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Avaliação da influência da temperatura e da precipitação na ocorrência da ferrugem asiática da soja por meio da técnica de árvore de decisão / Evaluation of the influence of temperature and precipitation in the occurrence of Asian soybean rust by using the technique of decision treeMegeto, Guilherme Augusto Silva, 1984- 07 October 2012 (has links)
Orientadores: Stanley Robson de Medeiros Oliveira, Carlos Alberto Alves Meira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-20T23:34:35Z (GMT). No. of bitstreams: 1
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Previous issue date: 2012 / Resumo: A ferrugem asiática, causada pelo fungo Phakopsora pachyrhizi, atualmente é considerada uma das doenças mais importantes e agressivas da soja. A principal forma de controle é a aplicação calendarizada de fungicidas a qual desconsidera o risco de ocorrência da doença. Estudos epidemiológicos buscam compreender os fatores que influenciam na ocorrência e desenvolvimento das epidemias, especialmente aqueles relacionados ao ambiente tais como condições meteorológicas. Com o avanço da tecnologia da informação e do armazenamento de dados, técnicas de mineração de dados (data mining) apresentam-se promissoras para a descoberta de conhecimento em bases de dados epidemiológicos. Este trabalho tem como objetivo avaliar a influência da chuva e da temperatura na ocorrência da ferrugem asiática da soja utilizando árvores de decisão. Para tal, foram obtidos dados de ocorrências da doença em quatro safras, de 2007/2008 a 2010/2011, oriundos do banco de dados do Consórcio Antiferrugem, e dados meteorológicos, provenientes do sistema Agritempo. A análise exploratória dos dados permitiu obter subsídios para compor o conjunto de dados final e definir o escopo deste trabalho, buscando-se características intrínsecas à doença e sua interação com o ambiente, utilizando apenas variáveis de base meteorológica. As variáveis utilizadas foram relacionadas à precipitação e à temperatura, que deram origem a nove atributos avaliados para cada período temporal...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The Asian soybean rust, caused by Phakopsora pachyrhizi, is now considered one of the most important and aggressive diseases of soybean. The main form of control is the scheduled application of fungicides which disregards the the risk of disease occurrence. Epidemiological studies seek to understand the factors that influence the occurrence and development of epidemics, especially those related to the environment such as weather conditions. With the development of information technology and data warehousing, data mining techniques appear to be promising for knowledge discovery in epidemiological databases. This study aims to evaluate the influence of rainfall and temperature on the occurrence of soybean rust by using decision trees models. To accomplish that, data of the occurence of the disease were collected from four seasons, 2007/2008 to 2010/2011, from the Consórcio Antiferrugem and weather data from the Agritempo system. Exploratory data analysis allowed for obtaining subsidies to generate the final data set and define the scope of this work, seeking intrinsic characteristics of the disease and its interaction with the environment, using only meteorological variables. The variables used were related to precipitation and temperature, resulting into nine attributes evaluated in different periods. Such attributes were related to the event of occurrence (Oc) and non occurrence (NaoOc) of the disease (assumed as the thirtieth day prior to the event of occurrence). The results include a predictive model and an interpretive model for classifying events of occurrences and non occurrences of the disease...Note: The complete abstract is available with the full electronic document / Mestrado / Planejamento e Desenvolvimento Rural Sustentável / Mestre em Engenharia Agrícola
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Qualitative evaluation of smallholder and organic farmer decision support tool (DST) and its improvement by inclusion of a disease management component.Molefe, Thato. January 2011 (has links)
Historically, South Africans, particularly small-scale farmers have had little support and hence lack tools and information when faced with production decisions. Information plays an important role in enlightening people, raising their level of knowledge and in turn improving their standard of living and participation in decision making process. Research shows that Information Communication Technology (ICT) like Decision support tools (DSTs) plays an important role in systematic dissemination of information in agriculture, thus improving the quality of farmers’ decisions. Decision support tools provide up-to-date data, procedures and analytical capacity leading to better-informed decisions, especially in rural areas. A body of research is emerging around issues of effectiveness of DSTs for farmers in the developed world. However, few studies have focused on issues around effectiveness of these tools for farmers in the developing world, particularly for resource-limited farmers.
This study set out to evaluate the effectiveness of a new DST for organic and small-scale farmers with a group of extension officers and researchers in KwaZulu-Natal. As an extension to the DST, a crop disease management component linked to the DST was developed. The study also set to evaluate the effectiveness of the crop disease management component. Extension officers and researchers were purposively selected for this study because both groups play a major role as far as organising and disseminating information to organic and small-scale farmers is concerned.
This study identified key measures for effectiveness of DSTs and crop disease management guides using literature from the study. Two frameworks for measuring effectiveness were developed to evaluate the effectiveness of the new DST and its crop disease management component with the extension officers and researchers. Focus group discussions were used for data collection. The frameworks were used as a base for the focus group discussions. Focus groups were conducted to explore and establish whether in the light the groups (extension officers and researchers), the new DST and its crop disease management component are effective.
