Evaluation of different salts for the control of lettuce varnish spot: when phytotoxicity rules

2018 ◽  
Vol 98 (3) ◽  
pp. 753-761 ◽  
Author(s):  
Maxime Delisle-Houde ◽  
Vicky Toussaint ◽  
Hicham Affia ◽  
Russell J. Tweddell

Five generally recognised as safe (GRAS) salts with antimicrobial activity were investigated for their potential use as bactericides for the control of lettuce varnish spot [Pseudomonas cichorii (Swingle) Stapp]. The phytotoxicity of salts was first assessed using greenhouse and in vitro assays. Greenhouse assays revealed that salts showed different levels of phytotoxicity. Potassium sorbate, sodium benzoate, and sodium carbonate at higher concentrations caused a noticeable decrease of growth along with foliar phytotoxicity symptoms while sodium metabisulfite and sodium bicarbonate caused exclusively foliar symptoms. Based on the phytotoxic doses 5% determined in vitro, salts can be ranked in ascending order of phytotoxicity as follows: sodium bicarbonate, potassium sorbate, sodium carbonate, sodium benzoate, and sodium metabisulfite. When applied at concentrations causing mild to moderate foliar symptoms of phytotoxicity and no noticeable effect on growth, salts did not significantly affect (p ≤ 0.01) survival of P. cichorii on lettuce leaf tissue and did not significantly reduce (p ≤ 0.01) varnish spot severity. Although sodium metabisulfite was applied at concentrations higher than the minimum inhibitory concentration and minimum bactericidal concentration, it did not affect P. cichorii survival on leaf tissue.

2009 ◽  
Vol 89 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Mélanie R. Mecteau ◽  
Joseph Arul ◽  
Russell J. Tweddell

The objectives of this study were (1) to evaluate the effect of different salts on the in vitro development of Fusarium solani var. coeruleum, and (2) to evaluate the efficacy of the salts for reducing dry rot severity caused by the pathogen in potato tubers. The study showed that several salts significantly inhibited the mycelial growth of F. solani var. coeruleum. Aluminium acetate, aluminium chloride, sodium benzoate, sodium metabisulfite, potassium sorbate and trisodium phosphate completely inhibited mycelial growth. Exposure of F. solani var. coeruleum conidia to aluminium acetate, potassium sorbate, sodium benzoate, sodium metabisulfite or trisodium phosphate at 0.2 M resulted in 100% mortality of the conidia after 1 h while aluminium chloride and aluminium lactate caused 100% mortality after an exposure of 24 h. In order to evaluate the effect of salts on potato dry rot development, F. solani var. coeruleum-inoculated tubers were treated with the different salts and disease severity was evaluated following an incubation period of 7 d. Among the test salts, only aluminium chloride caused a significant reduction in potato dry rot compared with the control. The study points out the possibility of using aluminium chloride to control potato dry rot.


2008 ◽  
Vol 14 (4) ◽  
pp. 311 ◽  
Author(s):  
K. PARTANEN ◽  
T. JALAVA

An in vitro gas production technique was used to screen different organic acids (formic, propionic, lactic, citric, and fumaric acid), organic salts (calcium formate, potassium sorbate, and sodium benzoate), and inorganic phosphoric acid for their ability to modulate microbial fermentation in the digestive tract of piglets. For the incubation, 40 ml of culture medium (53% buffer, 45% frozen ileal digesta, and 2% fresh faeces) was dispensed in vessels containing 5 ml of buffer, 0.5 g of feed, and 20 ìl of liquid or 20 mg of solid acidifiers. Gas production was measured every 15 min during the 24 h incubation at 39°C, and a Gompertz bacterial growth model was applied to the gas production data. Formic acid was the only acid that reduced the maximum rate of gas production (ìm) compared to that in the control treatment (P < 0.05). The ìm was slower in vessels with formic acid than in those with calcium formate, citric acid, and potassium sorbate (P < 0.05) Calcium formate increased the ìm compared to the control treatment (P < 0.05). The maximum volume of gas produced and the lag time did not differ between different acidifiers (P > 0.05). When investigating formic-acid-based mixtures that contained 1–5% of potassium sorbate and/or sodium benzoate, the estimated parameters for the Gompertz growth model did not differ from those for treatments with plain formic acid (P > 0.05). However, concentrations of total volatile fatty acids, acetic acid, propionic acid, and n-butyric acid were reduced by all the mixtures (P < 0.05), but not by plain formic acid (P > 0.05). In conclusion, organic acids and salts were found to differ in their ability to modulate microbial fermentation in the digestive tract of piglets. Mixing formic acid with potassium sorbate or sodium benzoate changed fermentation patterns, and the possibility to use them to enhance the antimicrobial effect of formic acid should be investigated further in vivo.;


