scholarly journals Control of root rot (Phytophthora cinnamomi) in avocado (Persea Americana) with bioagents

2020 ◽  
Vol 46 (3) ◽  
pp. 205-211
Author(s):  
Ciro Hideki Sumida ◽  
Lucas Henrique Fantin ◽  
Karla Braga ◽  
Marcelo Giovanetti Canteri ◽  
Martin Homechin
Keyword(s):  
Biological Control ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Persea Americana ◽  
Field Conditions ◽  
In Vitro Tests ◽  
Trichoderma Spp ◽  
Maize Cultivation ◽  
Antagonistic Potential

ABSTRACT Despite the favorable edaphoclimatic conditions for avocado production in Brazil, diseases such as root rot caused by the pathogen Phytophthora cinnamomi compromise the crop. With the aim of managing root rot in avocado, the present study aimed to evaluate chemical and biological control with isolates of Trichoderma spp. and Pseudomonas fluorescens. Thus, three assays were conducted to assess: (i) mycelial inhibition of P. cinnamomi by isolates of Trichoderma spp. and P. fluorescens from different crop systems; (ii) effect of autoclaved and non-autoclaved metabolites of P. fluorescens, and (iii) chemical or biological treatment of avocado seedlings on the control of root rot under field conditions. The isolates of Trichoderma spp. from maize cultivation soil and the commercial products formulated with Trichoderma presented greater antagonism (p <0.05) to the pathogen P. cinnamomi in the in vitro tests. Similarly, non-autoclaved metabolites of P. fluorescens presented antagonistic potential to control P. cinnamomi. Under field conditions, the fungicide metalaxyl and the bioagents showed effectiveness in controlling P. cinnamomi, as well as greater root length and mass. Results demonstrated potential for the biological control of avocado root rot with Trichoderma spp. and P. fluorescens.

scholarly journals Endophytic Trichoderma Species Isolated from Persea americana and Cinnamomum verum Roots Reduce Symptoms Caused by Phytophthora cinnamomi in Avocado

Plants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1220
Author(s):  
Petra Andrade-Hoyos ◽  
Hilda Victoria Silva-Rojas ◽  
Omar Romero-Arenas
Keyword(s):  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Disease Incidence ◽  
Persea Americana ◽  
Dual Culture ◽  
Internal Transcribed Spacer Region ◽  
Trichoderma Spp ◽  
Trichoderma Species ◽  
Potato Dextrose Agar Medium

Avocado root rot caused by the oomycete Phytophthora cinnamomi is a severe disease that affects avocado production in Mexico and worldwide. The use of biological control agents such as Trichoderma species isolated from places where the disease is always present, represents an efficient alternative to reduce losses. Thus, the objective of this research was to evaluate the biocontrol ability of 10 endophytic Trichoderma spp. strains against P. cinnamomi tested both in vitro and in the greenhouse. The endophytic Trichoderma spp. were recovered from Persea americana and Cinnamomum verum roots, isolated and purified on potato–dextrose–agar medium. Ten strains were identified by phylogenetic reconstruction of the internal transcribed spacer region of rDNA sequences as T. asperellum (T-AS1, T-AS2, T-AS6, and T-AS7), T. harzianum (T-H3, T-H4, and T-H5), T. hamatum (T-A12), T. koningiopsis (T-K8 and T-K11), and P. cinnamomi (CPO-PCU). In vitro dual-culture assay, the percentage of inhibition of radial growth (PIRG) between Trichoderma spp. and P. cinnamomi strains was measured according to the Bell’s scale. PIRG results indicated that T-AS2 reached the highest value of 78.32%, and T-H5 reached the lowest value of 38.66%. In the greenhouse, the infection was evaluated according to the percentage of disease incidence. Plants with the lowest incidence of dead by avocado root rot were those whose seedlings were inoculated with T-AS2 and T-AS7, resulting in only 5% death by root rot caused by P. cinnamomi. The disease incidence of seedlings with wilt symptoms and death decreased more than 50% in the presence of Trichoderma spp. Relying on the results, we conclude that T. asperellum and T. harzianum contribute to the biocontrol of soil-borne pathogenic oomycete P. cinnamomi.

