Loading...
9 results
Search Results
Now showing 1 - 9 of 9
- Controlo de Sclerotinia homoeocarpa em relva com compostos orgânicosPublication . Coelho, Luísa; Dionísio, Lídia; Guerrero, Carlos; Reis, MárioOs relvados são suscetíveis a doenças causadas por fungos, sendo Sclerotinia homoeocarpa um dos que causa maiores prejuízos em muitos países. A compostagem permite a valorização e tratamento de resíduos orgânicos, originando compostos com aplicações agrícolas, nomeadamente para controlo de doenças causadas por patogénicos do solo. Produziram-se dois compostos, designados P1 e P2, por compostagem de resíduos agroindustriais, em pilhas com arejamento por reviramento. Desde o final da fase termofílica até ao final dos processos de compostagem recolheram-se amostras onde se isolaram e identificaram fungos presentes em ambos os compostos. Dos isolados, 26 apresentaram potencial antagonista, sendo 12 provenientes de P1 e 14 de P2. Realizaram-se ensaios in vitro, pelo método de confrontação direta, para avaliar a capacidade antagonista destes fungos para S. homoeocarpa. Doze dos isolados, dos géneros Trichoderma, Fusarium e Bionectria, impediram o crescimento de S. homoeocarpa, com taxas de inibição entre 52 e 68%. Os compostos obtidos foram também testados, in vivo, em relva (Agrostis stolonifera L.) cultivada em vaso. No cultivo em vaso, usando os compostos como substratos, verificou-se redução da área de relva afetada pela doença, principalmente em P2. Os compostos testados controlaram S. homoeocarpa tanto in vitro como em vaso destacando-se o composto P2.
- First report of curvularia trifolii causing curvularia blight in agrostis stolonifera in South of PortugalPublication . Coelho, Luísa; Borrero, C.; Bueno-Pallero, Francisco Angel; Guerrero, Carlos; Fonseca, Filomena; Reis, Mário; Avilés, M.; Dionísio, LídiaAlgarve region (Portugal) has nearly 40 golf courses with a significant economic impact. Summer surveys on 10 golf courses detected an unknown disease on one course in 2009 and on another course in 2012 and 2013 at 29 to 30°C daily average. The second course had symptoms on about 25% of the turf of two putting greens. Diseased bentgrass (Agrostis stolonifera L.) had a green dappled pattern with irregular patches of turfgrass on yellowed leaves. Prior to decaying, affected leaves turned brown and then gray. Crown and leaf sheath infections resulted in dark brown dry rot. No lesions were observed on the roots. Leaves were surface disinfected with 5% commercial bleach (0.225% sodium hypochlorite) and cultured on potato dextrose agar (PDA). Ten fungal colonies grew from the leaf tissue, and brown mycelia, conidiophores, and conidia were observed under a microscope. Conidia were ventricose pyriform, mostly abruptly curved, 20 to 36 µm (30 µm, SD = 4) × 7 to 12 µm (10.5 µm, SD = 1.3) (n = 50), predominantly three-septate, with a prominent hilum and enlarged and darkened central cells. Colonies grown on PDA were black-brown with a black reverse side. Conidia differed in size, 15.4 to 24.6 µm (19.99 µm, SD = 3.00) × 6 to 11 μm (8.68 µm, SD = 1.54) (n = 50) and morphology (cylindrical or slightly curved). These characteristics were consistent with Curvularia trifolii (Kauffm.) Boedijn. (Ellis 1971; Falloon 1976; Khadka 2016). Species identification of the representative isolate A2 1.12 was confirmed by analysis of nucleotide sequences of the ITS1-5.8S-ITS2 region using primers ITS1 and ITS4 (White et al. 1990) and GPDH gene region with primer set gpd (Koike et al. 2013). BLAST searches of GenBank showed a high similarity of the isolate ITS sequence (MG029439) to the reference sequence JN712458 of C. trifolii (99% identity) and GPDH sequence (MK570108) with LT715803.1 (97.88% identity). The maximum likelihood phylogenetic tree showed that our isolate clustered with C. trifolii. The pathogenicity assay of this isolate was conducted in greenhouse on A. stolonifera ‘Penncross’. The isolate was grown on PDA (25°C, 10 days). Five pots (100 ml) were filled with a sand and peat mix (9:1 v/v) with 0.06 g of seeds per pot, covered with a fine sand layer. Turfgrass was cut once a week beginning 2 weeks after seeding and was fertigated with 0.5 g/liter of Peter’s foliar feed (27 + 15 + 12; N + P2O5 + K2O; and