Images
Carrot (Daucus carota)
Cottony soft rot (Sclerotinia sclerotiorum). Greyish, white mold forms at the base of stem. Black round structures appear as disease progresses. Can extend underground to the root.
Leaf blight (Alternaria dauci). Small, irregular, black to purplish coloured spots. Spots may coalesce to cover the entire leaf.
Damping-off (Pythium spp.)