The antagonistic properties of Trichoderma spp. inhabiting woods for potential biological control of wood-damaging fungi

Holzforschung ◽  
2012 ◽  
Vol 66 (7) ◽  
pp. 883-887 ◽  
Author(s):  
Jaejung Lee ◽  
Nayoon Huh ◽  
Joo Hyun Hong ◽  
Beom Seok Kim ◽  
Gyu-Hyeok Kim ◽  
...  
Keyword(s):  
Biological Control ◽  
Chitinase Activity ◽  
Dual Culture ◽  
Trichoderma Spp ◽  
Trichoderma Longibrachiatum ◽  
Antagonistic Effects ◽  
Volatile Metabolites ◽  
Antagonistic Potential ◽  
Trichoderma Aureoviride

Abstract The antagonistic potential of Trichoderma spp. for biological control of wood-damaging fungi was investigated in the present paper. In vitro assays to investigate antifungal characteristics of Trichoderma spp. were conducted with various wood-damaging fungi. Exo-chitinase activity of the isolates was also measured. Three typical wood decayers and three sap-stainers served as target fungi. The antagonistic abilities of each Trichoderma species differed markedly according to the target fungus. The growth inhibition rates shown by the non-volatile metabolites against the wood decayers reached 100% for Trichoderma harzianum KUC1459. The antibiotics produced by Trichoderma dorotheae KUC5027, a recently reported species of Trichoderma, revealed strong antagonistic effects against sap-stainers. Trichoderma gamsii KUC1747 effectively inhibited the growth of all wood-damaging fungi in dual culture tests. The exo-chitinases of Trichoderma longibrachiatum KUC1540, Trichoderma aureoviride KUC1335, and T. harzianum KUC1459 showed significantly high activity.

scholarly journals Biological Efficacy of Trichoderma spp. and Bacillus spp. in the Management of Plant Diseases

2020 ◽  
Author(s):  
Francisco Daniel Hernández-Castillo ◽  
Francisco Castillo-Reyes ◽  
Marco Antonio Tucuch-Pérez ◽  
Roberto Arredondo-Valdes
Keyword(s):  
Biological Control ◽  
Fruit Trees ◽  
Plant Diseases ◽  
In Vitro Tests ◽  
Taxonomic Identification ◽  
Trichoderma Spp ◽  
Antifungal Effect ◽  
Bacillus Spp ◽  
Microbial Strain

This chapter will cover topics about the microbial antagonists Trichoderma spp. and Bacillus spp. from the perspective of use as potential biological control agents on plant diseases. Results obtained in the laboratory about from their isolation, microbial strain collections for both genera, taxonomic identification, antifungal activity in in vitro tests, obtained evaluation of the antifungal effect of secondary metabolites from microbial antagonists will be shown. Besides, results obtained from bioassays in the greenhouse and field are used as biopesticides in the control of diseases in fruit trees and vegetables and their effects on the promotion of plant growth and increased crop yield.

scholarly journals Antagonistic Potential of Native Trichoderma spp. against Phytophthora cinnamomi in the Control of Holm Oak Decline in Dehesas Ecosystems

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 945
Author(s):  
Francisco J. Ruiz-Gómez ◽  
Cristina Miguel-Rojas
Keyword(s):  
Root Rot ◽  
Mycelial Growth ◽  
Phytophthora Cinnamomi ◽  
Antagonistic Activity ◽  
Selective Medium ◽  
Trichoderma Spp ◽  
Phytophthora Root Rot ◽  
Alternative Measures ◽  
Oak Mortality ◽  
Antagonistic Potential

Phytophthora root rot caused by the pathogen Phytophthora cinnamomi is one of the main causes of oak mortality in Mediterranean open woodlands, the so-called dehesas. Disease control is challenging; therefore, new alternative measures are needed. This study focused on searching for natural biocontrol agents with the aim of developing integrated pest management (IPM) strategies in dehesas as a part of adaptive forest management (AFM) strategies. Native Trichoderma spp. were selectively isolated from healthy trees growing in damaged areas by P. cinnamomi root rot, using Rose Bengal selective medium. All Trichoderma (n = 95) isolates were evaluated against P. cinnamomi by mycelial growth inhibition (MGI). Forty-three isolates presented an MGI higher than 60%. Twenty-one isolates belonging to the highest categories of MGI were molecularly identified as T. gamsii, T. viridarium, T. hamatum, T. olivascens, T. virens, T. paraviridescens, T. linzhiense, T. hirsutum, T. samuelsii, and T. harzianum. Amongst the identified strains, 10 outstanding Trichoderma isolates were tested for mycoparasitism, showing values on a scale ranging from 3 to 4. As far as we know, this is the first report referring to the antagonistic activity of native Trichoderma spp. over P. cinnamomi strains cohabiting in the same infected dehesas. The analysis of the tree health status and MGI suggest that the presence of Trichoderma spp. might diminish or even avoid the development of P. cinnamomi, protecting trees from the worst effects of P. cinnamomi root rot.

