Symptoms and Control Methods
Symptoms
Also known as cabbage yellows or wilt disease.
It mainly attacks
cruciferous vegetables such as cabbage, Chinese kale, cauliflower, etc.
Infected plants show wilting, stunting, and yellowing.
On Chinese kale and heading cabbage, leaf margins turn purple and leaf bases become brown.
Lower leaves drop one after another.
Vascular bundles in infected leaves and stems turn black, extending from the base toward the leaf margins, which distinguishes it from black rot.
Pathogen
Fusarium oxysporum f.sp. conglutinans (Wollenw.) Snyd. et Hans.
A fungus belonging to Deuteromycetes.
- Stroma and mycelium: initially white, gradually turning brown to pink.
- Macroconidia: scarce, cylindrical to fusiform, both ends pointed, basal spur present, mostly 2–3 septa,size 25–33 × 3.5–5.5 μm.
- Microconidia: abundant, ovoid to elliptical, unicellular,size 6–15 × 2.5–4 μm.
- Chlamydospores: terminal or intercalary.No sporodochia, synnemata, or sclerotia produced.
Transmission and Disease Conditions
The pathogen survives in the soil.
In dry years, excessively high or prolonged soil temperature burns roots in the plow layer and slows secondary root growth, impairing water uptake and causing root suberization and disease.
Outbreaks often occur in some years or under off‑season cultivation in Shaanxi, Hubei, Sichuan, etc.
It has become an important disease in cruciferous crop production.
Control Methods
Use resistant varietiese.g., Changchun Kuai Cai, Shenyang Kuai Cai, Jiyan No. 3, Danza No. 1 rapeseed, etc.
Sow at proper timeAvoid early sowing; try to avoid high‑temperature and dry seasons.
Improve field managementPractice moderate hardening‑off.
Prevent soil drought at the seedling stage.
Irrigate frequently to cool the soil when soil temperature is high, ensuring normal root development.
Chemical controlSpray or drench with the following fungicides at about 10‑day intervals, 1–2 times:
- 40% Carbendazim·Sulfur SC, 600–700×
- 50% Thiophanate‑methyl·Sulfur SC, 800×
- 50% Mixed Sulfur SC, 500×
- 20% Sodium Dichloroisocyanurate (Cai Jun Qing) SP, 400×
- 12.5% Enhanced Carbendazim Concentrate SL, 200–300×Apply 100 mL per plant.
Plant growth regulatorsSpray leaves 2–3 times with:
- Yunda‑120 plant growth regulator, 3000×, or
- Fuer 655 liquid fertilizer: 80 g/667 m² in 30 kg water.
Nutrient solutionsApply Plant Power 2003 nutrient solution or Huangye Su Lü (Yellow Leaf Green‑up agent).
