Final diagnosis


Damping-off, Basal root rots (Oomycetes  Pythium spp. and Phytophthora spp.)

Outbreak of <i>Pythium</i> sp. on tobacco seedlings produced in the float water system. Note the browning of gradually rotting roots. (damping-off)
After having invaded and rotten the roots, the pathogen has colonised the stem causing the same damage in it. <i>Pythium aphanidermatum</i> (damping-off)
This root system is almost totally rotten. The vessels located at the taproot level are yellowish and several roots are brown ( P = main root or taproot, RS = secondary root, Co = cortex) <i>Pythium aphanidermatum</i> (damping-off)
The presence of oospores and sporangia in root tissues indicates infection by <i>Pythium</i> spp. <i>Pythium ultimum</i> (damping-off)