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No description available.

Podosphaera aphanis which causes powdery mildew of strawberry is of economic importance in strawberry production in United Kingdom as it affects yield and fruit quality. Silicon has been shown to reduce the severity of a number of plant diseases. In strawberry, the mechanism of suppression against powdery mildew remains uncertain. Therefore, it has been suggested that supplying silicon would help strawberry plants to absorb silicon and improve resistance against the pathogen. The silicon based wetter Omex SW7 was used and three different concentrations of silicon wetter were applied on the leaves of the strawberry plants (foliar application). Each treatment was applied at three different timings. Enhanced level of silicon was quantified by the Autoclave Induced Digestion (AID) method. Whilst the main study has used the variety Elsanta, other varieties have also been used. It was observed that the weekly application (total 5 sprays) of 3 different concentrations of Omex SW7 on leaves showed significantly (P<0.05) higher silicon concentrations compared to application 3 times in weeks 1, 3 and 5 or twice in weeks 1 and 5. Microscopic observations showed that weekly application of standard, high and very high concentrations of Omex SW7 significantly (P<0.05) increased the number and length of leaf hairs on both the upper and lower surfaces of strawberry leaves. The different varieties of strawberry used showed morphological changes in the leaves with regard to the density and length of leaf hairs. Untreated leaves from Rhapsody had no hairs on the upper leaf surface, but a low density of hairs was observed after treatment with the high concentration of Omex SW7. In this study, Omex SW7, a silicon based wetter was applied to the roots of strawberry plants (root application) and silicon accumulation and physical changes in leaves were assessed. Strawberry variety Elsanta was used in this experiment. Results revealed that weekly application (total 5 applications) of 2 different concentrations (standard and high) of Omex SW7 to roots showed significantly (P<0.05) higher silicon concentrations compared to application 3 times in weeks 1, 3 and 5 or twice in weeks 1 and 5. It was found that the weekly application of two different concentrations of Omex SW7 showed significantly higher (P<0.05) leaf hair numbers and significantly (P<0.05) longer leaf hair length on both the upper and lower surfaces of leaves compared to application 3 times in weeks 1, 3 and 5 or twice in weeks 1 and 5. The effect of foliar application of silicon and potassium carbonate to limit P. aphanis infection was examined in a field trial under polythene tunnel at Wisbech. Treatments were arranged in a randomised block design of 3 replicates. There were a total of 18 plots. There were six treatments and all treatments were applied to the strawberry variety Sonata. Results revealed that application of silicon based wetter Omex SW7 onto the leaf surface does result in accumulation of silicon in the leaves. The application of Omex SW7 has stimulated an increase in the number and length of leaf hairs in strawberry plants. Results showed that germinating ascospores and colonies were present in all plots before the trial was sprayed. Treatments with standard and high Omex SW7 significantly (P<0.05) reduced the number of germinating ascospores and colonies in this trial. However, Potassium carbonate alone gave some reduction in the number of colonies and germinating ascospores. Moreover, potassium carbonate mixed with silicon based wetter Omex SW7 significantly (P<0.05) reduced the number of germinating ascospores and colonies.

O mosaico rugoso, causado pelo begomovirus ToSRV, é uma das principais doenças do tomateiro. Neste trabalho avaliou-se a eficácia de quatro inseticidas, ciantranilliprole foliar, ciantraniliprole solo, espiromesifeno e tiametoxam no controle das infecções primária e secundária do ToSRV, em tomateiros, transmitido por Bemisia tabaci biótipo B. Os tratamentos, confinados separadamente em gaiolas a prova de insetos, foram: controle, representado por tomateiros sadios e infectados, pulverizados com água, mais insetos avirulíferos; infecção primária, simulada com tomateiros sadios pulverizados com inseticida, mais insetos virulíferos e infecção secundária, simulada com tomateiros sadios e infectados com o ToSRV, pulverizados com inseticida, mais insetos avirulíferos. Nenhum inseticida foi eficiente no controle da infecção primária. No caso da simulação da infecção secundária, 4% e 16% respectivamente, dos tomateiros tratados com os inseticidas ciantraniliprole solo e ciantraniliprole foliar foram infectados, contra 84% e 74% de tomateiros infectados nos respectivos controles. Para os tratamentos com os inseticidas tiametoxam e espiromesifeno, na simulação da infecção secundária, 58% e 62% dos tomateiros foram infectados, respectivamente, contra 66% e 74% de plantas infectadas nos respectivos controles. O uso racional de inseticidas que reduzem a infecção secundária associado com a eliminação de fontes externas de inóculo poderá contribuir para o manejo da doença. / The severe mosaic, caused by ToSRV begomovirus, is a major disease of tomato. This study evaluated the efficacy of four insecticides, sprayed cyazypyr, drench cyazypyr, sprayed spiromesifen and thiamethoxam on controlling primary and secondary infections by ToSRV to tomato plants, transmitted by Bemisia tabaci biotype B. Treatments were confined separately in proof insects cages, which were: control, represented by healthy and infected tomato plants sprayed with water and aviruliferous insects releasing; primary infection, simulated by healthy tomato plants with insecticide spraying and viruliferous insects releasing, and secondary infection, simulated with healthy tomato plants and ToSRV infected tomato plants, sprayed with insecticide, and aviruliferous insects releasing. None of the insecticides was effective in controlling primary infection. In the case of secondary infection simulation, 4% and 16% of the tomato plants treated with soil and foliar cyazypyr insecticides, respectively, were infected; against 84% and 74% of infected tomato plants in their respective controls. For treatments with thiamethoxam and spiromesifen insecticides spraying, in secondary infection simulation, 58% and 62% of tomato plants were infected, respectively, versus 66% and 74% of infected plants in their respective controls. The rational use of insecticides to reduce secondary infection associated with elimination of external sources of inoculum may contribute to disease management.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniv., 2002. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2004. / Härtill 5 uppsatser.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2007. / Härtill 5 uppsatser.

