates showed significant growth inhibition to a virulent R. necatrix isolate in in vitro conditions. In addition, none of the Entoleuca sp. isolates produced any symptoms on inoculated avocado plants and in 24 of them, symptoms of avocado white root rot were reduced, with significant differences among the Entoleuca sp. isolates when they were used as biocontrol agents. New virus-carrying Entoleuca sp. isolates were obtained, which are capable of controlling avocado white root rot.

Siderophore containing extract from Serratia plymuthica AED38 as an efficient strategy against avocado root rot caused by Phytophthora cinnamomi

ABSTRACT Phytophthora cinnamomi Rands. is a widely distributed pathogen in avocado crops. Root rot caused by Phytophthora cinnamomi decreases the yield and growers are to establish new productive areas in order to meet demand which in turn is causing the loss of native forests. Therefore, sustainable production of avocado is only possible by addressing yield issues and the efficient use of lands. In this work, the effectiveness of two promising antagonistic bacterial isolates associated to healthy avocado trees to protect avocado seedlings against P. cinnamomi was assessed. First, the virulence of five isolates of P. cinnamomi from different avocado growing regions in Colombia was evaluated. The most virulent isolate was used to infect five-month-old avocado seedlings. The native bacterial isolates, both identified as Serratia plymuthica, were used to produce extracts in solid medium and their inhibitory activity against P. cinnamomi was tested. One of the extracts was selected and submitted to a bioguided metabolite isolation. A siderophore molecule (serratiochelin C) was purified and fully characterised by Nuclear Magnetic Resonance. Finally, the protective capacity of one bacterial extract was assessed in vivo against the infection of Phytophthora cinnamomi on avocado along with a commercial product based on fosetyl-aluminum. The crude metabolic extract of S. plymuthica AED38 was found to be effective and nontoxic on seedlings at 60 µg.mL−1. The results were comparable with the effect of fosetyl-aluminum at 0.5 µg.mL−1. S. plymuthica extracts possess a promising potential as bioproduct for the control of P. cinnamomi.

English

Tolima is one of the largest zones in Colombia where avocado and rice are produced. The disease management programs for these crops are mainly chemical-dependent and tend to have variable results since the diagnosis of some diseases is based on unspecific symptoms. In this context, the present study aims to bring information about the phytopathogens affecting Tolima&acute;s rice and avocado crops. From foliar tissue, culm, and roots of rice plants, 18 isolates closely related to Gaeumannomyces graminis var. graminis/G. oryzae and 06 Magnaporthe oryzae were obtained. The isolation of these fungi was concordant with the crown sheath rot and rice blast symptoms observed. Also, 13 different fungi belonging to the C. acutatum and C. gloeosporioides complex were isolated from avocado fruits with symptoms of anthracnose. Interestingly, only two Phytophthora sp. isolates were purified from necrotic roots of avocado trees. However, several fungi belonging to the Cylindrocarpon/Ilyonectria genera and one strain identified as Bjerkandera adusta were isolated from these samples. Symptoms caused by these fungi are similar making it necessary to do a differential diagnosis of the actual pathogen causing avocado root necrosis. The data obtained constitute the first report of the above-mentioned phytopathogens in Tolima avocado crops and established the basis for an epidemiologic study of its distribution in Colombia. &nbsp; Key words: Rice, avocado, Gaeumannomyces, Magnaporthe, Phytophthora, Cylindrocarpon, Ilyonectria, Colletotrichum

Cartografía del aguacate en el sur del estado de México mediante tratamiento digital de imágenes sentinel-2

El cultivo de aguacate (Persea americana Mill.) es uno de los más importantes en México, entre los estados con mayor producción se encuentra el Estado de México, que es el tercer estado productor a nivel nacional. Coatepec Harinas y Donato Guerra son dos de los municipios más representativos en lo respectivo a esta actividad; sin embargo, no existe un censo que especifique la superficie del cultivo, por lo que el objetivo de esta investigación fue probar métodos de índices de vegetación, algoritmos spectral angle mapper (SAM) y spectral information divergence (SID) y la combinación de estos en las imágenes del sensor Sentinel-2 para evaluar su desempeño en la identificación de áreas plantadas con el cultivo de aguacate. Los resultados se validaron con una matriz de confusión y la comparación de los datos de referencia de entrenamiento y validación. El algoritmo SID alcanzó una precisión de 97.5% para detectar aguacate, mientras que el tratamiento SAM obtuvo una precisión de 63.1%. La combinación de SID con el índice Anthocyanin Reflectance Index 1 (ARI1), proporcionó un mejor resultado sobre la cartografía de validación regional con 85% de precisión. Otras combinaciones de índices y tratamientos dieron resultados inferiores al 50% de la precisión por lo que no se recomiendan. Esta metodología podría ser probada para la detección de otros cultivos de interés comercial, dado que Sentinel-2 muestra ser una alternativa viable para este tipo de estudios, teniendo una buena resolución espectral, además de ser de fácil acceso y manipulación.

Mitigation of the Adverse Effects of the El Niño (El Niño, La Niña) Southern Oscillation (ENSO) Phenomenon and the Most Important Diseases in Avocado cv. Hass Crops.

