Gary W. Moorman, Professor of Plant Pathology
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.
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.
Stem and crown cankers form.
Damping-off of seedlings. Root and stem cankers develop.
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.
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.
caused diseases are favored by humid, warm, 23-27oC (75-80oF), conditions and overhead irrigation. Over-fertilization and other plant stresses may contribute to the problem.
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 a fungicide to protect healthy plants (Contact Cooperative Extension to obtain a list of fungicides currently recommended for use.
Avoid overhead watering
Home or Commercial Planting
Remove and destroy severely affected plants
Indepth, scientific treatment of this organism:
Crous, P. W. 2002. Taxonomy and pathology of Cylindrocladium (Calonectria)
genera. 294 pp. 320 b & w illustrations. APS Press. 1-800-328-7560) $69.00.
Notice: The user of this information assumes all risks for personal injury or property damage.
Warning! Pesticides are poisonous. Read and follow all directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams or ponds.
Issued in furtherance of Cooperative Extension work, Acts of Congress, May 8 and June 30, 1914, in cooperation with the U. S. Department of Penn State College of Agricultural Sciences research and extension programs are funded in part by Pennsylvania counties, the Commonwealth of Pennsylvania, and the U.S. Department of Agriculture.
Visit Penn State Extension on the web at extension.psu.edu.
Where trade names appear, no discrimination is intended, and no endorsement by Penn State Cooperative Extension is implied.
This publication is available in alternative media on request.
The Pennsylvania State University is committed to the policy that all persons shall have equal access to programs, facilities, admission, and employment without regard to personal characteristics not related to ability, performance, or qualifications as determined by University policy or by state or federal authorities. It is the policy of the University to maintain an academic and work environment free of discrimination, including harassment. The Pennsylvania State University prohibits discrimination and harassment against any person because of age, ancestry, color, disability or handicap, national origin, race, religious creed, sex, sexual orientation, gender identity, or veteran status. Discrimination or harassment against faculty, staff, or students will not be tolerated at The Pennsylvania State University. Direct all inquiries regarding the nondiscrimination policy to the Affirmative Action Director, The Pennsylvania State University, 328 Boucke Building, University Park, PA 16802-5901; Tel 814-865-4700/V, 814-863-1150/TTY.