Search

Objective: The objective of this investigation is to identify huanglongbing (HLB) in the field and know their control altenatives. Design/methodology/approach: Was investigated the introduction of the phytopathogen Candidatus Liberibacter, symptoms and control of HLB. The generally observed symptoms of this disease are irregular yellowing in the leaves and reversed ripening on the fruit. Results: According to various authors, an integrated control of the disease must be carried out, such as pest control, production of seedlings in certified nurseries, a suitable nutrition management and working together with educational and research institutions. Limitations on study/implications: HLB or citrus greening is the most devastating disease of citrus trees which has caused millions of dollars in losses worldwide. However, although there are several research, there is still no established cure. Findings/conclusions: Research such as that carried out by geneticist Hailing Jin at the University of California Riverside can give hope for the cure or control of this disease, however, there are limitations to this product since it is not yet commercialized. [ABSTRACT FROM AUTHOR]

Synthetic chemicals are mainly used for the control of fungal diseases in tomato, causing the phytopathogens to generate resistance to the chemical active ingredient, with a consequent risk to human health and the environment. The use of plant extracts is an option for the control of these diseases, which is why the main objective of this research was to study an alternative biocontrol strategy for the management of plant diseases caused by fungi through obtaining polyphenol extracts from mistletoe plants growing on three different tree species—mesquite (Prosopis glandulosa), cedar (Cedrus), and oak (Quercus), which contain flavones, anthocyanins, and luteolin. The overall chemical structure of the obtained plant extracts was investigated by RP-HPLC-ESI-MS liquid chromatography. The antifungal effect of these extracts was examined. The target phytopathogenic fungi were isolated from tomato plantations located in Altamira, Tamaulipas, Mexico. The microorganisms were characterized by classical and molecular methods and identified as Alternaria alternata, Fusarium oxysporum, Fusarium sp., and Rhizoctonia solani. [ABSTRACT FROM AUTHOR]

Five samples of agricultural soil and five samples of Aloe barbadensis (P. Mill., 1768) plants with symptoms of wilt and root necrosis were collected in five localities of the state of Tamaulipas, México. The aims of this study were the morphological identification, molecular identification and in vitro evaluation of the antagonistic activity of Trichoderma spp. on Fusarium spp. Four strains of Trichoderma asperellum, one strain of Trichoderma harzianum and five strains of Fusarium oxysporum were identified by morphological and molecular methods. The evaluation of the antagonistic activity of T. harzianum isolate (TP) showed the highest inhibition in Fusarium spp. (78.80%). The evaluation of the antagonistic activity of Trichoderma spp. extracts in Fusarium spp. did not show significant differences between treatments (P ≤ 0.05), with Trichoderma growth percentages that oscillated between 81.08 and 94.38%. The native isolate of T. harzianum (TP) showed significant competitive capability against the mycelial growth of F. oxysporum. Trichoderma species are promising agents of biological control in the central area of the State Tamaulipas, Mexico. [ABSTRACT FROM AUTHOR]

Copyright of Investigación y Ciencia de la Universidad Autónoma de Aguascalientes is the property of Universidad Autonoma de Aguascalientes, Direccion General de Investigacion y Posgrado 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 Acta Agrícola & Pecuaria is the property of Universidad Autonoma del Estado de Morelos 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.)

