scholarly journals Influence of Earthworm Activity on Soil Microbes and Soilborne Diseases of Vegetables

Plant Disease ◽  
2009 ◽  
Vol 93 (2) ◽  
pp. 175-179 ◽  
Author(s):  
Wade H. Elmer
Keyword(s):  
Soil Health ◽  
Solanum Melongena ◽  
Lumbricus Terrestris ◽  
Disease Suppression ◽  
Asparagus Officinalis ◽  
Trichoderma Spp ◽  
Soilborne Diseases ◽  
Progress Curve ◽  
Race 1 ◽  
Earthworm Activity

Earthworm densities have been regarded as reliable indicators of soil health, but their role in suppression of plant disease has not received much attention. Several greenhouse studies were done to determine if soils infested with soilborne pathogens and augmented with earthworms (Lumbricus terrestris) could reduce disease of susceptible cultivars of asparagus (Asparagus officinalis), eggplant (Solanum melongena), and tomato (Solanum lycopersicum). Soils planted with asparagus were infested with Fusarium oxysporum f. sp. asparagi and F. proliferatum, eggplant with Verticillium dahliae, and tomato with F. oxysporum f. sp. lycopersici Race 1. In each host–disease system, earthworm activity was associated with an increase in plant growth and a decrease in disease. In general, plant weights were increased 60 to 80% and estimates of disease (area under the disease progress curve, percent vascular discoloration, and percent root lesions) were reduced 50 to 70% when soils were augmented with earthworms. Soil dilutions on selective media revealed that densities of fluorescent pseudomonads and filamentous actinomycetes were consistently higher for rhizosphere soils augmented with earthworms. In the studies with Verticillium wilt of eggplant, compared to the controls, the densities of total bacteria and Mn-transforming microbes were reduced in the presence of earthworms while population densities of bacilli and Trichoderma spp. were not affected. Disease suppression may have been mediated through microbiological activity. These studies suggest that strategies to increase earthworm densities in soil should suppress soilborne diseases.

scholarly journals Suppression of Verticillium Wilt of Eggplant by Earthworms

Plant Disease ◽  
2009 ◽  
Vol 93 (5) ◽  
pp. 485-489 ◽  
Author(s):  
Wade H. Elmer ◽  
Francis J. Ferrandino
Keyword(s):  
Verticillium Wilt ◽  
Untreated Control ◽  
Extraction Procedure ◽  
Solanum Melongena ◽  
Growth Yield ◽  
Lumbricus Terrestris ◽  
Disease Suppression ◽  
Progress Curve ◽  
Field Plots ◽  
Earthworm Populations

The role of earthworms in plant disease has received little attention. To address whether earthworms would affect the severity of Verticillium wilt of eggplant (Solanum melongena) in the field, we grew eggplants in experimental field plots that were naturally infested with Verticillium dahliae in 2005, 2006, and 2007. Three earthworm treatments were compared: (i) no treatment (untreated control), (ii) earthworm populations reduced via chemical eradicants (carbaryl or hot mustard) (reduced treatment), and (iii) earthworm populations increased by addition of adult Canadian nightcrawlers (Lumbricus terrestris, 11 earthworms per m2) (augmented treatment). Compared to the untreated control, the estimates of the area under the disease progress curve (AUDPC) were reduced while estimates of the canopy growth curve (CGC) and the final plant weights were increased in plots augmented with earthworms in all 3 years. In 2 out of 3 years, eggplant yield (weight and number of fruit) was increased in plots augmented with earthworms. When a carbaryl drench was used to reduce earthworm numbers, the treatment resulted in plants with more disease than in the untreated controls in 2005. However, in 2005 and 2006, carbaryl-treated plants had larger CGC values and higher yield than in the untreated controls and were not significantly different from the augmented plots. When a hot mustard extraction procedure was used to reduce earthworm densities in 2007, plant growth, yield, and disease variables did not differ from the untreated control. Although the effects of reducing earthworms were variable and difficult to explain, our findings suggest that augmenting earthworm populations can suppress Verticillium wilt of eggplant, and strategies that increase earthworm numbers may contribute to disease suppression.

scholarly journals Response of Horticultural Soil Microbiota to Different Fertilization Practices

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1501
Author(s):  
Iratxe Zarraonaindia ◽  
Xabier Simón Martínez-Goñi ◽  
Olaia Liñero ◽  
Marta Muñoz-Colmenero ◽  
Mikel Aguirre ◽  
...  
Keyword(s):  
Organic Fertilizer ◽  
Soil Health ◽  
Disease Suppression ◽  
Glutathione Metabolism ◽  
Plant Interactions ◽  
Organic Fertilization ◽  
Soil Microbiota ◽  
Xenobiotic Compound ◽  
Soil Prokaryotes ◽  
Rapid Shift

