ISHS Acta Horticulturae 532: International Symposium on Chemical and Non-Chemical Soil and Substrate Disinfectation
CHEMICAL DISINFECTION OF A SANDBED FOR CONTROL OF PHYTOPHTHORA NICOTIANAE |
| Authors: | T.M. O'Neill, D. Pye |
| Keywords: | Phytophthora, disinfectant, sandbed, root rot, Dieffenbachia |
| Abstract:
Container-grown ornamental plants stood on a contaminated sandbed can develop root disease, particularly from the root infecting fungi Phytophthora spp., Pythium spp., Rhizoctonia solani and Thielaviopsis basicola. Limited information is available on the relative effectiveness of disinfectants for controlling specific plant pathogens, or treating particular surfaces commonly found in commercial horticulture. Following continued problems with Dieffenbachia root rot, caused by Phytophthora nicotianae, on a commercial nursery where the crop was grown intensively on sandbeds, 11 chemical disinfectants were evaluated in vivo for their effectiveness in disinfecting sand. Treatments were applied as drenching sprays to naturally infested sand and to sand amended with pieces of Phytophthora-infected Dieffenbachia roots and effectiveness determined in pots of Dieffenbachia placed on the treated areas. No fungicides were applied to the plants. Symptoms of Phytophthora root rot were first observed after 4 weeks and at crop maturity 35% of plants on untreated sand were dead. Eight disinfectant products (based on: formaldehyde; glutaraldehyde; glutaraldehyde + a quaternary ammonium compound; a quaternary ammonium compound; dichlorophen; sodium hypochlorite; tar acids; hydrogen peroxide + peractetic acid) significantly reduced the incidence of phytophthora root rot and increased the number of marketable plants; formaldehyde and two glutaraldehyde-based products were particularly effective. Efficacy of most treatments was greatly reduced where added Phytophthora-infested roots were present in the sand. | |
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