Rhizopus stolonifer is a fungus that can cause stem and fruit rot in several crops. It is also a well-known bread mould. Rhizopus is usually visible as fluff on the surface of damaged plant parts. Often the black spore heads on the fungal hairs are visible with the naked eye. The fungus occurs naturally in the soil.
Contamination can occur through soil contact or contact with infested fruits. The fungus can grow rapidly under warm and humid conditions and the spores travel from plant to plant via the greenhouse air. The initial infection often occurs as a result of plant damage. In horticultural crops Rhizopus is most prevalent on fruits such as strawberry, tomato and eggplant but it can also cause rotten spots on the leaves and stems of pot plants.
Although Erwinia is often the primary cause of stem rot in sweet peppers, Rhizopus is also found in these rotten areas. Infected fruits can completely rot away within a few days, especially when products are packaged in foil. Infected fruits often leak sap, a typical characteristic of Rhizopus fruit rot.
Text and images: Groen Agro Control