The decline and death of strawberry plants in Spain was mainly attributed to three pathogens - Macrophomina phaseolina, Phytophthora cactorum and Fusarium spp.
Researchers from IFAPA in Seville (Spain) studied the inoculum sources of M. phaseolina and P. cactorum as well as the incidence of all three genres both in nurseries and open fields for three consecutive seasons.
"It emerged that M. phaseolina and P. cactorum inoculum sources were present both in fumigated production soils (50 and 20% respectively) and in nursery fumigated soils (47 and 15% respectively), even though the pathogen was not detected in mother nor runner plants."
The average incidence of M. phaseolina and P. cactorum in production plants is of respectively 4.2% and 3.7%. As regards Fusarium spp., inoculum sources have yet to be quantified, though tests showed that Fusarium oxysporum f. sp. fragariae (Fof) was absent. It also emerged that F. solani is the main pathogen of the Fusarium genre.
Researchers concluded that ineffectively fumigated soil and infected plants can be sources of inoculum of pathogenic agents for strawberries cultivated in Spain.
Source: Ana María Pastrana, María José Basallote-Ureba, Ana Aguado, Nieves Capote, 'Potential Inoculum Sources and Incidence of Strawberry Soilborne Pathogens in Spain', 2017, Plant disease.