Cylindrocladium
Fungi belonging to the genus Cylindrocladium
attack over 100 woody ornamentals including azaleas, rhododendrons,
camellias, junipers, white pine, and holly. Many foliage plants
including asparagus ferns, palms, and spathiphyllum are susceptible
as well. Depending on the host plant and species of Cylindrocladium
involved, damping-off, wilt, root rot, stem canker, crown rot, or
leaf spot may occur.
Symptoms
- Azalea
- Outer root tissues die and root vascular tissue
is discolored. Discoloration of vascular tissue may extend 2.5
cm (1 in) above soil line but seldom more. Root rot results in
wilting even in plants several years old. Leaves turn brown and
black and then fall. Cuttings may rot at base but roots develop
above the rot. These plants often die after potting.
- Rhododendron
- Stem and crown cankers form.
-
- White Pine
- Damping-off of seedlings. Root and stem cankers
develop.
-
- Holly
- Very small chlorotic leaf spots become purplish-black
in color and have a light green halo. Leaves fall even if only
one or a very few spots form. Twig dieback occurs if defoliation
is severe.
-
- Ferns (Polystichum,
Dryopteris, Nephrolepis)
- Reddish-brown leaf spots form at the base of petioles.
Brown to black leaf spots have yellow halos.
-
- Spathiphyllum
- Older foliage wilts and yellows. Roots die allowing
the plant to be easily removed from the soil. Sunken black spots
form at the base of petioles. Brown to black leaf spots have yellow
halos.
Cylindrocladium-caused
diseases are favored by humid, warm, 23-27°C (75-80°F),
conditions and overhead irrigation. Overfertilization and other
plant stresses may contribute to the problem.
Management
- Nursery
- Plant Cylindrocladium-free
seedlings.
- Pot in sterile mix.
- Propagate from only healthy stock plants since
the disease spreads rapidly in most propagation beds.
- Rogue out and destroy infected plants.
- Rake and destroy fallen leaves.
- Apply thiophanate methyl (Clearys 3336*, SysTec
1998, Domain FL*), chlorothalonil (Daconil*), mancozeb (Dithane*),
or triflumizole (Terraguard*) to protect healthy plants.
- Avoid overhead watering.
- Home or Commercial Planting
- Remove and destroy severely affected plants.
*Trade name
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