Pepper Crops Research Articles

Botanical formulations for the ecological management of Myzus persicae (Sulzer) and Aphis gossypii (Clover) (Hemiptera: Aphididae) and their side effects on parasitoids

The peach aphid Myzus persicae (Sulzer) and cotton aphid Aphis gossypii (Clover) (Hemiptera: Aphididae) are considered to be key pests affecting greenhouse pepper crops in Argentina as a result of their frequent occurrence and the seriousness of the damage caused by their feeding behavior and the transmission of virus. The goal of this research was to determine the efficiency of botanical products to control aphids and their side effects on parasitoids in this crop. Thus, three biorational pest control formulations derived from essential oils (EO) and plant extracts (Es) were tested, namely (i) neem EO, cinnamon EO, clove EO, oregano EO and American marigold EO (formulation 1); (ii) garlic EO and cinnamon EO (formulation 2); (iii) garlic E and rue E (formulation 3); and a soy lecithin adjuvant (lecithin), and finally, a control (water spray method). For this research, a completely randomized design was replicated 3 times. These treatments were applied directly to the foliage by means of a backpack sprayer on a weekly basis until the end of this trial. Subsequently, the total number of healthy aphids and parasitized aphids (mummies) on every leaf was recorded in the field and the laboratory through repeated measures Analysis of Variance (ANOVA) and LSD Fisher method. The results showed that formulation 1 and formulation 3 recorded a lower number of aphids and mummies compared to the other treatments. This evidence would demonstrate that these formulations repel aphids and parasitoids without the lethal effects caused by the use of broad spectrum insecticides.

Mutualistic interaction of aphids and ants in pepper, Capsicum annuum and Capsicum frutenscens (Solanaceae)

Introduction: Adequate biological identification is fundamental for establishing integrated pest management programs and identifying the trophic and mutualist relationships that can affect pest population dynamics. Aphids are the main pest of pepper Capsicum spp. (Solanaceae) crops in Southwestern Colombia, due to their role as vectors of viruses. However, the identification of aphid species is complex, limiting the investigations performed to address their interactions with other organisms. Ants and aphids present a facultative mutualistic relationship, that promotes the growth of hemipteran colonies, for this reason, the study of the ecological mutualistic association between aphids and ants is important. Objective: The main objective was to discriminate the aphid species present in commercial crops of Capsicum spp., and to identify the ant community that attends the aphid colonies and its effects on the size of the aphid colonies. Methods: Aphid species, and their ant mutualist, were collected from Capsicum annuum and Capsicum frutescens, in the Cauca valley, Southwestern Colombia. We use the DNA barcoding approach to identify aphid species, and the ants were identified by morphology‐based taxonomy. To evaluate the effect of ant care on the size and structure of aphid colonies, generalized linear models were calculated using as the response variables the total number of aphids for each colony and the proportion of nymphs. Results: The aphid species that attack pepper crops, are: Aphis gossypii and Myzus persicae (Hemiptera: Aphididae), with A. gossypii being the species that interacts with ants (19 ant species). A. gossypii colonies attended by ants had larger sizes and more nymphs per colony, than those not attended. Conclusions: Although the aphid-ant interaction is not species-specific, it is necessary to consider its role in the propagation of viral diseases in peppers and to determine how this interaction may affect regional biological control strategies.

Cinnamaldehyde inhibits the growth of Phytophthora capsici through disturbing metabolic homoeostasis.