scholarly journals Evaluación de la capacidad antagónica in vitro de cepas de Trichoderma spp frente a Phytophthora cinnamomi, fitopatógeno de Persea americana (Palta)

2020 ◽  
Vol 23 (1) ◽  
pp. 65-70
Author(s):  
Ebeling M. Morales T. ◽  
Mirko D. Lino N. ◽  
Eddy Ortega R. ◽  
Pedro L. Castellanos S.
Keyword(s):  
Phytophthora Cinnamomi ◽  
Persea Americana ◽  
Trichoderma Asperellum ◽  
Trichoderma Spp

Phytophthora cinnamomi es un fitopatógeno reportado como el agente causal de la pudrición radicular del palto en el Perú. En este estudio se evaluó la capacidad antagónica de cepas nativas de Trichoderma spp aisladas de la rizósfera de un cultivo de paltos del distrito de Quilmaná, Cañete. Para la evaluación in vitro de la capacidad antagónica de las cepas aisladas se utilizó la técnica de cultivo dual en donde se midió los porcentajes de inhibición del crecimiento radial (PICR) de P. cinnamomi. Del total de cepas aisladas, 3 (P1.1, P4.9 y P5.3) presentaron mayores PICR con 53.86, 56,24 y 60,49 % respectivamente. La identificación molecular indicó que la cepas P4.9 y P1.1 presentan un 99,66 y 100% de similitud con Trichoderma asperellum mientras que la cepa P5.3 un 98,17% de similitud con Trichoderma spp, según el análisis BLAST. En base a los resultados obtenidos estas cepas de Trichoderma asperellum representan un potencial para ser utilizadas como agentes biocontroladores de P. cinnamomi. por lo que se recomienda realizar ensayo en campo.

scholarly journals Biological Control of Fusarium Crown and Root Rot of Wheat by Streptomyces Isolates – It’s Complicated

2019 ◽  
Vol 3 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Mark Winter ◽  
Peter L. Samuels ◽  
Lindsey K. Otto-Hanson ◽  
Ruth Dill-Macky ◽  
Linda L. Kinkel
Keyword(s):  
Biological Control ◽  
Root Rot ◽  
In Vitro Tests ◽  
Fusarium Spp ◽  
Wheat Seedlings ◽  
Genus Streptomyces ◽  
Stem Base ◽  
Crown And Root Rot ◽  
Streptomyces Isolate

The predominant causal agents of Fusarium crown and root rot (FCR) of wheat, along with Fusarium pseudograminearum, are F. graminearum and F. culmorum. Members of the Gram-positive bacterial genus Streptomyces have been shown to inhibit isolates of the genus Fusarium, and Fusarium spp. isolates are also able to inhibit Streptomyces isolates in vitro. However, little is known about these complex antagonistic interactions and the potential for inhibitory Streptomyces to reduce FCR of wheat. The aim of this study was to analyze whether inhibitory Streptomyces isolates affect FCR of wheat and reduce root and stem base colonization by Fusarium culmorum. We enriched sterilized potting soil with spore suspensions of two Streptomyces isolates, inoculated the soil with F. culmorum-colonized wheat straw, and planted pre-germinated wheat seedlings. At 4 weeks, F. culmorum-inoculated plants had significant FCR symptoms on roots and showed reduced fresh weight of roots and above-ground plant biomass compared with the non-inoculated controls. Enrichment of soil with an inhibitory Streptomyces isolate reduced F. culmorum DNA in roots and stem bases by 75% compared with inoculation with F. culmorum alone. Interestingly, co-inoculation of F. culmorum with a non-inhibitory Streptomyces isolate led to the highest levels F. culmorum DNA in stem base tissue and greatest Streptomyces densities (CFU per g of soil) in the rhizosphere. In vitro assays revealed that F. culmorum showed a strong inhibitory activity against the pathogen-inhibitory Streptomyces isolate but not against the non-inhibitory isolate. In vitro tests with a larger set of 17 Streptomyces and five Fusarium spp. isolates revealed that there was little variation among Fusarium spp. isolates in capacities to inhibit the collection of Streptomyces isolates. In contrast, the sensitivity to inhibition by pathogenic Fusarium spp. isolates varied widely among Streptomyces isolates. The results of this study suggest the potential of Streptomyces isolates for biocontrol of FCR of wheat, while highlighting the specificity of Streptomyces−Fusarium interactions. Broader understanding of the variation in susceptibility within Fusarium spp. populations to Streptomyces inhibition and vice versa are needed to advance the potential for successful biological control.

