Characterization of the Fusarium Causing Pitch Canker of Southern Pines

SUMMARYThe cause of pitch canker of southern pines is Fusarium moniliforme var. subglutinans rather than F. lateritium f. sp. pini. Isolates of Fusarium from pine trees with symptoms of pitch canker are characterized by abundant production of microconidia on simple phialides and polyphialides which develop in complex, sympodially branching conidiophores. These isolates are pathogenic to slash and loblolly pine seedlings. Optimum temperature for growth in culture is 24 C. Five isolates of F. moniliforme var. subglutinans from pine paired with single ascospore isolates of Gibberella fujikuroi var. subglutinans from India formed fertile perithecia. Eight other Fusarium species, F. lateritium (G. boccata), F. moniliforme, F. solani (Nectria haematococca), F. tricinctum, F. equiseti, F. semitectum, F. oxysporum, and F. graminearum (G. seae), were also recovered from pine, but these were nonpathogenic or very weakly pathogenic to pine.