Areas cultivated with Hass avocado crops in Colombia have growth rapidly. One of the major limitations is the avocado wilt complex disease (AWC) caused by biotic and abiotic factors which have increased under the El Niño southern oscillation ENSO phenomenon (El Niño, La Niña). The objective of this study was to evaluate different strategies for mitigating the adverse effects associated with the ENSO phenomenon and AWC in avocado crops. We evaluated native materials, mulches, and parameters associated with the production of seedlings and planting practices in the field. The response variables tested were plant development, incidence, severity, mortality, and microbial dynamics, among others. The results indicated that native genotypes of Persea americana had different levels of adaptability to drought and flooding conditions. These genotypes also showed some degree of resistance to Phytophthora cinnamomi and Verticillium sp. infection with several degrees of rootstock-scion incompatibility with the Hass cultivar. In addition, mulch reduced the variability of soil moisture and temperature in the soil profile. Adequate selection of genotypes and new tools for planting have decreased the susceptibility to adverse effects associated with the ENSO phenomenon and the incidence and mortality caused by diseases under drought and flooding conditions. This work presents alternatives to mitigate adverse effects of climate variability in avocado crops under tropical conditions.

Integrated proposal for management of root rot caused by Phytophthora cinnamomi in avocado cv. Hass crops

Phytophthora cinnamomi is the most important pathogen in avocado crops that causes the disease named avocado root rot (PRR). This disease affects the root system and induces multiple symptoms that end with plant death and causes large economic losses. PRR management is based almost exclusively on the use of fungicides (metalaxyl and phosphites). This situation led to inefficient management practices with apparently satisfactory results only in short periods. The objective of this work was to evaluate different PRR management practices under in vitro, net house and field conditions. The initial part of the study was carried out under in vitro and net house conditions evaluating different types of ions (boron, zinc and manganese chelate), the auxin α naphthaleneacetic, fungicides (potassium phosphite, fosetyl aluminium and metalaxyl) and microorganisms associated with biological control of diseases. For field conditions, the most promising strategies were selected, which included fungicide use (rotation of metalaxyl and phosphites), organic matter in the form of residues of vegetables and mushrooms, use of foliar (manganese) and soil (calcium, magnesium, phosphorus, and silicon) ions, additions of bovine manure, beneficial microorganisms (Rizoglomus fasciculatum, Trichoderma sp., and Bacillus sp.), edaphic application of auxin and an energy source (sucrose). Results indicated that individual control methods of PRR are not sustainable over time. However, the implementation of a disease integrated management program including several strategies of control proved to be effective for PRR. At the same time that PRR was satisfactorily managed, the economic sustainability was achieved and it was possible to reduce the reliance on phosphonate applications.

Validation of black spot [(Pseudocercospora purpurea (Cooke) Deighton] management strategies in avocado crops in northern Tolima (Colombia)

Leaf spot or black spot (BS) in avocado, caused by the fungus Pseudocercospora purpurea (Cooke) Deighton, is one of the main sanitary limitations for the production of avocado, particularly for the Antillean cultivars (Lorena, Choquette, Santana, and Semil 44) in the northern region of the department of Tolima, Colombia. During 2014-2017, different experiments were carried out in the field, aiming to determine the period of higher fruit susceptibility, the effect of pruning on inoculum reduction, and chemical molecules with a high degree of control, adjusting their chronology and frequency of application. The results allow the technical, economic, and environmental implementation and validation of a chemical strategy for management of this disease. The management strategy carried out by Agrosavia reported a 10% lower incidence of BS in fruits, compared to the one carried out by producers, and a 23.75% return, due to the increase in high quality fruits. In the latter, DMI fungicides (demethylation inhibitors), even without resistance reports, and fungicides with a mixture of two active ingredients (DMI and QoI) in interspersed application and sometimes in conjunction with CuOCl during periods of higher susceptibility to BS were used, aiming to reduce the resistance induction risk in P. purpurea.

Effectiveness of the Sex Pheromone for Monitoring Stenoma catenifer (Lepidoptera: Elachistidae) in Avocado Orchards.

The sex pheromone of the avocado moth Stenoma catenifer Walsingham has potential use in the detection of S. catenifer males in the Antillean race avocado in Chiapas, Mexico, although the study of local parameters that influence its effectiveness is required. In this study, trap type, trap height, pheromone release rate and duration of pheromone activity were evaluated to determine the effectiveness of this pheromone in field conditions in the Antillean race avocado crops of the coast of Chiapas, Mexico. The results obtained indicate that the capture of moths with the traps Pherocon III (delta type) and Pherocon 1C (wing type) was higher than that with the boat-type traps. The frequency of capture of S. catenifer males was higher when the traps were placed 4 and 6m above ground level than that when they were 2m high. The septum releases 85% of the amount of pheromone during the first 4weeks, and there were no differences between the number of moth captures during the first 3weeks, only between the fourth and the first 2weeks. Our results suggest that the efficiency of the pheromone in Antillean race avocado depends on trap placement height and type as well as on the time of use of the pheromone septum.