BackgroundPhytophthora capsici Leonian (P. capsici) can cause wilting and roots rotting on pepper and other cash crops. The new fungicide cinnamaldehyde (CA) has high activity against this pathogen. However, its potential mechanism is still unknown.MethodsIn order to gain insights into the mechanism, isobaric tags for relative and absolute quantification (iTRAQ)-based quantitative proteomics was used to analyze P. capsici treated with CA. The iTRAQ results were evaluated by parallel reaction monitoring (PRM) analysis and quantitative real-time PCR (qRT-PCR) analysis. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was used to speculate the biochemical pathways that the agent may act on.ResultsThe results showed that 1502 differentially expressed proteins were identified, annotated and classified into 209 different terms (like metabolic process, cellular process, single-organism process) based on Gene Ontology (GO) functional enrichment analysis and nine different pathways (glyoxylate and dicarboxylate metabolism, fatty acid metabolism and so on) based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. This study suggested that CA disordered fatty acid metabolism, polysaccharide metabolism and leucine metabolism. Based on PRM analysis, five proteins including CAMK/CAMK1 protein kinase, glucan 1,3-beta-glucosidase, 1,3-beta-glucanosyltransferase, methylcrotonoyl-CoA carboxylase subunit alpha and isovaleryl-CoA dehydrogenase were down-regulated in P. capsici treated with CA. Furthermore, the qRT-PCR analysis showed that the gene expression level of the interested proteins was consistent with the protein expression level, except for CAMK/CAMK1 protein kinase, acetyl-CoA carboxylase and fatty acid synthase subunit alpha.ConclusionsCA destroyed the metabolic homoeostasisof P. capsici, which led to cell death. This is the first proteomic analysis of P. capsici treated with CA, which may provide an important information for exploring the mechanism of the fungicide CA against P. capsici.

Production of bio-fungicide, Trichoderma harzianum CH1 under solid-state fermentation using coffee husk

A novel and effective bio-fungicide, Trichoderma harzianum CH1 was isolated earlier and characterized for its potential to prevent infestation of pepper and ginger crops by phytopathogens like Phytophthora spp., Rhizoctonia spp., and Fusarium spp. Response surface methodology based central composite design has been applied with T. harzianum on coffee husk (lab-scale, 10 g of substrate) for optimizing the fermentation parameters for enhancing biomass production. The bioprocess parameters such as temperature, moisture content, carbon sources and ammonium sulphate were optimized. A combination of temperature (30 °C), moisture content (67.5% v/w), jaggery (2% w/v), and ammonium sulphate (2% w/v) was found optimum for maximum production. The biomass yield of 143.24 mg/gram of dried fermented substrate was 2.05 times the yield on the optimized conditions by the one-factor-at-a-time method and 3.64 times of the randomly selected conditions. Enhanced production of T. harzianum has great potential to be developed as substitute of toxic fungicides.

Novel root zone soil water retention improves production with half the water in arid sands

AbstractUrbanization and industrial competition continue to reduce both farmland and available water for food production. Therefore, a new root zone soil water retention technology was modified to transform highly permeable soils into sustainable agriculture. This long‐term drought avoidance technology was tested in two arid regions of Iraq, an arid country with declining irrigation water supplies. Manually installed U‐shaped impermeable membrane troughs were compared with manually installed thin layers of partially decomposed organic matter. Tomato (Solanum lycopersicum L.) variety Dafnis (Syngenta Sweden) and spicy pepper (Capsicum solanaceae L.) crops were spring planted at Najaf and Diyala field sites during a 2‐yr study. Soil water, temperature, and salinity were measured hourly, and compared to crop growth parameters, yields, and irrigation water use efficiency. Combined weights of four tomato and spicy pepper harvests were (P = .05) 15 and 25% greater on sand soils equipped with root zone soil water retaining technology (SWRT) membranes and required 61% less irrigation water than crops grown on locally practiced organic matter‐lined and no water retaining control soils. Spicy pepper production on SWRT membranes (P = .05) increased 30% with concomitant (P = .05) 125% greater irrigation water use efficiency (IWUE) than organic matter‐layered and control soils at Diyala.

Phenotypic, molecular and pathogenic characterization of Colletotrichum scovillei infecting Capsicum species in Rio de Janeiro, Brazil.

