Detection of black-foot and Petri disease pathogens in soils of grapevine nurseries and vineyards using bait plants

Little information is currently available regarding the number of species of black-foot and Petri disease pathogens present in soil and their capacity to infect grapevine roots and reach the xylem vessels. Seedlings of grapevine rootstock 41-B, and cvs. Bobal and Palomino were planted both in pots containing soil samples collected from commercial vineyards and in nursery fields. Roots and xylem vessels were later analyzed for fungal isolation. Black-foot pathogens: Ilyonectria alcacerensis, I. macrodidyma, I. novozelandica and I. torresensis were frequently isolated from roots of seedlings grown in all soils evaluated, whereas Petri disease pathogens: Cadophora luteo-olivacea, Phaeoacremonium aleophilum, Pm. parasiticum and Phaeomoniella chlamydospora were only isolated from xylem vessels of seedlings grown in nursery soils, with a low incidence. Ilyonectria alcacerensis, I. novozelandica and I. torresensis were isolated for the first time from grapevines in Spain, and Pm. parasiticum and Ca. luteo-olivacea were detected for the first time in nursery soils. Our results confirm nursery and vineyard soils as an important inoculum source for black-foot pathogens and demonstrate the presence of several Petri disease pathogens in nursery soils.