Environmentally friendly agricultural production necessitates manipulation of microbe–plant interactions, requiring a better understanding of how farming practices influence soil microbiota. We studied the effect of conventional and organic treatment on soil bacterial richness, composition, and predicted functional potential. 16S rRNA sequencing was applied to soils from adjacent plots receiving either a synthetic or organic fertilizer, where two crops were grown within treatment, homogenizing for differences in soil properties, crop, and climate. Conventional fertilizer was associated with a decrease in soil pH, an accumulation of Ag, Mn, As, Fe, Co, Cd, and Ni; and an enrichment of ammonia oxidizers and xenobiotic compound degraders (e.g., Candidatus Nitrososphaera, Nitrospira, Bacillus, Pseudomonas). Soils receiving organic fertilization were enriched in Ti (crop biostimulant), N, and C cycling bacteria (denitrifiers, e.g., Azoarcus, Anaerolinea; methylotrophs, e.g., Methylocaldum, Methanosarcina), and disease-suppression (e.g., Myxococcales). Some predicted functions, such as glutathione metabolism, were slightly, but significantly enriched after a one-time manure application, suggesting the enhancement of sulfur regulation, nitrogen-fixing, and defense of environmental stressors. The study highlights that even a single application of organic fertilization is enough to originate a rapid shift in soil prokaryotes, responding to the differential substrate availability by promoting soil health, similar to recurrent applications.

scholarly journals Screening Cultivated Eggplant and Wild Relatives for Resistance to Bacterial Wilt (Ralstonia solanacearum)

Agriculture ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 157 ◽  
Author(s):  
Namisy ◽  
Chen ◽  
Prohens ◽  
Metwally ◽  
Elmahrouk ◽  
...  
Keyword(s):  
High Temperatures ◽  
Resistance Genes ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Solanum Melongena ◽  
Wild Relatives ◽  
Sources Of Resistance ◽  
Race 1 ◽  
Moderately Resistant ◽  
Phylotype I

Bacterial wilt, caused by Ralstonia solanacearum, is highly diverse and the identification of new sources of resistance for the incorporation of multiple and complementary resistance genes in the same cultivar is the best strategy for durable and stable resistance. The objective of this study was to screen seven accessions of cultivated eggplant (Solanum melongena L.) and 40 accessions from 12 wild relatives for resistance to two virulent R. solanacearum strains (Pss97 and Pss2016; phylotype I, race 1, biovar 3). The resistant or moderately resistant accessions were further evaluated with Pss97 in a second trial under high temperatures (and also with Pss2016 for S. anguivi accession VI050346). The resistant control EG203 was resistant to Pss97, but only moderately resistant to Pss2016. One accession of S. sisymbriifolium (SIS1) and two accessions of S. torvum (TOR2 and TOR3) were resistant or moderately resistant to Pss97 in both trials. Solanum anguivi VI050346, S. incanum accession MM577, and S. sisymbriifolium (SIS1 and SIS2) were resistant to Pss2016 in the first trial. However, S. anguivi VI050346 was susceptible in the second trial. These results are important for breeding resistant rootstocks and cultivars that can be used to manage this endemic disease.

scholarly journals Methods for Management of Soilborne Diseases in Crop Production

Agriculture ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 16 ◽  
Author(s):  
Milan Panth ◽  
Samuel C. Hassler ◽  
Fulya Baysal-Gurel
Keyword(s):  
Crop Production ◽  
Management Strategies ◽  
Soil Health ◽  
Disease Outbreaks ◽  
Cropping System ◽  
Montreal Protocol ◽  
Production Costs ◽  
Soilborne Diseases ◽  
Soilborne Disease ◽  
Anaerobic Soil Disinfestation

The significant problems caused by soilborne pathogens in crop production worldwide include reduced crop performance, decreased yield, and higher production costs. In many parts of the world, methyl bromide was extensively used to control these pathogens before the implementation of the Montreal Protocol—a global agreement to protect the ozone layer. The threats of soilborne disease epidemics in crop production, high cost of chemical fungicides and development of fungicide resistance, climate change, new disease outbreaks and increasing concerns regarding environmental as well as soil health are becoming increasingly evident. These necessitate the use of integrated soilborne disease management strategies for crop production. This article summarizes methods for management of soilborne diseases in crop production which includes the use of sanitation, legal methods, resistant cultivars/varieties and grafting, cropping system, soil solarization, biofumigants, soil amendments, anaerobic soil disinfestation, soil steam sterilization, soil fertility and plant nutrients, soilless culture, chemical control and biological control in a system-based approach. Different methods with their strengths and weaknesses, mode of action and interactions are discussed, concluding with a brief outline of future directions which might lead to the integration of described methods in a system-based approach for more effective management of soilborne diseases.