Anthracnose is a disease caused by Colletotrichum spp., one of the world’s most damaging sweet and chili pepper pathogens, especially in tropical and subtropical regions. In the state of Rio de Janeiro, anthracnose is one of the main obstacles for pepper crops. However, to date no research has focused on the identification and characterization of the pathogen, which is fundamental to understand the scope of the disease in the state. Thus, the correct identification of the fungal species and pathogenicity studies can provide important support for disease management and control, apart from identifying possible resistance sources for exploitation in peppers breeding programs. In this study, 11 Colletotrichum isolates were collected from peppers with typical symptoms in the Rio de Janeiro state. These isolates were characterized based on morpho-cultural characteristics and sequencing data from five regions (ITS, ACT, CAL, β-TUB and GAPDH), and the genetic variability was estimated by AFLP markers. Simultaneously, microscopy images of the colonization by the fungal species on unripe Capsicum annuum fruits were taken. Pathogenicity was tested and resistance sources were sought by means of infection of ripe and unripe fruits of 50 Capsicum baccatum accessions. The resulting data showed that all isolates belong to Colletotrichum scovillei specie. About the pathogenicity of Capsicum baccatum, differentiated, stage-specific responses, with higher resistance of ripe fruits were recorded. In addition, four possible sources of Colletotrichum scovillei resistance were detected among the tested accessions. The combination of these data can contribute to future studies on the interaction of Colletotrichum scovillei-Capsicum spp., a research line that is still unexploited in the main areas of this anthracnose fungus.

Efficiency of use of microelements in cultivation of sweet pepper during irrigation in the subzone of light chestnut soils of the Volgograd region

The results of studies of scientifically grounded use of microelements in sweet pepper crops, as an important factor in increasing the yield of vegetable crops and improving the quality of products, are presented. The purpose of our research was to substantiate the influence of the use of trace elements in the technology of sweet pepper cultivation on the growth and development of plants, the productivity and quality of the products of this culture. The experimental part of the work was carried out in 2014-2019 in the subzone of light chestnut soils of the Volgograd region. Experiments on the study of trace elements were carried out by pre-sowing seed treatment and foliar feeding of plants. Chemically pure compounds of manganese sulfate, zinc sulfate, copper sulfate, ammonium molybdate, boric acid were used as microelements. The use of trace elements in the dry-steppe zone of the Lower Volga region is an important agricultural technique that helps to accelerate growth, development, increase productivity and improve the quality of pepper fruits. It is recommended to carry out pre-sowing treatment of seeds with solutions of boric acid (0.29 g / 1 l of water), copper sulfate (0.20 g / 1 l of water) and manganese sulfate (0.16 g / 1 l of water) (the ratio of the weight of seeds to the solution 1: 2) as a way to increase seed vitality, speed up yield and improve seedling quality. In order to increase the yield and improve the quality during the budding period of peppers, it is necessary to carry out foliar dressing, first of all, with solutions of boric acid (0.29 g / 1 l of water), ammonium molybdenum (0.10 g / 1 l of water), water consumption 1 l / 10 m2. Due to its high efficiency, simplicity and availability, pre-sowing seed treatment and foliar feeding of plants with microelements will find wide application in vegetable growing.

Improved growth of bell pepper (Capsicum annuum) plants by inoculating arbuscular mycorrhizal fungi and beneficial rhizobacteria

Background: Plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) are an alternative for sustainable management of pepper crops.
 Objective: To investigate the beneficial effects of PGPR and AMF inoculation on the growth of bell pepper plants.
 Methods: Two PGPR strains were used (Pseudomonas tolaasii P61 and Bacillus pumilus R44) as well as their mixture, and an uninoculated control. In addition, bacterial treatments were combined with an AMF-consortium (Funneliformis aff. geosporum and Claroideoglomus sp.). A 4×2 factorial experiment [four levels for the bacterial inoculation and two levels of AMF-inoculation (non-AMF and AMF)] was performed with eight treatments, at greenhouse conditions for 80 days after inoculation. AMF inoculation was done at sowing and PGPR after 15 days of seedling emergence.
 Results and Conclusions: Uninoculated control showed lower growth responses than plants inoculated with PGPR and AMF, alone or in combination. Overall, inoculation of the strain P61 or the combination of R44+AMF increased plant growth. AMF improved the photochemical efficiency of PSII in comparison to either control plants or plants inoculated with R44 or with the bacterial mix. Both PGPR and AMF improved growth and vigor of bell pepper plants.

