Control Of Wilt Research Articles

Effect of timing of diseased plant cutting, altitude and banana cultivar on efficacy of singly removing Xanthomonas wilt infected banana plants

The single diseased stem removal (SDSR) technology (i.e. timely cutting of diseased banana plants) is an important Xanthomonas wilt (XW) control method being promoted in XW-endemic zones of east/central Africa. Proper SDSR application leads to quick field recovery. However, its efficacy on farms has been variable. For example, delayed cutting of diseased stems/plants is postulated to increase Xcm inoculum buildup and risk of infection in other physically attached shoots, while larger suckers were thought to be less reliant on the mother plants for nutrients and water thus being less susceptible than small suckers. Previous SDSR evaluations took place at mid-high altitudes dominated by east African highland bananas whereas low-lying altitudes especially dominated by ABB types exist, and this site and type is more prone to insect-mediated XW infections. This study hence determined effects of: i) timing of cutting symptomatic plants on recovery of mats, ii) size of attached suckers at infection on their susceptibility to infection, and iii) the efficacy of SDSR at an ABB banana dominated low altitude site. XW incidence in suckers increased with a delay in cutting of symptomatic mother plants, with lowest incidence (0.27%) observed when symptomatic plants were immediately cut upon symptom expression and highest (1.61%) when plants decayed in situ. The larger maiden (32.1% diseased shoots) and sword suckers (22.2%) were significantly more susceptible than the small peepers (7.4%). XW incubation period was shorter for the maiden suckers (4.5 to 6.2 months) compared to 8.9–11.3 months for sword suckers and 11.3 months for peepers. Immediate cutting of plants after first visible symptoms should be recommended to farmers, while additional studies to understand the low susceptibility of small peepers would be warranted. SDSR was observed to be as effective at the ABB banana dominated low altitude sites as previously reported for highland bananas and environments.

Biological control of Fusarium wilt in tomato by endophytic rhizobactria

The Fusarium Wilt disease that is caused by Fusarium oxosporium is considered one of the most important diseases that threatens the agricultural production of tomato. In this study, the isolation of 52 Enterobacter strains that were isolated from the roots of healthy tomato plants in fields also containing tomato plants infected with the Fusarium Wilt disease were present. These Enterobacter strains were diagnosed by two methods: Api Kit 20E and biochemical test. In this study the antagonism of these isolated Enterobacter strains against the etiological agent for Fusarium Wilt disease were tested in vitro. The recent study of antagonism against Fusarium oxosporium showed that there are only two species strains out of 52 have antagonism against Fusarium oxosporium, and these strains are: Pseudomonas flourscence, and Basillus subtilis.However these three isolated strains have antagonism against growth of Fusarium oxosporium and the inhibition zone ranged from (1.5 to 11 ml). The selected isolates were evaluated in vitro for their activities related to plant nutrition and plant growth regulation. Both of these assessed endophytes were found to exhibit capabilities in ammonia and indole acetic acid (IAA) production as well as phosphate solubilization. It is concluded that application of Pseudomonas flourscence and Basillus subtilis may be promising approach for biological control of the tomato bacterial wilt and may play an important role in sustainable agriculture.

海产品下脚料发酵物对香蕉枯萎病的防治试验

海产品下脚料发酵物对香蕉枯萎病的防治试验

The economic viability of suppressive crop rotations for the control of verticillium wilt in organic strawberry production

ABSTRACTSoil-borne diseases and nitrogen availability are important limits on organic strawberry production. A trial using suppressive crop rotations to combat Verticillium wilt was conducted to see its effects on strawberry yields and net returns using a split-split-plot design. An ANOVA analysis was run to understand determinants of net returns. Results show that the suppression of wilt through the planting of non-host crops such as broccoli before the planting of strawberries can have significant effects on yield and net returns, and that suppressive crop rotations are potentially commercially viable.

A practical random mutagenesis system for Ralstonia solanacearum strains causing bacterial wilt of Pogostemon cablin using Tn5 transposon.