Results from the study revealed that extension officers and researchers felt that the DST and its crop disease management component are effective since they meet key measures for effectiveness identified in the framework. The groups agreed that the DST and its crop disease management component are relevant to small-scale farmers. They also agreed that the DST has the ability to improve access to information for small-scale farmers. Lastly, they also agreed that the DST and its crop disease management component are transparent (meaning flexible and user friendly) for small-scale farmers. Some of the areas for improvement identified by the groups included a need for information on pests and more diseases for the DST and the crop disease management component.
Although the groups felt that both the DST and crop disease management were effective, they strongly recommended a need for another study that will aim at developing a pest management component of the DST as this was clearly requested by groups in this study. Results of this study showed that half the respondents felt that the DST was easy enough to be used by small-scale farmers without help from extension officers, while the other half believed that small-scale farmers will still need the help of extension officers to show them how to use the DST. Government and other relevant institutions need to provide appropriate training for these farmers, making the DST useful to them. / Thesis (M.Agric)-University of KwaZulu-Natal, Pietermaritzburg, 2011.
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Studies on Sclerotinia sclerotiorum (Sclerotinia stem rot) on soybeans.Visser, Dael Desiree. January 2007 (has links)
Soybeans, Glycine max, are an economically and strategically important crop in South
Africa (SA). In order to meet local demands, large imports of soybeans are required,
e.g., in the 2005/2006 soybean production period, 842 107 tonnes of oilcake were
imported. Due to an increase in soybean production throughout the world, diseases that
affect this crop have also increased in incidence and severity.
Sclerotinia sclerotiorum, the causal organism of sclerotinia stem rot (SSR), is an
important yield limiting disease of soybeans, as well as numerous other crops. The
pathogen was first reported in SA in 1979. However, it was only in 2002 that this fungus
was considered a major pathogen of soybeans in SA.
The research reported in this thesis was conducted to investigate the epidemiology of
S. sclerotiorum and examine numerous potential control methods for this pathogen, i.e.,
resistant cultivars, biocontrol, chemical control and seed treatments. A S. sclerotiorum
isolate was obtained from sunflowers in Delmas, Mpumulanga, SA, in the form of
sclerotia. This isolate was cultured and sent for identification and deposition in the Plant
Protection Research Institute collection. This isolate, in the form of mycelia, was used
for the duration of the study.
For epidemiology studies, the effect of temperature, leaf wetness duration (LWD) and
relative humidity (RH) were examined for their effect on rate of pathogen development.
Twenty four combinations of temperature (19°C, 22°C, 25°C and 28°C), LWD (24, 48
and 72 hr) and RH (85 and 95%) were investigated. No interaction between
temperature, LWD and RH was found. Temperature alone was the only factor that
affected disease development. At 22°C, the rate of pathogen development (0.45 per
unit per day) was significantly higher than all other temperatures, indicating that this
temperature is optimum for disease development.
Thirteen different soybean cultivars, i.e., LS6626RR, LS6710RR, LS666RR, LS555RR,
LS6514RR, LS678RR, Prima 2000, Pan 626, AG5601RR, AG5409RR, 95B33, 95B53
and 96B01B, commercially grown in SA were investigated for their reaction to
S. sclerotiorum. Prima 2000, 96B01B, 95B33 and AG5409RR were considered to be
the least susceptible as they showed a significantly low rate of pathogen development
(0.28, 0.28, 0.24, 0.23 per unit per day, respectively) and produced a significantly low
number of sclerotia (3.03, 3.42, 3.21, 2.38, respectively). LS6626R and LS666RR may
be considered most susceptible because of their significantly high rate of pathogen
development (0.45 and 0.42 per unit per day, respectively) and high sclerotia production
(8.16 and 7.50, respectively). Regression analysis showed a positive correlation
coefficient (R2=0.71) between rate of growth of the pathogen and number of sclerotia
produced, indicating that a higher rate is associated with a higher number of sclerotia.
In vitro dual culture bioassays were performed to identify the biocontrol mechanisms of
the biocontrol agents, EcoT® (a seed treatment) and Eco77® (a foliar treatment), against
hyphae and sclerotia of S. sclerotiorum. Ultrastructural studies revealed that
mycoparasitism is the probable mode of action as initial signs of hyphae of EcoT® and
Eco77® coiling around hyphae of S. sclerotiorum were observed. Surface colonization
of sclerotia by hyphae of EcoT® and Eco77® was also observed.
