Fusarium yellows has recently (2002) been
identified in a radish stock seed crop in the
Columbia Basin of central Washington, causing
complete crop failure. Although the disease had
not previously been an identified problem in
radish seed production in the Pacific Northwest,
additional confirmed diagnoses of this disease
causing severe losses to radish seed crops in the
Willamette Valley of Oregon and the Columbia
Basin of Washington, warrant careful monitoring
and management because F. oxysporum has an
extended period of viability in the soil (at least 10-
15 years in some soils), the pathogen may be
seedborne, and the disease can have devastating
effects on a crop. F. oxysporum f. sp.
conglutinans is host specific to crucifers, with
several races identified. Race 1 infects a wide
range of crucifers, including radish. Race 2 is able
to infect radish and some other brassicas, but not
B. oleracea crops like cabbage, cauliflower, and
Brussels sprouts. Race 2 has also been designated
as F. oxysporum f. sp. raphani. Symptoms appear
as wilting and dieback of plants, often starting on
one side of the plant of even one side of the leaf,
accompanied by dark vascular discoloration. Root
symptoms appear as a dark discoloration and rot.
Severely infected roots readily become infested
with cabbage maggot (see Insect Pests below).
Crop rotation is critical as the pathogen is
soilborne.