Brazilian Citrus Research Articles

A robust method for quantifying 42 phenolic compounds by RP-HPLC/DAD: Columns performance and characterization of Brazilian Citrus peels

Reliable analytical methods are the basis for the elucidation of phenolic compounds in foods. This study aimed to optimize and validate a method for determining 42 phenolics using reverse-phase (RP) high-performance liquid chromatography (HPLC) coupled to diode-array-detector-DAD. The performance of two RP columns was evaluated. The 150x4.6 mm 3-μm column showed superior separation quality, whereas 35 of the 42 phenolics showed a separation resolution ≥1.5. The method's linearity, precision (coefficient variation< 3.09%), recovery (87.5-103.2%), specificity, limits of detection (0.04-0.25 mg/L), and quantification (0.06-0.25 mg/L) had acceptable ranges. Thirty phenolics were quantified in Citrus peels, mainly flavanones, flavanols, flavonols, and phenolic acids, highlighting the high values of hesperidin (535-35070 mg/kg) and naringin (26-36466 mg/kg). Lemon peels named 'Lisboa,' 'Thaiti,' 'Thaiti-2000', and 'Thaiti-2001' presented the main phenolics associated with antioxidant capacity. The presented method was robust for determining 42 phenolic compounds, offering a new approach for bioactive compound quantification in food matrices.

Behavior of ponkan mandarin tree canopy grafted onto rangpur lime and flying dragon rootstocks

The Rangpur lime rootstock was the basis of Brazilian citrus growing for many years. However, this rootstock has been gradually replaced due to the occurrence of Citrus Sudden Death. The Flying Dragon rootstock has stood out as one of the options for replacement as it has different characteristics, such as reducing the size of the plant. There is no information in the literature about the behavior of Flying Dragon as a rootstock for Ponkan mandarin. Therefore, the objective of this study was to evaluate the behavior of Ponkan mandarin tree canopy grafted onto Rangpur lime and Flying Dragon rootstocks concerning physiological, agronomic, and fruit quality parameters. In the experiment, productivity, soil moisture, water potential, plant height, fruit diameter, fruit length, fruit mass, fruit pH, soluble solids content, titratable acidity, and ratio were evaluated. The Flying Dragon rootstock was responsible for the decrease in average productivity in the Ponkan mandarin culture. Greater plant heights were obtained when canopies were grafted on Rangpur lime. The soluble solids content of fruits from scions grafted on Flying Dragon was higher, but the degree of uniformity of the soluble solids values obtained from the Rangpur lime tree was higher.

Citrus genotypes inoculated with Xanthomonas citri subsp. citri: a study on disease severity and plant stomatic anatomy

Brazilian citrus culture became the world's largest producer of fruit since 2012. However, in all harvests it is noted that there are reports of production losses due to the attack of pathogens, among them, we highlight the citrus canker caused by the Xanthomonas citri subsp. citri bacterium. Among the various control methodologies, studying plant resistance is the method considered most economical and efficient. Many studies claim that the variability in relation to the resistance of citrus cultivars may be related to the morphology of their structures, with stomatal density and stomata anatomy influencing the bacterium's ability to penetrate the plant. Thus, the objective of the present study was to evaluate 16 genotypes of citrus (Citrus spp.) relating the influence of the plant's morphology on the severity levels of the Xanthomonas citri subsp. citri bacterium. For this, we used to analyze the severity of the disease through detached leaves and analyze the morphology of the plant through scanning electron microscopy. From the results obtained, it was observed that both the number of stomata present in the plant and the diameter of its stomatal opening did not influence the levels of resistance to the disease. However, important information regarding the defense mechanisms of the plant against the pathogen was observed, such as the production of exudates, in addition to the classification of the Pera 436 genotype as a material with interesting characteristics of resistance to citrus canker.

Climate zoning: identifying suitable regions for the occurrence of Alternaria Brown spot in tangerine trees in Brazil.

