Cause Fusarium oxysporum f. sp. asparagi, F. proliferatum, and F. redolens, fungi that persist in soil and can be seed-transmitted. High soil temperatures (optimum about 82°F) favor the disease, which is more severe on plants in light soils. Low soil pH, poor soil drainage, or low levels of available Mn in soil may all favor disease. A high soil K to Mg ratio, if it creates a Mg deficiency, is associated with disease. These soil factors may negatively impact plant growth, making plants more susceptible.
Symptoms Yellowing, stunting, and wilting of the stalk and ferns. Reddish lesions can develop on stalks bases. Rusty red discoloration of vascular bundles can be detected in roots, crowns, or stems. Fine roots rot away while storage roots eventually collapse from rot. Rot of the crown leads to plant death.
- Rotate with grasses and cereals.
- Plant only transplants grown from treated seed on clean ground.
- Avoid planting crowns too deeply in the ground,
- The cultivars 'UC72', 'UC500', and 'UC66' are moderately resistant in California but not in eastern Washington.
- NaCl fertilization has been reported to reduce root lesions by promoting changes in the rhizosphere (root-soil interface).
Chemical control Soak clean (free of soil), loosely packed crowns in a continuously agitated fungicide suspension for 5 min. Drain and plant immediately.
- Manzate 75 DF at 1 lb/100 gal water. Wash dirty crowns before dipping. 24-hr reentry.
- SoilGard 12G at 0.5 to 10 lb/A at 4-week intervals can suppress Pythium and Rhizoctonia, and perhaps Fusarium. See label for specific application types and timings. Can be applied on the day of harvest. O
References Elmer, W.H. 2003. Local and systemic effects of NaCl on root compositions, rhizobacteria, and Fusarium crown and root rot of asparagus. Phytopathology 93:186-192.
Hamel, C. et al. 2005 Factors associated with Fusarium crown and root rot of asparagus outbreaks in Quebec. Phytopathology 95:867-873.