Fusarium javanicum Koorders in Israel.

Abstract

Fusarium javanicum Kds. has been isolated from wilted vegetable marrows and melons and from the soil of a citrus grove in Israel. The morphology of the species is described, and measurements and drawings of macroconidia are presented.In vitro tests showed thatF. javanicum failed to develop at either 12 or 40° C, and developed better at 24° C than 18 or 30° C. Mycelial growth on potato dextrose agar was always better at pH 7 than at pH 4.2. Darkness favored such growth to a marked extent only at 18° C and pH 4.2. In glasshouse inoculation tests one isolate ofF. javanicum from vegetable marrow proved clearly pathogenic to cucumber, melon, watermelon and marrow. Measurements of macroconidia have been made, for comparative purposes, on isolates ofF. javanicum var.ensiforme and ofF. solani f.cucurbitae furnished from abroad, and on isolates ofF. solani from cucurbits in Israel. Comparing the data for 3-septate macroconidia with those given in literature forF. solani and forF. javanicum and its var.radicicola and var.ensiforme, it is concluded that two groups can be distinguished: One group comprises, with one exception, all isolates ofF. javanicum and its varieties as well asF. solani f.cucurbitae, and is characterized by slender macroconidia. The other group is represented byF. solani with its typically sausage shaped conidia. It is concluded thatF. javanicum should be maintained as a species distinct fromF. solani. It is further suggested that what has been calledF. solani f.cucurbitae may have closer affinity toF. javanicum than toF. solani.