10 research outputs found
Detection of coffee berry necrosis by digital image processing of landsat 8 oli satellite imagery
No full textCoffee berry necrosis is a fungal disease that, at a high level, significantly affects coffee productivity. With the advent of surface mapping satellites, it was possible to obtain information about the spectral signature of the crop on a time scale pertinent to the monitoring and detection of plant phenological changes. The objective of this paper was to define the best machine learning algorithm that is able to classify the incidence CBN as a function of Landsat 8 OLI images in different atmospheric correction methods. Landsat 8 OLI images were acquired at the dates closest to sampling anthracnose field data at three times corresponding to grain filling period and were submitted to atmospheric corrections by DOS, ATCOR, and 6SV methods. The images classified by the algorithms of machine learning, Random Forest, Multilayer Perceptron and Naive Bayes were tested 30 times in random sampling. Given the overall accuracy of each test, the algorithms were evaluated using the Friedman and Nemenyi tests to identify the statistical difference in the treatments. The obtained results indicated that the overall accuracy and the balanced accuracy index were on an average around 0.55 and 0.45, respectively, for the Naive Bayes and Multilayer Perceptron algorithms in the ATCOR atmospheric correction. According to the Friedman and Nemenyi tests, both algorithms were defined as the best classifiers. These results demonstrate that Landsat 8 OLI images were able to identify an incidence of the coffee berry necrosis by means of machine learning techniques, a fact that cannot be observed by the Pearson correlation
Detection and factors that induce Stenocarpella spp. survival in maize stubble and soil suppressiveness under tropical conditions.
No full textStenocarpella spp. causes stalk and ear rot in maize and overwinters in stubble during the off-season. Understanding the factors that guide saprophytic colonization is a crucial strategy for management. In this study, we analyzed the abiotic factors and crop management practices in relation to the inoculum of Stenocarpella spp. in stubble by qPCR. Soil samples were used for suppressiveness tests against Fusarium verticillioides, Fusarium graminearum, and Stenocarpella maydis. In the 29 fields, different levels of Stenocarpella spp. were detected. Only three fields were considered suppressive for the three pathogens. Heat maps showed that soil suppressiveness was inversely related to the pathogen concentration, and the suppressiveness of one pathogen was correlated with the suppressiveness of other pathogens. Under no-tillage systems in which rotation with soybeans was adopted, Stenocarpella spp. were detected at lower concentrations than in areas that adopted notillage systems with maize monocultures. While in tillage systems, the maize?maize monocropping increases the inoculum level of Stenocarpella spp. Crop rotation is a factor related to the observed reduction in the pathogen concentration and increases in the broad-spectrum antagonistic microbial communities. These communities guide the suppressiveness of soil-borne diseases in maize fields cultivated under tropical conditions
Potassium phosphite: a promising product in the management of diseases caused by Colletotrichum gloeosporioides in coffee plants
No full textIn recent years coffee productivity has been harmed by diseases caused by Colletotrichum gloeosporioides (Cg), for example, anthracnose, dieback and blister spot. Therefore, it has become necessary to develop alternative measures to control these diseases, since there are no fungicides registered in Brazil for their control. The aims of this work were: to evaluate the effect of potassium phosphite on the germination, fungal appressorium formation and mycelial growth of Cg and to verify this action in the reduction of disease severity of anthracnose in coffee leaves. The treatments used in an in vitro experiment were: potassium phosphite at doses of 1.25, 2.50, 5.0 and 10.0 mL.L-1, Acibenzolar-S-methyl at dose 0.1g.L-1 and Chlorothalonil fungicide at dose 2.0 g.L-1. In an in vivo experiment, beyond the treatments used in the in vitro experiment, we used a control sprayed with water without inoculation and another inoculated with Cg. Potassium phosphite at doses of 5.0 mL.L-1 and 10.0 mL.L-1 and the Chlorotalonil fungicide showed greater inhibition of conidial germination, greater inhibition of appressorium formation and further reduction of mycelial growth of the pathogen. In the in vivo experiment, Potassium phosphite at a dose of 10.0 mL.L-1 provided a greater reduction in disease severity, around 62.5%. This work demonstrated the potential of potassium phosphite in the management of diseases caused by fungi from the Colletotrichum complex in coffee plants
