Weather-based prediction of anthracnose severity using artificial neural network models

Data were collected and analysed from seven field sites in Australia, Brazil and Colombia on weather conditions and the severity of anthracnose disease of the tropical pasture legume Stylosanthes scabra caused by Colletotrichum gloeosporioides. Disease severity and weather data were analysed using artificial neural network (ANN) models developed using data from some or all field sites in Australia and/or South America to predict severity at other sites. Three series of models were developed using different weather summaries. of these, ANN models with weather for the day of disease assessment and the previous 24 h period had the highest prediction success, and models trained on data from all sites within one continent correctly predicted disease severity in the other continent on more than 75% of days; the overall prediction error was 21.9% for the Australian and 22.1% for the South American model. of the six cross-continent ANN models trained on pooled data for five sites from two continents to predict severity for the remaining sixth site, the model developed without data from Planaltina in Brazil was the most accurate, with >85% prediction success, and the model without Carimagua in Colombia was the least accurate, with only 54% success. In common with multiple regression models, moisture-related variables such as rain, leaf surface wetness and variables that influence moisture availability such as radiation and wind on the day of disease severity assessment or the day before assessment were the most important weather variables in all ANN models. A set of weights from the ANN models was used to calculate the overall risk of anthracnose for the various sites. Sites with high and low anthracnose risk are present in both continents, and weather conditions at centres of diversity in Brazil and Colombia do not appear to be more conducive than conditions in Australia to serious anthracnose development.

Soil attributes and efficiency of sulfentrazone on control of purple nutsedge (Cyperus rotundus L.)

Herbicidas aplicados ao solo são submetidos à adsorção, lixiviação e degradação por processos físicos, químicos e biológicos, além da absorção pelas plantas. Todos esses processos são afetados pela classe dos solos onde foram aplicados e das condições climáticas reinantes logo após a aplicação, que afetarão a eficiência dos produtos no controle de plantas daninhas. Investigaram-se as influências dos atributos de solos e condições de cultivo na eficiência do herbicida sulfentrazone no controle da planta daninha tiririca (Cyperus rotundus L.). O Latossolo Vermelho-Amarelo Distrófico (LVAd), o Latossolo Vermelho (LVd - Distrófico; LVdf - Distroférrico; LVef - Eutroférrico) e o Nitossolo Vermelho Eutrófico (NVe) foram coletados sob duas condições de cultivo, visando obter solos com teores diferenciados de argila, óxido de ferro e matéria orgânica. As amostras dos solos foram submetidas à caracterização granulométrica, química e mineralógica e, em seguida, utilizadas no bioensaio de avaliação da eficiência do sulfentrazone (1,6 L p.c. ha-1) no controle da tiririca em condições de pré-emergência. O sulfentrazone apresentou comportamento diferenciado entre as classes de solos estudados e a sua eficiência diminuiu com o aumento do teor de óxido de ferro nos solos, na seguinte ordem: LVAd, LVd, NVe, LVef e LVdf, sendo que as variações nos teores de argila (240 a 640 g kg-1) e da matéria orgânica (12 a 78 g kg-1) dos solos não interferiram na eficiência do sulfentrazone.

Qualidade tecnológica da cana-de-açúcar em função da aplicação de maturadores em meio de safra

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

Recuperação de larvas de Trichostrongylus colubriformis em diferentes estratos de Brachiaria decumbens E Panicum maximum