scholarly journals Biological and Application-Oriented Factors Influencing Plant Disease Suppression by Biological Control: A Meta-Analytical Review

2006 ◽  
Vol 96 (11) ◽  
pp. 1168-1174 ◽  
Author(s):  
P. S. Ojiambo ◽  
H. Scherm
Keyword(s):  
Biological Control ◽  
Effect Size ◽  
Untreated Control ◽  
Plant Disease ◽  
Biocontrol Agent ◽  
Disease Suppression ◽  
Effect Sizes ◽  
Biological Control Agents ◽  
Control Effect ◽  
Soilborne Diseases

Studies to evaluate the effectiveness of biological control in suppressing plant disease often report inconsistent results, highlighting the need to identify general factors that influence the success or failure of biological control in plant pathology. We conducted a quantitative synthesis of previously published research by applying meta-analysis to determine the overall effectiveness of biocontrol in relation to biological and application-oriented factors. For each of 149 entries (antagonist-disease combinations) from 53 reports published in Biological & Cultural Tests between 2000 and 2005, an effect size was calculated as the difference in disease intensity expressed in standard deviation units between the biocontrol treatment and its corresponding untreated control. Effect sizes ranged from -1.15 (i.e., disease strongly enhanced by application of the biocontrol agent) to 4.83 (strong disease suppression by the antagonist) with an overall weighted mean of 0.62, indicating moderate effectiveness on average. There were no significant (P >0.05) differences in effect sizes between entries from studies carried out in the greenhouse versus the field, between those involving soilborne versus aerial diseases, or among those carried out in conditions of low, medium, or high disease pressure (expressed relative to the disease intensity in the untreated control). However, effect sizes were greater on annual than on perennial crops, regardless of whether the analysis was carried out for all entries (P = 0.0268) or for those involving only soilborne diseases (P = 0.0343). Effect sizes were not significantly different for entries utilizing fungal versus bacterial biocontrol agents or for those targeting fungal versus bacterial pathogens. However, entries that used r-selected biological control agents (i.e., those having short generation times and producing large numbers of short-lived offspring) were more effective than those that applied antagonists that were not r-selected (P = 0.0312). Interestingly, effect sizes for entries that used Bacillus spp. as biological control agents were lower than for those that applied other antagonists (P = 0.0046 for all entries and P = 0.0114 for soilborne diseases). When only aerial diseases were considered, mean effect size was greater for entries that received one or two sprays than for those that received more than eight sprays of the biocontrol agent (P = 0.0002). This counterintuitive result may indicate that investigators often attempt unsuccessfully to compensate for anticipated poor performance in antagonist-disease combinations by making more applications.

scholarly journals Bacterial Wilt of Solanaceae Caused by Ralstonia solanacearum Race 1 Biovar 3 in Mali

Plant Disease ◽  
2010 ◽  
Vol 94 (3) ◽  
pp. 372-372 ◽  
Author(s):  
A. T. Thera ◽  
B. J. Jacobsen ◽  
O. T. Neher
Keyword(s):  
Surface Water ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Solanum Tuberosum L ◽  
Solanum Melongena ◽  
Potato Seed ◽  
Relative Distribution ◽  
Tetrazolium Chloride ◽  
Wide Range ◽  
Race 1

