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;t of Fi~;
The first report of a Corynespora leaf spot of a foliage plant was made in 1973 on zebra
plant (Aphelandra squarrosa) (4). Since that time, Corynespora cassiicola has been identified as
the cause of leaf spots on weeping fig (Ficus benjamin) (3), lipstick vine (Aeschynanthus pulcher)
(1), china doll (Radermachera sinica), and African violet (Saintpaulia ionantha). Woody
ornamentals including azalea (Rhododendron obtusum) (6), hydrangea (Hydrangea macrophylla)
(6), and ligustrum (Ligustrum sinense) (5) have also been found infected by this pathogen over the
past 20 years. Most recently we have found that the same pathogen can cause a leaf spot and
stem rot of the bedding plant Salvia splendens.
Symptoms of Corynespora infection on salvias start as small black spots on leaves when
plants are no more than an inch tall. At this stage the disease can also cause damping-off due
to stem rot at the potting medium surface. Stem rot can occur on plants up to 12 inches tall in
Figure 1. Leaf spot of Salvia splendens Figure 2. Stem rot of Salvia splendens
caused by Corynespora cassiicola. caused by Corynespora cassiicola.
SProfessor of Plant Pathology, University of Florida, IFAS, Central Florida Research and Education
Center Apopka, 2807 Binion Rd., Apopka, FL 32703.
CORYNESPORA LEAF SPOT AND STEM ROT OF SALVIAS
A. R. Chase'
University of Florida, IFAS
Central Florida Research and Education Center Apopka
CFREC-Apopka Research Report, RH-93-12
6 inch pots. The rotted areas are usually within 3 inches of the potting medium and can be
covered with the black spores of the fungus. Overhead irrigation and rainfall splash these spores
all over the lower leaves and cause new leaf infections.
This disease is very common in both production and the landscape. Plants with an active
Corynespora infection will never fill in adequately making a poor showing in the landscape. Some
cultivars are very susceptible to stem rot and damping-off such as 'Empire Lilac' and 'Empire
Light Salmon'. Other cultivars are more susceptible to the leaf spot phase of the disease ('Red
Hot Sally'). Leaf spots can enlarge to 1/4 inch wide and sometimes have a bright yellow halo
surrounding the black center. When infections are severe, leaf loss is very common and plant
quality is drastically reduced. When Corynespora has been a problem in the landscape, use
resistant cultivars such as 'Fuego' to minimize losses in stand quality.
Only two reports of fungicide control have been made on ornamentals infected with C.
cassiicola. The first, on Ligustrum sinense, reported good control with benomyl, mancozeb,
chlorothalonil or thiophanate methyl (5). However, use of benomyl or thiophanate methyl for a
disease caused by C. cassiicola (or the related fungi Altemaria and Helminthosporium) is
questionable since these compounds have been shown to increase similar diseases on some
ornamentals. A test performed on weeping fig showed both mancozeb and chlorothalonil to
provide excellent disease control while benomyl failed to give control (2). At this time, iprodione
(Chipco 26019) is the only fungicide registered for use on salvias in Florida which could give good
control of this disease. Be sure to test all fungicides for safety before broad scale use on your
crops and follow labels for rates and intervals.
1. Chase, A. R. 1982. Corynespora leaf spot of Aeschynanthus pulcher and related plants.
Plant Disease 66:739-740.
2. Chase, A. R. 1983. Controlling Corynespora leaf spot of Ficus benjamin variegata.
Foliage Digest 6(11):10.
3. Chase, A. R. 1984. Leaf spot of Ficus benjamin caused by Corynespora cassiicola. Plant
Disease Note 68:251.
4. McRitchie, J. J., and Miller, J. W. 1973. Corynespora leaf spot of Zebra plant. Proc. Fla.
State Hort. Soc. 86:389-390.
5. Miller, J. W., and S. A. Alfieri, Jr. 1974. Leaf spot of Ligustrum sinense caused by
Corynespora cassiicola and its control. Phytopathology 64:255-256.
6. Sobers, E. K. 1966. A leaf spot disease of azalea and hydrangea caused by Corynespora
cassiicola. Phytopathology 56:455-457.