scholarly journals Factors Affecting Root Rot Control in Mulched Avocado Orchards

2002 ◽  
Vol 12 (4) ◽  
pp. 601-605 ◽  
Author(s):  
Jim Downer ◽  
Ben Faber ◽  
John Menge
Keyword(s):  
Biological Control ◽  
Enzyme Activities ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Soil Water Potential ◽  
Persea Americana ◽  
Long Term Effects ◽  
Short Term ◽  
Cellulase Enzyme

Mulches can exert positive (disease controlling) or negative (disease enhancing) potential when applied to young avocado (Persea americana) trees. Regulation of root disease in avocado is a complicated process that is affected by host resistance, inoculum density, temperature, soil salinity and soil water potential. There are short-term immediate effects from mulching and subtle long-term effects that regulate disease caused by the root rot pathogen Phytophthora cinnamomi. Short-term effects include increased soil moisture and soil temperature moderation. Long-term effects include increases of: soil mineral nutrients, soil aggregation and drainage; microbial activity; and cellulase enzyme activities. Biological control of Phytophthora in mulched soil is partially regulated by cellulase enzyme activities. This soil enzyme concept of biological control is discussed in regard to the classical Ashburner method of biological control.

scholarly journals Cellulase Activity as a Mechanism for Suppression of Phytophthora Root Rot in Mulches

2011 ◽  
Vol 101 (2) ◽  
pp. 223-230 ◽  
Author(s):  
Brantlee Spakes Richter ◽  
Kelly Ivors ◽  
Wei Shi ◽  
D. M. Benson
Keyword(s):  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Cellulase Activity ◽  
Enzyme Concentration ◽  
Disease Suppression ◽  
In Vitro Assays ◽  
Infested Soil ◽  
Phytophthora Root Rot ◽  
Standard Curve

Wood-based mulches are used in avocado production and are being tested on Fraser fir for reduction of Phytophthora root rot, caused by Phytophthora cinnamomi. Research with avocado has suggested a role of microbial cellulase enzymes in pathogen suppression through effects on the cellulosic cell walls of Phytophthora. This work was conducted to determine whether cellulase activity could account for disease suppression in mulch systems. A standard curve was developed to correlate cellulase activity in mulches with concentrations of a cellulase product. Based on this curve, cellulase activity in mulch samples was equivalent to a cellulase enzyme concentration of 25 U ml–1 or greater of product. Sustained exposure of P. cinnamomi to cellulase at 10 to 50 U ml–1 significantly reduced sporangia production, but biomass was only reduced with concentrations over 100 U ml–1. In a lupine bioassay, cellulase was applied to infested soil at 100 or 1,000 U ml–1 with three timings. Cellulase activity diminished by 47% between 1 and 15 days after application. Cellulase applied at 100 U ml–1 2 weeks before planting yielded activity of 20.08 μmol glucose equivalents per gram of soil water (GE g–1 aq) at planting, a level equivalent to mulch samples. Cellulase activity at planting ranged from 3.35 to 48.67 μmol GE g–1 aq, but no treatment significantly affected disease progress. Based on in vitro assays, cellulase activity in mulch was sufficient to impair sporangia production of P. cinnamomi, but not always sufficient to impact vegetative biomass.

The in vitro inhibition of Phytophthora clandestina by some rhizobia and the possible role of Rhizobium trifolii in biological control of Phytophthora root rot of subterranean clover

1999 ◽  
Vol 50 (8) ◽  
pp. 1469 ◽  
Author(s):  
S. Simpfendorfer ◽  
T. J. Harden ◽  
G. M. Murray
Keyword(s):  
Biological Control ◽  
Root Rot ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Root Disease ◽  
Rhizobium Trifolii ◽  
Biological Control Agents ◽  
Control Activity ◽  
Phytophthora Root Rot

The interaction between 29 isolates of Rhizobium and the in vitro growth of 3 strains of Phytophthora clandestina was investigated to determine the potential of these bacteria as biological control agents against root rot of subterranean clover (Trifolium subterraneum L.). The biological control activity of Rhizobium on the severity of root disease in seedlings was also investigated under glasshouse conditions. Thirteen of the 29 Rhizobium isolates caused significant reductions in the hyphal growth of the 3 P. clandestina isolates examined. Inoculation of seedlings with Rhizobium trifolii reduced the severity of root disease by 14–58% with corresponding increases in dry matter production of 20–73%. These results indicate that Rhizobium species have potential as biological control agents against the root rot of T. subterraneum seedlings caused by P. clandestina.

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