Department of Plant Pathology |
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Fusarium
Wilt and Crown Rot caused by species
of Fusarium (F. oxysporum and F. monilforme), is characterized
by the production of weak, spindly spears in the spring. As the season
progresses, shoots from severely infected crowns may exhibit a brilliant
yellow coloration and they may exhibit a limited amount of vascular
discoloration. Feeder roots are frequently rotted and dust colored,
with the discoloration extending into the storage roots. Stems infected
with the stem miner frequently exhibit extensive Fusarium lesions
near the soil line. Affected crowns are found to have a low number
of shoot buds and a reddish-brown discoloration of tissue when cut
in cross section. Damping-off is common in crown nurseries. Plants
weakened by adverse growing conditions and by extending harvest too
long are most severely affected by Fusarium wilt and crown rot.
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Rust caused by the fungus Puccinia asparagi, appears as red or brown
elongated spots on asparagus spears, shoots, or needles. The discoloration
is due to dusty fungus spores produced in small pustules; a reddish
color predominates at first but becomes blacking later in the season.
The discoloration can make entire plantins look like they ripened
prematurely. The rust fungus passes its entire life cycle on the asparagus.
Black weather-resistant spores overwinter on old asparagus stems and
stubble. Heavy dews favor development of the disease.
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