Brazilian citrus farming has been migrating to nontraditional citrus-growing regions, which can be considered a challenge for citrus growers, as not all these areas are suitable for tangerine cultivation. Thus, the mapping of regions exhibiting favorable climatic conditions for Alternaria brown spot has become crucial in the selection of appropriate locations for the establishment of new orchards. This mapping enables the implementation of an avoidance strategy, which entails steering clear of areas where the disease is prevalent, aligning with fundamental principles of disease control. Thus, this study seeks to zone areas with high and low climatic favorability for the occurrence of Alternaria brown spot in tangerine trees in Brazil. Historical climate data series from the NASA-POWER database were used for all municipalities in Brazil. Agrometeorological variables used to determine the development of Alternaria brown spot were average monthly air temperature (Tmean) and duration of leaf wetness period (LWD). Areas were considered unsuitable climatically when Tmean was <17 °C or >33 °C, relatively suitable when Tmean was between 13 °C and 33 °C and LWD <10%, and climatically suitable when Tmean was between 13 °C and 33 °C and LWD >10%. The states of Paraná, Santa Catarina and Rio Grande do Sul showed greater thermal amplitude within months and throughout the year. The southern region of the country has harsher winters, with minimum temperatures below 15 °C, which is unfavorable for the disease incidence. The states with the greatest favorability for Alternaria brown spot were Paraná, Santa Catarina, and Rio Grande do Sul, mainly from May to September. Rio Grande do Sul was the state in this region that showed the greatest favorability, as a consequence of leaf wetness exceeding 10 h. The main tangerine-producing regions in Brazil, including the southern part of Minas Gerais, the state of São Paulo and the metropolitan region of Porto Alegre, were mostly classified as relatively favorable areas for the occurrence of Alternaria brown spot. It is recommended that when establishing new tangerine orchards, regions with lower favorability for the occurrence of Alternaria brown spot, such as the North and Central-West regions of Brazil, particularly the states of Amazonas, Pará and Mato Grosso, should be selected. © 2023 Society of Chemical Industry.

Occurrence of Tegolophus brunneus and Phyllocoptruta oleivora (Acari: Eriophyidae) on the main citrus belt of Brazil and the differential toxicity of the acaricides to these species.

Many mites of the family Eriophyidae are important pests worldwide. In citrus crops, the eriophyid Phyllocoptruta oleivora stands out for the economic losses caused. The pest's injuries cause the darkening of leaves, twigs, and fruits, making them unfit for the fresh fruit market and affecting plant productivity. Another species that causes similar symptoms was described in Brazil recently, the brown citrus rust mite, Tegolophus brunneus. Although studies have not been performed with this species, growers and technicians have attributed the rise in rust damages in Brazil to T. brunneus, affirming that this mite is more aggressive and resistant to acaricides than P. oleivora. In this study, the distribution of T. brunneus in the main Brazilian citrus belt and the differential toxicity of the acaricides sulfur and abamectin were evaluated for both species. Infested fruits were collected from different orchards in many municipalities, covering the main citrus species and cultivars grown, aiming to show the main T. brunneus hosts. It was observed that only plants of Tahiti acid lime (Citrus latifolia) were infested by T. brunneus, whereas P. oleivora infested all citrus cultivars and species evaluated (Citrus spp.). In our study, T. brunneus and P. oleivora were never observed coinfesting the same fruit/leaf or plant. The acute toxicity test of sulfur and abamectin as acaricides showed that T. brunneus has greater tolerance to abamectin than P. oleivora. However, the acute toxicity of sulfur was similar for both species. These results showed T. brunneus specificity to infest Tahiti acid lime, causing important damage to this crop, and suggest that attention should be paid to managing this mite using abamectin.

Long-term field evaluation of Pera sweet orange selections under the Brazilian humid subtropical climate