In vitro antagonism of EcoT® against S. sclerotiorum on soybean seed was performed to
determine pre-emergence and post-emergence disease. There was no significant
difference in percentage germination between seeds treated with EcoT® and plated with
the pathogen, untreated seeds and no S. sclerotiorum, and the control (i.e. no EcoT®
and no pathogen). However, percentage non infected seedlings from seeds not treated
with EcoT® was significantly lower, suggesting that EcoT® may be successfully used as
a seed treatment for the control of SSR. In vivo trials were performed to investigate the
effect of silicon (Si) alone, and in combination with Eco77®, on the effect of the rate of
disease development. Plants treated with Eco77® had a significantly lower rate of
disease development (0.19 per unit per day for plants treated with Eco77® and S.
sclerotiorum and 0.20 per unit per day for plants treated with Eco77®, S. sclerotiorum
and Si), compared to plants not treated with Eco77® (0.29 per unit per day for plants
treated with S. sclerotiorum and 0.30 per unit per day for plants treated with S.
sclerotiorum and Si), regardless of the application of Si. Similarly, plants treated with
Eco77® had a significantly lower number of sclerotia (0.46 for plants treated with Eco77®
and S. sclerotiorum and 0.91 for plants treated with Eco77®, S. sclerotiorum and Si),
compared to plants not treated with Eco77® (3.31 for plants treated with S. sclerotiorum
and 3.64 for plants treated with S. sclerotiorum and Si). The significantly lower rate of
disease development coupled with a significant reduction in sclerotia showed that
Eco77®, and not Si, was responsible for reducing the severity of SSR. A strong positive
correlation between rate of disease development and the number of sclerotia produced
(R2=0.79) was observed.
For the investigation of various fungicides for the control of S. sclerotiorum, in vitro trials
to determine the potential of three different fungicides at different rates, i.e., BAS 516
04F (133 g a.i. ha-1), BAS 516 04F (266 g a.i. ha-1), BAS 512 06F (380 g a.i. ha-1) and
Sumisclex (760 g a.i. ha-1) were initially conducted. The control (non-amended PDA)
had a significantly higher area under mycelial growth curve (243.0) than all fungicides
tested. BAS 516 04F (at both concentrations) and BAS 512 06F completely inhibited
the mycelial growth of S. sclerotiorum. Sumisclex inhibited the fungus by 89.07%. For
in vivo trials, preventative treatments, i.e., BAS 516 04F (133 g a.i. ha-1), BAS 516 04F
(266 g a.i. ha-1), BAS 512 06F (380 g a.i. ha-1), curative treatment, i.e. Sumisclex (760 g
a.i. ha-1) and a combination preventative/curative treatment, i.e., BAS 512 06F (380 g
a.i. ha-1)/Sumisclex (570 g a.i. ha-1) were investigated. No significant difference in
disease severity index (DSI) was found between fungicide treatments and the inoculated
control. BAS 512 06F and BAS 512 06F/Sumisclex had significantly lower grain yields
(6.09 g and 5.96 g, respectively) compared to all other treatments. There was a positive
correlation coefficient (R2=0.76), between DSI and grain yield, indicating that a high DSI
is correlated with low grain yield.
Trials to evaluate the effect of commercially available and currently unregistered seed
treatments for the control of S. sclerotiorum on soybean seeds in vivo and in vitro were
performed. Seed germination tests were performed to determine if seed treatments had
any negative effects on seed germination in vitro. All seed treatments tested, i.e., BAS
516 03F (8, 16 and 32 ml a.i. 100 kg-1 seed), BAS 512 00F (7.5, 15 and 32 ml a.i. 100
kg-1 seed), Celest XL (100, 125, 200 and 250 ml a.i. 100 kg-1 seed), Sumisclex (5 and 10
ml a.i. 100 kg-1 seed), Benomyl (150 g a.i. 100 kg-1 seed), Captan (240 ml a.i. 100 kg-1
seed), Thiulin (180 g a.i. 100 kg-1 seed) and Anchor Red (300 ml a.i. 100 kg-1 seed),
showed no negative effect on seed germination. For in vivo trials, BAS 516 03F (16 and
32 ml a.i. 100 kg-1 seed), BAS 512 00F (7.5, 15 and 32 ml a.i. 100 kg-1 seed), Celest XL
(100, 125, 200 and 250 ml a.i. 100 kg-1 seed), Sumisclex (5 and 10 ml a.i. 100 kg-1
seed), Benomyl and Anchor Red had significantly similar percent germination and
percent seedling survival as the untreated/uninoculated control. These seed treatments
should be recommended for the control of S. sclerotiorum, as they protected seed
during germination and subsequent seedling development. BAS 516 03F (8 ml a.i. 100
kg-1 seed) should not be recommended for the control of SSR, as it gave the lowest
percent germination and percent seedling survival.
The results presented in this thesis have helped to identify optimal environmental
conditions for the development of S. sclerotiorum, which is important for the
development of forecasting models for disease control. The least and most susceptible
cultivars of those tested have been identified. Biocontrol using Eco77® as a foliar
application showed great potential.
