The antimicrobial effects of Citrus limonum and Citrus aurantium essential oils on multi-species biofilms

The aim of this study was to evaluate the effects of Citrus limonum and Citrus aurantium essential oils (EOs) compared to 0.2% chlorhexidine (CHX) and 1% sodium hypochlorite (NaOCl) on multi-species biofilms formed by Candida albicans, Enterococcus faecalis and Escherichia coli. The biofilms were grown in acrylic disks immersed in broth, inoculated with microbial suspension (106 cells/mL) and incubated at 37°C / 48 h. After the biofilms were formed, they were exposed for 5 minutes to the solutions (n = 10): C. aurantium EO, C. limonum EO, 0.2% CHX, 1% NaOCl or sterile saline solution [0.9% sodium chloride (NaCl)]. Next, the discs were placed in sterile 0.9% NaCl and sonicated to disperse the biofilms. Tenfold serial dilutions were performed and the aliquots were seeded onto selective agar and incubated at 37°C / 48 h. Next, the number of colony-forming units per milliliter was counted and analyzed statistically (Tukey test, p ≤ 0.05). C. aurantium EO and NaOCl inhibited the growth of all microorganisms in multi-species biofilms. C. limonum EO promoted a 100% reduction of C. albicans and E. coli, and 49.3% of E. faecalis. CHX was less effective against C. albicans and E. coli, yielding a reduction of 68.8% and 86.7%, respectively. However, the reduction of E. faecalis using CHX (81.7%) was greater than that obtained using C. limonum EO. Both Citrus limonum and Citrus aurantium EOs are effective in controlling multi-species biofilms; the microbial reductions achieved by EOs were not only similar to those of NaOCl, but even higher than those achieved by CHX, in some cases.

Controle de doenças fúngicas e de danos por frio em pós-colheita de lima ácida Tahiti

The Tahiti lime appears very susceptible to attack by post-harvest diseases, primarily by the fungi Penicillium and Phomopsis, and also because of its high sensitivity to storage at low temperatures. In order to reduce such damage, the present study aimed to verify the efficiency of heat treatment and disinfection of pathogens in the prevention of post-harvest chilling injury of this cultivar and to compare this treatment with other products using the conventional fungicides. The heat treatments were studied with hot-water temperatures ranging between 48 and 56° C. Water at room temperature was used as a control treatment. After treatment, the fruits were kept under cold temperature at 10° C and RH 90% for about 45 days. For comparison, three other treatments were carried out simultaneously, one using imazalil, one with baking soda, and a third with sodium carbonate, these three products being applied by baths in cold water. Two groups of fruit were evaluated, one treated by immersion considering pathogens coming from the field and another by inoculation with spores of the previously isolated pathogens. For the evaluation of physical and chemical parameters of fruits, determinations were made of the skin color, texture, weight loss, size, juice yield, soluble solids, total acidity and vitamin C content. The determination of the sensitivity of the fruit to cold was made by their exposure at temperatures inducing cold damage. The design was a randomized block design with nine treatments, analyzed by the Statgraphics statistical package. Heat treatments, especially at 52° C, were shown to be more promising in the control of pathogenic fungi and cold damage, surpassing the conventional fungicides. No changes were found in the intrinsic and extrinsic parameters in relation to the application of the different treatments.

Interferência da redução no volume de aplicação sobre o controle da mancha preta (Guignardia citricarpa Kiely) em frutos de laranja 'Valência'

