Control of powdery mildew (Leveillula taurica) on tomato by foliar sprays of liquid potassium silicate (K2SiO3) (original) (raw)
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Journal of the …, 1992
The effect of soluble potassium silicate applied to cucumber (Cucumis sativus L.), muskmelon (C. melo L.), and zucchini squash (Cucurbita pepo L.) on the severity of powdery mildew was examined. Application methods included amending nutrient solutions to a concentration of 1.7 mM Si and foliar sprays containing 1.7, 8.5, 17, and 34 mM Si. Untreated plants and plants sprayed with distilled water were used as controls. The leaves of all plants were inoculated with known concentrations of conidia of Sphaerotheca fuliginea (Schlecht.:Fr.) Poll. (cucumber and mu&melon) or Erysiphe cichoracearum DC.: Merat (zucchini squash) 1 day after the sprays were applied. Inoculated leaves on plants receiving the Si-amended nutrient solution or foliar sprays of ≥ ≥ 17.0 mM Si developed fewer powdery mildew colonies than those on control plants. Results of a separate experiment that included a potassium spray, indicated that the active ingredient of the potassium silicate sprays appears to be Si. Experiments to test the persistence of Si foliar sprays on cucumber demonstrated that a 17 mM Si spray applied 7 days before inoculation with S. fuliginea reduced mildew colony formation.
Phytopathologia Mediterranea, 2011
Among foliar diseases of tomato grown in soilless systems, powdery mildew and grey mould (caused by Botrytis cinerea), are the most economically important in northern Italy. The causal agent of powdery mildew in greenhouse tomato crops is frequently Oidium neolycopersici, a pathogen which has spread into several tomato production areas in Europe, North America and Japan (Fletcher et al., 1988; Kiss et al., 2001, 2005; Matsuda et al., 2001), causing signifi cant damage. Despite considerable effort expended in the search for resistance in wild tomato species to powdery mildew (Lindhout et al., 1994; Laterrot et al., 1995; Ciccarese et al., 1998), most of the tomato hybrids available for commercial cultivation are susceptible to O. neolycopersici (Jones et al., 2001). Furthermore, few chemicals are registered for use in soilless crops. For these reasons, other methods of disease control need to be found. Many plant species accumulate silicon (Si) in their tissues and its benefi cial ro...
Effect of potassium silicate on epidemic components of powdery mildew on melon
Plant Pathology, 2011
The effects of silicon (Si) supplied in the form of potassium silicate (PS) were evaluated on epidemic components of powdery mildew of melon under greenhouse conditions. The PS was applied to the roots or to leaves. In the first experiment, epidemic components were evaluated after inoculation with Podosphaera xanthii. In the second experiment, the disease progress rate was evaluated on plants subjected to natural infection. The area under the disease progress curve was reduced by 65% and 73% in the foliar and root treatments, respectively, compared to control plants, as a consequence of reductions in infection efficiency, colony expansion rate, colony area, conidial production and disease progress rate. However, root application of PS was more effective than foliar application in reducing most of the epidemic components, except for infection efficiency. This can be explained by the high Si concentration in leaf tissues with root application, in contrast to the foliar treatment where...
African journal of agricultural research
The effect of concentration, frequency of application and runoff of foliar-applied soluble silicon (Si) on the severity of powdery mildew (PM) of zucchini (Cucurbita pepo L.) was evaluated. Soluble Si (250 to 1000 mgL -1), together with Break-Thru ® (0.25 ml/L), was sprayed onto zucchini plants at frequencies of 1 to 3 times per week. The leaves of all plants were inoculated with a known concentration of conidia of Podosphaera xanthii 2 days after the sprays were applied. The effect of runoff was determined by covering some of the pots with polyethylene sheets, while others were left uncovered. Spraying Si onto zucchini plants reduced the severity of PM significantly. The efficacy of Si was improved by increasing the spray frequency. The best results were obtained when the frequency of the treatment was increased, and when Si was allowed to reach the root zone of the plants. When Si was applied onto leaves, direct contact between the spray and the pathogen seemed to be the main mech...
Foliar applications of fertilizer salts inhibit powdery mildew on tomato 1
Canadian Journal of Plant Pathology, 2002
Foliar applications of a number of inorganic fertilizer salts were found to significantly reduce powdery mildew [Erysiphe orontii] on greenhouse tomato (Lycopersicon esculentum, cv. Trust) leaves. In a series of singleapplication experiments, the foliar applications, each with 0.1% surfactant, were applied to the third and fourth leaves of young tomato plants 24 h before inoculation with an atomized application of mildew conidia. Control treatments consisted of a water application and a water plus surfactant application. Powdery mildew colonies were counted 7-10 days later. Surfactant alone significantly reduced mildew colony numbers. CaCl 2 , Ca(NO 3 ) 2 , and K 2 HPO 4 reduced colony counts compared with the surfactant alone. All combinations of Ca salts, or Ca salts plus elemental S, significantly reduced mildew colony counts compared with surfactant alone. In a second set of experiments, the effects of repeated applications on already naturally infected tomato plants were evaluated. Young tomato plants were moved to a greenhouse containing several heavily mildew-infected tomato plants, allowing natural infection. The following day and every 7-10 days thereafter, treatments were applied to all leaves. Colony counts on selected leaves were made weekly or just before spraying. Surfactant alone was not as effective as in the single-application treatments, often having no effect. All the Ca-salt treatments that were effective in the single-application series were effective as multiple applications. Repeated applications of combinations of Ca salts were often just as effective as applications of elemental S. KCl, MgSO 4 , and K 2 HPO 4 also significantly reduced mildew counts with multiple applications. This study did not attempt to explain the differences or similarities in efficacy of the salts tested; both osmotic (concentration) and specific-ion effects could play a role.
