Survival of Botrytis Cinerea in Southeastern Spanish Greenhouses

The relative importance of sclerotia and mycelia of Botrytis cinerea Pers ex Fr. as structures of survival in southeastern Spanish greenhouses was investigated. Sclerotia were not found in the SE region, neither on plant debris nor on living plant material, suggesting it may serve only a minor role in epidemic development. B. cinerea survived mostly as mycelium. The percentage of artificially inoculated tomato stem pieces from which mycelium was recovered, was used to quantify its survival rate. Outside the greenhouses, mycelium survived in 33% and 5% of the tomato stem pieces 110 days after inoculation in 1995 and 1997, respectively. After the same number of days inside the greenhouses, no mycelium was recovered from stem pieces in 1995, and in 1997 only 7% of the stem pieces contained mycelium. Survival of mycelium outside and inside the greenhouses was significantly (P < 0.05) different after 47, 83, and 110 days of exposure to field conditions in 1995, but they were not different in 1997. Under controlled conditions, mycelium of B. cinerea lost viability at 100% relative humidity at temperatures ranging from 5 to 40°C, suggesting that air temperature and relative humidity accounted for loss of viability of mycelium.