Pyricularia grisea (Cooke) Sacc. is the causal organism of blast, the most serious disease of ric... more Pyricularia grisea (Cooke) Sacc. is the causal organism of blast, the most serious disease of rice because of its devastating nature, widespread distribution and existence of several physiologic races. It occurs in epiphytotic conditions in all major ricegrowing regions of the world, as well as in Italy. Nowadays, no strategies in current use are based on the dynamics of airborne conidia, the most important means of dissemination of the pathogen, and chemicals and management practices are the only means of blast control. However, blast forecasting may open the possibility of more rational use of fungicides and blast simulation models might prove to be useful in predicting the potential for the disease. During three growing seasons (2002, 2003 and 2004) and in two different rice fields located in Northern Italy (Sali Vercellese, Vercelli Province and Castello d’Agogna, Pavia Province), concentrations of P. grisea airborne conidia were measured using automatic spore traps. Temperature...
St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) is used for lawns in southern Italy b... more St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) is used for lawns in southern Italy because it is much more resistant to biotic and abiotic adversities than other turfgrass species. Because few seeds are viable, this species is established by vegetative propagation. A new disease was noticed during the spring of 2002 and 2003 on cuttings of St. Augustinegrass growing in three greenhouses in eastern Sicily. The disease affected leaves and culms and caused a progressive drying of the plants. The infection was first seen on leaves as gray, necrotic spots that enlarged in high-humidity conditions to form oval, and later, spindle-shaped lesions. In association with the lesions, it was possible to observe fungal spore development and sunken areas with blue-gray centers and slightly irregular, brown margins with yellow halos. Spots were concentrated without specific arrangement along longitudinal veins and the midrib and at the base, tip, and margins of the leaf blade. Symptoms...
Blast, caused by Pyricularia grisea, is one of the most widespread and serious diseases of rice. ... more Blast, caused by Pyricularia grisea, is one of the most widespread and serious diseases of rice. The fungus is highly variable with respect to its infectivity. In order to define the Italian P. grisea population with respect to this variability, 45 different strains were analysed using rep-PCR (repetitive-element-based polymerase chain reaction). Statistical analysis of the results allowed the identification of 9 different lineages. Symptoms of brown spot (caused by Bipolaris oryzae), another disease of worldwide occurrence, are frequently mistaken with those of blast infection. PCR-based methods to distinguish brown spot from rice blast disease were developed. Preventive spraying with fungicides against blast is widely practiced in Italy; the use of these molecular methods to distinguish between the two diseases could lead to a more rational use of chemicals. (Resume d'auteur)
Pyricularia grisea (Cooke) Sacc. is the causal organism of blast, the most serious disease of ric... more Pyricularia grisea (Cooke) Sacc. is the causal organism of blast, the most serious disease of rice because of its devastating nature, widespread distribution and existence of several physiologic races. It occurs in epiphytotic conditions in all major ricegrowing regions of the world, as well as in Italy. Nowadays, no strategies in current use are based on the dynamics of airborne conidia, the most important means of dissemination of the pathogen, and chemicals and management practices are the only means of blast control. However, blast forecasting may open the possibility of more rational use of fungicides and blast simulation models might prove to be useful in predicting the potential for the disease. During three growing seasons (2002, 2003 and 2004) and in two different rice fields located in Northern Italy (Sali Vercellese, Vercelli Province and Castello d’Agogna, Pavia Province), concentrations of P. grisea airborne conidia were measured using automatic spore traps. Temperature...
St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) is used for lawns in southern Italy b... more St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) is used for lawns in southern Italy because it is much more resistant to biotic and abiotic adversities than other turfgrass species. Because few seeds are viable, this species is established by vegetative propagation. A new disease was noticed during the spring of 2002 and 2003 on cuttings of St. Augustinegrass growing in three greenhouses in eastern Sicily. The disease affected leaves and culms and caused a progressive drying of the plants. The infection was first seen on leaves as gray, necrotic spots that enlarged in high-humidity conditions to form oval, and later, spindle-shaped lesions. In association with the lesions, it was possible to observe fungal spore development and sunken areas with blue-gray centers and slightly irregular, brown margins with yellow halos. Spots were concentrated without specific arrangement along longitudinal veins and the midrib and at the base, tip, and margins of the leaf blade. Symptoms...
Blast, caused by Pyricularia grisea, is one of the most widespread and serious diseases of rice. ... more Blast, caused by Pyricularia grisea, is one of the most widespread and serious diseases of rice. The fungus is highly variable with respect to its infectivity. In order to define the Italian P. grisea population with respect to this variability, 45 different strains were analysed using rep-PCR (repetitive-element-based polymerase chain reaction). Statistical analysis of the results allowed the identification of 9 different lineages. Symptoms of brown spot (caused by Bipolaris oryzae), another disease of worldwide occurrence, are frequently mistaken with those of blast infection. PCR-based methods to distinguish brown spot from rice blast disease were developed. Preventive spraying with fungicides against blast is widely practiced in Italy; the use of these molecular methods to distinguish between the two diseases could lead to a more rational use of chemicals. (Resume d'auteur)
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