Petiole sap nitrate concentration to assess crop nitrogen status of greenhouse sweet pepper

Vegetable production requires improved nitrogen (N) management practices. Monitoring petiole sap nitrate concentration ([NO3−–N]) is a simple and cheap method to evaluate crop N status. The sensitivity of petiole sap [NO3−–N] to assess crop N status of sweet pepper was evaluated. Three sweet pepper crops were grown in different cropping seasons, each with an autumn-winter growing period. The crops commenced in 2014, 2016, and 2017. Combined fertigation and drip irrigation frequently applied (every 1–4 days) complete nutrient solution throughout each crop. The crops were grown in a greenhouse in soil. Five N treatments as N concentrations were applied throughout each crop: N1 (2.0–2.4 mmol L−1); N2 (5.3–6.2 mmol L−1); N3 (9.7–12.6 mmol L−1); N4 (13.1–16.1 mmol L−1); N5 (16.7–20.0 mmol L−1). These corresponded to very deficient, deficient, conventional, excessive and very excessive N supply. Petiole sap [NO3−–N] was determined every 1–2 weeks and related to Nitrogen Nutrition Index (NNI), which was used as an indicator of crop N status. For each of the N treatments in each crop, petiole sap [NO3−–N] was relatively constant throughout the crop. The relationship between petiole sap [NO3−–N] and NNI, for pooled data from the three pepper crops, was described by (a) the polynomial equation NNI=−1.10E−07×Sap2+0.000473×Sap+0.5514 with an R2 of 0.84, and (b) the segmented linear equations NNI=0.00034×Sap+0.572 and NNI = 1.04, with an R2 of 0.83. Sufficiency values for maximum growth of sweet pepper were obtained by (a) solving the polynomial equation for NNI = 1.0, and (b) using the intercept value of the horizontal line of the segmented linear regression. The corresponding sufficiency values for the duration of a complete crop cycle were 1441 and 1367 mg NO3−–N L−1, respectively. A sufficiency value of 1400 mg NO3−–N L−1 was rounded-off and suggested for the duration of a complete crop cycle of greenhouse-grown sweet pepper in SE Spain. The relationships between petiole sap [NO3−–N] and NNI, and the derived sufficiency values for the flowering and early fruit growth, and harvest phenological stages were similar to those determined for the entire crop. Petiole sap [NO3−–N] is a sensitive and effective method to monitor crop N status of sweet pepper.

Analytical Economic Study of The Production of Cucumber and Pepper Crops In Greenhouses (A Case Study in Giza Governorate) دراسة اقتصادية تحليلية لإنتاج محصولي الخيار والفلفل بالصوب الزراعية (دراسة حالة بمحافظة الجيزة)

