Mallet wound canker of almond trees
Limb cankers that expand rapidly and often girdle and kill major limbs within three or four years are reported to be of increasing incidence in California almond orchards. One or several limbs may be attacked in a single season. Where the condition continues, the trees must be severely pruned or removed. The cankers are typified by a depression of the infected tissues and the production of an orange, frothy gum. The disease is frequently found in the Winters, Chico, and Rumsey areas and occasionally as far south as Stanislaus County. The Texas (Mission) variety is most susceptible to the cankers, as measured by the girdling and killing of branches, but Nonpareil, Peerless, and Ne Plus Ultra are often severely damaged. The Drake variety is less susceptible, and cankers on these trees apparently expand more slowly than the cankers on trees of the other varieties.