The objective was to evaluate the effects of In vitro biocontrol of Trichoderma spp. and Bacillus spp. against Fusarium oxysporum and its in vivo effect on Solanum lycopersicum plants. The antagonistic effect in vitro of microcapsules of Trichoderma spp. and Bacillus spp. against F. oxysporum, was evaluated by inhibition and antagonism classification, in the in vivo part growth variables in plant and fruit were measured. Trichoderma asperellum showed inhibition of 84.7% and class 1 and Bacillus spp., obtained an inhibition of 83.7% with a positive classification. The canonical correspondence analysis of the fruit, the T1 treatment indicates that the variables that highlight the effect of the treatment are the firmness of the fruit and the Brix. The canonical correspondence analysis of the plant, the height presents a significant difference (P < 0.05), highlighting B. subtilis, Bacillus liquefasciens, T. harzianum and T. asperellum + Bacillus amiloliquefasciens, with 1.05 and 1.1 m compared to the control of 74 cm, also highlighted the number of total fruits in the T. harzianum treatment with an average of 22.6 fruits and root weight in B. subtilis with 37.12 g. Strains of Trichoderma spp. and Bacillus spp. successfully inhibited F. oxysporum also induced growth in the tomato plant. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the insecticidal activity of the polyphenolic compounds found in neem on S. frugiperda larvae. Three neem extracts (1:12 (m/v) with 70% ethanol, 1:12 (m/v) with 0% ethanol (only water), and 1:4 (m/v) with 0% ethanol) were employed. Subsequently, the extraction of phytochemical compounds of each extract was performed using ultrasound and microwave technologies simultaneously. The compound characterization was performed by HPLC-mass. In addition, the insecticidal evaluation of the neem extract was performed against S. frugiperda of the second-stage larvae. The extracts were applied by spraying the larvae according to each bioassay. Results showed that the extract obtained with a 1:12 (m/v) relationship and 70% ethanol was effective for the control of S. frugiperda larvae. In this extract, the predominant organic compound families were: methoxyflavones, flavonols, hydroxycoumarins, anthocyanins, methoxycinnamic acid, and alkylflavones. Phytochemical compounds obtained from neem seeds with environmentally friendly solvents and alternative technologies (ultrasound and microwave) have potent insecticidal activity against S. frugiperda larvae. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the antagonistic effect in vitro of native strains of Trichoderma asperellum, Trichoderma harzianum and two isolates of Bacillus spp. against Fusarium oxysporum and Dickeya chrysanthemi. Bacillus, isolated from soil samples of Aloe vera plantations, was morphologically identified and a modified dual culture confrontation was carried out, placing the F. oxysporum in the center of the Petri dish and Bacillus in the four cardinal points; it was arranged under a completely randomized experimental design with five repetitions, the variables registered were percentage of antagonism, inhibition halo and concentration of conidia. For Trichoderma they were confronted against F. oxysporum and D. chrysanthemi with a dual confrontation, a percentage of inhibition and antagonism classification were determined. In the confrontation of T. asperellum it obtained a percentage of inhibition of 70.5% against F. oxysporum and 41.9% against D. chrysanthemi. Regarding the inhibition halos of Bacillus (B5 and B4), they obtained 4 mm. In the conidia concentration B5 showed 1.3, B4 2.6 and the control 12.6 spores per dilution. Trichoderma and Bacillus represent a viable alternative for the control of F. oxysporum and D. chrysanthemi. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of three resistance inducers and an organic fertilizer on the titles of Candidatus Liberibacter asiaticus in Citrus sinensis (L.) Obseck cv. Valencia. Design/methodology/approach: The treatments consisted of Vacciplant Max and UPL-08, Fosetil aluminum. Likewise, BIO-FOM was applied on the periphery of the trees, with moisture for nutrients absorption. The evaluated variables were fruit weight, equatorial diameter, skin thickness, °BRIX, severity and chlorophyll, in each of the five treatments, which consisted of 20 repetitions. Results: The fruits of the trees treated with Vacciplant Max had lower skin thickness and a higher °BRIX. Also, the highest chlorophyll index was recorded with BIO-FOM fertilizer. However, none of the evaluated treatments significantly decreased the fruit harshness. Findings/conclusions: The best treatment against Huanglongbing was fosetyl aluminum which conferred greater fruit weight and diameter. [ABSTRACT FROM AUTHOR]

In Mexico, more than 100 varieties of chili (Capsicum annuum L.) are planted, it is a highly profitable crop and represents an economic activity of national importance. Currently, it faces serious phytosanitary problems due to the presence of diseases such as the wilting of chili, caused by a complex of soil pathogens. To control these diseases, toxic and residual fungicides are used, which pollute the environment and induce genetic resistance in phytopathogens. Therefore, it is necessary to look for control alternatives to solve this problem, therefore, the objective of this work was to evaluate the antagonistic effect of Trichoderma spp., against the causal agents of wilting in in vitro confrontations by means of dual cultures. The study was carried out in 2016, at the Intercultural University of the State of Puebla, Huehuetla, Puebla, Mexico. Three Trichoderma isolates from avocado tree rhizospheres, T. viride, T. harzianum and T. asperellum and three isolates of the phytopathogens P. capsici, F. oxysporum and R. solani obtained from the roots of plant plants were evaluated chili with wilting symptoms. The isolates were morphologically characterized for identification. The three antagonistic fungi presented a high percentage of inhibition, T. asperellum showed 88.25%, T. viride 87.22% and T. harzianum with 87.8%. Under the conditions of the study, T. asperellum, T. viride and T. harzianum, were efficient antagonistic microorganisms against the studied phytopathogens. It is suggested to carry out biocontrol evaluations with these isolates in the greenhouse and in the open field. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Ciencias Agrícolas is the property of Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias 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.)