استهدف البحث الوقوف على مدي التفاوت بين المستوى الفعلي ونظيرة المرتقب لإنتاج الصوب من اهم محاصيل الخضر، وما مقدار انعکاس استخدام الزراعة المحمية علي کفاءة استخدام عناصر الانتاج المستخدمة في انتاج اهم محاصيل الخضر، هذا وقد تم الاعتماد على بعض طرق التحليل الإحصائي لتحقيق أهداف البحث، کأسلوبي الانحدار الخطي البسيط والمتعدد، هذا إلى جانب استخدام الصورة اللوغاريتمية المعروفة في التطبيقات الإحصائية بدالة کوب- دوجلاس، نموذج التعديل الجزئي، هذا وقد أمکن التوصل إلى عدة نتائج أهمها ما يلى: تبين تزايد معدلات التغير أو النمو السنوية لعدد الصوب ومساحتها المنزرعة بالخضر الشتوي، الأمر الذى أدى إلى تزايد معدلات النمو السنوية لإنتاجها خلال الفترة ( 2004-2018). أوضحت نتائج البحث توقع تزايد المستوى المرتقب لإنتاج الخضر بالعروة الشتوي بالصوب الزراعية خلال الفترة (2023-2027) من حوالى 260.87 ألف طن عام 2023 إلى نحو 283.53 ألف طن عام 7202 بمتوسط سنوى قدر بحوالى 272.20 ألف طن خلال الفترة المذکورة. کما أوضحت النتائج توقع تزايد المستوى المرتقب لإنتاج محصول الخيار خلال الفترة ((2023-2027) من حوالى 140.95 ألف طن عام 2023 إلى نحو 152.16 ألف طن عام 7202 بمتوسط يقدر بحوالى 146.56 ألف طن خلال الفترة المذکورة. کما أوضحت النتائج توقع تزايد المستوى المرتقب لإنتاج محصول الفلفل خلال الفترة ((2023-2027) من حوالى 92.585 ألف طن عام 2023 إلى نحو 107.35 ألف طن عام 7202 بمتوسط يقدر بحوالى 99.96 ألف طن خلال الفترة المذکورة هذا وقدرت ربحبة الجنية المنفق بحوالي 0.82، 0.61 جنيها لمحصولي الخيار والفلفل بالصوب الزراعي على الترتيب، بينما بالأراضي المکشوفة قدرت بحوالي 0.71، 0.44 جنيها کل على الترتيب.

Conventional sampling plan for green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), in bell pepper crops

The green peach aphid Myzus persicae is one of the most important pests in bell pepper crops. Conventional sampling plans are the starting point for the generation of pest control decision-making systems. However, sampling plans have not yet been determined for this pest in bell pepper crops. Thus, the objective of this work was to determine conventional sampling plans feasible for M. persicae in bell pepper crops in the vegetative and reproductive stages. The adequate sample for the evaluation of M. persicae populations in bell pepper plants in the vegetative stage was the 5th most apical leaf. For plants in the reproductive stage, the adequate sample for the evaluation of M. persicae populations was the 3rd most apical leaf. The beating of the apical part of the plants in a white plastic tray was the best technique for sampling M. persicae in bell pepper fields. M. persicae densities adjusted to the negative binomial distribution had a common aggregation parameter (Kcommom = 0.1816). The sampling plan consisted of 158 samples per field. This sampling plan was carried out in 42 min, 57 min and 1 h: 08 min in plots of 1, 5 and 10 ha respectively. The cost of the sampling plan was US$ 1.19, US$ 1.59 and US$ 1.90 for plots of 1, 5 and 10 ha, respectively. The sampling plan developed in this study can be incorporated into integrated pest management programs, as it allows for an adequate assessment of M. persicae populations in bell pepper.

Improving Encryption Digital Watermark by Using Blue Monkey Algorithm

Watermarking enables the users to share the digital contents in public domain without any issue. In the present day, the tremendous development in the digital technologies and networks caused an increase in the threats of unauthorized copying, tampering of digital media and image theft. To face these threats, digital watermark technology can be applied. However, the current paper uses new technique with two main algorithms that are the following ones: improved honey algorithm that is used to encrypt the digital watermark and blue monkey meta-heuristic algorithm which is used to find the best location in the host image to hide the digital watermark. Furthermore, in order to check the security and the robustness of the proposed method against various common image processing attacks such as Gaussian noise, Rotation, Salt and pepper noise, Sharpen, Median filter, Average filter, compression and Cropping is computed, certain performance metrics such as Peak to Signal Noise Ratio (PSNR)and Mean Square Error (MSE) also are computed. Likewise, Normalized Correlation (NC) is used to check similarity between the original and extracted digital watermark. The results demonstrate that the proposed method is efficient, provides high security and robustness against most attacks compared to the pervious methods.

