RESULTS
Isolation and identification of Pythium We could recover 11 isolates of Pythium from samples collected from the normal appearance roots of lettuces and the infected ones that showed symptomatic disease appearance. Results are summarized in Table 1. It was found that the Gy-S-4 isolate caused the highest percentage (94.2%) of infection in plants, whereas only 89.9% of infected plants were caused by the isolate Ry-S-4.
Comparing its nucleotide sequences subsequently identified the Gy-S-4, and it was suggested as P. aphanidermatum (data not shown).