The effect of Si needs to be further investigated, including the testing of more frequent
applications and higher concentrations. The fungicides tested in this research did not
show any potential for the control of SSR. However, the spray programme tested is for
the control of soybean rust (Phakopsora pachyrhizi), and was investigated for its
potential for the control of SSR. The spray programme, fungicide application and rating
scale needs to be modified, to determine the true potential of these fungicides for the
control of SSR. Numerous seed treatments have shown potential for the control of seed
infection by SSR. Due to difficulties in producing ascospores, which are the primary
source of inoculum for this pathogen in the field, all studies in this research were
conducted with mycelia and not ascospores. The production, collection and storage of
ascospores needs to be thoroughly investigated, and research conducted with
ascospores. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.
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Inibição do crescimento micelial de Macrophomina phaseolina (Tassi.). Goid por óleos vegetais. / Inhibition of mycelial growth of Macrophomina phaseolina (Tassi.).UGULINO, Andressa Lacerda Nóbrega 03 May 2018 (has links)
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Previous issue date: 2017 / O fungo Macrophomina phaseolina (Tassi.). Goid é o agente etiológico de uma das principais doenças na cultura do feijão-caupi, vulgarmente conhecida como podridão cinzenta do caule. Em decorrência da falta de produtos fitossanitários registrados para o controle desta doença um aumento na busca por métodos de controle alternativo é cada vez mais comum. O objetivo do presente trabalho foi avaliar o efeito de óleos essenciais sobre o crescimento micelial do fungo M. phaseolina. Os óleos testados foram de hortelã (Mentha sp.), eucalipto (Eucalyptus spp.), copaíba ( Copaifera sp.) e alecrim-da-chapada (Lippia gracilis), nas concentrações 0,4; 0,6; 0,8 e 1,0%. Os óleos foram incorporados ao meio de cultura do tipo BDA e posteriormente vertidos em placas de Petri de 90x15mm, após a solidificação do meio, discos de 8mm contendo o micélio do patógeno foram repicados para as placas com os respectivos tratamentos. O experimento foi conduzido no delineamento experimental inteiramente casualizado (DIC) em arranjo fatorial 4 x 4 + 1 +1, sendo dezesseis tratamentos mais uma testemunha negativa e uma testemunha positiva que constou da aplicação suplementar no meio (BDA) do fungicida Sportak 450 EC (Procloraz), e cinco repetições, totalizando 90 parcelas experimentais. Posteriormente todas as placas foram transferidas para incubadora do tipo B.O.D. (biochemical oxygen demand) a 27 ± 2 ºC. Foram realizadas medições diárias do diâmetro da colônia em dois sentidos perpendiculares até que tomasse toda a superfície do meio de cultura de uma das placas. Os dados obtidos foram interpretados por meio de análise de variância não paramétrica e as médias foram comparadas pelo teste de Kruskal-wallis, a 5% de probabilidade de erro e Scott Knott a 5% de probabilidade nos casos em que existiram
diferenças significativas e normalidade dos dados. Os óleos essenciais de hortelã e alecrimda-chapada apresentaram melhores resultados quanto a inibição do crescimento micelial, enquanto que os óleos de eucalipto e copaíba apesar de potencialmente promissores, apresentaram inibição intermediária do crescimento micelial do fungo. / Macrophomina phaseolina (Tassi.). Goid is the etiological agent of one of the major diseases in cowpea bean crop, commonly known as gray rot stem. Due to the lack of registered phytosanitary products to control this disease, the search for alternative control methods is increasingly common. The objective of this study was to evaluate the effect of essential oils on the mycelial growth of M. phaseolina. The oils tested were Mentha sp.,Eucalyptus spp., Copaifera sp., and Lippia gracilis at concentrations of 0.4; 0.6; 0.8 and 1.0%. The work was conducted in Phytopathology Laboratory of the Federal University of Campina Grande. Daily measurements of the colony diameter were performed in two perpendicular directions until it filled the entire surface of the culture medium of one of the plates. The experiment was conducted in a completely randomized experimental design in a factorial arrangement 4 x 4 + 1+1, with sixteen treatments plus one negative control and one positive control, which consisted of the supplemental application in the medium (BDA) of the fungicide Sportak 450 EC (Procloraz), and five replications, totaling 90 experimental plots. The data were interpreted through non-parametric analysis of variance and the means were compared by the Kruskal-wallis test, with a 5% probability of error and Scott Knott at 5% probability in cases where there were significant differences and data normality. The Mentha sp. essential oil and Lippia gracilis showed better results in inhibiting mycelial growth, while the Eucalyptus essential oil and Copaifera, although potentially promising, showed intermediate inhibition of fungal mycelial growth.
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