O mosaico rugoso, causado pelo begomovirus ToSRV, é uma das principais doenças do tomateiro. Neste trabalho avaliou-se a eficácia de quatro inseticidas, ciantranilliprole foliar, ciantraniliprole solo, espiromesifeno e tiametoxam no controle das infecções primária e secundária do ToSRV, em tomateiros, transmitido por Bemisia tabaci biótipo B. Os tratamentos, confinados separadamente em gaiolas a prova de insetos, foram: controle, representado por tomateiros sadios e infectados, pulverizados com água, mais insetos avirulíferos; infecção primária, simulada com tomateiros sadios pulverizados com inseticida, mais insetos virulíferos e infecção secundária, simulada com tomateiros sadios e infectados com o ToSRV, pulverizados com inseticida, mais insetos avirulíferos. Nenhum inseticida foi eficiente no controle da infecção primária. No caso da simulação da infecção secundária, 4% e 16% respectivamente, dos tomateiros tratados com os inseticidas ciantraniliprole solo e ciantraniliprole foliar foram infectados, contra 84% e 74% de tomateiros infectados nos respectivos controles. Para os tratamentos com os inseticidas tiametoxam e espiromesifeno, na simulação da infecção secundária, 58% e 62% dos tomateiros foram infectados, respectivamente, contra 66% e 74% de plantas infectadas nos respectivos controles. O uso racional de inseticidas que reduzem a infecção secundária associado com a eliminação de fontes externas de inóculo poderá contribuir para o manejo da doença. / The severe mosaic, caused by ToSRV begomovirus, is a major disease of tomato. This study evaluated the efficacy of four insecticides, sprayed cyazypyr, drench cyazypyr, sprayed spiromesifen and thiamethoxam on controlling primary and secondary infections by ToSRV to tomato plants, transmitted by Bemisia tabaci biotype B. Treatments were confined separately in proof insects cages, which were: control, represented by healthy and infected tomato plants sprayed with water and aviruliferous insects releasing; primary infection, simulated by healthy tomato plants with insecticide spraying and viruliferous insects releasing, and secondary infection, simulated with healthy tomato plants and ToSRV infected tomato plants, sprayed with insecticide, and aviruliferous insects releasing. None of the insecticides was effective in controlling primary infection. In the case of secondary infection simulation, 4% and 16% of the tomato plants treated with soil and foliar cyazypyr insecticides, respectively, were infected; against 84% and 74% of infected tomato plants in their respective controls. For treatments with thiamethoxam and spiromesifen insecticides spraying, in secondary infection simulation, 58% and 62% of tomato plants were infected, respectively, versus 66% and 74% of infected plants in their respective controls. The rational use of insecticides to reduce secondary infection associated with elimination of external sources of inoculum may contribute to disease management.

In the most recent years, many deep learning models have been used to identify and classify diseases of plant leaves by inputting plant leaf images as input to the model. However, there is still a gap in research on how to improve the accuracy of the deep learning models of plant leaf diseases. This thesis is about investigating various techniques for improving the MobileNetV2 model's accuracy for plant disease detection in leaves and classification. These techniques involved adjusting the learning rate, adding additional layers, and various data-augmented operations. The results of this thesis have shown that these techniques can significantly improve the accuracy of the model, and the best results can be achieved by using random rotation and crop data augmentation. After adding random rotation and crop data augmentation to the model, it achieved an accuracy of 94%, a precision of 91%, a recall of 96%, and an F1-score of 95%. This shows that the proposed techniques can be used to improve the accuracy of plant leaf disease detection and classification models, which can help farmers identify and treat plant diseases.