Cercospora spp, Pseudocercospora  spp. 

General

• Fungi quite widely distributed in the world, very present in many countries on all continents. Several Sigatoka agents affect vegetables grown in tropical areas. They cause lesions on the aerial organs of plants, mainly the leaves, even the petioles and the stem. On leaves, they exhibit two types of behavior: some cause necrotic spots on which they fructify once the tissues are dead, others sporulate mainly on the underside of the leaf blade, on tissues that are still alive and in the form of a velvety purplish gray to black ("black cladosporioses"). They produce brown conidiophores and transversely septate hyaline conidia (Figures 1-3).
• More or less polyphagous fungi; several can be found on vegetable species of the same botanical family. Distrust, some can colonize tissue damaged by a primary invader.
• Rather observed in the open field.

• Sensitive botanical family (s)

Biology

• Preservation : on plant debris thanks to their mycelium, their spores and the mycelial stroma they form and whose viability is several months. They persist in the crop environment, probably on various cultivated or wild plant species: be wary of certain weeds belonging to the same botanical families as sensitive cultivated plants. Some perennialize on seeds ( C. capsici )
• Infection : germination of spores on the surface of polluted plant organs, and penetration of the germ tubes into the tissues via the stomata. Then the mycelium invades the tissues.
• Sporulation : production on injured lesions of septate brown conidiophores, bearing more or less elongated and septate hyaline conidia depending on the species.
• Dissemination : by spores by the wind over long distances (preferably Pseudocercospora ), by splashing water ( preferably Cercospora ) following rain and sprinkler irrigation, by workers and agricultural tools.
• Favorable conditions : humidity above all influences Sigatoka epidemics on vegetables. Contamination often occurs following wet periods, thanks to rainfall and sprinkler irrigation.

Protection

• There are differences in varietal susceptibility . Choose to grow the least susceptible varieties.
• Disinfect seeds if necessary ( C. capsici ).
• Use healthy plants .
• Establish crop rotations not involving sensitive crops, for 2 or 3 years.
• Destroy in the crop or nearby any spontaneous plant species that may harbor these fungi.
• Ensure good drainage of cultivated plots.
• Avoid too high planting densities in order to favor the aeration of the foliage.
• Avoid irrigation , prefer drip irrigation. If they are essential, carry them out in the morning so that the vegetation drains quickly during the day.
• Under cover, ventilate as much as possible.
• Do not allow workers to work while vegetation is wet.
• Get out of the crop and destroy the affected plants and especially the diseased fruits. Eliminate plant residues at the end of cultivation. Deep plowing can bury the remaining debris, this measure must be combined with a crop rotation .
• If necessary, spray fungicides taking into account authorized uses ( e-phy )