Ineffectiveness of pruning to control citrus huanglongbing caused by Candidatus Liberibacter americanus

The huanglongbing (HLB) disease of citrus trees, caused by Candidatus Liberibacter asiaticus and Ca. Liberibacter americanus, was first reported in Brazil in March, 2004. The presence of the disease has caused serious concerns among growers. Pruning experiments were conducted to determine if removal of symptomatic branches or the entire canopy (decapitation) would eliminate infected tissues and save HLB-affected trees. Pruning was done in five blocks on a total of 592 3- to 16 year-old 'Valencia', 'Hamlin' or 'Pera' sweet orange trees showing no symptoms or with two levels of symptom severity. Ten decapitated trees per block were caged and all trees were treated with insecticides to control the psyllid vector, Diaphorina citri. Mottled leaves reappeared on most symptomatic (69.2%) as well on some asymptomatic (7.6%) pruned trees, regardless of age, variety, and pruning procedure. Presence of the pathogen (Ca. Liberibacter americanus) in all symptomatic trees was confirmed by PCR. In general, the greater the symptom severity before pruning the lower the percentage of trees that remained asymptomatic after pruning.

Modelling fungus dispersal scenarios using cellular automata

This study focused on representing spatio-temporal patterns of fungal dispersal using cellular automata. Square lattices were used, with each site representing a host for a hypothetical fungus population. Four possible host states were allowed: resistant, permissive, latent or infectious. In this model, the probability of infection for each of the healthy states (permissive or resistant) in a time step was determined as a function of the host's susceptibility, seasonality, and the number of infectious sites and the distance between them. It was also assumed that infected sites become infectious after a pre-specified latency period, and that recovery is not possible. Several scenarios were simulated to understand the contribution of the model's parameters and the spatial structure on the dynamic behaviour of the modelling system. The model showed good capability for representing the spatio-temporal pattern of fungus dispersal over planar surfaces. With a specific problem in mind, the model can be easily modified and used to describe field behaviour, which can contribute to the conservation and development of management strategies for both natural and agricultural systems. © 2012 Elsevier B.V.

Uma abordagem probabilística do número de reprodução básica em modelos epidemiológicos com aplicação na ferrugem do eucalipto

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Impacto do aumento da concentração de CO2 do ar sobre a brusone do arroz

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Classificação de fungicidas de acordo com o mecanismo de ação proposto pelo FRAC

Pós-graduação em Agronomia (Proteção de Plantas) - FCA

Therapeutic interventions to reduce the risk of progression from prediabetes to type 2 diabetes mellitus

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Mapeamento de áreas de risco para ocorrência da ferrugem do eucalipto no Espírito Santo e extremo sul da Bahia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Multiplicação de Diaphorina citri e de Candidatus Liberibacter asiaticus em híbridos de citros indicados como porta-enxerto

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Oral changes in individuals undergoing hematopoietic stem cell transplantation

INTRODUCTION: Patients undergoing hematopoietic stem cell transplantation receive high doses of chemotherapy and radiotherapy, which cause severe immunosuppression. OBJECTIVE: To report an oral disease management protocol before and after hematopoietic stem cell transplantation. METHODS: A prospective study was carried out with 65 patients aged > 18 years, with hematological diseases, who were allocated into two groups: A (allogeneic transplant, 34 patients); B (autologous transplant, 31 patients). A total of three dental status assessments were performed: in the pre-transplantation period (moment 1), one week after stem cell infusion (moment 2), and 100 days after transplantation (moment 3). In each moment, oral changes were assigned scores and classified as mild, moderate, and severe risks. RESULTS: The most frequent pathological conditions were gingivitis, pericoronitis in the third molar region, and ulcers at the third moment assessments. However, at moments 2 and 3, the most common disease was mucositis associated with toxicity from the drugs used in the immunosuppression. CONCLUSION: Mucositis accounted for the increased score and potential risk of clinical complications. Gingivitis, ulcers, and pericoronitis were other changes identified as potential risk factors for clinical complications.

Reaction and colonization of common bean genotypes by Curtobacterium flaccumfaciens pv. Flaccumfaciens

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Potential use of bioagents in the control of postharvest rot in melon

Rot caused by Fusarium pallidoroseum has had a severely negative impact on the export of melons from Brazil. Uncertainty regarding the health of the fruit due to the quiescent infection of the pathogen has led producers to use fungicides in the postharvest treatment of the fruit, thereby causing contamination and risking the health of consumers. Consequently, there is a demand for clean and safe natural technologies for the postharvest treatment of melons, including biological control. The present study aimed at evaluating bioagents for use in controlling Fusarium rot in 'Galia'melon. The following bioagents were evaluated: two isolates of Bacillus subtilis, B. licheniformis and a mixture of B. subtilis and B. licheniformis, as well as the yeasts Sporidiobolus pararoseus, Pichia spp., Pichia membranifaciens, P. guilliermondii, Sporobolomyces roseus, Debaryomyces hansenii and Rhodotorula mucilagenosa. Treatment with imazalil and water were used as controls. Two experiments were conducted in a completely randomised design with 10 replicates per treatment with four fruit per replicate; the disease incidence was evaluated in the first experiment, and the disease severity was evaluated in the second. Similarity analysis of the temporal evolution profiles of rot incidence caused by F. pallidoroseum allowed the evaluated treatments to be clustered into four groups. In the first experiment, the yeasts P. membranifaciens and D. hansenii produced results similar to that of the fungicide imazalil. The second experiment highlighted the yeasts P. guilliermondii and R. mucilaginosa. Electron microscopy studies confirmed that once applied to the fruit, the yeasts colonised the skin and damaged the pathogen mycelium; the action of the yeasts affected the mycelium of F. pallidoroseum, which had infected wounds on the fruit's surface. Bacillus spp. did not provide good disease control. These results demonstrated that yeasts have the potential to control postharvest rot caused by F. pallidoroseum in 'Galia'melon.

Curtobacterium flaccumfaciens PV. flaccumfaciens: aspectos epidemiológicos e variabilidade genética

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Métodos de aplicação e de avaliação do residual de fungicidas no controle de mofo-branco em soja e feijão

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeitos de produtos alternativos no controle de doenças na videira

Pós-graduação em Agronomia - FEIS

Gibberellic acid, ozone and 1-methylcyclopropene on the gray mold control in avant garde rose

Gray mold caused by Botrytis cinerea is considered the major disease of greenhouse grown flowers. The goal of this study was to evaluate the effects of gibberellic acid (GA3), ozone, and 1-MCP, applied on postharvest, on the gray mold control in 'Avant Garde' rose. Rose flowers were artificially inoculated with B. cinerea (104 conidia ml-1) and non-inoculated. After treatments, roses were stored under room conditions (20±2°C/80±5% RH) and checked for gray mold incidence and severity. Spraying of GA3 at 25, 50, and 75 mg L-1 on non-inoculated roses reduced the area under the disease progress curve (AUDPC) of gray mold incidence in 41, 40 and 54%, respectively. Continuous application of ozone at 2.7 ppm reduced 14-folds B. cinerea sporulation. On the other hand, 1-MCP did not control gray mould in rose. These results showed that GA3 sprays and ozone contribute to postharvest control of gray mold in cut rose and can be utilized on integrated disease management.