The purpose of the experiment was to evaluate infective Trichostrongylus colubriformis larvae vertical migration in two forage grass species. Experimental modules formed by eight plots, established with Brachiaria decumbens cv. Australian and Panicum maximum cv. Aruana, were used in the study, totaling four plots for each grass species. Each plot was divided into six 30 x 30 cm subplots. Larval migration was evaluated in the four seasons of the year, in different plant strata (0-7, 7-14, 14-21, 21-28 and above 28 cm). Four feces deposits were made, one in each season of the year, in the middle of 30-cm tall forage. The feces were collected from the forage ten days after each feces deposit in the experimental subplots. Grass height was measured in each of the strata immediately before the collections. The forage of the different strata was cut from an area measuring 10-cm in radius. The feces were collected manually from the subplots. There was a grass species and grass stratum interaction in the deposit made in autumn (P < 0.05). During that season, most of the larvae were recovered from the Brachiaria grass base; meanwhile, at the forage apex, the biggest average was registered in the aruana grass. Infective larvae (U) recovery was similar among the different strata during spring. In springtime, the biggest L3 recovery occurred at the 21-28 cm stratum from both forage species. No L3 was recovered from any of the No L3 was recovered from any of the grass strata during winter and summer. Study results show that migration of T colubriformis larvae was more influenced by weather conditions Than by forage species.

Seasonal effect of three pasture plants species on the free-living stages of Haemonchus contortus

Avaliaram-se o desenvolvimento e a sobrevivência dos estágios de vida livre de Haemonchus contortus em fezes obtidas de ovinos infectados por esse nematódeo, depositadas nas quatro estações do ano, em pastagens de três espécies de gramíneas (Brachiaria decumbens cv Australiana, Cynodon dactylon cv. Coast-cross e Panicum maximum cv. Aruana), com duas alturas (5cm e 30cm) no momento da deposição das fezes. Amostras de fezes e de capim foram coletadas uma, duas, quatro, oito, 12 e 16 semanas após a deposição das fezes e processadas em laboratório, para recuperação de larvas infectantes. O maior número de larvas infectantes foi recuperado das amostras de capim e de fezes nas pastagens com 30cm de altura. As condições climáticas que mais favoreceram o desenvolvimento e a sobrevivência das larvas nas fezes, bem como a sobrevivência e a manutenção das larvas no capim foram aquelas com temperaturas médias em torno de 17ºC, acompanhadas de baixas precipitações pluviométricas. As temperaturas mais altas e as precipitações elevadas, que ocorrem na chamada estação das águas, foram desfavoráveis para a recuperação de larvas infectantes da pastagem. de forma geral, a pastagem de Aruana foi a que possibilitou as maiores recuperações de larvas.

Atividade das enzimas invertases e acúmulo de sacarose em cana-de-açúcar sob efeito do nitrato de potássio, etefon e etil-trinexapac

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

Analysis of Mortality in Africanized Honey Bee Colonies with High Levels of Infestation by Varroa destructor

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effects of Natural Infestations of the Mite Varroa destructor on the Development of Africanized Honeybee Workers (Apis mellifera)

The mite Varroa destructor (Anderson & Treuman 2000) has caused extensive damage to beekeeping worldwide. In Brazil, weather conditions and the strains of bees do not provide ideal conditions for mite parasitism, which is reflected in the low number of deaths of colonies caused by varroatosis well as the stability of infestation levels. The aim of this study was to evaluate the damage caused by the mite infestation in hives maintained in natural conditions. For this purpose the number of mites per bee was calculated and used to quantify the level of infestation in each colony. To record the mortality rates of parasitized bees during development daily checks were performed. The data were analyzed by G test of independence and a Test of Proportions. The results indicate that the rate of mortality of pupae and larvae was proportional to the degree of infestation in each colony, and all colonies showed mortality rates significantly higher than the control rate. A significant interaction among death rates recorded between the third and fourth days of larval life and the total death of larvae was found (G Test = 50.22; P < 0.0001). So, it can be concluded that bee inbreeding contributed significantly to the increase of the larval rate of mortality. In Africanized honeybee colonies infested by the mite Varroa destructor mortality rates in conditions of natural infestation varied from 6.65 to 9.89% in pupae (<(x)over bar>= 8.78%) and from 6.13 to 13.48% in larvae ((x) over bar = 9.91%), against 3.85% and 3.74% in the control colony, respectively. Therefore, in the infested colonies the average rates of mortality caused by the harmful effects of the mite were, respectively, 2.28 times and 2.65 times greater in those two developmental stages.

