White, frothy material sometimes exudes from cracks or holes in bark, commonly on elm, liquidambar (sweet gum), oak, and pittosporum.
Identification
Where exudate occurs on bark, the cambium and inner bark (phloem) may be discolored, mushy, or dead. The exudate has a pleasant alcoholic or fermentative odor.
Similar diseases include wetwood, or slime flux, which causes fluids on bark with a rancid, unpleasant odor. Foamy bark canker also causes discolored, oozing bark, but only on coast live oak, which may die back or be killed by the disease.
Life cycle
The foamy canker material appears for a short time during summer and typically on stressed trees.
Solutions
The cause of foamy canker, or alcoholic flux, is unknown, but apparently it is due to various bacteria and yeasts that colonize wounds. Providing plants with proper cultural care and preventing injuries to bark may help to prevent foamy canker.