Effect of border crops and intercropping on aphid infestation and the associated viral diseases in hot pepper (Capsicum sp.)

Aphids are associated with loss in yield and quality of pepper crop due to damage they cause and the transmission of viruses in a non-persistent manner. The aim of the study was to determine the potential of border crops and intercrops in the management of aphids and the associated viruses in hot pepper production. Field experiments were carried out for two seasons in 2018/2019 at Rubona Research station, Huye District, Rwanda. Maize (Zea Mays L.), sorghum (Sorghum bicolor L.) and sunflower (Helianthus annuus) were tested as companion crops associated with hot pepper either as border crops or as intercrops. Randomized complete block design was used with four treatments and three replications per experiment. Data on aphid population, the virus disease incidence, the area under the disease progress curve (AUDPC), growth and yield of hot pepper were recorded. Diseased leaf samples were collected and analysed serologically to detect the viruses present in the experimental plots. Aphid-transmitted viruses; Cucumber mosaic virus, Potato virus Y and Pepper veinal mottle virus, and aphid species, namely Aphis gossypii and Macrosiphum euphorbiae were identified in the experimental plots. The use of maize, sorghum or sunflower as border crops or as intercrops significantly reduced (p < 0.05) the incidence of viral diseases in hot pepper compared with control at later stages of growth. At 12 weeks after transplanting (WAP), use of maize, sunflower or sorghum as border crops significantly reduced (p < 0.05) the incidence of viral diseases by 24%, 31% and 38% compared with the control in season one and by 32%, 54% and 46% in season two. Similarly, intercropping with maize, sunflower or sorghum was also effective in reducing incidence of viral diseases in hot pepper by 24%, 35% and 27% in season one, and by 39%, 39% and 32% in season two, respectively. The AUDPC differed significantly (p < 0.05) while the population of aphids did not differ (p > 0.05) among treatments for both experiments. Results revealed that maize, sorghum and sunflower can be utilized either as border crops or intercrops for the control of viral diseases in pepper production. This technology is environmentally friendly, easily adaptable and appropriate since the production of pepper is mainly done by resource-poor farmers.

Photocatalytic degradation of four insecticides and their main generated transformation products in soil and pepper crop irrigated with reclaimed agro-wastewater under natural sunlight

This work is the first-ever study of the concurrence of four insecticides (chlorantraniliprole, imidacloprid, pirimicarb and thiamethoxam) and their main transformation products (TPs) in soil and pepper crop irrigated with reclaimed and non-reclaimed water under agricultural field conditions. Field experiments were conducted using different irrigation supplies: control water (CW), wastewater polluted with phytosanitary commercial products containing the studied insecticides (WW) and reclaimed wastewater after a photocatalytic processing with TiO2/Na2S2O8 at pilot plant under sunlight (RWW). Photocatalytic treatments removed most of the insecticides and their TPs generated during the photoperiod. Neither target insecticides nor their TPs were detected in pepper samples when CW and RWW were used as irrigation source, whereas the four insecticides and two TPs were detected when WW was used. In the experiment carried out with WW, all insecticides and eight TPs were detected in soil samples. The impact of using reclaimed water on the quality of pepper crop was also assessed, showing barely any significant difference.

Study of the Wet Bulb in Stratified Soils (Sand-Covered Soil) in Intensive Greenhouse Agriculture under Drip Irrigation by Calibrating the Hydrus-3D Model

The development of the wet bulb under drip irrigation in sand-covered soils presents a different behavior compared to the one observed in homogeneous soils. Moreover, the presence of a very active crop imposes a series of variations that have not been fully characterized. The aim of this work is to present the data acquisition methodology to calibrate and validate the Hydrus-3D model in order to safely define the evolution of moisture in wet bulbs generated in stratified “sanded” soils characteristic of greenhouses with intensive pepper crop under drip irrigation. The procedure for collecting and processing moisture data in stratified soils has been defined. Soil permeability; retention curve, texture, and bulk density have been measured experimentally for each material. It has been found that the inclusion of a previous day in the simulation improves model predictions of soil moisture distribution. In soils with less gravel, a lower average stress and a more homogeneous moisture distribution were observed. It has been proved that the Hydrus-3D model can reproduce the behavior of sand covered soils under intensive greenhouse growing conditions, and it has been possible to verify that the predictions are adequate to what has been observed in the field. In view of the results, the Hydrus-3D model could be used to establish future irrigation strategies or to locate the optimal placement point of tensiometers that control irrigation in sandy soils for intensive agriculture.