Potassium phosphite: a promising product in the management of diseases caused by Colletotrichum gloeosporioides in coffee plants
No full textIn recent years coffee productivity has been harmed by diseases caused by Colletotrichum gloeosporioides (Cg), for example, anthracnose, dieback and blister spot. Therefore, it has become necessary to develop alternative measures to control these diseases, since there are no fungicides registered in Brazil for their control. The aims of this work were: to evaluate the effect of potassium phosphite on the germination, fungal appressorium formation and mycelial growth of Cg and to verify this action in the reduction of disease severity of anthracnose in coffee leaves. The treatments used in an in vitro experiment were: potassium phosphite at doses of 1.25, 2.50, 5.0 and 10.0 mL.L-1, Acibenzolar-S-methyl at dose 0.1g.L-1 and Chlorothalonil fungicide at dose 2.0 g.L-1. In an in vivo experiment, beyond the treatments used in the in vitro experiment, we used a control sprayed with water without inoculation and another inoculated with Cg. Potassium phosphite at doses of 5.0 mL.L-1 and 10.0 mL.L-1 and the Chlorotalonil fungicide showed greater inhibition of conidial germination, greater inhibition of appressorium formation and further reduction of mycelial growth of the pathogen. In the in vivo experiment, Potassium phosphite at a dose of 10.0 mL.L-1 provided a greater reduction in disease severity, around 62.5%. This work demonstrated the potential of potassium phosphite in the management of diseases caused by fungi from the Colletotrichum complex in coffee plants
Temporal analysis of brown eye spot of coffee and its response to the interaction of irrigation with phosphorous levels
No full textBrown eye spot (BES—Cercospora coffeicola) is a major disease of coffee, and its occurrence is affected by water supply and nutritional balance. Little is known about the effect of phosphorous (P) on coffee fields under irrigation. Thus, this study evaluated the effect of the interaction between different water application levels and phosphorus levels (5 irrigation levels × 4 phosphorus levels) on the intensity of this disease. The area under the incidence progress curve (AUIPC) was calculated and subjected to analysis of variance. The progress curve of the average incidence of BES varied in both evaluation years. In Year 1 (November 2011 to December 2012), the incidence peaked on August 12, 2012 (22.45%), while in Year 2 (January 2013 to January 2014), the incidence reached its highest level on September 12, 2013 (16.29%). The exponential nonlinear model was adjusted for the two years. There was an interaction between irrigation and phosphorus levels on October 07, 2012. The incidence interacted significantly with the harvest dates. On the first evaluation date, an increase in phosphorus levels at shallower irrigation depths and an absence of phosphate fertilizer at higher irrigation levels caused higher incidences
Viability and susceptibility of propagation material from coffee plants to Colletotrichum sp.
No full textThis study aimed to verify the viability of propagation material from coffee plants descended from germplasm susceptible to blister spot disease as well as its susceptibility to Colletotrichum sp. relative to commercial coffee cultivars. In the first experiment, fruits were harvested from plants with and without symptoms of blister spot and sowed in trays containing a commercial sterilized substrate. The percentages of germinated seeds, viable plantlets and seedlings were evaluated. In diseased tissues, pathogens were isolated and identified though a pathogenicity test. In the second experiment, ten commercial cultivars and one cultivar originating from plants with blister spot were inoculated with the pathogens to assess the severity of anthracnose. Significant differences were not observed with respect to seed germination. However, the viability of plantlets and seedlings was reduced in the cultivar originating from plants with blister spot (Genotype Originated from Diseased Plants-GODP). These plants showed characteristic symptoms of blister spot, including necrosis in the leaves and hypocotyls, wilting and death. In the necrotic lesions, we observed characteristic sporulation of Colletotrichum sp. The cultivar most susceptible to anthracnose in cotyledonary leaves was Catuaí Vermelho (GODP), which presented the highest area under the disease progress curve (AUDPC). In conclusion, the viability of propagation material from coffee plants that had descended from plants with symptoms of blister spot (GODP) was reduced compared with plants from other genotypes, although seed germination was not affected. Moreover, GODP species are more susceptible to Anthracnose on the cotyledonary leaves relative to the other analyzed commercial cultivars. This work is the first to report on different symptoms exhibited by seedlings originating from the seeds of plants with symptoms of blister spot..</p
