scholarly journals Evaluation of potential bio-control agents on root-knot nematode Meloidogyne incognita and wilt causing fungus Fusarium oxysporum f.sp. conglutinans in vitro

2016 ◽  
Vol 15 (19) ◽  
pp. 798-805 ◽  
Author(s):  
Rompalli Rajinikanth ◽  
Rao Mehendrakar Sreenivasa ◽  
Kantabathini Venkata Pavani
Plant Disease ◽  
2017 ◽  
Vol 101 (6) ◽  
pp. 948-956 ◽  
Author(s):  
Alois A. Bell ◽  
Robert C. Kemerait ◽  
Carlos S. Ortiz ◽  
Sandria Prom ◽  
Jose Quintana ◽  
...  

Locally severe outbreaks of Fusarium wilt of cotton (Gossypium spp.) in South Georgia raised concerns about the genotypes of the causal pathogen, Fusarium oxysporum f. sp. vasinfectum. Vegetative complementation tests and DNA sequence analysis were used to determine genetic diversity among 492 F. oxysporum f. sp. vasinfectum isolates obtained from 107 wilted plants collected from seven fields in five counties. Eight vegetative complementation groups (VCG) were found, with VCG 01117B and VCG 01121 occurring in 66% of the infected plants. The newly recognized VCG 01121 was the major VCG in Berrien County, the center of the outbreaks. All eight VCG resulted in significant increases in the percentages of wilted leaves (27 to 53%) and significant reductions in leaf weight (40 to 67%) and shoot weight (33 to 60%) after being stem punctured into Gossypium hirsutum ‘Rowden’. They caused little or no significant reductions in shoot weight and height or increases in foliar symptoms and vascular browning in a soil-infestation assay. Soil infestation with Meloidogyne incognita race 3 (root-knot nematode) alone also failed to cause significant disease. When coinoculated with M. incognita race 3, all VCG caused moderate to severe wilt. Therefore, the VCG identified in this study belong to the vascular-competent pathotype, and should pose similar threats to cotton cultivars in the presence of the root-knot nematode. Use of nematode-resistant cultivars, therefore, is probably the best approach to control the disease in Georgia.


2017 ◽  
Vol 4 (3) ◽  
pp. 1-7 ◽  
Author(s):  
Amir Khan ◽  
Moh Tariq ◽  
Mohd Asif ◽  
Mansoor Siddiqui

Nematology ◽  
2007 ◽  
Vol 9 (3) ◽  
pp. 343-349 ◽  
Author(s):  
Michael Boppré ◽  
Tim Thoden ◽  
Johannes Hallmann

Abstract1,2-dehydropyrrolizidine alkaloids (PAs) represent a class of secondary plant compounds that are active in defence against herbivory. They are present in Chromolaena odorata, one of the most invasive weeds of Asia and Africa. In vitro studies demonstrate that pure PAs from C. odorata roots have nematicidal effects on the root-knot nematode Meloidogyne incognita, even at concentrations of 70-350 ppm. In vivo experiments show that mulch or aqueous crude extracts from C. odorata roots reduce the infection of lettuce by M. incognita. Thus, the use of PA-containing plants appears to be a valuable element for integrated nematode management.


Nematology ◽  
2013 ◽  
Vol 15 (5) ◽  
pp. 545-555 ◽  
Author(s):  
Yong Seong Lee ◽  
Muhammad Anees ◽  
Hae Nam Hyun ◽  
Kil Yong Kim

Lysobacter antibioticus HS124 is an antagonistic bacterial strain that was previously isolated from the rhizosphere soil of pepper and showed an enhanced ability to produce lytic enzymes as well as an antibiotic that was identified as 4-hydroxyphenylacetic acid (4-HPAA). In the present study, nematicidal activity of the strain and 4-HPAA against the root-knot nematode, Meloidogyne incognita, causing disease in tomato was investigated in both in vitro and in vivo conditions. For this purpose, adding different concentrations of culture filtrate, crude extract collected from extraction with ethyl acetate and 4-HPAA, in 24-well plates containing ca 500 eggs or 300 second-stage juveniles (J2), significantly decreased the rate of nematode hatch and caused higher mortality of J2 compared with the control treatments. Nematicidal activity of the bacterial strain was further confirmed by conducting pot experiments in which tomato plants were inoculated with M. incognita and the HS124 culture (BC). The control pots were treated with commercial nematicide (CN, 5% Ethoprophos), tap water (TW) or the non-inoculated bacterial culture medium (BCM). In these pot experiments, results demonstrated a strong antagonistic potential of L. antibioticus HS124 against M. incognita where the disease was significantly reduced in the pots treated with BC as compared to TW or BCM. Furthermore, the shoot fresh weight was also increased significantly, which may be attributed to the disease control ability of the strain. Hence, L. antibioticus HS124 may be further developed as a potential biocontrol of root knot nematode in the field.


2017 ◽  
Vol 14 (1) ◽  
pp. 467-471 ◽  
Author(s):  
Neeraj Neeraj ◽  
S. R. Goel ◽  
Anil Kumar ◽  
Gurpreet Singh ◽  
V. K. Madan

2019 ◽  
Vol 12 (1) ◽  
pp. 24-37
Author(s):  
M.A. Radwan ◽  
A.S.A. Saad ◽  
H.A. Mesbah ◽  
H.S. Ibrahim ◽  
M.S. Khalil

Summary Avermectins and spinosyns are structurally related natural products of microbial origin and belong to a new family of macrolides which are active against a vast array of invertebrate pests. In the present study, the effects of four members of macrolides; abamectin (ABM), emamectin benzoate (EMB), spinosad (SPI) and spinetoram (SPIT), on Meloidogyne incognita were investigated under in vitro and in vivo conditions. All compounds reduced egg hatching and led to high mortality of the nematode second-stage juveniles (J2). ABM showed the maximum rate of egg hatching inhibition and J2 mortality while SPIT recorded the minimum. All treatments reduced the number of galls, egg masses, eggs/egg mass in roots and J2 in the soil when compared to the control. Based on the 10 folds of the 24 h-LC50 values of J2 mortality in vitro, EMB and ABM exhibited higher percent reduction in galls (79.68 and 71.45%), egg masses (75.19 and 70.54%), eggs/egg mass (60.49 and 40.91%) and J2 in the soil (90.31 and 86.54%), respectively, compared to SPI and SPIT. Significant increase in tomato shoot height occurred in all biopesticides (10 folds) and SPIT (20 folds). SPI at 10 folds of the 24 h-LC50 values of J2 mortality in vitro, significantly increased root length while ABM at 50 folds and SPIT at 20 folds decreased root length by 5.15% and 5.88%, respectively, compared to the untreated inoculated plants. In all treatments, the dry shoot and root weights increased, compared to the untreated control. Our findings suggest that these macrolides have the ability to regulate nematode population densities and may be an alternative to classical nematicides.


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