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 thiophanate methyl, chlorothalonil, mancozeb, copper, or triflumizole to protect healthy plants
Avoid overhead watering
Home or Commercial Planting
Remove and destroy severely affected plants
Active Ingredients and Trade Names of the Chemicals
|FRAC Group No.
||REI Restricted Entry Interval
||Trade names (EPA Reg. no.)
||12||3336 (1001-69), OHP 6672 (51036-329-59807), Fungo Flo
Systec 1998 (48234-12)
|2||3||Dicarboximide||prodione||12||Chipco 26GT (100-1138), Chipco 26019 (264-481), Iprodione (51036-361),
||Daconil (50534-9), Exotherm Termil (70-223)
||Echo (60063-7), PathGuard (60063-7-499), Concorde (72167-24-1812), Pegasus
||Camelot (1812-381), Phyton 27 (49538-3)
||Kocide (352-656), Champion (55146-1)
||Dithane (707-180), FORE (707-87), Pentathlon (1818-251)
|manganese + zinc
||Protect T/O (1001-65)
|Combined 1 products
|thiophanate methyl + chlorothalonil
||Spectro 90 (1001=72)|
||thiophanate methyl + mancozeb
Fungicides and Fungicide Resistance Management
Certain fungicides, usually systemic fungicides, are said to be 'at risk' to the development of resistance if they are used repeatedly. See the Risk Level in the above table (1 = low risk; 3 = high risk). The Fungicide Resistance Action Committee has developed a numbering system in which chemicals with the same FRAC Group number have the same mode of action (See http://www.frac.info/frac/index.htm ). It is recommended that chemicals at high risk be used sparingly and in rotation or mixed with chemicals with different modes of actions (different FRAC number).
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.
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