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IOBC/WPRS Bulletin

Disease development is the cumulative effect of various factors on the host and pathogen whereby either a-biotic effects such as climate or beneficial microorganisms may affect the severity of the disease. Oidium neolycopersici is the causal agent of tomato powdery mildew; it causes powdery white lesions on the leaf surface, petioles and the calyx. Severe infections lead to marked reduction in fruit size and quality and to leaf wilt. A slight change in temperatures may allow either more severe disease (22 to 24°C change) or reduction in disease severity (26 to 28°C). Beneficial microorganisms can provide sufficient control, but they are sensitive to environmental conditions. A better understanding of the influence of environmental factors on pathogen – biocontrol agent interaction can help in improving their efficacy. The effect of microclimate on the development and survival of two powdery mildew antagonists was evaluated. When applied on detached leaves and incubated for 7-14 days at different temperatures, RH, and disease levels, the bacterium (B2) survival was poorer at high temperatures and low RH compared to the yeast (Y13). The microorganisms survived well at 10-15oC and high RH. Tomato plants were grown in a net house with climate regimes of high and low RH, and two disease levels were induced. Plants were sprayed weekly with the two microorganisms. The bacterium survived better under high RH as compared with lower RH and on leaves with powdery mildew as compared with symptomless leaves. The yeast was less affected by microclimate conditions, and survived well for 14 days even with a single application. We can conclude that the yeast survives better under different microclimate conditions. In the present study, various abiotic factors were found to affect different aspects of the tomato powdery mildew disease cycle. It was demonstrated that a slight change in microclimate conditions can affect the outcome of the interaction of plants with a pathogen, and of the plant-pathogen relationship with populations of control agents. The effects of climate change may be different in different plant-pathogen systems. Nevertheless, it is clear that such effects will occur and that adaptive measures need to be developed in order to respond to these expected changes.

פותח על ידי קלירמאש פתרונות בע"מ -
הספר "אוצר וולקני"
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תנאי שימוש
Climate effect on pathogen–biocontrol agents interaction in the tomato–powdery mildew (Oidium neolycopersici) pathosystem
78

Disease development is the cumulative effect of various factors on the host and pathogen whereby either a-biotic effects such as climate or beneficial microorganisms may affect the severity of the disease. Oidium neolycopersici is the causal agent of tomato powdery mildew; it causes powdery white lesions on the leaf surface, petioles and the calyx. Severe infections lead to marked reduction in fruit size and quality and to leaf wilt. A slight change in temperatures may allow either more severe disease (22 to 24°C change) or reduction in disease severity (26 to 28°C). Beneficial microorganisms can provide sufficient control, but they are sensitive to environmental conditions. A better understanding of the influence of environmental factors on pathogen – biocontrol agent interaction can help in improving their efficacy. The effect of microclimate on the development and survival of two powdery mildew antagonists was evaluated. When applied on detached leaves and incubated for 7-14 days at different temperatures, RH, and disease levels, the bacterium (B2) survival was poorer at high temperatures and low RH compared to the yeast (Y13). The microorganisms survived well at 10-15oC and high RH. Tomato plants were grown in a net house with climate regimes of high and low RH, and two disease levels were induced. Plants were sprayed weekly with the two microorganisms. The bacterium survived better under high RH as compared with lower RH and on leaves with powdery mildew as compared with symptomless leaves. The yeast was less affected by microclimate conditions, and survived well for 14 days even with a single application. We can conclude that the yeast survives better under different microclimate conditions. In the present study, various abiotic factors were found to affect different aspects of the tomato powdery mildew disease cycle. It was demonstrated that a slight change in microclimate conditions can affect the outcome of the interaction of plants with a pathogen, and of the plant-pathogen relationship with populations of control agents. The effects of climate change may be different in different plant-pathogen systems. Nevertheless, it is clear that such effects will occur and that adaptive measures need to be developed in order to respond to these expected changes.

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