2018 ◽  
Vol 71 ◽  
pp. 285-288 ◽  
Author(s):  
Echo M. Herewini ◽  
Peter M. Scott ◽  
Nari M. Williams ◽  
Rosie E. Bradshaw

Phytophthora agathidicida is an aggressive soil-borne oomycete pathogen that kills New Zealand kauri trees (Agathis australis). When artificially inoculated, P. agathidicida causes lesions on leaves as well as roots, providing a non-invasive method for virulence screening. However, little is known about the extents to which the pathogen varies in virulence and kauri trees vary in disease susceptibility. Three isolates of P. agathidicida grown in culture were inoculated onto detached leaves from six kauri trees. Visible disease lesions were measured and the extent of asymptomatic leaf colonisation determined by culturing. All six trees were susceptible to P. agathidicida, but one showed higher susceptibility than the others. The pathogen also showed variability in virulence among isolates. Asymptomatic colonisation of leaf tissue was also found, suggesting a latent or biotrophic phase for the pathogen. Although further work is needed, the variability of both pathogen virulence and host susceptibility have important implications for management of kauri dieback. Furthermore, asymptomatic colonisation of kauri tissues suggests that P. agathidicida could be present outside of regions with visible disease symptoms.


Author(s):  
N. Indra ◽  
A. S. Kauvyashree ◽  
D. S. Swetha ◽  
M. Asmina ◽  
. Shalini

The laboratory experiments were carried out to study the effect of different salts viz., potassium chloride (KCl), potassium phosphate dibasic (K2HPO4), sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3) and ammonium molybdate (NH4)6 Mo7O24) on seed borne M. phaseolina and Fusarium sp. as an alternative to synthetic fungicides for the control of charcoal rot and wilt diseases in blackgram. The evaluation of different salts was performed in vitro using various concentrations viz., 0.5, 1.0, 2.0, 4.0 and 8.0 per cent (w/v). Among the salts tested against M. phaseolina, sodium carbonate, sodium bicarbonate and ammonium molybdate at 0.5, 2.0 and 4.0 per cent respectively inhibited the fungal growth. Among the salts tested against Fusarium sp. sodium carbonate (Na2CO3) at 4.0 per cent concentration recorded complete inhibition of the mycelial growth compared to the other salts. Also seed priming of these salts significantly reduced the seed borne infection due to M. phaseolina and Fusarium sp. under standard blotter test. The salts like potassium chloride and potassium phosphate dibasic (K2HPO4) at all concentrations did not inhibit M. phaseolina and Fusarium sp. which recorded 100 per cent mycelial growth as that of control.


2008 ◽  
Vol 65 (6) ◽  
pp. 589-594 ◽  
Author(s):  
André de Faria Pedroso ◽  
Luiz Gustavo Nussio ◽  
Daniele Rebouças Santana Loures ◽  
Solidete de Fátima Paziani ◽  
José Leonardo Ribeiro ◽  
...  

