Control Of Bacterial Wilt Disease Research Articles

Greenhouse tomato farmers' knowledge, perceptions, and management of tomato bacterial wilt (Ralstonia solanacearum) disease

A major constraint to tomato cultivation is bacterial wilt disease. The use of greenhouses to cultivate tomato is vital to controlling the bacterial wilt disease. Bacterial wilt can be successfully managed when farmers are well-informed with better knowledge of bacterial wilt in tomatoes. This study was conducted to assess farmers’ knowledge and experiences on the cultivation practices, prevalence, detection, spread, and control of bacterial wilt disease in tomato in greenhouses in the Volta, Eastern, Central, and Greater Accra regions of Ghana. Questionnaires were administered for fifty (50) greenhouse farmers, purposefully selected using a database of greenhouse tomato producers in southern Ghana provided by the Ministry of Food and Agriculture (MOFA). Frequency data was analyzed using descriptive statistical analysis. The majority (86%) of respondents had formal education. Most of the greenhouses in operation were in the Greater Accra Region, and none was under cultivation in the Volta region at the time of the study. Most respondents have been involved in greenhouse tomato cultivation for barely three years. The frequency of greenhouse tomatoes production varied from one region to the other. Only 28% of greenhouse farmers knew the test to detect the disease with 64% of greenhouse farmers without any knowledge about how the disease spreads. 62% of respondents used roughing and burying of the infected plants to control the disease. Out of the 54 greenhouses (domes) surveyed, 12 were infected with the bacterial wilt disease. Greenhouse farmers had little knowledge on the spread, detection, and control of the bacterial wilt disease of tomato. The findings of this study would lead to the design of targeted training programs on cultivation practices, detection, spread and management of bacterial wilt of tomato to increase yield and boost income levels of greenhouse tomato farmers in Ghana. Key words: bacterial wilt, tomatoes, spread, detection, control, greenhouse, farmers, constraints

PH-responsive bentonite nanoclay carriers control the release of benzothiazolinone to restrain bacterial wilt disease

Ralstonia solanacearum (R. solanacearum) is one of the most devastating pathogens in terms of losses in agricultural production. Bentonite (Bent) is a promising synergistic agent used in development of effective and environmentally friendly pesticides against plant disease. However, the synergistic mechanism of Bent nanoclays with benzothiazolinone (BIT) against R. solanacearum is unknown. In this work, acid-functionalized porous Bent and cetyltrimethylammonium bromide (CTAB) were employed as the core nanoclays, and BIT was loaded into the clay to form BIT-loaded CT-Bent (BIT@CT-Bent) for the control of bacterial wilt disease. BIT@CT-Bent exhibited pH-responsive release behavior that fit the Fickian diffusion model, rapidly releasing BIT in an acidic environment (pH = 5.5). The antibacterial effect of BIT@CT-Bent was approximately 4 times greater than that of the commercial product BIT, and its biotoxicity was much lower than that of BIT under the same conditions. Interestingly, R. solanacearum attracted BIT@CT-Bent into the nanocomposites and induced cytoplasmic leakage and changes in membrane permeability, indicating an efficient and synergistic bactericidal effect that rapidly reduced bacterial density. In addition, BIT@CT-Bent significantly inhibited R. solanacearum biofilm formation and swimming activity, by suppressing the expression of phcA, solR and vsrC. Indeed, exogenous application of BIT@CT-Bent significantly suppressed the virulence of R. solanacearum on tobacco plants, with control effect of 75.48%, 72.08% and 66.08% at 9, 11 and 13 days after inoculation, respectively. This study highlights the potential of using BIT@CT-Bent as an effective, eco-friendly bactericide to control bacterial wilt diseases and for the development of sustainable crop protection strategies.

Functionalized boron nitride nanosheets conjugated with plant micronutrients as seed dressing agents towards control of bacterial wilt disease

A novel strategy for bacterial wilt disease control was proposed involving boron nitride nanosheets to immobilize plant micronutrients and form a defensive barrier in plant roots to block or inhibit the invasion of pathogen.

