Fusarium solani association with branch and trunk cankers on citrus weakened by cold weather in Florida

Injury or inoculation of apparently healthy citrus trunk bark and wood with Fusarium solani immediately prior to and after the December 1983 freeze resulted in cankers similar to natural branch and trunk cankers which formed on trees following the freeze. Fusarium solani was consistently isolated from active lesions of natural and induced cankered bark. Phytophora spp. were not isolated from cankered tissue. Earliest cankers appeared as a water-soaked area under the bark around the point of inoculation, later F. solani sporodochia formed on the bark surface. Older cankers became dry and cracked but produced no gum. Canker size ranged from 10–90 cm vertical diameter in spring 1984 inoculations but were only several cm diameter following late summer inoculations. Active cankers developed again after inoculation following the January 1985 freeze. Similar cankers were produced on Hamlin sweet orange stems inoculated with F. solani.