Ceylon Journal of Science, 2016
Effect of soluble silicon (Si) on downy mildew in bitter gourd (Momordica charantia L.) leaves caused by Pseudoperonospora cubensis was tested using three concentrations of liquid potassium silicate (100, 200, 300 mg Si/kg) added to the growing medium containing top soil, compost and sand. Disease severity, plant growth parameters, silicon accumulation on leaves and cuticle-epidermal layer thickness of transverse sections of leaves were measured. Si treated plants exhibited less disease severity than that of control plants and 200 mg Si/kg treatment resulted in highly significant disease suppression (37-53% reduction against controls). The suppression of the disease strongly correlated with the Si accumulation in leaves. Cuticle-epidermis thickness was higher in Si-treated leaves (17.2-21.3 µm) against non-treated (10.3-13.81 µm). Numbers of leaves, flowers or fruits in Si treated plants were significantly higher (p < 0.05) than control plants except in 300 ppm Si level. Structural changes created by Si may at least be partly responsible for reducing the fungal disease severity in bitter gourd leaves.
European Journal of Plant Pathology, 2007
Foliar and root applications of different silicon (Si)-based formulations were evaluated for their effects in reducing powdery mildew and promoting growth of wheat plants. X-ray microanalyses of treated plants revealed that root applications resulted in consistent deposition of Si in the leaves. In terms of powdery mildew control, root applications at 1.7 mM Si gave consistently the best results, reducing disease severity by as much as 80%, regardless of the product used. Although less effective than root applications, foliar treatments with both Si and nutrient salt solutions led to a significant reduction of powdery mildew on wheat plants. This suggests a direct effect of the products on powdery mildew rather than one mediated by the plant as in the case of root amendments. In our experiments, Si amendment, either through the roots or the leaves, did not increase plant growth. These results lead to the conclusion that Si is primarily, if not exclusively, absorbed by the root system and that such absorption by the roots is necessary for an optimal prophylactic effect.
Evaluation of Silicon for Managing Powdery Mildew on Gerbera Daisy
Journal of Plant Nutrition, 2008
Powdery mildew, caused by Erysiphe cichoracearum or Podosphaera fusca, is a common disease of gerbera daisy (Gerbera jamesonii) grown in Florida. Previous studies demonstrated that silicon reduces powdery mildew in Arabidopsis, cucumber, grape, strawberry, and wheat. In this study, two silicon (Si) sources, calcium silicate and potassium silicate, were evaluated for their ability to reduce powdery mildew in gerbera 'Snow White'. The effect of calcium silicate in flower quality and the silicon uptake was also determined. Calcium silicate was not effective in reducing powdery mildew or in improving flower quality. The silicon content of gerberas treated with potassium silicate was slightly greater than that in plants treated with calcium silicate. However, the severity of powdery mildew was not reduced by potassium silicate. The results suggest that silicon may not be useful for managing this disease of gerbera daisy, possibly due to the low accumulation of silicon by gerbera leaves.
Powdery mildew, Oidiopsis taurica (Leveillula taurica) and early blight, Alternaria solani induce significant losses in yield and quality of tomato fruits. Therefore, this study was an attempt to evaluate some of non-traditional methods (culture filtrate of Bacillus subtilis, Artemisia cina and clove oil extracts as well as nanosilica) against powdery mildew and early blight of tomato under greenhouse conditions for two growing seasons; 2010 and 2011. Penconazole and Equation® Pro (cymoxanil + famoxadone) were used as a recommended compound against powdery mildew and early blight diseases, respectively. All treatments were applied four times with 7 days intervals relative to control in each season. Obtained results showed that all tested treatments were effective against the powdery mildew and the early blight diseases relative to control. Penconazole, B. subtilis filtrate and clove oil were the most effective treatments, followed by A. cina extract while nanosilica was the lowest effective one against powdery mildew in both seasons. B. subtilis filtrate and Equation-pro were the most effective against early blight, followed by clove oil, A. cina extracts and nanosilica treatments in both seasons. The results suggest possible use of natural products and nanosilica as effective and safe alternative control methods for powdery mildew and early blight diseases in tomato under greenhouse conditions.