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D. J. Norman, Ph.D.*
University of Florida/IFAS
Central Florida Research and Education Center
CFREC-Apopka Research Report RH-96-5
The two most common pathogens affecting Spathiphyllum production are Cylindrocladium spathiphylli and Phytophthora parasitica; however, there are four additional pathogens which are encountered to a lesser extent, but under appropriate conditions can also cause extensive damage. These four additional pathogens are as follows: Myrothecium roridum; Rhizoctonia spp.; Sclerotium rolfsii; and Xanthomonas campestris pv. dieffenbachiae. All six of these pathogens can be controlled by following sound horticultural recommendations and with prudent pesticide applications.
Cylindrocladium spathiphylli: Cylindrocladium root rot is probably the most common disease affecting Spathiphyllum production. This disease is most prevalent during the warm summer months. Chlorotic lower leaves and a wilted appearance are usually the first symptoms observed with a Cylindrocladium infection. These symptoms are the result of extensive root damage caused by this pathogen. If roots of infected plants are examined, reddish-brown lesions can be found on newly infected roots. These lesions grow rapidly causing a total root collapse and later rot. Thousands of spores are produced in these infected root masses. If spores are splashed onto leaves, dime size circular brown necrotic lesions form surrounded by yellow halos.
Disease Management Practices: Spores are moved from plant to plant via water. Plants should never be set directly on the floor of production facilities. Large Spathiphyllum plants should be placed either on benches or (at minimum) on inverted saucers so that roots and soil do not come in contact with contaminated water. When infections are detected in a production facility, plants showing severe symptoms should be removed and remaining plants should be treated with triflumizole (TerraguardŽ).
Phytophthora root rot and leaf spot: Phytophthora parasitica is a common pathogen infecting Spathiphyllum plants. This pathogen colonizes soil and can gain access to production facilities via contaminated soil mixes or may gain access if plants are set onto soil surfaces.
Spathiphyllum plants infected with Phytophthora can exhibit leaf chlorosis, wilting, root die-back and discoloration similar to symptoms caused by Cylindrocladium. Phytophthora can spread to leaf surfaces by either zoospores, which are highly mobile spores capable of swimming across wet leaf surfaces, or via splashing contaminated soil onto leaf surfaces. When this happens, black lesions can appear on leaves; however, these lesions do not have the yellow halos characteristic of Cylindrocladium infections.
Disease Management Practices: Plants should always be kept on raised benches or on inverted saucers to avoid Phytophthora infestations. If infections are detected, leaf surfaces should be kept dry. Heavily infected plants should be discarded and remaining plants should be treated with either fosetyl aluminum (AlietteR) or metalaxyl (SubdueR). Occasionally, Spathiphyllum plants become infected with Pythium spp.; management and control practices are the same as those for Phytophthora.
Myrothecium leaf spot: Myrothecium roridum can cause severe damage to young Spathiphyllum leaves and stems. This pathogen is very opportunistic usually infecting small tissue-cultured plantlets or young plants which have been damaged by excessive handling, fertilizing or improper application of pesticides. Mounds of dark black spores (sporodochia) develop on infected tissue and thousands of spores are contained within these structures. Spores are easily spread between plants by splashing water.
Disease Management Practices: To lower spore concentrations it is advantageous to remove highly infected or dead plants. Applications of triflumizole (TerraguardŽ) or thiophanate methyl + mancozeb (ZybanŽ) should be applied to remaining plants.
Rhizoctonia root rot and Sclerotium rolfsii (Southern Blight): Both of these pathogens colonize soil readily and usually gain access to production facilities via contaminated potting mix. If potting mix components such as bark, compost or peat moss are stored on soil surfaces, these pathogens can readily grow into these products, thus contaminating future plantings. R. solani, under normal cultural conditions, produces few spores, although it may produce small hyphal mats (sclerotia) which can be splashed between plants. Sclerotium rolfsii forms many small hard round sclerotia which vary in color from yellow to brown.
Disease Management Practices: Both of these soil diseases should not be a problem in Spathiphyllum production if soil mixes and plants are kept off of the ground. However, if infections occur, highly infected plants should be discarded and remaining plants should be treated with PCNB (TerraclorŽ).
Xanthomonas campestris ps. dieffenbachiae: Necrotic water-soaked lesions develop on the leaf margins of plants infected with Xanthomonas. This particular bacterial disease is not usually a problem in Spathiphyllum production because most cultivated Spathiphyllum plants are produced via tissue culture. However, this pathogen has a very broad host range infecting most aroid species. Therefore, bacteria can become established on Spathiphyllum plants when they are grown in close proximity to other aroids such as Dieffenbachia, Anthurium, or Syngonium.
Disease Management Practices: The primary mechanism of movement of Xanthomonas within the nursery is in splashing water; therefore, limiting the amount of water on leaf surfaces is advantageous to disease control. When infected leaves are observed, these should be removed in order to lower inoculum in the nursery. If outbreaks occur, applications of fosetyl aluminum (AlietteŽ) will help slow the spread of infections within the production facility.
- Simone G, Elliott, M., and Mullin, R. 1994. Florida Plant Disease Control Guide, Volume 1. Plant Pathology Dept., University of Florida, Gainesville FL. 362 pp.
- Turf and Ornamental Reference for Plant Protection Products. 1995. 4th edition, C & P Press, N.Y., 747 pp.
*Assistant Professor of Plant Pathology, Central Florida Research and Education Center, 2807 Binion Road, Apopka, FL 32703-8504
Pesticides should be applied according to label directions.
Regardless of the
pesticide or mixture of pesticides used, it is
strongly recommended that the effects be evaluated on a few
plants, under your particular conditions before treating all plants.
Mention of a commercial
or proprietary product in this paper
does not constitute a recommendation by the authors,
nor does it imply registration under FIFRA as amended.
Reference to University of Florida/IFAS Pest Control Guides