VIEW ARTICLE

Etiology

Common Hosts for Fusarium oxysporum formae speciales spinaciae and betae. G. M. Armstrong, Research Associate, Department of Plant Pathology, University of Georgia, College of Agriculture Experiment Stations, Georgia Station, Experiment 30212; Joanne K. Armstrong, Research Associate, Department of Plant Pathology, University of Georgia, College of Agriculture Experiment Stations, Georgia Station, Experiment 30212. Phytopathology 66:542-545. Accepted for publication 10 November 1975. DOI: 10.1094/Phyto-66-542.

Inoculations of cultivars of spinach, beet, mangel, and Swiss chard with Fusarium oxysporum f. sp.spinaciae and f. sp. betae revealed common hosts in cultivars of sugar and garden beet. Due to common hosts, the wilt Fusarium from spinach and the one from beet are classified as race 1 and race 2, respectively, of F. oxysporum f. sp. spinaciae. Mangel and cultivars of Swiss chard were resistant to race 1 but susceptible to race 2. Cultivars of spinach and Lychnis chalcedonica were susceptible only to race 1. No external symptoms of wilt were noted on plants of spinach and sugarbeet after inoculation with 50 other ff. sp. and races of F. oxysporum. Forma specialis spinaciae race 1 was nonpathogenic on plants in 45 different species and cultivars of numerous genera, which have been useful in separating forms and races of F. oxysporum; f. sp. spinaciae race 2 was nonpathogenic on plants in 44 of these species and cultivars. All isolates of the sugarbeet Fusarium (race 2) from Colorado failed to produce macrospores in culture unless exposed to fluorescent light. This character was found in three collections made during a period of 26 years.