The chemical control of the causal agent of citrus black spot (CBS) has been highlighted for the excessive required number of sprayings, considerably increasing citrus production costs. Improvements in the spray efficiency and reductions in the quantity of phytosanitary products have already been searched, but the results of that practice are not consistent yet for its use at commercial scale. Thus, the aim of the present study was to evaluate the interference of reduced spray volumes in black spot control in citrus fruits. The experiment was carried out in commercial citrus orchard with 16-year-old plants of 'Valencia' variety, during 2007 agricultural season. Treatments consisted of three spray volumes: 3.5; 4.5 and 8.5 liters.plant-1, applied with Arbus 2000/Export airblast sprayer with special manifold of hydraulic nozzles, using fungicides and periods recommended for the disease control, totaling four sprayings plus a control treatment (without spray). The disease incidence and severity were evaluated by visual diagrammatic scale of notes in two different periods (preharvest and harvest), at three plant heights (low, middle and top) and three horizontal sections (entrance, frontal and exit) in two sides of the plant. The fallen fruits were counted every fifteen days, for previously selected plants, from the beginning of maturation to harvest, and the production was quantified (kg.plant-1). The disease incidence and severity were significantly lower when sprayings were done with 8.5 liters.plant-1 in the first evaluation period (pre-harvest), but in the harvest period there were not differences between the same parameters when 4.5 or 8.5 liters.plant-1 were sprayed. None of those treatments reduced the disease on the top section of plants, compared to control. The plant sections with fruits more exposed to sun rays, top and right side of the plant, demonstrated higher disease incidence and severity. The volume reduction from 8.5 to 4.5 liters.plant-1 can be adopted for citrus orchards without damaging the CBS control level.

Geostatistics and remote sensing methods in the classification of images of areas cultivated with citrus

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo dos mecanismos de ação de leveduras envolvidos no biocontrole de doenças de pós-colheita em citros

Pós-graduação em Microbiologia Agropecuária - FCAV

Candidatus Liberibacter asiaticus Titers in Citrus and Acquisition Rates by Diaphorina citri Are Decreased by Higher Temperature

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Healing Actions of Essential Oils from Citrus aurantium and d-Limonene in the Gastric Mucosa: The Roles of VEGF, PCNA, and COX-2 in Cell Proliferation

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

The effect of a minor constituent of essential oil from Citrus aurantium: The role of beta-myrcene in preventing peptic ulcer disease

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

The influence of citrus rootstocks on the relationship between the mite Brevipalpus phoenicis and citrus leprosis disease

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

Comparative proteomic analysis reveals that T3SS, Tfp, and xanthan gum are key factors in initial stages of Citrus sinensis infection by Xanthomonas citri subsp citri

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

Occurrence of Helicoverpa armigera (Hübner, 1808) on citrus in the state of Sao Paulo, Brazil

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

Citrus pulp and enzyme complex for growing and finishing pigs

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

Estrutura de populações e inoculações recíprocas de Xylella fastidiosa subsp. pauca com ocorrência em cultivos vizinhos de Citrus sinensis e Coffea arabica sob condições do estado de São Paulo

Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV

Atividade larvicida dos óleos essenciais de Syzygium aromaticum e Citrus sinensis em populações de Aedes aegypti

Pós-graduação em Biociências - FCLAS

Technical and economic evaluation of different types of control of Brevipalpus phoenicis (Acari: Tenuipalpidae) in citrus leprosies management

The objective of this work was to evaluate the effect of acaricide applications and pruning of symptomatic branches in citrus leprosis management in Brazil. It was conducted in an orange plantation of the 'Pera' variety, grafted onto the 'Cleopatra' tangerine, in two seasons (2006-2007 and 2007-2008). The experimental design was randomized blocks in a factorial scheme consisting of the following factors: (A) acaricide, in three levels: spirodiclofen and cyhexatin applied in rotation, lime sulphur; no acaricides; (B) pruning to remove branches that showed symptoms of leprosis, with two levels: with pruning, without pruning. We carried out periodic assessments of Brevipalpus phoenicis (Geijskes) populations (vector of the leprosis virus), leprosis incidence and severity, fruit yield, and the economic feasibility of the applied strategies. Based on the results, we concluded that spirodiclofen and cyhexatin were more effective than lime sulphur in B. phoenicis control. Control with lime sulphur required more applications than spirodiclofen and cyhexatin in rotation, making it more expensive. Pruning of symptomatic branches used in isolation was not sufficiently effective to control leprosis and significantly increased control costs. Profits were higher when the control involved sprayings of spirodiclofen and cyhexatin in alternation, with or without pruning.