A practical random mutagenesis system of Ralstonia solanacearum by electroporation with Tn5 transposon was established, which may be utilized to provide genetic approach to study virulence genes of R. solanacearum strains and create nonpathogenic mutants for biological control of bacterial wilt in Pogostemon cablin. R. solanacearum strain PRS-84 used in this study was isolated from P. cablin plants infected with bacterial wilt. The bacterial suspension of R. solanacearum strain PRS-84 was mixed with Tn5 transposome complex and the mixture was transformed by electroporation. The electroporated cells were then spread on the 2, 3, 5-triphenyltetrazolium chloride agar plates containing kanamycin to select the kanamycin-resistant colonies. Several factors which determined the bacterial transformation efficiency were optimized. The transformation process was shown to be optimal at the electric field strength of 12.5kVcm-1. Bacterial cells harvested at mid-exponential phase gave the highest transformation efficiency. 10µgmL-1 kanamycin was found to be the optimal concentration for transformant selection. Tn5 insertion mutants of R. solanacearum strain PRS-84 were identified by PCR amplification and Southern blot analysis. Mutants subcultured for 100 passages were also detected by PCR amplification and Southern blot analysis. Furthermore, pathogenicity screening test of mutants was performed by inoculating in vitro regenerated patchouli plants. Results revealed that mutants with a single Tn5 insertion in their genomes were obtained from R. solanacearum strain PRS-84, and the Tn5 insertion could be stably inherited in the mutants. Then, mutants with reduced pathogenicity were selected.

Control of Fusarium wilt of melon by combined treatment with biocontrol, plant-activating, and soil-alkalizing agents

Fusarium wilt of melon is one of the destructive diseases of melon worldwide. To develop a method to control the soilborne disease Fusarium wilt of melon, we applied various combinations of a crop-protective microbe, a plant activator, and a soil pH increaser during seedling cultivation in preliminary greenhouse tests and chose the crop-protective Fusarium oxysporum strain SL0037, plant activator probenazole (PBZ), and soil-alkalizer slag fertilizer (SFR) for further tests in the field. From 2012 to 2014, the effects of treatment combinations with SL0037, PBZ, and SFR were tested in a field that was amended with the melon wilt pathogen F. oxysporum f. sp. melonis. Although disease incidence varied among the 3 years of the study, the main stem of melon plants was longer than that of the untreated control plants or those treated with one or two of the three agents. Results suggest a combination of SL0037, PBZ, and SFR treatments can be used to control Fusarium wilt of melon and improve growth of melon plants.

Control of Fusarium wilt of lisianthus by reassembling the microbial community in infested soil through reductive soil disinfestation

Continuous monocropping often influences negatively the soil microbial community and leads to the occurrence of soil-borne diseases. In this study, a pre-cultivation soil management strategy, reductive soil disinfestation (RSD), involving amendment by the use of reed straw, bagasse, and rice straw, and creating anaerobic soil conditions, was used to regulate the microbial community in a soil infested by Fusarium wilt of lisianthus and make it suitable for plant cultivation. The results showed that RSD significantly decreased F. oxysporum population by 97.1%–99.1% and the incidence of lisianthus wilt disease to 3.0%–14.3% compared with that of the untreated soil. The lowest disease incidence was found in the soil treated with RSD where bagasse was incorporated. The replantation of the host plant differently stimulated the pathogen proliferations across the different soils. MiSeq sequencing and culture-dependent investigation showed that the RSD treatments established distinct microbial communities compared to that of the untreated soil. Furthermore, the relative abundances of representatives of the families Cytophagaceae, Chitinophagaceae, Chaetomiaceae, and an unclassified family within Sordariomycetes, as well as soil microbial activity and the proportions of antagonists were significantly and negatively correlated with the pathogen population increase. Overall, the RSD treatment contributed to the reassembly of the soil microbiome which contained more beneficial agents that successfully controlled the pathogen inoculum level and lisianthus Fusarium wilt disease.