Currently, a low number of citrus varieties are commercially planted to supply the Brazilian citrus industry demand. The diversification of citrus scion and rootstock varieties is an important strategy to prevent disease outbreaks and to obtain higher off-season profits, as well as to extend fruit supply for the citrus processing industry. The aim of this study was to evaluate 16 Pera sweet orange selections (Citrus ×sinensis Osbeck) under a humid subtropical climate in the northwest region of the state of Paraná, Brazil regarding tree development, production, and disease incidence. The experimental orchard was planted in December 2012 in a randomized block design with three replications and five trees per plot. All scions were grafted on Rangpur lime rootstock (C. ×limonia Osbeck). The evaluations were performed from 2016 through 2022, and included vegetative growth, yield, fruit quality, estimated tree density and productivity for new plantings, and incidence of diseases as citrus canker, huanglongbing (HLB), and citrus tristeza virus (CTV). All data was submitted to ANOVA and means grouped by the Scott Knott’s test (p ≤ 0.05). Pera Perão was the most vigorous variety, with the heaviest and largest fruit, and was among the selections with the highest content of soluble solids (SS), titratable acidity (TA) and juice. However, this variety showed a light-yellow juice color, and one of the lowest SS·TA−1 ratio. This selection had the lowest percentage of fruits with citrus canker but was among the selections with the highest HLB incidence. The selections Ovale, Clone 9, and Clone 42 also showed higher vegetative growth and fruit length, but lower SS content, juice yield and technological indices. All other Pera selections had lower tree height and canopy volume than Ovale, Clone 9, and Clone 42, and adequate overall fruit quality. Conversely, Pera Comprida, Dibbern, Morretes, and Seleç ão 12 scored lower cumulative fruit yield. Pera Pirangi and Comprida had the highest citrus canker incidence on fruits, while Morretes, Ovo, Pirangi, Seleç ão 12, and Seleç ão 27 had the highest HLB incidence alongside Perão. Low severity level of stem pitting was observed within the evaluated selections. The scores ranged from one (absence of stem pitting) to two (sparse surface stem pitting). IAC, Olímpia, Mel, Bianchi, and IPR 159 revealed to be the most suitable for new plantings under humid subtropical edaphoclimatic conditions, as trees had small vegetative growth, high yield performance and fruit quality, in addition to showing lower incidences of citrus canker, HLB and CTV.

Acaricide resistance in predatory mites of the genus Euseius (Acari: Phytoseiidae) and predation capacity on Brevipalpus yothersi (Acari: Tenuipalpidae)

One of the main citrus diseases in Brazil is citrus leprosis, transmitted by the mite Brevipalpus yothersi Baker (Acari: Tenuipalpidae). The predatory mites Euseius citrifolius Denmark & Muma and Euseius concordis (Chant) (Acari: Phytoseiidae) are important natural enemies for the pest mite. The objective of this work was to evaluate the susceptibility of different populations of E. concordis and E. citrifolius, from citrus groves in the state of São Paulo (SP), to the acaricides abamectin, fenpropathrin and chlorfenapyr; characterize the abamectin resistance in E. citrifolius, including studies on cross-resistance and biochemical mechanisms of resistance; and evaluate the predation capacity of an abamectin resistant population of E. citrifolius on B. yothersi. Significant differences in susceptibility to acaricides were observed among populations of E. citrifolius. Resistance ratios of 15.5 and 3.1 (times) were observed for abamectin and chlorfenapyr, respectively, comparing populations of E. citrifolius collected in the municipalities of Taquaral-SP and Bofete-SP. Studies with the synergist piperonyl butoxide indicated the involvement of cytochrome P450-dependent monooxygenases in the resistance of E. citrifolius to abamectin. Populations of E. concordis and E. citrifolius collected in Taquaral-SP showed low susceptibility to fenpropathrin, with LC50 values at least 95 times higher than the recommended concentration for the control of Brevipalpus mites in citrus in Brazil. The population of E. citrifolius from Taquaral showed a high capacity for predation of B. yothersi larvae, with consumption of up to 49.4 larvae per adult female per day.

