Cause The soilborne fungus, Fusarium oxysporum f. sp. betae. This pathogen can survive many years as hardy spores (chlamydospores) in soil or can persist as colonized plant debris. It also can survive on many weedy hosts. Periodically, the disease can be severe.
Symptoms Often noticed first is interveinal yellowing on older leaves, mimicking nutrient deficiency. As the disease progresses, younger leaves also may yellow. Frequently, only one side of affected leaves shows yellow. Affected areas turn brown, dry, and brittle and may break off in wind, leaving a tattered appearance. Plants may be stunted and show wilting. Root vascular tissue shows brown discoloration. Sometimes, the root tip may rot, causing lateral root proliferation.
- Practice longer rotations with good weed control.