The effect of strip-intercropping pepper and garlic on the control of the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae)

The two-spotted spider mite, Tetranychus urticae Koch, is an important pest of agricultural crops in Iran. In this study, intercropping pepper (P),Capsicum annuum L., with garlic (G), Allium sativum L., in the three patterns 3T:5G, 3T:8G and 3T:11G (row ratios) along with sole pepper crop were assessed on the densities of T. urticae,diversity of natural enemies and crop yield in an experimental field, based on a randomized complete block design during the two growing seasons 2017 and 2018. The densities of T. urticae eggs and mobile forms were lower in the three intercrops compared with sole pepper crop (p ≤ 0.05). The values of the Shannon diversity index (H´) and the Pielou’s evenness index (J´) for the composition of T. urticae predators were greater in the three intercrops compared with sole pepper crop. In the present study, Stethorus gilvifrons (Mulsant) and Orius niger (Wolff) were the main predators of T. urticae on pepper plants. The abundance of O. niger was higher in the three intercrops compared with sole pepper crop, but the populations of S. gilvifrons had not significant difference between intercrops and sole pepper crop (p ≤ 0.05). Moreover, the values of land equivalent ratio (LER) were greater than one in the three intercrops (LER ≥ 1.14) compared to sole crops. These results revealed that intercropping pepper with garlic could be an effective method in the integrated management of T. urticae in pepper fields.

Prevalence of Xanthomonas euvesicatoria (formally X. perforans) associated with bacterial spot severity in Capsicum annuum crops in South Central Chihuahua, Mexico.

BackgroundXanthomonas spp. causes bacterial spot disease, which reduces quality and yield of pepper crops in Mexico. Identification of phytopathogen species is necessary to implement more effective control strategies.ObjectiveThe aim of this study was to isolate and identify infecting Xanthomonas species in South Central Chihuahua pepper-producing areas.MethodsDiseased plants were collected from 30 cultivation lots and bacteria were isolated from damaged tissues. Potential causative agents were isolated, identified, and characterized by biochemical and molecular analysis. Pathogenicity tests from each isolate were then performed on 30-d-old pepper seedlings, exposing five leaves to 10 µL of 1 × 108 CFU/mL bacterial suspensions of each isolate, using sterile distilled water as a control. Disease severity was determined after 10 d by calculating leaf damage percentage. Furthermore, we evaluated the susceptibility of the highest bacterial spot severity-causing isolates (13 isolates) to copper sulphate (CuS), copper gluconate (CuG), copper oxychloride + oxytetracycline hydrochloride (Cu + Ox), gentamicin + oxytetracycline hydrochloride (Gen + Ox), and gentamicin sulphate (GenS). Copper-resistance genes (copLAB) were detected by PCR analysis among isolates.ResultsThirty-seven foliage isolates were identified as Xanthomonas euvesicatoria (14%), which were associated with bacterial spot disease in jalapeño pepper. Tested Xanthomonas isolates were resistant to Cu-based compounds, but susceptible to Cu + Ox. All isolates were susceptible to Gen + Ox and GenS. CopLAB genes were detected in all but one strain.ConclusionsX. euvesicatoria (formally X. perforans) may be considered as an emerging pathogen of bacterial spot pepper in Mexico. Among disease management strategies, alternatives to copper should be taken into consideration.