Soil fumigation with ammonium bicarbonate or metam sodium under high temperature alleviates continuous cropping-induced Fusarium wilt in watermelon

The induction of Fusarium wilt by continuous cropping has become a severe problem for watermelon cultivation around the world. Here, the feasibility and underlying mechanism of soil fumigation with ammonium bicarbonate (AB) or metam sodium (MS) under high temperature (HT) were investigated for the control of Fusarium wilt during watermelon growth on continuously cropped soils. Both AB + HT and MS + HT decreased the density of Fusarium oxysporum f. sp. niveum (FON) in soil, improved the soil properties (i.e. increased the pH, reduced salinity, improved soil nutrients, balanced soil micro-ecology, and increased soil enzyme activities), and consequently decreased the Fusarium wilt incidence and improved the watermelon fruit quality. In vitro, MS treatment stopped the growth of FON on medium, while AB mixed with lime (but not AB) alone inhibited FON growth. AB or MS fumigated soils under HT also decreased Fusarium wilt incidence of watermelon seedlings after artificial FON infection. Consequently, AB + HT and MS + HT can control continuous cropping-induced Fusarium wilt by both inhibiting FON growth and improving the soil environment.

Soil sterilization, pathogen and antagonist concentration affect biological control of Fusarium wilt of cape gooseberry by Bacillus velezensis Bs006

Background and aimFusarium wilt (FW) is the major constraint on cape gooseberry (Physalis peruviana L.) production. Fungicides have been ineffective in disease control and alternative tools are not available. Bacillus velezensis (formerly Bacillus amyloliquefaciens) strain Bs006 has an antagonistic potential against Fusarium oxysporum f. sp. physali (Foph). However, results of in vivo tests have been variable. We examined the effect of biotic sources of variability on the biocontrol activity of Bs006.MethodsPot experiments in greenhouse were carried out to determine the influence of soil sterilization and concentration of both pathogen and antagonist in soil on biocontrol activity and the effect of pathogen on plant growth promotion by Bs006.ResultsEfficacy of Bs006 against FW was significantly lower under sterile than non-sterile soil condition. Diluted liquid culture of Bs006 at 1 × 106 and 1 × 107 cfu.mL−1 reduced FW by up to 97% under low Foph inoculum pressure (102 to 104 cfu.g−1 of soil) but at 1 × 108 cfu.mL−1 biological treatment significantly reduced FW only when the concentration of Foph was 1 × 104 cfu.g−1 by 71%. The evaluation of biomass of Bs006 (1 × 108 cfu.mL−1) and supernatant free of bacteria added at 10% allowed to observe that the supernatant was an additional source of biocontrol variability, since high volumes of supernatant favored the development of the disease. Plant growth promoting activity by Bs006 was reduced by the presence of Foph in the soil. Bs006 grew endophytically in cape gooseberry and had high population levels in the rhizosphere inoculated with Foph.ConclusionsThe efficacy of Bs006 to reduce FW was affected by soil sterilization, the concentration of both antagonist and pathogen, and high volumes of supernatant. This work has practical implications for the design of control strategies based on B. velezensis Bs006.

Characterization and sequence analysis of potential biofertilizer and biocontrol agent Bacillus subtilis strain SEM-9 from silkworm excrement.

Fusarium wilt is a devastating soil-borne disease caused mainly by highly host-specific formae speciales of Fusarium oxysporum. Antagonistic microorganisms play a very important role in Fusarium wilt control, and the isolation of potential biocontrol strains is becoming more and more important. We isolated a bacterial strain (SEM-9) from the high-temperature stage of silkworm excrement composting, which had a marked ability to solubilize phosphorus, promote the growth and increase the yield of the small Chinese cabbage, and which also exhibited considerable antagonistic effect towards Fusarium sambucinum and other fungi. The result of physiological and biochemical analyses, as well as genome sequencing, showed that SEM-9 was a strain of Bacillus subtilis. Through genome annotation and analysis, it was found that SEM-9 contained genes related to the regulation of biofilm formation, which may play an important role in colonization, and gene clusters encoding the biosynthesis of antimicrobials, such as surfactin, bacilysin, fengycin, and subtilosin-A. The production of such antifungal compounds may constitute the basis of the mode-of-action of SEM-9 against Fusarium spp. These data suggested that the SEM-9 strain has potential as both a biofertilizer and a biocontrol agent, with the potential to manage Fusarium wilt disease in crops.