Pollutants and microbiota present in the residual sludge of hydraulic fracturing were determined and characterized physicochemically. Analyses included determination of pH, electric conductivity, organic matter percentage, as well as total carbonates, inorganic nitrogen and extractable phosphorous. In addition, presence of hydrocarbons by gas chromatography, potentially toxic elements (PTEs) by atomic absorption and presence of radioactive isotopes by gamma spectrometry were determined. Moreover, fungi and bacteria present in the residual sludge were classified taxonomically to the level of genus. Medium and heavy hydrocarbon fractions were found in concentrations above the maximum limits permitted (MLP) by Mexican environmental norms. Cu, Pb, Zn, Fe and Mg, however, were below the MLP. Likewise, gamma spectrometry analysis revealed naturally occurring Ac228, Ra226 and K40. The microbiological analysis found presence of the bacteria Bacillus spp., Micrococcus sp., Diplococcus sp. and Staphylococcus sp. and the fungi Trichoderma sp., Aspergillus sp. and Penicillium spp. [ABSTRACT FROM AUTHOR]

An agricultural pest of economic importance is Spodoptera frugiperda, in Tamaulipas it is common the incidence in corn, causing foliar damage which reduces the yield of grain, a solution to this problem is to use resistant cultivars; the native germplasm of Tamaulipas co-evolved with this insect, causing resistance to it. In order to evaluate the genetic effects and resistance of maize cultivars derived from native germplasm, foliar damage caused by S. frugiperda was determined in six inbred lines and their 30 crosses, under application conditions and non-application of insecticide in the Location of Güemez, Tamaulipas (spring-summer, 2015), a dialelic analysis was carried out with Griffing's design I. For foliar damage, there were significant effects of general combinatorial aptitude (ACG), specific (ACE) and ACG interaction×insecticide treatment; there were only significant effects of ACG in the non-application treatment. The genetic expression of this germplasm determined by the mean values of the leaf damage showed a wide variation, the line LlHL5S3 had significant and negative effects of ACG and the crosses TGL2S3×LlHL5S3 the greater effects of negative ACE and less leaf damage (1.12), the crosses PWL1S3×TGL2S3, PWL1S3×LlNL4S3, TML3S3×LlNL4S3 and TML3S3×PWL6S3 excelled with leaf damage greater than 1.70; however, they had a reduction of less than 15.5% of grain yield. The variation of leaf damage depended on additive and non-additive effects and there was resistance to S. frugiperda, both due to non-preference and tolerance to leaf damage. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Ciencias Agrícolas is the property of Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias 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.)

Huanglongbing (HLB) reduces the growth and development of citrus and induces changes in secondary metabolites such as flavonoids, limonoids, and polyamines. Likewise, infected plants have a deficient absorption of nutrients such as zinc, potassium, manganese, and copper. Therefore, the objective of this study was to evaluate the influence of different rootstocks on morphology and mineral changes of Citrus limon and Citrus sinensis cv. Valencia plants inoculated with Candidatus Liberibacter asiaticus. In a greenhouse of the Experimental Station-Autonomous University of Tamaulipas, the Candidatus Liberibacter asiaticus bacteria were inoculated to Citrus limon plants (growing on Citrus volkameriana, Citrus macrophylla, and Citrus aurantium rootstocks) and Citrus sinensis cv. Valencia (growing on Citrus volkameriana and Citrus aurantium rootstocks). The experiment was established under a completely randomized design with 45 graft/rootstock repetitions. In each graft/rootstock combination, the plant height and stem diameter were determined using a tape measurer and a Vernier, respectively. In addition, the nutrient content of foliar samples was determined by an X-ray fluorescence spectrometer. In both citrus species, the C. aurantium rootstock promoted a higher concentration of the bacteria. On the other hand, the rootstock that showed the best agronomical results after inoculation with the bacteria was C. volkameriana, presenting the least variation in mineral content and conferring greater plant height (15%) and stem diameter (23%). In contrast, the presence of Ca. Liberibacter asiaticus decreased S content and increased Cu concentration in C. lemon plants. Similarly, plants infected with C. sinensis presented higher Fe content. Finally, in both species, no significant differences were observed for Mn, P, and Zn concentration. [ABSTRACT FROM AUTHOR]