Ralstonia solanacearum (Smith) Yabuuchi et al. causes bacterial wilt worldwide on a wide range of plant species. In Mali, the disease is commonly found on potato (Solanum tuberosum L.), tomato (Lycopersicon esculentum var. esculentum L.), pepper (Capsicum annuum L.), eggplant (Solanum melongena L.), tobacco (Nicotiana tabacum L.), and peanut (Arachis hypogaea L.). Determination of race and biovar is critical for development of potato seed certification programs for management of the disease. Isolates (25) of R. solanacearum were obtained from wilting potato, pepper, eggplant, tobacco, and tomato plants collected from fields near Baguineda, Sonityeni, Sotuba, Sikasso, and Kolikoro. Isolations were made from bacterial streaming by dilution plating on triphenyl tetrazolium chloride medium (TZC) (2). Characteristic colonies were selected and identified by ELISA or Immunostrips (Pathoscreen Rs, Agdia Inc., Elkhart, IN). These isolates were used in host range studies and hypersensitivity (HR) tests on tobacco (cv. xanthi) (3) and tested for their ability to produce acids on Ayers basal media amended with disaccharide and hexose alcohol carbon sources (1). These isolates caused characteristic wilt 40 days postinoculation on greenhouse-grown tobacco (cv. Xanthi), peanut (cv. 4610), and tomato (cv. Roma VF) plants when stems of five plants of each host were syringe inoculated with 0.1 ml of a 1 × 109 CFU/ml of bacteria. Plants inoculated with sterile distilled water remained symptomless and R. solanacearum was reisolated from infected plants on TZC and identified with Immunostrips. All HR tests were negative. Infection of peanut, tobacco, and tomato and the results of the HR tests indicated that all isolates were Race 1 and no significant variation was noted between isolates. Acid was produced from the hexose alcohols: mannitol, sorbitol, and dulcitol; and the disaccharides: cellobiose, lactose, and maltose. This indicated that all isolates were biovar 3, the same as a known Race 1 strain from tobacco (MSU Plant Pathology teaching collection) (1). To assess relative distribution of R. solanacearum, 20 soil samples collected from potato fields in the vicinity of Baguineda, Kati, Koulikoro, and Sikasso were placed in pots (30 × 25 cm) under shade cloth at the IER Station in Sotuba and planted with 30-day-old tobacco plants. After 90 days, infected plants (35 to 100% infection) were found in all soils. Infected plants exhibited classical wilt symptoms and tested positive for R. solanacearum infections as confirmed by Immunostrip tests. Six of nine surface water samples taken near potato fields in Baguineda, Sikasso, Mopti, and Koulikoro tested positive for the presence of R. solanacearum by an Agdia Inc. enrichment kit and ELISA. A weed, Commelina forskalaei (Vahl), collected by Farako creek near Sikasso tested positive in the Immunostrip test even though no symptoms were obvious. No attempt was made to characterize the race, biovar, or phylotype of the soil, water, and weed isolates. To our knowledge, this is the first time that the race and biovar of R. solanacearum from Mali has been reported and the wide distribution of this pathogen in Malian soils and surface water has been demonstrated. It is significant that we did not detect Race 3 biovar 2, which is subject to quarantine and biosecurity regulations. References: (1) A. C. Hayward. J. Bacteriol. 27:265, 1964. (2) A. Kelman. Phytopathology 44:693, 1954. (3) J. Lozano and L. Sequeira. Phytopathology 60:833, 1970.

scholarly journals Control of Bacterial Spot on Tomato in the Greenhouse and Field with H-mutant Bacteriophages

HortScience ◽  
2000 ◽  
Vol 35 (5) ◽  
pp. 882-884 ◽  
Author(s):  
J.E. Flaherty ◽  
G.C. Somodi ◽  
J.B. Jones ◽  
B.K. Harbaugh ◽  
L.E. Jackson
Keyword(s):  
Chemical Control ◽  
Xanthomonas Campestris ◽  
Bacterial Spot ◽  
Water Control ◽  
Tomato Seedling ◽  
Manganese Zinc ◽  
Progress Curve ◽  
Race 1 ◽  
Field Season ◽  
Early Vigor

A mixture of host-range mutant (h-mutant) bacteriophages specific for tomato race 1 (T1) and race 3 (T3) of the bacterial spot pathogen, Xanthomonas campestris pv. vesicatoria (Doidge) Dye was evaluated for biological control of bacterial spot on `Sunbeam' tomato (Lycopersicon esculentum Mill.) transplants and field-grown plants for two seasons (Fall 1997 and Fall 1998). Foliar applications of bacteriophages were compared with similar applications of water (control) and of copper/mancozeb bactericides, the commonly used chemical control strategy for tomato seedling and field production. In 1997, the incidence of bacterial spot on greenhouse-grown seedlings was reduced from 40.5% (control) to 5.5% or 0.9% for bactericide- or bacteriophage-treated plants, respectively. In 1998, the incidence of bacterial spot was 17.4% on control plants vs. 5.5% and 2.7% for bactericide- and bacteriophage-treated plants, respectively, although these differences were not statistically significant at P ≤ 0.05. Applications of bacteriophages to field-grown tomatoes decreased disease severity as measured by the area under the disease progress curve (AUDPC) by 17.5% (1997) and 16.8% (1998) compared with untreated control plants. Preharvest plant vigor ratings, taken twice during each field season, were higher in the bacteriophage-treated plants than in either bactericide-treated plants or nontreated controls except for the early vigor rating in 1998. Use of bacteriophages increased total weight of extra-large fruit 14.9% (1997) and 24.2% (1998) relative to that of nontreated control plants, and 37.8% (1997) and 23.9% (1998) relative to that of plants treated with the chemical bactericides. Chemical names used: manganese, zinc, carboxyethylene bis dithiocarbamate (mancozeb).

