scholarly journals Use of Pseudomonas aeruginosa in the control od root-knot disease complex in tomato: the effects of different inoculum levels of Meloidogyne javanica and Rhizoctonia solani

2013 ◽  
Vol 54 (1) ◽  
pp. 45-54 ◽  
Author(s):  
I. A. Siddiqui ◽  
S. Ehteshamul-Haque ◽  
S. S. Shaukat
Keyword(s):  
Rhizoctonia Solani ◽  
Root Rot ◽  
Root Colonization ◽  
Biological Control Agent ◽  
Meloidogyne Javanica ◽  
Macrophomina Phaseolina ◽  
Control Agent ◽  
Population Densities ◽  
Culture Suspension ◽  
Rot Disease

The potential impact of <em>Pseudomons aeruginosa</em> strain IE-6 as a biological control agent against <em>Meloidogyne javanica</em> at four inoculum densities (0, 250, 500 and 1000 eggs/plant) and <em>Rhizoctonia solani</em> at three inoeulum levels (0, 1 and 3 ml culture suspension/kg of soil) was examined on tomato in the greenhouse experiments. The biocontrol bacterium suppressed root infection caused by <em>R. solani</em> and <em>M. javanica</em> on tomato in both sterilized and non-sterilized soils. Root-rot infection increased with the increase in pathogen(s) concentration. <em>P. aeruginosa</em> showed better biocontrol effects at low population levels of <em>M.javanica</em> and <em>R. solani</em> than at higher population densities of the pathogen(s). Root-rot disease severity was more pronounced in sterilized soil compared to the non-sterilized one. Soil infested with high population densities ofR. solani (3 ml /kg of soil) and <em>M. javanica</em> (2000 eggs/pot) resulted in complete mortality of tomato seedlings in sterilized soil, whereas some plants were found to survive in non-stenlized soil. There seems to be a correlation between population density of <em>M. javanica</em> and root colonization by <em>R. solani</em>. Root colonization by other three root-infecting fungi including <em>Macrophomina phaseolina, Fusarium oxysporum</em> and <em>Fusarium solani</em> was also lower in the presence of <em>P. aeruginosa</em> in non-sterilized soil. <em>P. aeruginosa</em> enhanced plant growth in both types of soil.

The effect of the hyperparasite (Gliocladium virens) on Rhizoctonia solani and on Rhizoctonia root rot of white beans

1981 ◽  
Vol 59 (1) ◽  
pp. 22-27 ◽  
Author(s):  
J. C. Tu ◽  
O. Vaartaja
Keyword(s):  
Rhizoctonia Solani ◽  
Root Rot ◽  
Biological Control Agent ◽  
Light And Electron Microscopy ◽  
Control Agent ◽  
Host Cells ◽  
Sequence Of Events ◽  
Rhizoctonia Root Rot ◽  
Gliocladium Virens

Using light and electron microscopy, Gliocladium virens is proved to be a hyperparasite of Rhizoctonia solani. When hyphae of G. virens come in contact with those of R. solani, the following sequence of events are observed (i) contact of G. virens with host cells, (ii) formation of appresoria, (iii) penetration of host cells, (iv) formation of intracellular hyphae, and (v) collapse and death of host cells. In vitro, G. virens effectively inhibited sclerotial formation of R. solani.Greenhouse tests showed that the presence of G. virens in soil artificially infested with R. solani reduced at planting the severity of Rhizoctonia root rot in white beans. Root rot severity decreased with increasing concentrations of G. virens. A similar result was obtained in soil treated with the two fungi 2 months prior to planting. This study suggests that G. virens may be a promising biological control agent for Rhizoctonia root rot of white beans.

Effectiveness of 3 antagonistic bacterial isolates to control Rhizoctonia solani Kühn on lettuce and potato

2005 ◽  
Vol 51 (4) ◽  
pp. 345-353 ◽  
Author(s):  
Rita Grosch ◽  
Franziska Faltin ◽  
Jana Lottmann ◽  
A Kofoet ◽  
Gabriele Berg
Keyword(s):  
Rhizoctonia Solani ◽  
Pseudomonas Fluorescens ◽  
Biological Control Agent ◽  
Dry Mass ◽  
Control Agent ◽  
Disease Suppression ◽  
Growth Chamber ◽  
Bacterial Strains ◽  
Serratia Plymuthica ◽  
Suppression Effect

Rhizoctonia solani causes yield losses in numerous economically important European crops. To develop a biocontrol strategy, 3 potato-associated ecto- and endophytically living bacterial strains Pseudomonas fluorescens B1, Pseudomonas fluorescens B2, and Serratia plymuthica B4 were evaluated against R. solani in potato and in lettuce. The disease-suppression effect of the 3 biocontrol agents (BCAs) was tested in a growth chamber and in the field. In growth chamber experiments, all 3 BCAs completely or significantly limited the dry mass (DM) losses on lettuce and the disease severity (DS) caused by R. solani on potato sprouts. Strain B1 showed the highest suppression effect (52% on average) on potato. Under field conditions, the DS on both crops, which were bacterized, decreased significantly, and the biomass losses on lettuce decreased significantly as well. The greatest disease-suppression effect on potato was achieved by strain B1 (37%), followed by B2 (33%) and then B4 (31%), whereas the marketable tuber yield increased up to 12% (B1), 6% (B2), and 17% (B4) compared with the pathogen control at higher disease pressure. Furthermore, in all experiments, B1 proved to be the most effective BCA against R. solani. Therefore, this BCA could be a candidate for developing a commercial product against Rhizoctonia diseases. To our knowledge, this is the first report on the high potential of endophytes to be used as a biological control agent against R. solani under field conditions.Key words: biocontrol, Rhizoctonia solani, field grown lettuce and potato, antagonistic bacteria, endophytes.

A laboratory investigation of Paulinia acuminata (DeGeer) (Orthoptera: Acrididae) as a biological control agent for Salvinia molesta

1979 ◽  
Vol 69 (1) ◽  
pp. 111-114 ◽  
Author(s):  
I. F. Chisholm
Keyword(s):  
Biological Control ◽  
Growth Rate ◽  
Plant Tissue ◽  
Feeding Rate ◽  
Consumption Rate ◽  
Biological Control Agent ◽  
Control Agent ◽  
Salvinia Molesta ◽  
Population Densities ◽  
Lake Kariba

AbstractThe feeding rate of nymphs of Paulinia acuminata (Deg.) on Salvinia molesta was studied in the laboratory using single nymphs on different numbers of Salvinia leaves. Each successive instar ate more plant tissue, but at population densities likely to occur in nature it was unlikely that consumption rate could match the natural Salvinia growth rate. The controlling effect of Paulinia on Salvinia in Lake Kariba, Rhodesia, may therefore be negligible.

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