Exportação de nutrientes minerais por frutos de aceroleira colhidos em diferentes épocas do ano

A aceroleira produz, no Nordeste brasileiro, de quatro a seis safras por ano e é de se esperar que as exportações de elementos minerais variem em função das diferentes épocas de colheita e das progênies, entre outros fatores. Nesse contexto, este trabalho foi conduzido no Campo Experimental da Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) Agroindústria Tropical, em Pacajus-CE (4º10' S; 38º27' W), no ano agrícola de 1999/2000, com o objetivo de determinar a exportação de N, P, K, Ca, Mg, S, Cu, Fe, Mn e Zn por tonelada de fruta fresca, em diferentes progênies e épocas de colheita. Avaliaram-se os frutos de seis progênies (plantas com 2,5 anos de idade e produção média de 18,16 a 27,62 kg/planta/ano, cultivadas em sistema de sequeiro), em seis épocas de colheita. Adotou-se o delineamento em blocos casualizados, em esquema de parcelas subdivididas no tempo (considerando as progênies como parcelas e as épocas de avaliação as subparcelas), com 4 repetições. Verificou-se que a maior exportação de nutrientes ocorreu nos meses de maior precipitação (fevereiro a abril); as progênies não diferiram entre si quanto à exportação de macronutrientes; as progênies P-52, P- 93 e P-97 exportaram maior quantidade de Cu e Zn; a seqüência de exportação de nutrientes por tonelada de frutos frescos de aceroleira foi: K>N>P>Mg>Ca>S>Fe>Zn>Mn>Cu.

Secagem e armazenamento de sementes de juçara

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

Qualidade tecnológica, produtividade e margem de contribuição agrícola da cana-de-açúcar em função da aplicação de reguladores vegetais no início da safra

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

Efeitos da poluição atmosférica na saúde infantil em São José dos Campos, SP

OBJETIVO: Dentre os efeitos da poluição ambiental na saúde da criança, destaca-se o aumento de internações por pneumonias. O objetivo do estudo foi estimar a associação dessas internações com o aumento dos poluentes atmosféricos. MÉTODOS: Trata-se de estudo ecológico de séries temporais, realizado na cidade de São José dos Campos, SP, nos anos de 2000 e 2001. Foram utilizados dados diários sobre o número de internações por pneumonia, dados diários de poluentes (SO2, O3 e PM10) e de temperatura e umidade do clima. Foram estimadas as correlações entre as variáveis de interesse pelo coeficiente de Pearson. Para estimar a associação entre as internações por pneumonia e a poluição atmosférica, utilizaram-se modelos aditivos generalizados de regressão de Poisson. Foram estimados os acréscimos das internações por pneumonia para o intervalo interquartil para cada um dos poluentes estudados, com um intervalo de confiança de 95% RESULTADOS: Os três poluentes apresentaram efeitos defasados nas internações por pneumonia, iniciada três a quatro dias após a exposição e decaindo rapidamente. Na estimativa de efeito acumulado de oito dias observou-se ao longo desse período que para aumentos de 24,7 µg/m³ na concentração média de PM10 houve um acréscimo de 9,8% nas internações. CONCLUSÕES: O estudo confirma que o potencial deletério dos poluentes do ar sobre a saúde pode ser detectado, também, em cidades de médio porte. A magnitude do efeito foi semelhante ao observado na cidade de São Paulo. Além disso, mostra a elevada susceptibilidade das crianças aos efeitos adversos advindos da exposição aos contaminantes atmosféricos.

