Four-week-old salvia (Salvia splendens F. Sellow `Red Pillar') seedlings were treated with 0 or 50 ppm paclobutrazol, followed 5 h later by 0, 1, 2, or 4 times (0×, 1×, 2×, or 4×, respectively) the recommended label rate of bendiocarb (0.6 g a.i./liter), a carbamate insecticide. Seven days after treatment (DAT), phytotoxicity ratings increased with bendiocarb rate on all plants, but 50 ppm paclobutrazol reduced damage at 1× and 4× bendiocarb. Paclobutrazol also improved plant recovery from phytotoxicity damage at 21 DAT. Bendiocarb decreased the height of plants not treated with paclobutrazol at 7, 14, and 21 DAT. Plants treated with 40 ppm paclobutrazol had lower maximum phytotoxicity damage at 14 DAT, and even better recovery at 21 DAT than plants treated with 20 or 60 ppm paclobutrazol. Plants treated with paclobutrazol 4 days before applying bendiocarb had lower maximum phytotoxicity ratings relative to controls than plants treated 8 days before, the same day as, or 4 days after bendiocarb application. Chemical names used: β- [(4-chlorophenyl)methyl]- α -(1,1-dimethylethyl)-1 H- 1,2,4-triazole-1-ethanol (paclobutrazol); 2,2-dimethyl,1,3-benzodioxol-4-yl-methylcarbamate (bendiocarb).
Herbicides can runoff during storms or irrigation and contaminate ponds that are used for irrigation. Overseeded turf areas are particulary vulunerable to low concentrations of herbicides in irrigation water. A greenhouse study was conducted to determine the phytotoxic concentration of simazine in irrigation water perenial ryegrass (Lolium perenne), creeping bentgrass (Agrostis palustris), and fine fescue (Festuca rubra). Irrigation of 6.5 mm of herbicide contaminated and uncontaminated water was applied to seeded pots during a six week period. Concentrations of water containing simazine levels of 0.0001. 0.01, 0.1 and 1.00 ppm were used. Visual injury and number of live seedlings were evaluated every seven days after the beginning of the treatments and a threshold concentration was determined. An immunoassay kit was evaluated for practicality to the golf industry. Species varied in their response to simazine concentrations and immunoassay diagnostic kits have potential for use in detecting phytotoxic simazine concentrations.
optimum dose to control zoospores from waterborne pathogens, such as Pythium and Phytophthora species ( Hong and Richardson 2004 ; Hong et al. 2003 ). The discrepancy between the effective dose and phytotoxicity threshold suggests that the suitability
Copper is one of the essential micro-nutrient elements for plants, but when in excess, is toxic to plants and other living organisms. Electrolytically generated copper and cupric sulphate are increasingly used by the greenhouse industry to control diseases and algae in hydroponic systems. However, there is little information regarding appropriate strategies for employing copper in greenhouse crop production. We investigated the physiological responses, growth and production of several ornamental crops (miniature rose, chrysanthemum and geranium) and greenhouse vegetable crops (pepper, cucumber, and tomato) with respect to Cu2+ concentration in the root zone. Tests were conducted using plants grown in nutrient solution, Promix and rockwool. Results showed that phytotoxic levels of Cu2+ were dependent on the crop species and growing substrate. Plants grown in nutrient solution exhibited symptoms of phytotoxicity at lower Cu2+ concentrations than those on the solid substrates. The ability of copper to control Pythium aphanidermatum and green algae was evaluated under both laboratory and greenhouse conditions. Copper was effective in suppressing green algae in nutrient solution, but did not control Pythium effectively. This presentation is a comprehensive summary of the research conducted over the last three years by our group on copper application in greenhouse systems.
paclobutrazol at 60 mg·L −1 were effective for height control and lateral branching ( Hilgers et al., 2005 ). Symptoms of phytotoxicity are a known issue with most plant growth retardants. The severity of phytotoxicity depends on plant species or cultivar and
to any treatment to minimize potential phytotoxicity. A untreated check was included for comparison. Wildflower species were at the following heights at the time of herbicide application: California poppy, 15.2 to 16.5 cm; common sunflower, 25.4 to 35
annual bluegrass postemergence when applied at 0.5 to 1 kg·ha –1 two to five times per year ( Flessner et al., 2013 ; Koo et al., 2014 ; Xiong et al., 2015 ). Despite various research, little has been published to date on the phytotoxicity of
). Oils applied to corn can damage the plant tissues if applied in a high enough dose ( Hazzard, 1998 ). The efficacy of oil treatments has been demonstrated in some experiments, but phytotoxicity or damage to the developing ear from reduced pollination
after treatment (WAT). The development of phytotoxicity was slower with the diesel compared with gasoline. Diesel killed the existing perennial ryegrass within 2 weeks leaving the dead leaf tissue with a greasy black appearance. The hydraulic fluid
A greenhouse study was conducted from Oct. 1999 through Feb. 2000, and Mar. 2001 through Apr. 2001, to determine the potential phytotoxic effects of selected insecticides on Spanish lavender (Lavandula stoechas L.), oregano (Origanum vulgare L. `Santa Cruz'), rosemary (Rosmarinus officinalis L.), St. Johnswort (Hypericum perforatum L. `Topaz'), wolly thyme (Thymus vulgaris L. `Wolly'), and nutmeg thyme (Thymus vulgaris L. `Nutmeg'). Insecticides used for the study were Beauveria bassiana Strain GHA, pyrethrin [+ piperonyl butoxide (PBO)], azadirachtin, potassium salts of fatty acids, two rates of cinnamaldehyde, paraffinic oil, and capsaicin. Visual observations of phytotoxicity were made 7 days after the final application. Pyrethrin, potassium salts of fatty acids, and both rates of cinnamaldehyde were consistently more phytotoxic than the other insecticides. Despite the phytotoxic effects from some of the insecticides, new growth that emerged following treatments compensated for the initial damage, and the herbs were still saleable.