Bacterial Formulations in Induction of Resistance and Growth Promotion of Tomato Plants

The objective of this work was to evaluate the effectiveness of seed treatment with fresh suspensions and powder formulations with Bacillus methylotrophicus to promote plant growth and induction of resistance against fusarium wilt (Fusarium oxysporum f. sp. lycopersici) in tomato plants under greenhouse conditions, verifying the occurrence of morphological and biochemical changes in the evaluated plants. Powder formulations based on Cassava (Manihot esculenta), Arrowroot (Maranta arundinacea) and sodium alginate containing Bacillus, in addition to the commercial product Quartz®, were used to microbiolize the tomato seeds of the cultivar Santa Cruz. The formulations promoted plant growth, with a seedling vigor index greater than 50% for all treatments containing B. mthylotrophicus, in addition to a significant increase in total dry matter. The treatments induced systemic resistance, controlling the fusarium wilt with a 75% reduction of the disease and activation of enzymes such as peroxidase and polyphenoloxidase, only β-1,3-glucanase presented less activity than controls (treatments without B. mthylotrophicus). Thus, the use of formulations containing Bacillus are efficient in promoting plant growth of tomato plants and in inducing resistance to the control of fusarium wilt.

Compatibility of tomato cultivar Santa Cruz Kada grafted on different Solanaceae species and control of bacterial wilt

ABSTRACT The objective of this work was to evaluate the compatibility, gas exchange and yield of tomato cultivar Santa Cruz Kada, susceptible to bacterial wilt (Ralstonia solanacearum) when grafted on different Solanaceae species. Rootstock sources were the mini-tomato RVTC-66, Cayenne pepper, Jerusalem cherry (Solanum pseudocapsicum), sticky nightshade (Solanum sisymbriifolium), and cultivar Santa Cruz Kada itself (self-grafting). Two materials were tested to promote the union between rootstocks and scions: grafting clips and biodegradable tape (Parafilm). Grafting success index (GSI) was evaluated and, for treatments using biodegradable tape, grafting incompatibility, gas exchange, agronomic characteristics and bacterial wilt epidemiology were assessed throughout the cycle. The use of biodegradable tape favored graft healing. Cayenne pepper, Jerusalem cherry, and sticky nightshade should not be employed as rootstocks for scions of tomato cultivar Santa Cruz Kada. The mini-tomato accession RVTC-66 showed low graft incompatibility, high photosynthetic efficiency and, when compared to self-grafting, the same fruit production, but with higher plant health index concerning the bacterial wilt.

Changes in soil microbial diversity and control of Fusarium oxysporum in continuous cropping cucumber greenhouses following biofumigation

Soil biofumigation with Brassia plant parts has been demonstrated to suppress soil-borne pathogens. This effect has been attributed to the bactericidal effect of their glucosinolate degradation products. However, little is known regarding the effect of biofumigation on the microbial community structure and control of Fusarium oxysporum in continuous cropping cucumber systems. Field and pot experiments were performed to study the effect of biofumigation with brassica crops of different glucosinolate contents on the microbial diversity and control of Fusarium oxysporum during the cucumber growth period in a continuous cropping culture system. Samples collected from biofumigation and control treatments differed in the number of soil bacterial bands observed by denaturing gradient gel electrophoresis (DGGE) profiling, suggesting that biofumigation changed the soil microbial diversity. Compared with control and chemically-fumigated (HY) soils, the biofumigated soil exhibited significantly higher Shannon-Weaver diversity indices for bacteria and fungi. Cluster analysis and principal component analysis revealed that soil bacteria communities were different in the hymexazol (HY)-treated soils compared with the communities before biofumigation (BB) and those in the no fumigation (CK) groups. This was true for the mustard containing high glucosinolates (MHG), mustard containing low glucosinates (MLG), mustard (MU), and turnip (TU) groups. Pot experiments demonstrated that the amounts of Fusarium oxysporum in MHG- and HY-treated soils were significantly lower than those in other biofumigation treatments. These results demonstrate the potential utility of Brassica crops in the control of Fusarium wilt in continuous cucumber cropping systems, and the control effect of MGH was the best compared with other treatments, which could effectively reduce Fusarium oxysporum in soil by more than 60%.