scholarly journals Substrate incubation time after fungi inoculation in the control tomato seedling damping-off

2021 ◽  
pp. 411-415
Author(s):  
Gabriel Danilo Shimizu ◽  
Rafael de Freitas Orozimbo da Silva ◽  
Luana Tainá Machado Ribeiro ◽  
Maíra Tiaki Higuchi ◽  
Jean Carlo Baudraz de Paula ◽  
...  
Keyword(s):  
Incubation Time ◽  
Trichoderma Harzianum ◽  
Crop Production ◽  
Plant Diseases ◽  
Damping Off ◽  
Trichoderma Spp ◽  
Tomato Crop ◽  
Tomato Seedling ◽  
Tomato Seedlings ◽  
Progress Curve

The use of fungi of the genus Trichoderma spp. for the control of plant diseases it has proved to be an important and promising tool, mainly for the tomato crop production system, however, there are difficulties in establishing the bioagent. This work aimed to evaluate the effect of substrate incubation time after inoculation with Trichoderma harzianum to control the damping-off of tomato seedlings. The experimental design was completely randomized, consisting of six treatments and four replications. The treatments are two incubation times in two doses of T. harzianum (0 and 10 days of substrate incubation [DIST] after inoculation with T. harzianum in 1.0 or 5.0 g of T. harzianum) and two controls (control inoculated and not inoculated with Rhizoctonia solani). The variables analyzed were incidence of damping-off, area under the disease progress curve, percentage of emergence, emergency speed index, average emergency time, germination speed coefficient, total fresh mass, root length (cm) and height of the area part (cm). The treatments containing Trichoderma harzianum have proven to be promising for the control of R. solani and for the growth of tomato seedlings.

scholarly journals Potential of Trichoderma spp. Secondary Metabolite in Controlling Vascular Streak Dieback (VSD) on Cacao Seedlings

2017 ◽  
Vol 4 (2) ◽  
pp. 57 ◽  
Author(s):  
Rita Harni ◽  
Widi Amaria ◽  
Syafaruddin Syafaruddin ◽  
Anis Herliyati Mahsunah
Keyword(s):  
Secondary Metabolites ◽  
Secondary Metabolite ◽  
Plant Protection ◽  
Plant Diseases ◽  
Disease Suppression ◽  
Bioactive Molecules ◽  
Trichoderma Spp ◽  
Randomized Design ◽  
Dieback Disease ◽  
Number Of Leaves

<p class="Default">Trichoderma<em> spp. is a beneficial microbe that produces bioactive molecules (secondary metabolites) containing antibiotics, enzymes, hormones, as well as toxins, which play an important role in plant diseases biocontrol. The research aimed to determine the potential of secondary metabolite </em>Trichoderma<em> spp. to control vascular streak dieback disease in cacao seedlings. The research was conducted in Plant Protection Laboratory of Indonesian Industrial and Beverage Crops Research Institute (IIBCRI) and farmers' garden in Balubus village, Lima Puluh Kota, West Sumatera, from April to August 2016. The research used a complete randomized design of 7 treatments using 5 replications, each treatment with 5 plants. The treatment was a secondary metabolite of </em>T. virens<em> LP1, </em>T. hamatum<em> LP2, </em>T. amazonicum<em> LP3, </em>T. atroviride<em> JB2, and </em>T. viride<em> PRD, control (no secondary metabolite), and chemical fungicide as comparison. The 3 months old cacao seedlings were treated with secondary metabolite of </em>Trichoderma<em> spp. by spraying the metabolite suspension throughout the leaf surface. The secondary metabolite applied once a week for 6 times. </em>C. theobromae <em>inoculation was conducted naturally by placing cacao seedlings under a cacao tree infected with VSD. Observations were incubation period, VSD intensity, and growth of cacao seedlings. The results showed that secondary metabolites potentially utilized for controlling VSD in cacao seedlings. The most potential secondary metabolites are </em>T. amazonicum<em> LP3 and </em>T. virens<em> LP1 with respective disease suppression up to 81.8% and 63.2% or higher than and equivalent chemical fungicide (63.6%), and can increase plants height, number of leaves, and girth diameter.</em></p>

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