PH-Responsive On-Demand Alkaloids Release from Core-Shell ZnO@ZIF-8 Nanosphere for Synergistic Control of Bacterial Wilt Disease.

Developing an effective and safe technology to control severe bacterial diseases in agriculture has attracted significant attention. Here, ZnO nanosphere and ZIF-8 are employed as core and shell, respectively, and then a pH-responsive core-shell nanocarrier (ZnO-Z) was prepared by in situ crystal growth strategy. The bactericide berberine (Ber) was further loaded to form Ber-loaded ZnO-Z (Ber@ZnO-Z) for control of tomato bacterial wilt disease. Results demonstrated that Ber@ZnO-Z could release Ber rapidly in an acidic environment, which corresponded to the pH of the soil where the tomato bacterial wilt disease often outbreak. In vitro experiments showed that the antibacterial activity of Ber@ZnO-Z was about 4.5 times and 1.8 times higher than that of Ber and ZnO-Z, respectively. It was because Ber@ZnO-Z could induce ROS generation, resulting in DNA damage, cytoplasm leakage, and membrane permeability changes so the released Ber without penetrability more easily penetrated the bacteria to achieve an efficient synergistic bactericidal effect with ZnO-Z carriers after combining with DNA. Pot experiments also showed that Ber@ZnO-Z significantly reduced disease severity with a wilt index of 45.8% on day 14 after inoculation, compared to 94.4% for the commercial berberine aqueous solution. More importantly, ZnO-Z carriers did not accumulate in aboveground parts of plants and did not affect plant growth in a short period. This work provides guidance for the effective control of soil-borne bacterial diseases and the development of sustainable agriculture.

Application of Genetic Engineering for Control of Bacterial Wilt Disease of Enset, Ethiopia's Sustainability Crop.

Enset (Ensete ventricosum (Welw.) Cheesman) is one of the Ethiopia’s indigenous sustainability crops supporting the livelihoods of about 20 million people, mainly in the densely populated South and Southwestern parts of the country. Enset serves as a food security crop for humans, animal feed, and source of fiber for the producers. The production of enset has been constrained by plant pests, diseases, and abiotic factors. Among these constraints, bacterial wilt disease has been the most important limiting factor for enset production since its outbreak five decades ago. There is no known bacterial wilt disease resistant genetic material in the enset genetic pool to transfer this trait to susceptible enset varieties through conventional breeding. Moreover, the absence of effective chemicals against the disease has left farmers without means to combat bacterial wilt for decades. Genetic engineering has been the alternative approach to develop disease resistant plant materials in other crops where traditional breeding tools are ineffective. This review discusses enset cultivation and recent developments addressing the control of bacterial wilt disease in enset and related crops like banana to help design effective strategies.

Integrated effect of Glomus mosseae and selected plant oils on the control of bacterial wilt disease of tomato

This study investigated the efficacy of Glomus mosseae and thyme and peppermint oils in controlling bacterial wilt disease (BW) of tomato caused by Ralstonia solanacearum under in vitro conditions and under greenhouse and field conditions. In an in vitro study, we tested nine plant oils against R. solanacearum, and the results demonstrate that only caraway, thyme, peppermint and marjoram oils inhibited the growth of the BW pathogen with differing degrees, thyme oil caused the highest reduction of the growth of the pathogen followed by peppermint and the lowest was caraway and marjoram. We evaluated the effect of thyme and peppermint under greenhouse and field conditions. Under greenhouse conditions, the thyme treatment exhibited the highest disease reduction percentage followed by the thyme + peppermint treatment, while G. mosseae caused the least disease reduction percentage. Under field experiments, thyme oil treatment exhibited the highest ability to reduce the disease by 94.8 and 97.1% in the 2011 and 2012 growing seasons, respectively, followed by the treatment of thyme oil + peppermint oil with the reduction of 89.5 and 82.4%, respectively. G. mosseae exhibited the lowest percentage of disease reduction; however, it caused a greater yield increase percentage during both of the tested seasons.

