Biological control of plant diseases - present and future trends.

Patogenos foliares nao sao faceis de controlar usando agentes biologicos devido as dificuldades em garantir sua sobrevivencia. Especies de Bacillus e Pseudomonas controlaram alguns fungos e leveduras, e Trichoderma spp., alguns patogenos necrotroficos. Patogenos bacterianos foram controlados pelos saprofitas mencionados. Doenças radiculares oferecem maior potencial para biocontrole. Doencas causadas por Pythium foram eliminadas por bacterias. Chaetomium e um basidiomiceto nao identificado reduziram significativamente o mal-do-pe do trigo. Zygorrhynchus moelleri inibiu o crescimento de Rhizoctonia e Pythium ao produzir b-1, 3-glucanases e um composto antifungico, o indol-3-etanol. Z. moelleri aumentou o crescimento da raiz e brotos e causou o florescimento e frutificacao precoce de plantas horticolas. Ha boas perspectivas para o biocontrole de muitas doencas transmitidas por sementes. Dentre um conjunto de microorganismos que foi aplicado a sementes de linhaca para controlar Alternaria linicola, um isolado de Bacillus sp. e Trichoderma harzianum foram os mais efetivos. Varios aditivos empregados em peletes de alginato podem prolongar a sobrevivencia de organismos de biocontrole.Made available in DSpace on 2011-04-09T12:15:15Z (GMT). No. of bitstreams: 1 pab14abresp92.pdf: 711841 bytes, checksum: 12a169d9941784cf12796d9f2ef19f23 (MD5) Previous issue date: 2001-08-22199

Biological control of plant diseases - present and future trends.

Patogenos foliares nao sao faceis de controlar usando agentes biologicos devido as dificuldades em garantir sua sobrevivencia. Especies de Bacillus e Pseudomonas controlaram alguns fungos e leveduras, e Trichoderma spp., alguns patogenos necrotroficos. Patogenos bacterianos foram controlados pelos saprofitas mencionados. Doenças radiculares oferecem maior potencial para biocontrole. Doencas causadas por Pythium foram eliminadas por bacterias. Chaetomium e um basidiomiceto nao identificado reduziram significativamente o mal-do-pe do trigo. Zygorrhynchus moelleri inibiu o crescimento de Rhizoctonia e Pythium ao produzir b-1, 3-glucanases e um composto antifungico, o indol-3-etanol. Z. moelleri aumentou o crescimento da raiz e brotos e causou o florescimento e frutificacao precoce de plantas horticolas. Ha boas perspectivas para o biocontrole de muitas doencas transmitidas por sementes. Dentre um conjunto de microorganismos que foi aplicado a sementes de linhaca para controlar Alternaria linicola, um isolado de Bacillus sp. e Trichoderma harzianum foram os mais efetivos. Varios aditivos empregados em peletes de alginato podem prolongar a sobrevivencia de organismos de biocontrole

Species diversity and decomposition in laboratory aquatic systems: the role of species interactions

P>1. Interest in the effects of biodiversity on ecosystem processes is increasing, stimulated by the global species decline. Different hypotheses about the biodiversity-ecosystem functioning (BEF) relationship have been put forward and various underlying mechanisms proposed for different ecosystems. 2. We investigated BEF relationships and the role of species interactions in laboratory experiments focussing on aquatic decomposition. Species richness at three different trophic levels (leaf detritus, detritus-colonising fungi and invertebrate detritivores) was manipulated, and its effects on leaf mass loss and fungal growth were assessed in two experiments. In the first, monocultures and mixtures of reed (Phragmites australis), alder (Alnus glutinosa) and oak (Quercus cerris) leaf disks were incubated with zero, one or eight fungal species. Leaf mixtures were also incubated with combinations of three and five fungal species. In the second experiment, reed leaf disks were incubated with all eight fungal species and offered to combinations of one, two, three, four or five macroinvertebrate detritivores with different feeding modes. 3. Results from the first experiment showed that leaf mass loss was directly related to fungal mass and varied unimodally with the number of fungi, with a maximum rate attained at intermediate diversity in oak and reed and at maximum diversity in alder (the fastest decomposing leaf). 4. Mixing litter species stimulated fungal growth but interactions between species of fungi slowed down decomposition. In contrast, mixtures of macroinvertebrate detritivores reduced fungal mass and accelerated leaf decomposition. Possible explanations of the positive relationship between detritivore diversity and decomposition are a reduction in fungal dominance and a differentiation in the use of different resource patches promoted by higher fungal diversity. 5. In conclusion, the results show a general increase in decomposition rate with increasing biodiversity that is controlled by within- and between-trophic level interactions, and support the hypothesis of both bottom-up and top-down effects of diversity on this process