Occurrence of Multiple Glyphosate-Resistant Weeds in Brazilian Citrus Orchards

Glyphosate is the most widely used herbicide for weed control in citrus orchards in Brazil; therefore, it is likely that several species have gained resistance to this herbicide and that more than one resistant species can be found in the same orchard. The objective was to identify weeds resistant to glyphosate in citrus orchards from different regions of the São Paulo State (SP) and determine how many resistant species are present within the same orchard. Seeds of Amaranthus deflexus, A. hybridus, Bidens pilosa, Chloris elata, Conyza bonariensis, Digitaria insularis, Solanum Americanum, and Tridax procumbens, which, as reported by growers, are suspected to be resistant to glyphosate, were collected from plants that survived the last application of this herbicide (&gt;720 g of acid equivalent [ae] ha–1) in sweet orange and Tahiti acid lime orchards. Based on dose–response and shikimic acid accumulation assays, all populations of A. deflexus, A. hybridus, B. pilosa, and T. procumbens were sensitive to glyphosate. However, populations of B. pilosa from the Olimpia region (R-NS, R-PT and R-OdA) showed signs of resistance based on plant mortality rates by 50% within a population (LD50 = 355–460 g ae ha−1). All populations of C. bonariensis, C. elata, and D. insularis were resistant to glyphosate, presenting resistance ratios from 1.9 to 27.6 and low shikimate accumulation rates. Solanum americanum also showed resistance, with resistance ratios ranging from 4.3 to 25.4. Most of the citrus orchards sampled presented the occurrence of more than one species resistant to glyphosate: Nossa Senhora—one species; Olhos D’agua and Passatempo—two species; Araras—four species; and Cordeiropolis and Mogi-Mirim—up to five species. The results reported in this paper provide evidence of multiple species in citrus orchards from São Paulo that have exhibited resistance to glyphosate. This underscores the difficulties in managing glyphosate-resistant weeds which are prevalent throughout the country, such as C. bonariensis and D. insularis. The presence of these resistant species further complicates the control of susceptible species that may also develop resistance. In addition, the glyphosate resistance of S. americanum was identified for the first time.

Duration of fungicide spray program for the control of citrus black spot in sweet orange based on cultivar maturation and orchard age

Citrus black spot (CBS) damage and Phyllosticta citricarpa inoculum tend to increase in old orchards and in late-maturing cultivars of sweet orange. However, CBS control in São Paulo citrus belt is based on standard fungicide program of 180–220 days of fruit protection, regardless of cultivar and orchard age. This study aimed to investigate whether the protection period may be adjusted based on the cultivar maturation and age of orchards intended for juice processing. The efficacy of protection periods of 60, 100, 140, 180, 220 and 260 days was determined by assessing CBS incidence and severity and CBS-related fruit drop in 12 orchards over two seasons. The standard protection period, with 180 days targeted for mid-age and 220 days for old orchards, was the most cost effective for mid-season and late-maturing cultivars. These protection periods resulted in a significant reduction in CBS severity and fruit drop by up to ∼95% and ∼50%, respectively. For early-maturing cultivars, the duration of CBS spray program may be drastically reduced to 60 days for mid-age orchards and to 100 days for old orchards. These protection periods significantly reduced CBS severity and fruit drop by up to ∼92% and ∼50%, respectively. These adjustments in CBS fungicide protection period based on cultivar and orchard age may save up to US$14.3 million per season if adopted throughout the main Brazilian citrus belt. The results of this study allow citrus growers to save inputs, reduce costs, improve the operational efficiency within the farm and contribute to a more sustainable citrus industry.

Do Gridded Weather Datasets Provide High-Quality Data for Agroclimatic Research in Citrus Production in Brazil?

Agrometeorological models are great tools for predicting yields and improving decision-making. High-quality climatic data are essential for using these models. However, most developing countries have low-quality data with low frequency and spatial coverage. In this case, two main options are available: gathering more data in situ, which is expensive, or using gridded data, obtained from several sources. The main objective here was to evaluate the quality of two gridded climatic databases for filling gaps of real weather stations in the context of developing agrometeorological models. Therefore, a comparative analysis of gridded database and INMET data (precipitation and air temperature) was conducted using an agrometeorological model for sweet orange yield estimation. Both gridded databases had high determination and concordance coefficients for maximum and minimum temperatures. However, higher errors and lower confidence coefficients were observed for precipitation data due to their high dispersion. BR-DWGD indicated more accurate results and correlations in all scenarios evaluated in relation to NasaPower, pointing out that BR-DWGD may be better at filling gaps and providing inputs to simulate attainable yield in the Brazilian citrus belt. Nevertheless, due to the BR-DWGD database’s geographical and temporal limitations, NasaPower is still an alternative in some cases. Additionally, when using NasaPower, it is recommended to use a measured precipitation source to improve prediction quality.