Oligonychus perseae Hirst (Acari: Tetranychidae) is a major pest of avocado (Persea americana Mill.) crops, but it also causes damage to other crops and ornamental plants. Classifying and evaluating the type of spatial distribution pattern of mites on their host plants under natural conditions is ecologically and biologically important. Furthermore, to develop strategies to control the populations of pest mites in agroecosystems, it is essential to know the type of spatial pattern of distribution (uniform, random, or aggregate) of that mite on its host plant and its habitat. This study aimed to classify and assess the spatial distribution of O. perseae on A. saligna. The indices of Lloyd's mean crowding indices, Morisita, and mean-variance relationship classified the spatial pattern of dispersion of the persea mites as aggregate. Iwao's mean crowding regression and Taylor's power law confirmed these results, which indicated that O. perseae formed aggregate colonies to reproduce, avoid predators, and socialize. This is also the first report of O. perseae on A. saligna in Baja California and may help us developing sampling programs for O. perseae. Resumen Oligonychus perseae Hirst (Acari: Tetranychidae) es una plaga importante del aguacate (Persea americana Mill.), pero también causa daños a otros cultivos y plantas ornamentales. Clasificar y evaluar el tipo de patrón de distribución espacial de los ácaros en sus plantas hospederas bajo condiciones naturales es importante para desarrollar estrategias de control de sus poblaciones. La distribución espacial de O. perseae sobre A. saligna se midió con los índices de hacinamiento medio de Lloyd, Morisita y la relación mediavarianza clasificaron el patrón de dispersión espacial de los ácaros persea como agregado. La regresión de hacinamiento medio de Iwao y la ley de potencia de Taylor confirmaron estos resultados, indicando que O. perseae formó colonias agregadas para reproducirse, evitar depredadores y socializar. Este es también el primer reporte de O. perseae sobre A. saligna en Baja California, y nos puede sirvir para desarrollar programas de muestro para O. perseae. [ABSTRACT FROM AUTHOR]

Pectin is a co-product from juicing and the physico-chemical quality is important to functionality of pectin in food and pharmaceutical applications. Juice and peel from Huanglongbing (HLB) control and infected Valencia oranges were analyzed. Infected fruit had smaller diameter, lower L* and b* values and highly variable a* values. Juice from infected fruit had higher pectinmethylesterase (PME) activity of 1.5 Units/mL, which retained higher activity during 15 days of storage at 4 °C, and juice had higher cloud loss. Also, the juice obtained from infected fruit had lower °Brix (8.5–8.9), higher titratable acidity (0.71–0.88%), and lower pH (3.45–3.75). Molecular weights of 154–157 kDa and degrees of esterification of 65–67% were similar. Pectin yield from dried peel was reduced by 6% in infected fruit to 4.18 g/100 g. Total neutral sugars in pectin from control fruit were higher, 84.1 μg/mg, compared to infected fruit, 60.7 μg/mg. Glucose, galactose, and arabinose, were higher in control fruit, 25.0, 40.8, and 9.7 μg/mg, compared to 14.5, 27.4, and 8.3 μg/mg in infected fruit. Viscosity was 0.015 Pa s, in 1% pectin from control or infected fruit (p > 0.05). Juice quality, including cloud stability, was negatively impacted by HLB, however pectin functionality was minimally impacted. • Huanglongbing negatively impacts citrus juice ◦Bx, pH, titratable acidity, color. • Juice from infected fruit has higher pectinmethylesterase activity and cloud loss. • Lower yield of pectin from peel was obtained from infected fruit. • Pectin is similar in control or infected fruit. [ABSTRACT FROM AUTHOR]