Intercontinental transport of nitrogen oxide pollution plumes

We describe the first satellite observation of intercontinental transport of nitrogen oxides emitted by power plants, verified by simulations with a particle tracer model. The analysis of such episodes shows that anthropogenic NOx plumes may influence the atmospheric chemistry thousands of kilometers away from its origin, as well as the ocean they traverse due to nitrogen fertilization. This kind of monitoring became possible by applying an improved algorithm to extract the tropospheric fraction of NO2 from the spectral data coming from the GOME instrument.As an example we show the observation of NO2 in the time period 4-14 May, 1998, from the South African Plateau to Australia which was possible due to favourable weather conditions during that time period which availed the satellite measurement. This episode was also simulated with the Lagrangian particle dispersion model FLEXPART which uses NOx emissions taken from an inventory for industrial emissions in South Africa and is driven with analyses from the European Centre for Medium-RangeWeather Forecasts. Additionally lightning emissions were taken into account by utilizing Lightning Imaging Sensor data. Lightning was found to contribute probably not more than 25% of the resulting concentrations. Both, the measured and simulated emission plume show matching patterns while traversing the Indian Ocean to Australia and show great resemblance to the aerosol and CO2 transport observed by Piketh et al. (2000).

Intercontinental Differences in the Abundance of Solenopsis Fire Ants (Hymenoptera: Formicidae): Escape from Natural Enemies?

The absence of natural enemies often allows exotic pests to reach densities that are much higher than normally occur in their native habitats. When Solenopsis fire ants were introduced into the United States, their numerous natural enemies were left behind in South America. To compare intercontinental fire ant densities, we selected 13 areas in South America and another 12 areas in North America. Sample areas were paired with weather stations and distributed across a broad range of climatic conditions. In each area, we measured fire ant densities at 5 preselected roadside sites that were at least 5 km apart. At each site, we also measured foraging activity, checked for polygyne colonies, and recorded various kinds of environmental data. In most areas, we also measured fire ant densities in lawns and grazing land. Fire ant populations along roadsides in North America were 4-7 times higher than fire ant populations in South America. Similar intercontinental differences were found in lawns and on grazing lands. These intercontinental differences in fire ant abundance were not associated with sampling conditions, seasonal variability, habitat differences, or the frequency of polygyny. Although several correlations were found with long-term weather conditions, careful inspection of the data suggests that these correlations were probably more coincidental than causal. Cultural differences in roadside maintenance may explain some of the intercontinental differences in fire ant abundance, but they did not account for equivalent intercontinental differences in grazing land and mowed lawns. Bait tests showed that competition with other ants was much more important in South America; however, we were not able to determine whether this was a major cause of intercontinental differences or largely a consequence of other factors such as the numerous pathogens and parasites that are found in South America. Because this study was correlational, we were unable to determine the cause(s) of the large intercontinental difference in fire ant abundance that we observed. However, we were able to largely exclude a number of possible explanations for the differences, including sampling, season, polygyny, climate, and aspects of habitat. By a process of elimination, escape from natural enemies remains among the most likely explanations for the unusually high densities of fire ants found in North America.

Open urban spaces quality: A study in a historical square in Bath - UK

The quality of open urban spaces is very important for urban vitality. Nowadays urban designers have to face the great challenge of designing urban spaces able to respond to people's need for liveable spaces. The success of these spaces depends on various aspects and the microclimatic condition has been recognized as one of the most influential. However, studies on thermal comfort in open space have shown that the user's thermal sensation does not depend only on microclimate parameters but also on other local qualitative aspects. Thus, environmental quality evaluation of successful public spaces can contribute to understand this issue. This paper focuses on a case study regarding Queen Square's environmental quality, a public space of historical importance in Bath-UK. The first stage of the research, a study on local characteristics and people observations, allowed a preliminary evaluation of the space performance, their social aspects, while it characterized and quantified the hourly variation of the space use in different days and seasons. In the second stage, short microclimatic surveys were carried out simultaneously with a perception survey through a questionnaire. The results show the strong vitality of the square and socioenvironmental significance, not only for its location in the urban context, but also for its historical value. The environmental quality of the square contributes to the users' sensation of comfort even in adverse climatic conditions. This research is part of a project that aims to investigate the impact of the environmental stimuli in the use of open spaces and intend to develop design strategies that aim to maximise the use of open spaces in different weather conditions.