Utilization of sugarcane Saccharum officinarum L. silage is increasing in Brazil but intensive ethanol production during fermentation reduces forage quality. This experiment aimed to evaluate the effects of additives on fermentation and aerobic stability of sugarcane silages produced in minisilos. Treatments were (fresh basis): untreated silage (control), urea (5.0 g kg-1), sodium benzoate (1.0 g kg-1), potassium sorbate (0.3 g kg-1), Lactobacillus plantarum (1 x 10(6) cfu g-1), and Lactobacillus buchneri (3.64 x 10(5) cfu g-1). At the 94th day after ensilage, ethanol concentration was lower in urea, benzoate, sorbate and L. buchneri supplemented silages and higher in L. plantarum inoculated silage, as compared to control. Urea and benzoate treated silages showed the highest and L. plantarum treated silage the lowest in vitro dry matter digestibility. Effluent production was higher in the urea treated silage. Inoculation with L. buchneri reduced 50% ethanol production as compared to control. Urea and L. buchneri reduced yeast count. Aerobic stability was enhanced by L. buchneri and benzoate. Sodium benzoate and L. buchneri were the most promising additives, improving both silage fermentation and aerobic stability; inoculants containing L. plantarum can be deleterious to fermentation and conservation of sugarcane silages.


2010 ◽  
Vol 5 (4) ◽  
pp. 491-495
Author(s):  
Dragana Stanojević ◽  
Ljiljana Čomić ◽  
Olgica Stefanović

AbstractThe aim of the present study is to investigate the antibacterial activity of Salvia officinalis L. aqueous extracts and its synergistic action with preservatives sodium nitrite, sodium benzoate and potassium sorbate in vitro against selected food spoiling bacteria. Synergy was assessed by the checkerboard assay method and quantitatively represented by the FIC index. Synergistic action was established for aqueous extract/ sodium benzoate, aqueous extract/ potassium sorbate, aqueous extract/ sodium nitrite combinations. Synergy was detected in relation to: Agrobacterium tumefaciens, Bacillus subtilis and Proteus sp. Synergy was established at plant extract and preservative concentrations corresponding up to 1/8 MIC values.


Plant Disease ◽  
2002 ◽  
Vol 86 (9) ◽  
pp. 1014-1018 ◽  
Author(s):  
V. Hervieux ◽  
E. S. Yaganza ◽  
J. Arul ◽  
R. J. Tweddell

Potato silver scurf, caused by Helminthosporium solani, is an important postharvest disease of economic significance. Control of H. solani has been accomplished primarily by postharvest applications of thiabendazole. However, many strains of H. solani have become resistant to thiabendazole, resulting in failure of disease control. Consequently, alternative control strategies are needed. This study showed that several salts significantly reduced silver scurf development on potato tuber at a concentration of 0.2 M and that the timing of application also influenced salt efficacy. Among the 23 tested salts, aluminum chloride was the only one reducing silver scurf severity when applied either 2, 4, or 7 days after H. solani inoculation. Aluminum lactate, potassium sorbate, sodium carbonate, sodium metabisulfite, and trisodium phosphate also markedly reduced silver scurf severity but only when applied 2 or 4 days after inoculation. Ammonium acetate, calcium chloride, sodium benzoate, sodium citrate, and sodium formate reduced disease severity by at least 50% when applied 2 days after H. solani inoculation. With the exception of calcium chloride and sodium formate, these salts also were shown to strongly inhibit H. solani mycelial growth or spore germination in vitro. Results of this study further demonstrate the possibility of using selected salts for the control of potato silver scurf.


2010 ◽  
Vol 62 (1) ◽  
pp. 167-174 ◽  
Author(s):  
Dragana Stanojevic ◽  
Ljiljana Comic ◽  
Olgica Stefanovic ◽  
Slavica Solujic-Sukdolak

The aim of this work was to investigate the antibacterial activity of aqueous extracts of the species Salvia officinalis L. and its synergistic action with the preservatives sodium nitrite, sodium benzoate and potassium sorbate in vitro against selected food spoiling bacteria. Synergism was assessed by the checkerboard assay method and quantitatively represented by the FIC index. Synergistic action was established for aqueous extract/sodium benzoate, aqueous extract/potassium sorbate, aqueous extract/sodium nitrite combinations. Synergism was detected in relation to: Agrobacterium tumefaciens, Bacillus subtilis and Proteus sp. Synergism was established at plant extract and preservative concentrations corresponding up to 1/8 MIC values. <br><br><b><font color="red">Detected autoplagiarism. Link to the Editorial Decision <u><a href="http://dx.doi.org/10.2298/ABS1004251U">10.2298/ABS1004251U</a></u></font></b><br>


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