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Phyllosticta Leaf Spot of Peperomia Species and C ltivars irLi6rlaida
A. R. Chase1 OCT J1 4 :987
University of Florida, IFAS
Central Florida Research and Education Center -40jiopf of Florida
CFREC-Apopka Research Report RH-83
Diseases of Peperomia have been described in the past including
Cercospora leaf spot, Phytophthora root and stem rot, and Pythium root
rot and stunting. Few other diseases have been reported on these
During 1982 a leaf spot disease of many Peperomia cultivars and
species was observed in commercial nurseries. Initial symptoms were
tiny black specks on immature and mature leaves. Occasionally, lesions
up to 1/2 inch with concentric rings of light and dark tissue occurred.
Since these symptoms were distinct from those caused by Cercospora sp.,
the following studies were undertaken to elucidate the causal agent of
this disease as well as possible chemical controls.
Isolation of the causal agent was attempted from lesions collected
from Peperomia argyreia (watermelon peperomia), P. caperata 'Emerald
ripple', and P. puteolata 'Fosteri'. Discrete, 1/16 to 1/4 inch wide
lesions were plated on standard culture media. Plates were incubated at
75F for 3 to 10 days under intermittent light (100 ft-c.).
Peperomias were obtained as 4-5 inch tall plants from commercial
growers. They were transplanted to 4 inch square plastic pots
containing steam-treated (1.5 hours at 1900F) Canadian peat and pine
bark (50% each) medium. The medium was amended with 7 lb dolomite, 10
lb Osmocote 19:6:12 and 1 lb Micromax per cubic yard. Plants were grown
in a glasshouse for 2 to 4 weeks prior to use with temperatures from 65
to 90F and a maximum light level of 1500 ft-c.
Inoculum was prepared using a 3-week old PDA culture of eagh
suspect pathogen. Conidial suspensions were adjusted to 1 x 10
conidia/ml. Plants were subjected to intermittent mist (5 seconds/30
minutes 12 hours/day) starting 24 hours prior to inoculation and
continuing until test completion. Five plants each of each species or
cultivar were mist inoculated or treated with water and placed in a
polyethylene bag for 3 days. The following species and cultivars were
tested: Watermelon peperomia; 'Emerald ripple'; 'Pixie'; 'Rainbow'; P.
griseoargentea; 'Golden gate'; 'Variegata'; 'Red-edge'; 'Fosteri'; and
Phyllosticta sp. was consistently isolated from symptomatic leaves
of Peperomias. Inoculation trials showed that only this organism caused
the original symptoms noted. Lesions appeared on most hosts within 3
days of inoculation and were 1/16 inch, irregularly shaped and dark
Associate Professor of Plant Pathology, Central Florida Research and
Education Center, 2807 Binion Road, Apopka, FL 32703.
brown or black (Fig. 1). Petiole infection and leaf abscission also
occurred on P. argyreia.
Efficacy of fungicides for controlling Phyllosticta leaf spot was
tested on Peperomia obtusifolia 'Golden Gate'. Plants were grown under6
the conditions described above. Peperomias were inoculated with 1 x 10
conidia/ml of one strain of the pathogen, 3 days after the initial
fungicide application. Ratings, consisting of number of lesions, were
taken 3 days after the final pesticide application. This test evaluated
mancozeb (Manzate 200 80WP) at 1.5 lb/100 gal, benomyl (Benlate 50WP) at
0.5 lb/100 gal, chlorothalonil (Daconil 2787 75WP) 1.5 lb/100 gal,
iprodione (Chipco 26019 50WP) at 0.5 lb/100 gal, and cupric hydroxide
(Kocide 101 77WP) at 1.5 lb/100 gal. Fungicides were applied three
times at weekly intervals. Noninoculated and inoculated treatments were
included with 10 plants used for each treatment.
Excellent control of Phyllosticta leaf spot of Peperomia
obtusifolia 'Golden Gate' was achieved with weekly sprays of Benlate or
Daconil 2787. Very good control was also achieved with Manzate or
Chipco 26019, while Kocide 101 provided no control of this disease
1. Alfieri, Jr., S. A. 1968. Cercospora and edema of Peperomia.
Proc. Fla. State Hort. Soc. 81:388-391.
2. Ark, P. A., and DeWolfe, T. A. 1951. Phytophthora rot of
Peperomia. Plant Dis. Rep. 35:46-47.
3. Chase, A. R., and Munnecke, D. E. 1978. Pythium root rot and
stunting of Peperomia obtusifolia var. variegata. Plant Dis. Rep.
4. Humphreys-Jones, D. R. 1980. Phytophthora nicotianae var.
nicotianae on Peperomia magnoliaefolia and Kalanchoe blossfeldiana.
Pl. Path. 29:98-99.
5. Munnecke, D. E., and Chandler, P. A. 1953. Some diseases of
variegated Peperomia. Pl. Dis. Rep. 37:434-435.
6. Suradhana, B. S., Ellett, C. W., and Schmitthenner, A. F. 1968.
Crown rot of Peperomia. Pl. Dis. Rep. 52:244.
Table 1. Efficacy of fungicides for controlling Phyllosticta
leaf spot of Peperomia obtusifolia 'Golden Gate'.
Treatment Rate lb/ Mean no.
100 gal lesions
Noninoculated -- 0 ay
Inoculated -- 20 d
Manzate 200 80WP 1.5 5 bc
Benlate 50WP 0.5 1 ab
Daconil 2787 75WP 1.5 2 ab
Chipco 26019 50WP 0.5 8 c
Kocide 101 77WP 1.5 18 d
XTreatments were applied weekly for a total of 3 weeks.
YMean separation within columns by Duncan's new multiple range
test, P = 0.05.
Figure 1. Phyllosticta leaf spot of Peperomia argyreia (Watermelon
peperomia) 7 days after artificial inoculation with Phyllosticta sp.