Pure cultures of F. solani were grown on potato dextrose agar (PDA) at 25 C in the dark for 10 d. Conidia (spores) were harvested from the agar surface by flooding with a sterile 150 mM NaCl solution. The suspension was filtered through a sterilized cheese cloth before being centrifuged at 500g for 10 min. After washing twice and re-suspending in 150 mM NaCl, the suspension of fungal conidia was counted under a microscope, diluted to the appropriate concentration and used for all experiments.