Resistance management for mites vectoring citrus leprosis in Brazil

Citrus leprosis is the most important viral disease affecting Brazilian citrus orchards. The disease is caused by the cilevirus citrus leprosis virus C (CiLV-C) and transmitted by flat mites Brevipalpus yothersi Baker (Acari: Tenuipalpidae). Citrus leprosis can reduce yield by causing premature fruit drop, defoliation, and drying of branches of citrus trees.

Risk analysis of the spread of the quarantine pest mite Schizotetranychus hindustanicus in Brazil.

Schizotetranychus hindustanicus Hirst (Acari: Tetranychidae) known as the Hindustan citrus mite, is a quarantine pest present in Roraima, Brazil. In 1924 this pest was described in India. It was reported in 2002 in Venezuela and inRoraima in 2008. In 2010, the Hindustan citrus mite was reported in Colombia. It is possible that it will be introduced in other areas of Brazil, resulting in a threat to Brazilian citrus industry. Our objective was to determine the most suitable regions of Brazil for S. hindustanicus using a maximum entropy (Maxent) algorithm, based on native and invasive updated occurrence records from published research, field surveys and online databases. To avoid overfitting and improving transferability, we chose parameter settings of Maxent to construct and validate models by searching for the best combination of feature classes and regularization multipliers. The model obtained showed excellent performance according to all evaluation metrics used. A high potential for the establishment of S. hindustanicus was identified in large areas of Roraima, the extreme west of Amazonas, the entire north of the State of Pará, also in northeast, south, east, and north of the State of Amapá, and in a small portion northwest of the State of Maranhão (all states belonging to the northern region of Brazil). Our results provide information for policy making and quarantine measures, especially where S. hindustanicus is still absent in Brazil.

Glyphosate excessive use chronically disrupts the shikimate pathway and can affect photosynthesis and yield in citrus trees

Glyphosate excessive use is reported in Brazilian citrus orchards, whereas there is speculation about its consequences and the published studies are contradictory and inconclusive. This study aimed to describe the possible harmful effects by simulating glyphosate drift directly to the leaves of ∼4-yr-old citrus plants. As major results, glyphosate doses >360 g ae ha−1 increased the shikimate accumulation in leaves (up to 2.3-times above control), which was increased after a second glyphosate application (up to 3.5-times above control), even after a 240-d interval. Interestingly, shikimate accumulation was occasionally related to a dose-response of the herbicide at specific times; however, the doses had their accumulation peak on determined dates. These accumulations were directly correlated to reduced net photosynthesis even months after the glyphosate sprays. Quantum productivity based on electron transport through the photosystem II and apparent electron transport reductions up to 17% were also observed during the entire experiment course. Similarly, quantum productivity based on CO2 assimilation of glyphosate sprayed leaves decreased up to four times compared to the control after the second application. Glyphosate doses >360 g ae ha−1 increased stomatal conductance and transpiration as the carboxylation efficiency decreased, evidencing a carbon drainage in the Calvin-Benson cycle. These metabolic and physiological disturbances suggest possible photooxidative damage and an increase in photorespiration, which may be a mitigation strategy by the citrus plants to glyphosate effects, by the cost of reducing the citrus fruit yield (up to 57%). It is concluded that glyphosate phytotoxicity damages citrus plants over time due to chronic disturbances in the shikimate pathway and photosynthesis, even when there are no symptoms. This study is the first report to demonstrate how glyphosate damages citrus trees beyond the shikimate pathway.

Sampling approaches of the Hindustan citrus mite (Schizotetranychus hindustanicus) in Brazilian citrus orchards and climatic factors affecting its population dynamics.