Formulações de cobre no controle da mancha aureolada e efeitos fitotóxicos em mudas de cafeeiro
No full textBacterial blight of coffee (Pseudomonas syringae pv. garcae) is an important coffee disease and can be controlled using antibiotics and copper-based compounds. However, copper-based compounds raise doubts among coffee growers regarding bacterial blight control efficiency and phytotoxic potential. In this work, coffee plants were sprayed with different copper molecules in order to study their efficiency on bacterial blight control and the phytotoxic potential. Seven copper formulations, cuprous oxide, copper oxychloride, copper nitrate, copper hydroxide 1 (water-dispersible granules) and 2 (concentrated suspension), copper sulfate 1 (complexed with gluconic acid) and 2 (Bordeaux mixture) were studied. The copper formulations efficiency was compared with the antibiotic kasugamycin, saline solution, and control. In controlled environmental conditions of temperature, relative humidity, and photoperiod, coffee seedlings were sprayed with the treatments and after 24 hours they were inoculated with Pseudomonas syringae pv. garcae suspension. Disease incidence and severity assessments were performed in a 2-day interval during a 16-day period. Phytotoxicity incidence and severity, mapping, and quantification of copper on the leaf tissue surface, dried leaves weight, and total copper leaf content were assessed 16 days after pathogen inoculation. Data were submitted to the Scott-Knott test (p < 0.05). Cuprous oxide and copper sulfate 2 proved most efficient to bacterial blight control, causing lower phytotoxicity effect, best covering, and persistence on leaf tissues. Copper nitrate and copper sulfate complexed with gluconic acid were more phytotoxicity compared to other copper formulations.A mancha aureolada (Pseudomonas syringae pv. garcae) é uma importante doença do cafeiro e pode ser controlada com antibióticos e compostos à base de cobre. Entretanto, compostos à base de cobre levantam dúvidas entre os cafeicultores em relação à sua eficiência de controle e ao seu potencial fitotóxico. Neste trabalho, mudas de café foram pulverizadas com diferentes moléculas de cobre a fim de estudar sua eficiência no controle da mancha aureolada e seu potencial fitotóxico. Foram utilizadas sete formulações de cobre, óxido cuproso, oxicloreto de cobre, nitrato de cobre, hidróxido de cobre 1 (grânulos dispersáveis em água) e 2 (suspensão concentrada), sulfato de cobre 1 (complexado com ácido glucônico) e 2 (mistura de bordeaux). A eficiência das formulações de cobre foi comparada com o antibiótico Kasugamicina, solução salina e controle. Em condições ambientais controladas, as mudas de café foram pulverizadas com os tratamentos e após 24 horas foram inoculadas com a suspensão de Pseudomonas syringae pv. garcae. As avaliações de incidência e severidade da doença foram realizadas em um intervalo de dois dias durante o período de 16 dias. A incidência e a severidade da fitotoxicidade, o mapeamento e a quantificação de cobre na superfície do tecido foliar, o peso das folhas secas e o teor total de cobre nas folhas foram avaliados 16 dias após a inoculação do patógeno. Os dados foram submetidos ao teste de Scott-Knott (p> 0,5). O óxido cuproso e o sulfato de cobre 2 mostraram-se mais eficientes no controle da mancha aureolada, causando menor efeito fitotóxico, melhor cobertura e persistência nos tecidos foliares. O Nitrato de cobre e o sulfato de cobre complexado com ácido glucônico apresentaram maior fitotoxicidade em comparação as outras formulações de cobre utilizadas
Spatio-temporal aspects of brown eye spot and nutrients in irrigated coffee
