Cause Fusarium oxysporum f. sp. conglutinans) causes yellows of cabbage and other members of Brassicaceae. This fungus survives in soil as durable resting structures known as chlamydospores which can survive years between hosts. This pathogen can be spread through soil movement on equipment, tools, and footwear as well as infested soil being windborne or waterborne. Fusarium can also produce two additional spore types (macro- and microconidia) that can be moved with wind or water. This fungus can be seedborne and can be introduced into a new region through the movement of infected transplants or the sowing of infected seed. The severity of wilt disease on brassicas increases as soil temperature increases; disease may develop when the soil temperature is between 64°F to 96°F. Cabbage developed more severe symptoms in studies when day/night temperatures were between 72°F to 84°F, compared to cooler temperatures.
Symptoms Plants are susceptible at any stage. Early symptoms include yellowing of lower leaves, sometimes one-sided or V-shaped in appearance, and stunting of the plant. Leaves may die, and leaf yellowing as well as defoliation may progress up an affected plant. Wilting of plants is observed more commonly once flowering commences and yellowing spreads to younger leaves. Often the entire plant dies and remaining stems are silvery-tan in color. Dark-brown to blackish discoloration can found around vascular elements in roots. The vascular discoloration is commonly evident aboveground in plant stems and petioles, and may extend into the leaf veins. Vascular discoloration precedes wilting symptoms. A brown rot may develop on the tap root or the lower stem of affected plants. The root system may also be stunted with a brown rot of the lateral roots present.
Cultural control
- Plant pathogen-free seed in pathogen-free soil.
- Avoid establishment of seed fields in soils with high levels of plant residues or organic amendments.
- Time planting date to avoid warmer soil conditions.
- Remove and destroy infected plants.
- Clean soil from equipment, tools, and clothing after working in an infested field.
- Long rotations are required to rid infested ground of this; rotate out of susceptible crops for a minimum of 4 years.
Chemical control
- Regalia at 1 to 4 quarts/A as an in-furrow treatment. Does not benefit from the addition of an adjuvant. 4-hr reentry. O
Biological control
- Bexfond at 7 to 14 fl oz/A. O
- Double Nickel LC at 0.5 to 4.5 pints/A for soil application on 14- to 28-day intervals. Can be applied the day of harvest. 4-hr reentry. O
- Prestop WG as a soil drench or incorporation into growing medium. 4-hr reentry. O
- Stargus at 6 to 8 fl oz per 1,000 ft row as an in-furrow treatment, 3 to 4 quarts/A as a soil drench on 10- to 14-day intervals, or 3 to 4 quarts/A as a chemigation drip treatment on 14- to 21-day intervals. Preharvest interval is 0 days. 4-hr reentry. O
- Tenet WP at 2.5 to 5.0 lb/A at sowing will suppress certain fungal pathogens including Fusarium, Rhizoctonia, and Pythium spp. See label for specific application types and timings. 4-hr reentry. O
References Bosland, P.W., Williams, P.H., and Morrison, R.H. 1988. Influence of soil temperature on the expression of yellows and wilt of crucifers by Fusarium oxysporum. Plant Dis. 72 (9):777-80.
du Toit, L.J., and Pelter, G.Q. 2003. Wilt of radish caused by Fusarium oxysporum f. sp. raphani in Washington State. Online. Plant Health Progress. doi:10.1094/PHP-2003-0616-01-HN.
Jelínek, T., Koudela, M., Kofránková, V., and Salava, J. 2019. Effect of temperature on severity of Fusarium wilt of cabbage caused by Fusarium oxysporum f. sp. conglutinans. Eur. J. Plant Pathol. 155:1277-1286.1.
Morrison, R.H. 2007. Yellows (Fusarium Wilt). In: Rimmer, S.R., Shattuck, V.I., and Buchwaldt, L., editors. Compendium of Brassica Diseases. St. Paul, (MN): APS Press; p. 56-58.