The Hindustan citrus mite, Schizotetranychus hindustanicus (Acari: Tetranychidae), is an invasive pest in South America and constitutes a threat to Brazilian citriculture. This study aimed to determine the contribution of weather variables to the seasonal abundance of S. hindustanicus and the best sampling scheme (sampling variable and unit) for this mite. Populations of S. hindustanicus were monitored monthly in an orange orchard for 31 months in Roraima state, Brazil. Eggs, mobile stages, and the symptoms caused by S. hindustanicus were sampled in different combinations of canopy quadrants, vertical tree strata, and branch sections. The optimal sampling variable and sampling unit for S. hindustanicus scouting were determined according to fidelity and precision criteria. Rainfall and high air temperature were the main factors reducing S. hindustanicus populations. The most suitable variable for S. hindustanicus sampling was egg count. The optimal sampling unit was a leaf collected in the central section of branches located in the middle tree stratum. In addition, the sample should be taken from the southwest quadrant. Collectively, this study adds to the understanding of S. hindustanicus population dynamics and provides a sampling scheme for better management of this pest.

Late-Season Sweet Orange Selections Under Huanglongbing and Citrus Canker Endemic Conditions in the Brazilian Humid Subtropical Region.

The Brazilian citrus orchards are comprised by few genotypes, which increases the risk of pest and disease outbreaks. The diversification of sweet oranges (Citrus × sinensis) in orchards also generates off-season revenue and extend the fruit processing period. This study aimed to evaluate several horticultural traits of 19 late-season sweet orange selections under citrus canker and huanglongbing (HLB) endemic condition in northwestern Paraná state, Brazil, in a long-term field experiment. Tree size, yield, fruit quality for fresh fruit and industrial markets, estimates of tree density and yield, and citrus canker and huanglongbing (HLB) incidences were assessed. The experimental design was a randomized block with three replicates and five trees per unit. The orchard was drip-irrigated and arranged at tree spacing of 6.5 m × 4.5 m. All scions were graft-compatible with Rangpur lime (C. × limonia). Valencia selections had the tallest trees and largest canopies, particularly Olinda, Frost and #121 with heights and volumes greater than 4.20 m and 43 m3, respectively. Natal África do Sul and Whit’s Late Valencia trees were the most productive with cumulative yields above 640 kg per tree. Most of the selections produced fruits of excellent physicochemical quality attending the fresh fruit and industrial market requirements. All selections showed similar horticultural characteristics for the fresh market, while Natal África do Sul and Charmute de Brotas were more suitable for juice processing. Frost Valencia and Valencia Late Fla. had the highest incidence of citrus canker on fruits (>20%), whereas IPR Folha Murcha, Charmute de Brotas and some Valencia selections (Chafeei Late, Campbell 479, Campbell 294, Olinda, Mutação and Whit’s Late) exihibed low incidence (3.0–17.7%). At 9 years, Valencia Mutação trees had high HLB incidence (93%). In contrast, Natal IAC and Folha Murcha IAC showed the lowest HLB incidence (13%). Our results revealed that Natal IAC, Folha Murcha IAC, IPR Folha Murcha, Natal Murcha, Campbell 479 Valencia and Valencia Late Fla. had the best horticultural performance in addition to low HLB incidence. Together, these late-season sweet oranges are the most advantageous selections for citrus orchard diversification under citrus canker and HLB endemic conditions in humid subtropical regions.

Impact of diseases and pests on premature fruit drop in sweet orange orchards in São Paulo state citrus belt, Brazil.

Despite technical improvements in the citrus chain and leadership in orange production achieved in the past decades, premature fruit drop remains a major component of crop loss in São Paulo state citrus belt, the largest sweet orange production area in the world. The present study aimed to determine, during five consecutive seasons, the impact of the diseases and pests on premature fruit drop in the orange belt. Fruit drop due to the main diseases and pests averaged approximately 11.0%, which corresponded to approximately 63% of the annual fruit drop. The average fruit drop rate due to fruit borer and fruit flies combined was 4.0%, Huanglongbing (HLB) 3.3%, black spot 2.6%, leprosis 1.0% and citrus canker 0.3%. The average amount of fruit drop (million 40.8kg boxes) and value of crop losses (million US$ dollars), in five seasons, were 12.7 and 66.2 for fruit borer/fruit flies, 11.0 and 57.9 for HLB, 8.1 and 42.2 for black spot, 3.1 and 15.6 for leprosis, and 0.9 and 4.9 for citrus canker, respectively. Fruit borer and fruit flies (combined), HLB, black spot, leprosis and citrus canker are, in this order, the main diseases and pests in the orange belt of São Paulo state. All of these causes significantly increased the overall fruit drop rate in the evaluated seasons. The results will contribute to the development of the Brazilian citrus industry, while showing to other citrus-growing regions the potential that diseases and pests have to jeopardize production. © 2022 Society of Chemical Industry.