Assessment of crop risk due to climate change in Sao Tome and Principe

Sao Tome and Principe is a small insular country in the west coast of Central Africa. The small dimensions of the islands and the limited natural resources put these islands under highly vulnerable to climate change. To assess the possible future impacts and risks on their agricultural activities, the high-resolution 4-km downscaled climate change projections using Eta regional climate model are used. A crop risk index (CRI) is proposed to assess the risk of climate change on cocoa (Theobroma cacao L.), pepper (Piper nigrum L. and Piper guinesse L.), taro (Colocasia esculenta (L.) Schott), and maize (Zea mays L.). The index takes into account the vulnerability to climate conditions and the crop yield in the future, and it is classified into very-high, high, moderate, low, and very-low. The climate change projections indicate increase in the risk of taro crop, partly due to thermal stress and partly due to the susceptibility to the leaf blight crop disease in taro. The risk of production of the pepper crop is very-high, mainly due to water stress. In mountain regions, the greater risk is due to the thermal stress caused by low temperatures. The cocoa crop is at risk due to water stress, mainly in the northwestern part of the Sao Tome Island, where major local production occurs. The projection indicates increase of the area with very-high risk to maize crops due to the increase of thermal stress and susceptibility to rust. In addition, in parts of the coastal regions, the risk changed from very-low to high risk, due to the low productivity potential. In general, the risks of the four major crops of Sao Tome and Principe increase in the future climate conditions.

The influence of cropping pattern of pepper with citronella and lemongrass to the insect diversity and insect pests population

Lemongrass and Citronella contain essential oils which are repellent against insect pests. Research on the cropping pattern of pepper with lemongrass and citronella was conducted to determine the influence of two essential oil plants on the diversity and population of insect pests of pepper plants. The research was conducted at the Sukamulya Experimental Garden, from 2018 to 2020 on a 3000 m2 planting plot. The treatments of the cropping patterns tested included: 1) Climbing pepper, 2) Climbing pepper + Shrub pepper, 3) Climbing pepper + Citronella, 4) Climbing pepper + Lemongrass, 5) Climbing pepper + Shrub pepper + Citronella, 6) Climbing pepper + Shrub pepper + Lemongrass. Each treatment was repeated twice. Observation parameters were insect diversity and insect pests, the level of pest attack, and the number of plants attacked. The results obtained about 66 species of insects from 46 families and 9 orders. The insects associated with the pepper cropping pattern ecosystem were relatively evenly distributed in all treatments, except for treatment 3, where only 4 types of insect pests were found. Pests, especially Thrips sp., were distributed in all treatments, but in the combination treatment with citronella and lemongrass, the population of Thrips sp. relatively low.

Root distribution with the use of drip irrigation on layered soils at greenhouses crops

Greenhouse cultivation has proven to be an efficient solution to extra-early horticultural production, allowing the cycle of vegetable production to be closed throughout the year. This efficient solution depends on many factors, perhaps the main one being the localized irrigation system. On the other hand, the availability of water for irrigation will be one of the most limiting factors for the development of this agricultural practice. The permanent search for improving irrigation efficiency must be considered as one of the great challenges of sustainable agriculture and in the interest of environmental conservation. In this study, the distribution of the roots of the two main horticultural crops, tomato (Solanum lycopersicum L.) and peppers (Capsicum annuum L.), has been analyzed with the localized irrigation system. In addition, they have been studied for layered soils, which represent an advance in terms of resources, since they are artificial soils, where the natural soil does not allow a horticultural crop. It has been found for these stratified soils, that in pepper crop 90% of the root density is in the soil layer 0 to 9 cm. However, for tomato crops 90% of the root density is in the soil layer from 0 to 11 or 15.5 cm according to the type of soil, in other words filling almost all the added soil. The results obtained in this research allow the Hydrus 3D model for stratified soils to be calibrated. This work allows opening new perspectives in the efficient management of adding soils for new greenhouse construction and for localized irrigation of horticultural crops in general, tomato, and peppers in particular.