CHARACTERIZATION OF A VASCULAR WILT OF ERYTHROXYLUM-COCA CAUSED BY FUSARIUM-OXYSPORUM F-SP ERYTHROXYLI FORMA SPECIALIS NOVA

A new forma specialis of Fusarium oxysporum (F. oxysporum f. sp. eryth roxyli) pathogenic to Erythroxylum coca and E. novogranatense is descr ibed. The pathogen was isolated from the vascular tissue of diseased p lants from an Erythroxylum plantation in Hawaii. This pathogen causes vascular wilt symptoms and death in both E. coca and E. novogranatense plants as soon as 7 weeks after soil infestation. The pathogenicity o f seven isolates from the affected field was determined in field and g rowth-chamber studies. Genetic variation was not detected among the se ven Hawaiian isolates, using arbitrarily primed polymerase chain react ion. The seven isolates could be differentiated from a strain isolated from a diseased E. coca plant from South America. All Hawaiian isolat es and the South American isolate belonged to a single vegetative comp atibility group.