A. R. Chase,
Professor of Plant Pathology,
University of Florida, IFAS,
Central Florida Research and Education Center - Apopka,
2807 Binion Rd., Apopka, FL 32703.
CFREC-Apopka Research Report, RH-93-14
Fungicides continue to be an important part of ornamental plant production. Preventative control of Rhizoctonia diseases frequently relies on use of fungicides on many ornamental crops. Rhizoctonia spp. are soilborne fungi that commonly cause aerial blight and stem rot. The fact that the pathogen occurs in the potting medium but causes above ground diseases makes the application site for a fungicide critical. Soil drenches are more effective against diseases of roots while foliar sprays are generally more effective against aerial blights and stem rots. The following table summarizes results of fungicide tests for control of Rhizoctonia diseases of ornamentals conducted in 1993.
Many of the fungicides were tested on a variety of ornamentals. In most tests with thiophanate methyl compounds (Domain, Cleary and Topsin M), good to excellent disease control was achieved. PCNB (Terraclor) and triflumizole (Terraguard) have been found to give excellent control on some plants (vinca and spathiphyllum) but only good control on others (pothos and impatiens). Iprodione (Chipco 26019) gave excellent control of Rhizoctonia stem rot on vinca when used as a drench and Rhizoctonia stem rot on impatiens when used as a spray. Both maneb (Maneb) and mancozeb (Penncozeb) gave good control of Rhizoctonia diseases of pothos and English ivy with excellent control on Boston fern. The experimental compound from Ciba (CGA-17506) gave excellent control of Rhizoctonia diseases on vinca and impatiens.
Comparisons of these results to those of previous years indicate that on many ornamentals a large number of highly effective alternatives continue to be available for Rhizoctonia control. Be sure to read labels, check for legal uses and remember to spray fungicides when the disease affects leaves and stems and drench them when the disease affects roots.
| Plant | Disease | Excellent control | Some control |
| Catharanthus (Vinca) |
Rhizoctonia stem rot |
CGA-17506 drench Chipco 26019 drench Terraclor drench Terraguard drench |
|
| Epipremnum (pothos) |
Rhizoctonia petiole rot |
Topsin M drench Cleary drench Maneb drench Penncozeb drench |
|
| Hedera (English ivy) |
Rhizoctonia leaf spot |
Benlate spray | Topsin M spray Cleary spray Penncozeb spray Maneb spray |
| Impatiens | Rhizoctonia stem rot |
CGA-17506 drench Terraclor drench Chipco 26019 drench |
Terraclor drench Terraguard drench |
| Nephrolepis (Boston fern) |
Rhizoctonia aerial blight |
Cleary spray Topsin M spray Penncozeb spray Maneb spray |
|
| Pittosporum | Rhizoctonia aerial blight |
Domain spray | Terraguard spray |
| Spathiphyllum | Rhizoctonia petiole rot |
Terraclor spray Terraguard spray |
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