Crops
Biology, epidemiology
- Conservation, sources d'inoculum
M. phaseolina is able to be preserved in the soil for several years in the absence of susceptible hosts, in particular thanks to its sclerotia (figures 1, 2, 3, 6). These are very resistant, they withstand various difficult conditions, including temperatures above 55 ° C. The seeds and plant debris "host" or sclerotia are invaded by the mycelium (Figures 4 and 5), they also contribute to its conservation. M. phaseolina is also maintained thanks to alternative hosts , cultivated plants (tomato, pepper, eggplant, tobacco, potato, bean, chickpea, strawberry, okra, sunflower, corn, sorghum, soybean, alfalfa, white clover. .. ) or weeds .
- Penetration invasion
Mycelium in the soil or from sclerotia comes into contact with and penetrates the roots or stem tissues. It gradually invades them and gains the ships. Once firmly in place and having more or less degraded the tissues, the fungus produces more or less sclerotia depending on its location on the plant and the surrounding conditions. On the fruits, penetration takes place through a wide variety of injuries (growth cracks, sunburn, apical necrosis, insect bites, various shocks ) which are present on the portions of fruit in contact or not. of the ground
- Sporulation, dissemination
It can also form globular pycnidia (figure 7), with truncated ostioles, which produce hyaline, ellipsoid to oval conidia measuring 16-29 x 6-9 µm (figure 8).
The spread of M. phaseolina takes place via its sclerotia which are transported by tillage implements during tillage, but also by wind, rain and sprinkler irrigation (the origin of splashes, projections of soil particles). These structures also pollute the seeds which contribute to its dispersal.
The role of pycnidia and their conidia in the spread of the pathogen does not appear to be known.
- Conditions favorable to its development
The survival and activity of this fungus in the soil is influenced by mineral fertilization and organic amendments. Hot temperatures, around 28 to 35 ° C, and water stress favor its attacks. Its growth would be possible between 10 and 40 ° C.
- Conservation, sources d'inoculum
M. phaseolina is able to be preserved in the soil for several years in the absence of susceptible hosts, in particular thanks to its sclerotia (figures 1, 2, 3, 6). These are very resistant, they withstand various difficult conditions, including temperatures above 55 ° C. The seeds and plant debris "host" or sclerotia are invaded by the mycelium (Figures 4 and 5), they also contribute to its conservation. M. phaseolina is also maintained thanks to alternative hosts , cultivated plants (tomato, pepper, eggplant, tobacco, potato, bean, chickpea, strawberry, okra, sunflower, corn, sorghum, soybean, alfalfa, white clover. .. ) or weeds .
- Penetration invasion
Mycelium in the soil or from sclerotia comes into contact with and penetrates the roots or stem tissues. It gradually invades them and gains the ships. Once firmly in place and having more or less degraded the tissues, the fungus produces more or less sclerotia depending on its location on the plant and the surrounding conditions. On the fruits, penetration takes place through a wide variety of injuries (growth cracks, sunburn, apical necrosis, insect bites, various shocks ) which are present on the portions of fruit in contact or not. of the ground
- Sporulation, dissemination
It can also form globular pycnidia (figure 7), with truncated ostioles, which produce hyaline, ellipsoid to oval conidia measuring 16-29 x 6-9 µm (figure 8).
The spread of M. phaseolina takes place via its sclerotia which are transported by tillage implements during tillage, but also by wind, rain and sprinkler irrigation (the origin of splashes, projections of soil particles). These structures also pollute the seeds which contribute to its dispersal.
The role of pycnidia and their conidia in the spread of the pathogen does not appear to be known.
- Conditions favorable to its development
The survival and activity of this fungus in the soil is influenced by mineral fertilization and organic amendments. Hot temperatures, around 28 to 35 ° C, and water stress favor its attacks. Its growth would be possible between 10 and 40 ° C.