Control of Fusarium wilt in wheat seedlings by grain priming with defensin-like protein

The exogenous application of natural plant resistance inducer is a new interesting way for disease management. From this point of view, this study investigated the effect of wheat grain priming with defensin on the resistance of the grown plants against the Fusarium wilt. The results showed that priming enhanced the antioxidant system represented in antioxidant enzymes (superoxide dismutase, polyphenol oxidase, soluble and cell wall-bound peroxidase) and non-enzymatic antioxidant compounds (proline, free soluble and cell wall-bound phenols) in the plants. This results in decreasing the H2O2 content and lipid peroxidation in these plants, which protects plants from the oxidative stress. Defensin priming not only improved the antioxidant system but also improved the hydrolysis processes. Under infection, the protease activity in the primed plants decreased compared to its highly significant increase in the non-primed group. Defensin priming also increased the activity of the phosphatases and amylase which increased the soluble phosphate and sugar. This served the high metabolic activity of the defensin-primed plants. The highly significant decrease in the shikimic acid content in the defensin-primed group ensured its high metabolic activity. All these changes are initiated by the regulation of defense signal molecules such as jasmonic and abscisic acids. This helped the plants grown from defensin-primed grains to overcome the Fusarium infection.

Banana Fusarium Wilt (Fusarium oxysporum f. sp. cubense) Control and Resistance, in the Context of Developing Wilt-resistant Bananas Within Sustainable Production Systems

Banana (Musa spp.) is seriously threatened by the soil-borne fungus Fusarium oxysporum f. sp. cubense (Foc), also known as Panama disease. Attempts to control Fusarium wilt with fungicides damage soil health and have limited efficiency due to pathogenic variability. Elucidating the mechanism of infection and molecular basis of host defense through banana genome sequencing, genome editing and proteomic profile analysis will help formulate strategies to develop resistant cultivars. This will include research to better understand the functions of Fusarium wilt-resistance proteins. Transgenic approaches and protoplast fusion could be employed as tools for transferring resistance genes from wild relatives to commercial banana varieties, and may serve as a new strategy in solving the problems faced by banana breeding programmes. Evaluation of banana germplasm for resistance to Fusarium wilt using in vitro mutation and selection, along with somaclonal variation and somatic hybridization, could improve banana breeding efficiency for resistance against Foc. Plant hormones could also play an important role in regulating plant growth and defense by mediating developmental processes and signaling networks involved in banana responses to Foc. A complementary approach for managing Fusarium wilt, such as exclusion, surveillance and biological control as important components of integrated disease management programs must be considered to prevent and contain contagion. This includes studies on banana plant-microbe interactions, embracing both plant growth promoting rhizobacteria (PGPR) to induce Foc resistance, and exploring Foc-derived elicitors for inducing defense-related enzymes in bananas. The role of Silicon and crop and livestock integration must also be included in the Fusarium control toolbox. The current review also gathers knowledge of the biotechnological approaches along with biological control of Fusarium wilt of banana that will provide researchers insights and criteria to develop future studies.