Soil-borne antagonists for biological control of bacterial wilt disease caused by Ralstonia solanacearum in tomato and pepper.

Bacterial wilt is an important disease of tomatoes and peppers, causing plant death and significant yield losses. Control methods include use of resistant varieties, crop rotation, etc. Biological control is desirable because control with other methods gives variable results. This paper describes the effectiveness of microbial antagonists isolated from soils. Of 73 isolated antagonists, eight were screened and evaluated in vitro and in vivo against Ralstonia solanacearum. They all significantly reduced disease symptoms. The effects of carbon and nitrogen source, incubation temperature and broth culture pH were evaluated for production of inhibitory substances. Results indicated that the optima were sucrose 2.5% (w/v), peptone 2% (w/v), temperature 28°C, and initial medium pH of 7. Three antagonists isolated from soil (Bacillus megaterium, Enterobacter cloacae, Pichia guillermondii) and Candida ethanolica showed high potential for disease suppression and also increased fruit weight, biomass and plant height. These results provide encouragement for continued research on biological control of bacterial wilt by antagonistic isolates from soil.

Control of Bacterial Wilt Disease of Tomato Through Integrated Crop Management Strategies

Tomato cultivation is severely affected by bacterial wilt disease caused by the soilborne pathogen Ralstonia solanacearum (previously known as Pseudomonas solanacearum Smith). Effects of rotation of tomato (Lycopersicon esculentum Mill.) with other crops on soil populations of R. solanacearum and on bacterial wilt disease incidence of tomato were evaluated in the field. Monocropped Cassava (Manihot esculenta Crantz), Mucuna puriens L., Crotalaria juncea L., and intercrops of Cassava/Crotalaria, Cassava/Mucuna, and a natural grass mix (control) were rotated with the tomato cvs. Mira, Ronita, Roma VFN, and Ibadan Local. Monocropped Mucuna significantly reduced soil population of R. solanacearum by the end of the rotation period, whereas the natural grass rotation had the highest population of the pathogen. Other crops with the exception of monocropped cassava also reduced the pathogen soil population. The incidence of wilt was delayed in cvs. Mira, Roma VFN, and Ronita compared to ‘Ibadan Local’, but all were 80% or more infected after 8 weeks.

Colonization ofPythium oligandrumin the Tomato Rhizosphere for Biological Control of Bacterial Wilt Disease Analyzed by Real-Time PCR and Confocal Laser-Scanning Microscopy

It recently has been reported that the non-plant-pathogenic oomycete Pythium oligandrum suppresses bacterial wilt caused by Ralstonia solanacearum in tomato. As one approach to determine disease-suppressive mechanisms of action, we analyzed the colonization of P. oligandrum in rhizospheres of tomato using real-time polymerase chain reaction (PCR) and confocal laser-scanning microscopy. The real-time PCR specifically quantified P. oligandrum in the tomato rhizosphere that is reliable over a range of 0.1 pg to 1 ng of P. oligandrum DNA from 25 mg dry weight of soil. Rhizosphere populations of P. oligandrum from tomato grown for 3 weeks in both unsterilized and sterilized field soils similarly increased with the initial application of at least 5 x 10(5) oospores per plant. Confocal microscopic observation also showed that hyphal development was frequent on the root surface and some hyphae penetrated into root epidermis. However, rhizosphere population dynamics after transplanting into sterilized soil showed that the P. oligandrum population decreased with time after transplanting, particularly at the root tips, indicating that this biocontrol fungus is rhizosphere competent but does not actively spread along roots. Protection over the long term from root-infecting pathogens does not seem to involve direct competition. However, sparse rhizosphere colonization of P. oligandrum reduced the bacterial wilt as well as more extensive colonization, which did not reduce the rhizosphere population of R. solanacearum. These results suggest that competition for infection sites and nutrients in rhizosphere is not the primary biocontrol mechanism of bacterial wilt by P. oligandrum.