micronutrients; Scotts, Heerlen, The Netherlands). To obtain a conidial suspension for inoculation, cultured plates were scraped with a sterilized spreader and water. The suspension was filtered through a sterile gauze. Conidia were counted under a microscope (400×) with a hemocytometer. The suspension was adjusted to 8 × 103 conidia/ml, and 10 ml was sprayed per pot. Pots maintained humidity for 2 days under microtunnels. The first disease symptoms appeared 3 days after inoculation. Bentgrass from the five pots developed Curvularia blight and rotted crown symptoms. Control plants (five pots treated with water) did not display symptoms. This trial was repeated once. On PDA, C. trifolii was reisolated from leaf lesions and morphologically identified, confirming Koch’s postulates. Ellis (1971) referred to the presence of C. trifolii in Portugal, but no region, symptom description, or grass species was detailed. Sivanesan (1987) reported C. trifolii in Portugal only on Lolium multiflorum. Therefore, this is the first report of C. trifolii in Algarve, affecting A. stolonifera. This disease can increase maintenance costs in greens in this area.
- Use of cork residues to control turfgrass diseasesPublication . Coelho, Luísa; Dionísio, Lídia; Reis, Mário; Guerrero, CarlosThe worldwide increase in agricultural and industrial production has created environmental problems. Economic and environmental benefits can be gathered solving a problem of the agroindustry by applying their sub products to soil. The compromise to decrease the use of pesticides and fertilizers, which may be hazardous, has provided opportunities for the development of new sustainable crop management practices. From several strategies to enhance the use of organic matter in agriculture, one has been the use of composts of different mixtures of raw materials, from different agroindustry processes or the use of these raw material (agroindustry residues) directly without any treatment. The incorporation of these products to the soil and its application to the crops proved to be an interesting pathway to apply effective beneficial microorganisms for the crops and for the ecosystems globally. This strategy showed to achieve reasonable crops yields and suppressive effects on phytopathogenic microorganisms. Several microorganisms have been associated to cork throughout tree life and in the end products1, such as Trichoderma pseudoconingii, T. viride, Endothiella gyrosa, Mucor hiemalis, Rhysopus sp., Penicillium sp., Cytospora sp., Dichomera sp., Acremonium sp., Glyocladium sp., Botrytis silvatica, and Pestalotia sp. Considering the potential of these microorganisms, a study was carried out at the University of Algarve to identify the presence of beneficial microorganisms in cork residues and to evaluate, in vitro, their antagonistic effect against several fungi turfgrass diseases.
- Culture media performance on the detection of actinomycetes from compostsPublication . Coelho, Luísa; Reis, Mário; Dionísio, LídiaIn this study we evaluated the performance of six culture media on the detection of actinomycetes that were present in composts of agro-industrial wastes from the Algarve region. The composts were produced with orange wastes, olive pomace and grass clippings, in the proportion of 2:1:1 of volume. Two compost piles were built with different ventilation systems, one with forced ventilation and the other with mechanical turning and natural ventilation. In order to quantify the population of actinomycetes, different growth media containing antibiotics were tested and one culture medium containing only half of the concentration of the Plate Count Agar (½ PCA) was also tested. The incubation took place at two temperatures, 25º and 55ºC. Different results were obtained for the enumerations from the culture media. The population of actinomycetes achieved higher values when incubated at 55ºC and when the samples were inoculated in the ½ PCA culture medium. Thus, the antibiotics showed no beneficial effect in the tested culture media. The results suggest the use of the ½ PCA culture medium as the most adequate in order to count the bacterial populations in these samples. This medium is also the less expensive and the one that showed the fastest bacterial growth.