No full textBrown eye spot is one of the most common and important diseases of coffee in Brazil. Using geostatistics, this study evaluated the spatio-temporal aspects of the disease and how they relate to plant nutrition and soil fertility in plots irrigated by center pivot and drip irrigation. The experiments were conducted in Carmo do Rio Claro City, in southern Minas Gerais state, southeast Brazil. The sampling grid was georeferenced with 50 points in 17 ha and 52 points in 11 ha for center pivot and drip irrigation, respectively. Disease incidence was assessed at 60-day intervals from August 2012 to March 2015. Yield, plant mineral nutrition, and soil fertility were evaluated at each point annually. Weather data were obtained from climatological stations with sensors for temperature, relative humidity, wind velocity, leaf wetness duration, and total precipitation that were located inside and outside the coffee canopy in both experimental plots. Climate data were correlated with disease incidence. Disease progress curves were plotted, and semivariogram models were fitted for assessments with a high disease incidence over time. Then, the data were interpolated by ordinary kriging, and maps of disease, yield, and leaf nutrients (B, P, and K) were constructed. The average temperatures and accumulated rainfall rates were lower in periods of higher incidence, but relative humidity was high. All variables exhibited space-time variation in both plots. There was a correlation (p < 0.01) between disease incidence and leaf nutrients (B, K and P). The disease incidence in the center pivot and drip irrigation plots ranged from 0 to 23% and 0–25%, respectively, and varied over space, showing spatial dependence and the presence of disease foci with outward gradients. Areas with high intensity changed over planting years along with yield and nutrient availability
Uso de implantes zigomáticos como suporte alternativo ao all-on-4 em maxilas severamente reabsorvidas: uma revisão crítica
No full textThe rehabilitation of severely resorbed maxillae represents one of the greatest challenges in contemporary dentistry. Among the main available therapeutic alternatives, zygomatic implants and the All-on-4 technique stand out, both widely recognized for their effectiveness in cases of advanced bone atrophy. This study conducted a comparative analysis between these two approaches, highlighting their clinical indications, advantages, limitations, and prognoses. Zygomatic implants are indicated in situations of extreme bone loss, allowing anchorage in denser bone structures such as the zygomatic bone, while the All-on-4 protocol is recommended for moderate to severe resorption, using tilted implants in the anterior maxillary region. It is concluded that treatment selection should be individualized, taking into consideration the patient's anatomical conditions, associated costs, rehabilitation time, and the clinical experience of the team. Both techniques demonstrate high functional and aesthetic potential when properly indicated and planned.A reabilitação de maxilas severamente reabsorvidas configura-se como um dos maiores desafios da odontologia contemporânea. Entre as principais alternativas terapêuticas disponíveis, destacam-se os implantes zigomáticos e a técnica All-on-4, amplamente reconhecidas por sua eficácia em casos de atrofia óssea avançada. O presente estudo realizou uma análise comparativa entre essas duas abordagens, abordando suas indicações clínicas, benefícios, limitações e prognósticos. Os implantes zigomáticos são indicados em situações de atrofia extrema, permitindo a ancoragem em estruturas ósseas densas, como o osso zigomático, enquanto o protocolo All-on-4 é recomendado para casos de reabsorção moderada a severa, utilizando implantes inclinados na região anterior da maxila. Conclui-se que a escolha terapêutica deve ser individualizada, considerando as condições anatômicas do paciente, os custos envolvidos, o tempo de reabilitação e a experiência da equipe clínica. Ambas as técnicas demonstram elevado potencial funcional e estético, quando adequadamente indicadas e planejadas.La rehabilitación de maxilares severamente reabsorbidos es uno de los mayores desafíos de la odontología contemporánea. Entre las principales alternativas terapéuticas disponibles, destacan los implantes cigomáticos y la técnica All-on-4, ampliamente reconocidas por su eficacia en casos de atrofia ósea avanzada. El presente estudio realizó un análisis comparativo entre estos dos enfoques, abordando sus indicaciones clínicas, beneficios, limitaciones y pronóstico. Los implantes cigomáticos están indicados en situaciones de atrofia extrema, permitiendo el anclaje en estructuras óseas densas, como el hueso cigomático, mientras que el protocolo All-on-4 se recomienda para casos de reabsorción moderada a severa, utilizando implantes inclinados en la región anterior del maxilar. Se concluye que la elección terapéutica debe ser individualizada, considerando las condiciones anatómicas del paciente, los costos involucrados, el tiempo de rehabilitación y la experiencia del equipo clínico. Ambas técnicas demuestran un alto potencial funcional y estético, cuando se indican y planifican adecuadamente