Fungal Biosynthesis of Silver Nanoparticles and Their Role in Control of Fusarium Wilt of Sweet Pepper and Soil-borne Fungi in vitro

Fungal Biosynthesis of Silver Nanoparticles and Their Role in Control of Fusarium Wilt of Sweet Pepper and Soil-borne Fungi in vitro

Characterization of Mesorhizobium strains for salt tolerance and wilt control: Their potential for plant growth promotion of chickpea (Cicer arietinum L.)

Mesorhizobium sp. indirectly promote the growth of plants as a biocontrol agent by inhibiting the growth of pathogens particularly Fusarium wilt of chickpea. Out of 24 Mesorhizobium isolates obtained from chickpea nodules, eight isolates showed antagonistic effect against Fusarium oxysporum. Salinity stress severely affects growth, nodulation and yield of chickpea. Mesorhizobium isolates were tested for their salt tolerance capacity at 1, 2, 4, 6 and 8% NaCl concentrations. Only two Mesorhizobium isolates MCA5 and MCA22 were found salt-tolerant upto 8% of salt concentration. Maximum increase (45.5%) in shoot dry weight was observed by inoculation of isolate MCA20 at 40 days of chickpea growth under chillum jar conditions, whereas isolate MCA23 resulted in 166.2% increase in root dry weight. Likewise, 112.6% increase in shoot dry weight was observed on inoculation of MCA14 isolate at 80th day of observation. Further extensive research is required to understand the mechanism of potential Mesorhizobium isolates of chickpea in controlling Fusarium wilt disease and salt tolerance. Selection of mesorhizobia with twin functional traits (plant growth promoting and biocontrol agent) can be exploited as future biofertilizer in chickpea.

Biological control of tomato Fusarium wilt and whiteflies with two fungal biopesticides

This work summarizes the efforts and successes toward practical applications of two biopesticides. The first one, TRICOTEC®, based on Trichoderma koningiopsis Th003, to control Fusarium wilt (FW), and the second one, LECABIOL®, based on Lecanicillium lecanii Vl026, to control whitefly. For TRICOTEC®, our attention was focused on protection of the tomato spermosphere or rhizosphere. Application of TRICOTEC® reduced the incidence of damping-off in tomato seedlings from 38 to 96%, and FW incidence from 42 to 58%. On the other hand, LECABIOL® showed an efficacy against both Bemisia tabaci and Trialeurodes vaporariorum ranging from 60 to 70%, with increased profits, demonstrating economic benefits. Both biopesticides have been incorporated sequentially in efficacy tests to simultaneously control FW and whiteflies. Use directions, application rate, method, and timing were established to integrate them in commercial tomato production.

Evaluating crude extracts of Monsonia burkeana and Moringa oleifera against Fusarium wilt of tomato

ABSTRACTFusarium wilt is one of the major soil-borne diseases of tomato crop globally. The study aimed to evaluate the efficacy of medicinal plants in the control of Fusarium wilt in tomato. Methanolic extracts of Monsonia burkena and Moringa oleifera were assessed in vitro and under greenhouse conditions. The in vitro experiments evaluated the effect of both extracts on Fusarium oxysporum f. sp lycopersici growth and response to varying concentrations. In greenhouse experiment, tomato seedlings cv. HTX14 were inoculated with conidial suspension of F. oxysporum and transplanted into pasteurised growth media amended with plant extract. Seedlings were treated with aqueous extracts at varying concentrations with an interval of 7 days between applications. Control treatments were treated with sterile distilled water. Both plant extracts significantly reduced pathogen growth in vitro and reduced wilt severity under greenhouse conditions. The highest mycelial growth suppression was observed in Mon. burkeana treatments. Under greenhouse conditions, both plant extracts significantly (P ≤ 0.05) reduced Fusarium wilt severity and had a positive effect on plant growth parameters. A significant increase in soil-pH was also recorded in extract treated soil resulting in reduction in disease severity. The results further provide new scientific information on how their effect on soil pH can be beneficial in the control of Fusarium wilt.

Control of Fusarium wilt of tomato in the greenhouse using silver nanofungicides

Control of Fusarium wilt of tomato in the greenhouse using silver nanofungicides