- Trichoderma gamsii as a biological control agent of turfgrass diseasesPublication . Coelho, Luísa; Dionísio, Lídia; Bueno-Pallero, Francisco; Reis, Mário; Duarte, J.; Guerrero, CarlosGolf is a growing and economically important activity in Portugal with direct and indirect incomes respectively over 350 and 1.450 million of euros, corresponding nearly 1.25% of the Gross National Product. The correct maintenance of lawns in a sustainable manner is required. Sport lawns are quite susceptible to soil-borne diseases1 , which cause enormous economic losses, making environmental friendly disease control methods a practice to develop. The increasing interest regarding environment and public health protection have been increased the search for alternatives, leading researchers to seek strategies to reduce the use of synthetic products, such as fertilizers and pesticides2 . Also, the European legislation is directing the reduction of pesticides3 , facing itself towards more sustainable policies.
- Use of organic composts to suppress bentgrass diseases in Agrostis stoloniferaPublication . Coelho, Luísa; Reis, Mário; Guerrero, Carlos; Dionísio, LídiaTurfgrasses are affected by fungal diseases and their chemical control is currently limited by the legislation and the impact on the environment of fungicides and the possible development of fungicide resistance. This study was carried out during three years to evaluate the antagonistic effect of the microbiota associated with organic composts. Two composts were produced from agro-industrial residues, P1 and P2. Fungi from both composts were isolated and identified and their antagonistic capacity was evaluated, in vivo and in vitro tests, against Sclerotium rolfsii Sacc, Clarireedia gen. nov. (formerly Sclerotinia homoeocarpa (Benn, 1937)) and Rhizoctonia solani (Kuhn 1858). In vivo tests were run for Agrostis stolonifera L., seeded in P1, P2 and a commercial peat (T) based substrate (Hansa Torf Floragard, Germany), in 100 mL pots. A part of each substrate was submitted to a thermic treatment, obtained Pt, P1t and P2t substrates. Antagonistic properties of the P, P1 and P2 were compared with substrates with thermic treatment. In the in vitro tests Trichoderma atroviride and Trichoderma asperellum showed higher growth than the tested pathogenic agents. T. atroviride showed the best antagonistic capacity, with inhibition percentages of 67.5%, 63.8% and 62.5% against Clarireedia spp., S. rolfsii and R. solani, respectively. In the in vivo tests, the efficacy and biological control index (BCI) were higher in P1 and P2 than in P. BCI ranged from 1.66 (N) to 39.03 (P2) on S. rolfsii control, from 1.38 (Pt) to 14.66 (P1) on Clarireedia spp. control, and from 1.87 (Pt) to 21.45 (P1) for R. solani control. Compost P2 showed the highest suppressive effect on the studied soil diseases in turfgrass, which did not occur when its microbiota was eliminated by thermic treatment.
- Valorização de resíduos de fruticultura por compostagem: obtenção de produtos fertilizantes e com capacidade de controlo biológico de doençasPublication . Coelho, Luísa; Dionísio, Lídia; Guerrero, Carlos; Reis, MárioA compostagem pode valorizar os resíduos de fruticultura, obtendo-se compostos com interesse agrícola. Neste trabalho apresenta-se a caracterização físico-química de quatro compostos de resíduos de citrinos e outros resíduos agrícolas, e resultados obtidos no controlo de doenças. Os compostos testados são designados pelas letras A a D, indicando-se entre parenteses a proporção em volume dos resíduos de citrinos e seguida da dos restantes resíduos, sendo: A e B, compostos com bagaço de azeitona e aparas de relva (2:1:1) compostados com ventilação forçada e por reviramento mecânico, respetivamente; C, composto com bagaço de uva e aparas de relva (0,9:1:1,1); D, composto com bagaço de uva, aparas de relva e resíduos da produção de cogumelos (1,8:1,5:0,2:0,5 v/v) ambos por compostagem com reviramento. A compostagem reduziu o volume inicial das misturas, obtendo-se 55 % a 65 % (v/v) de composto. Os compostos apresentaram um bom valor fertilizante, pelo seu elevado teor em matéria orgânica, superior a 77 %, exceto no composto C com 64 %; pH próximo da neutralidade, entre 7,0 e 7,5; e condutividade elétrica entre 0,3 e 3,3 dS m-1 . Os compostos apresentaram propriedades físicas adequadas para uso como substratos ou componentes de substratos hortícolas. Os compostos A e B controlaram o crescimento de Rhizoctonia solani em pepino (Cucumis sativus L.), que exibiu menor severidade e incidência da doença. Os compostos C e D mostraram capacidade para reduzir a severidade e a incidência das doenças, como substratos para cultivo de relva (Agrostis stolonifera L.) para controlo de Sclerotinia homoeocarpa e Sclerotium rolfsii, e em estévia (Stevia rebaudiana Bertoni) para controlo de R. solani e S. rolfsii. Os resultados demonstram ser possível converter os resíduos de citrinos em fertilizantes agrícolas, capacidade supressiva, permitindo o biocontrolo de doenças de solo, melhorando a sustentabilidade da agricultura e concretizando a economia circular na citricultura.
