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Plant Pathology Circular No. 187, April 1978
Fla. Dept. Agric. & Consumer Services
Division of Plant Industry
F. W. Zettler*, G. C. Wisler, and J. J. McRitchie
In 1975, the species of Philodendron accounted for 20% of Florida's 150 million dollar foliage industry. Philodendron scandens C. Koch & H. Sello subsp. oxycardium (Schott) Bunt., sometimes referred to as P. cordatum Hort., is without doubt the most widely cultivated of the philodendrons and constitutes a 4.2 million dollar industry in this State (1).
Dasheen mosaic virus was first described in 1970 in various aroids, including those ornamentals such as Aglaonema, Caladium, and Dieffenbachia (2, 3, 4). Recently, this virus was reported in P. scandens subsp. oxyeardium, and studies (Wisler, Zettler, unpublished) suggest that this virus may cause significant losses. Indeed, unidentified virus-like disorders of this plant have been reported since the late 1950s by the Division of Plant Industry (unpublished records), and it is likely that dasheen mosaic virus was responsible in some instances.
Fig.1. (114K) Philodendron scandens subsp. oxycardium leaves. A. Chlorotic banding characteristic of dasheen mosaic. B. Healthy leaves.
SYMPTOMS. The most obvious symptom of infection by dasheen mosaic virus in P. scandens subsp. oxycardium is the formation of chlorotic bands in the leaves, which are parallel to, but not delimited by, the veins (fig. 1A). Leaves with these symptoms are generally somewhat smaller than normal and may be distorted so that the typical heart-shape of the leaf is not apparent (fig. 2). Mosaic symptoms are most conspicuous on newly unfurled leaves and may fade as the leaves attain maturity. Symptoms may vary from plant to plant. In some cases, the vine length of infected plants may be reduced considerably with each leaf showing mosaic and/or distortion symptoms. In other instances, the reduction in vine length may be less apparent, and symptoms may be intermittently distributed along the vine.
Fig. 2. (66K) Philodendron plant with chlorotic banding and leaf distortion caused by dasheen mosaic virus.
CONTROL. Since dasheen mosaic virus can be transmitted in a stylet-borne manner to healthy plants by aphids (2, 3, 4), good insect control is important. Because this virus can be perpetuated indefinitely by vegetative propagation, cuttings should not be taken from virus-infected plants. As an added precaution, diseased plants should be rogued from nursery plantings and destroyed. At present, this virus does not seem to pose a serious threat to the philodendron industry if good insect control, sanitation measures, and healthy stock are used.
Reference to University of Florida/IFAS Pest Control Guides
*Plant Pathologist, University of Florida, IFAS, Gainesville, FL 32611.
Contribution No. 447, Bureau of Plant Pathology, P. O. Box 1269, Gainesville, FL 32602.
Literature Cited
1. Smith, C. N., and J. R. Strain. 1976. Market outlets and product mix for Florida foliage plants. Proc. Fla. State Hort. Soc. 89:274-278.
2. Zettler, F. W., M. M. Abo El-Nil, and R. D. Hartman. 1978. Dasheen mosaic virus. Commonwealth Mycological Institute Descriptions of Plant Viruses No. 191. (in press).
3.__________, M. J. Foxe, R. D. Hartman, J. R. Edwardson, and R. G.Christie. 1970. Filamentous viruses affecting dasheen and other araceous plants. Phytopathology 60:983-987.
4.__________, W. H. Ridings, and R. D. Hartman. 1974. Dasheen mosaic virus of foliage aroids. Fla. Dept. Agric. & Consumer Serv., Div. Plant Pathology Circular No. 140. 2p.