Glyphosate Excessive Use Affects Citrus Growth and Yield: The Vicious (and Unsustainable) Circle in Brazilian Orchards

The excessive use of glyphosate by Brazilian citrus growers leads to a vicious and unsustainable circle: Increasing the glyphosate use and the selection pressure of resistant/tolerant weeds, as well as the phytointoxication of the crop. In addition, there is speculation on the consequences of using glyphosate and the studies are not conclusive. Therefore, this study aimed to evaluate the glyphosate management in citrus orchards by assessing its effects in a 5-year field experiment using different doses and application frequencies. Here, we determine the weed control levels, the orchard growth and fruit yield, as well as the economic viability of the treatments. Higher weed control was observed more often with the increasing frequency of glyphosate application, and occasionally with increasing doses. However, some species predominated even at high glyphosate usage, such as BIDPI (Bidens pilosa (L.)), RAPRA (Raphanus raphanistrum (L.)), and ERICA (Conyza canadensis (L.) Cronquist). Phytotoxicity symptoms were demonstrated up to the fourth year of the orchard, and onwards the plants no longer expressed them. This was a highlight, since there was a decrease over time in growth (up to 5.3 m3) and fruit yield (up to 36.3 t ha−1), with losses that reached −56% of the total income. This is the first report to demonstrate that the increase in glyphosate usage can occasionally increase weed control, but it can also decrease orchard development and its financial viability.

Liberibacter americanus - (Withdrawn) (brazilian citrus greening)

Liberibacter americanus - (Withdrawn) (brazilian citrus greening)

Price transmission between international and domestic prices in the Brazilian citrus sector

The orange juice chain is a representative sector of the Brazilian agribusiness sector and its performance warrants analysis to identify strategies to enhance its competitiveness. Analysis of asymmetry in food value chain is important because it provides valuable information on market structure and performance. We use an asymmetric threshold error correction model to examine threshold, short- and long-run asymmetries on price transmission from international to domestic prices of oranges in Brazil. We use monthly data on international frozen concentrated orange juice prices and domestic prices of oranges in Brazil for the period from January 1996 to December 2020 in the analysis. We find evidence of threshold and asymmetries in short- and long-run price transmission and asymmetric adjustment towards a long-run relationship between international and domestic orange prices in Brazil. Decreases in international prices that lead to reductions in marketing margins are passed on quickly to domestic prices, but this is not the case for increases in international prices. We discuss implications for the Brazilian citrus industry.

Fresh and pasteurized orange juice analysis by TXRF

Orange is considered the main product of the Brazilian citrus agro-industrial complex. However, in the end of 2016, the ANVISA pointed out orange as a risky product due to contamination using pesticides in its cultivation. Therefore, in this context, an analysis of the chemical elements present in fresh and pasteurized orange juices becomes extremely relevant. Thus, this work aims to quantify the elements that are present in fresh and pasteurized orange juices, using the TXRF technique. Samples of fresh orange juice of Pêra variety were acquired in a store in the city of Londrina-PR, were analysed; three samples of oranges were purchased at a store in Itápolis, São Paulo and five more samples of Pêra orange were obtained in the rural area. Samples of pesticides used in orange cultivation were quantified, and three different trademarks of pasteurized juice were analysed. In some of the samples that were collected in Itápolis-SP market, lead (Pb) element was quantified, however its concentration was within the limit established by Brazilian legislation. The aluminium (Al) element was detected in all samples of pasteurized orange juice, showing the influence of the packaging on the elemental concentration of the juice. All pesticides quantified in this work showed a significant concentration of some micro-contaminants, but when the pesticide was diluted in deionized water, those micro-contaminants could not be quantified.