Fusarium Leaf Spot of Dracaenas-Resistance of Species and Cultivars

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University of Florida/IFAS
Central Florida Research and Education Center
CFREC-Apopka Research Report RH-93-10

A. R. Chase*

Summary

Sixteen species and cultivars of dracaenas as well as seven other ornamentals were evaluated for susceptibility to F. moniliforme, the cause of Fusarium leaf spot. The most susceptible plants were D. marginata, D. marginata 'Magenta', D. reflexa 'Song of Jamaica' (Pleomele reflexa), and bird's nest Sansevieria. D. marginata 'Colorama' was moderately susceptible to the pathogen while two other cultivars ('Bicolor' and 'Tricolor') were very slightly susceptible. Other Dracaena spp. were either resistant or very slightly susceptible. Aloe barbadensis (A. vera), Beaucarnea recurvata, Chlorophytum comosum, Ophiopogon sp. and Yucca elephantipes were resistant.

Introduction

Fusarium leaf spot of dracaenas was first described in 1940 on Sansevieria spp. Since that time, it has been found on many species of Dracaena. The pathogen is F. moniliforme and it causes leaf spots in the terminals of D. marginata. Spots are initially water-soaked and form on immature leaves when they are kept wet. These symptoms are most common on the young leaves of dracaenas and sansevierias. As the spots enlarge, they turn reddish-brown or tan and frequently have a yellow margin. Individual spots can be pinpoint size or as large as inch depending upon the host plant involved. In cases of severe infection, the bud becomes infected and dies.

This disease has been found on many dracaenas but the relative susceptibility of different species and/or cultivars has not been known. This information is critical to selection of the most resistant plants when Fusarium leaf spot is a problem. The following report summarizes two experiments performed to evaluate resistance of selected Dracaena species and cultivars to Fusarium moniliforme.

Materials and Methods

Two tests were performed in the spring of 1993. Ten plants of each of those listed in Tables 1 and 2 were used in each test. All plants were inoculated by spraying with a spore suspension of the pathogen and then monitored for symptom development for about 4 weeks. Plants were grown in a glasshouse on a raised bench. Light levels were about 3000 ft-c with temperatures ranging from 65°F to 90°F. Final data included the number of leaf spots as well as the type of symptom found on each plant. Some plants developed symptoms which could not readily be attributed to F. moniliforme. The cause of all symptoms was confirmed by isolating the pathogen.

Results

The most susceptible dracaenas were D. marginata and a cultivar, D. marginata 'Magenta'. The next most susceptible dracaena was D. reflexa 'Song of Jamaica' (Table 1). The cultivars of D. deremensis were either resistant or slightly susceptible and developed tiny yellowish spots. Dracaena fragrans 'Massangeana' was also slightly susceptible, while the cultivars of D. sanderana were resistant. Cultivars of D. surculosa were slightly susceptible but developed unusual symptoms characterized by large tan papery spots which formed where the leaf joined the stem (Table 1). The remaining ornamentals examined were resistant to inoculation with F. moniliforme except Sansevieria trifasciata 'Hahnii' (bird's nest sansevieria) which was moderately susceptible (Table 2).

Conclusions

Perhaps the most interesting finding of this study is that the D. marginata cultivars tested showed such a range of susceptibility to the pathogen. Both 'Bicolor' and 'Tricolor' were some of the most resistant plants tested while the standard D. marginata and 'Magenta' were the most susceptible plants tested. This information could be useful when selecting new cultivars of this species. In addition, it is advisable to avoid use of either D. marginata (standard) or 'magenta' if Fusarium leaf spot is a longstanding problem in your nursery. Finally, watch D. reflexa and Sansevieria when they are grown near other susceptible dracaenas since they are very susceptible to Fusarium leaf spot and can act as a source of infection.

*Professor of Plant Pathology, Central Florida Research and Education Center-Apopka, 2807 Binion Road, Apopka, FL 32703-8504.

References

1. 1. Chase, A. R. 1981. Update - Fusarium leaf spot of dracaenas and sansevierias. Foliage Digest 4(1): 14.
   2. Jones, L. K. 1940. Fusarium leaf spot of Sansevieria. Phytopathology 30:527-530.
   3. Wehlburg, C., and A. P. Martinez. 1967. Leaf spot of Dracaena marginata Lam. caused by Fusarium moniliforme Sheld. Proc. Fla. Sate Hort. Soc. 80:454-456.