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Fusarium Yellows (or Wilt) - Fusarium
oxysporum
(many subspecies)  
 Clemson University, USDA Cooperative Extension Slide Series, www.ipmimages.org
 HOSTS: Broccoli and other
brassicas (cabbage, cauliflower, brussels sprouts, kohlrabi, kale); asparagus, celery, cucumber, pea, pepper, potato, radish, tomatoes, and dahlia. DESCRIPTION:
Fusarium
is a fungus that affects both seedlings and mature plants. It causes
top growth to wilt, yellow and die. Lesions form at plant base or
slightly below the soil line. Reddish-brown streaks appear in the root,
stems and leaf petioles. The earliest symptom is the yellowing of old
leaves, often on only one side of the plant. Fusarium is most
prevalent on acid, sandy soils. LIFE
CYCLE: Fusarium overwinters on seeds and plant debris or in the soil. Spores germinate
on susceptible roots through wounds, then spreads through xylem
tissues. It is especially active in growing, succulent plants. The
optimum temperature for spore production is 80°F.; spread of the
disease slows at either extreme. Fusarium remains in the soil
for several years, in some cases 10 years. CONTROLS:Preventative: Soak seeds (or, crowns, in the case of asparagus) in 1 part bleach to 4 parts water for 2 minutes, then rinse under running water for 1 minute. Cultural: Use a 5 - 7 year rotation. REMOVE AND DESTROY infected plants. Grow resistant varieties. In general, raise the pH to 6.5 – 7 if soil is acid. Use nitrate rather than ammonium nitrogen. Avoid poorly drained and cool soils. Biological: |
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