Biology, epidemiology

• Conservation, source d'inoculum

The Fusarium spp. are preserved in the soil in particular on plant debris thanks to their chlamydospores. They can be stored there for a longer or shorter time depending on the species, often several years. The role played by their sexual form (both in ensuring their conservation and dissemination) is not often well known. The seeds can be infected and therefore ensure the sustainability and dissemination of certain Fusarium .

• Penetration, invasion

The hyphae of these fungi penetrate through the epidermis, or via wounds. It can take place via the peduncle and the stylar end. The mycelium in place in the tissues develops inter and intracellularly and invades and destroys them. Once in the fruit, it reaches the flesh and colonizes the cavity where the seeds are located, eventually infecting them.

• Sporulation dissemination

Many Fusarium sporulate profusely on damaged tissue or nearby: sporodochia (Figures 1 and 2), macroconids (Figures 3 and 4), microconidia, and chlamydospores may be formed. This potential inoculum represents important sources of contamination at the origin of the very easy dissemination of these fungi. They are dispersed in particular by wind, splash and runoff of water, equipment and tools. Note that during tillage, the inoculum is redistributed in the plot and disseminated by the tillage equipment.

The seeds can be contaminated and ensure their transmission and conservation.

• Conditions favorable to its development

The temperature conditions favorable to these fungi can fluctuate depending on the species. In general, mild temperatures and humidity are very favorable conditions for their parasitism.