- Biological control of turfgrass diseases with organic composts enriched with Trichoderma atroviridePublication . Coelho, Luísa; Reis, Mário; Guerrero, Carlos; Dionísio, LídiaThe increasing demand of natural products for the control of plant diseases has led to the search for biological control agents, namely fungi, often isolated from composts of organic residues. By composting two different mixes of agro-industrial residues, P1 and P2 composts were obtained, from where a known antagonist, Trichoderma atroviride, was isolated. Later, a second composting process was performed and when the composting mix reached room temperature, the previously isolated T. atroviride was inoculated in both composts to enrich its population (E) and named as P1E and P2E. The suppressive capacity of these two composts against Sclerotium rolfsii, Clarireedia spp. and Rhizoctonia solani was tested two weeks after T. atroviride inoculation, in 100 mL pots with turfgrass seeded with Agrostis stolonifera. The tested treatments were: composts P1 and P2 without any treatment; thermally treated P1 and P2 (P1t, P2t); P1 and P2 enriched without and with previous thermic treatment (P1E, P2E, P1tE, P2tE), and a commercial peat-based substrate, natural (P) and thermally treated (Pt), enriched (PE) and enriched after thermal treatment (PtE). Enriched composts achieved the highest disease control. P1E was more effective in controlling Clarireedia spp.; pots with infected plants grown on P1E, showed 53.5% less affected area compared to P1t. P2E was more effective against R. solani; results showed 69.3% less affected area compared to P2t and both were effective in S. rolfsii control, with a reduction of 38.5% in P1E and 43.5% in P2E. The larger population of Trichoderma spp. observed in the enriched substrates associated to the greater enzyme activity, namely and N-acetyl-β-glucosaminidase, standing out in P2E, will have contributed strongly to the biocontrol of the studied diseases. An increase in some macro and micronutrients was observed in the enriched heat-treated substrates.
- Preparação de compostos para agricultura biológicaPublication . Ferreira, Jorge; Reis, Mário; Fernandes, Maria Mendes; Rosa, Armindo José Gonçalves; Oliveira, Paulo Miguel Gomes; Brito, João Manuel Carrasco de; Dionísio, Lídia; Guerrero, Carlos; Coelho, LuísaDurante o Projecto Agro 282 testou-se a compostagem de diferentes misturas de materiais de origem agrícola e agro industrial: resíduos hortícolas, palha de trigo, aparas de relva, laranjas de refugo e bagaço de azeitona. Procurou-se utilizar materiais de ocorrência vulgar na região, e por isso mais acessíveis aos agricultores, que contudo são comuns noutras regiões do país. A compostagem realizou-se em pilhas com reviramento mecânico e em pilhas com arejamento forçado. Para a preparação das pilhas empregaram-se equipamentos habituais em muitas explorações agrícolas. A moenda dos materiais mais grosseiros efectuou-se com um corta-forragem para milho, fixo, no qual se iam introduzindo os materiais a compostar, nas proporções adequadas. O reviramento realizou-se com um tractor agrícola com pá carregadora frontal. Numa das compostagens foi necessário uma trituração adicional do material em compostagem, para o que se usou um cultivador rotativo. O humedecimento do material durante a compostagem efectuou-se microaspersores, e com mangueira com ralo durante os reviramentos. A compostagem foi monitorizada, controlando-se a temperatura e algumas variáveis físico-químicas. Os compostos foram caracterizados no final do período de compostagem, isto é, após estabilização da sua temperatura.