A survey of an outbreak of fungal diseases of rice variety Phitsanulok2 (PLS91014-16-1-5-1) was conducted in Thailand during June 2014 to January 2015 using aW-random sampling pat-tern. The study revealed the incidence of several diseases including brown spot (Bipolaris oryzae), narrow brown leaf streak (Cercospora oryzae), and dirty panicle (Alternaria padwickii, C. oryzae, Curvularia lunata, Fusarium semitectum, and B. oryzae). This study evaluated the ef-ficacy of wood vinegar for control of these fungal diseases. A compleel randomized design was used, using the above variety in 3 replications. In the laboratory we found wood vinegar to be effective in inhibiting growth of representative pathogens such as C. lunata,B. oryzae,F. semi-tectum, and A. padwickii, the causal agent of dirty panicle disease. The field results confirmed the efficacy of wood vinegar under greenhouse conditions, with significantly reduced disease incidence of brown spot and dirty panicle, and significantly enhanced germination, seedling vigor,shoot height, root length, and fresh weight, when compared with the untreated control. However, seed treatment and 6 foliar sprays of wood vinegar under field conditions at Ang Thong showed no significant differences from the conventional treatment in suppression of brown spot, narrow brown leaf streak, and dirty panicle. The result demonstrates a promising alternative approach to control of key rice diseases.
Two-different carrier formulations, kaolin and talc-based products were developed with Pseudomonas fluorescens SP007s biocontrol agent. SP007s viability in different carriers stored at room temperature (28 to 33°C) slowly declined to approximately 46.2 and 61.0% after 12-month-old shelf life. The decreased population was first found in five and month months of storage for kaolin and talc-based formulations, respectively. Field experiment with 6-foliar spray intervals (1 × 10 8 cfu/ml) of SP007s was conducted against naturally-occurred dirty panicle disease caused by a multiplex fungus at Suphanburi. The two bioformulations significantly reduced pathogen colonization on rice panicle and exhibited the greatest yield that correlated with increased defense-related enzyme accumulation in treated plants, compared to 4-fungicide spray intervals and nontreated control. Protection of seeds collected from colonized and noncolonized plants of dirty panicle treated with bioformulations (1 × 10 6 cfu/ml) and fungicides (copper hydroxide) was further determined for 12 months of storage at room temperature. The best results in reducing 6-causal fungi including Alternaria padwickii, Cercospora oryzae, Curvularia lunata, Fusarium semitectum, Helminthosporium oryzaeqe and Sarocladium oryzae; and induced seedling vigor (35%) were obtained from SP007s kaolin-based formulation evaluated at 8-month storage, but not at 12 months which indicated that these causal pathogens totally recovered their colonization except S. oryzae. In 8-month trials, control efficacy with dose of 1 × 10 6 cfu/ml SP007s seed treatment, the increase in SP007s populations relatively with the decreased colonization of pathogens could be found. SP007s in kaolin-based formulation increased GABA in SP007s treated seeds suggesting this plant bioactivator may involve plant's defense against stress conditions also.
Xanthomonas axonopodis pv. glycines (Xag) causes bacterial pustule disease on soybean. This bacterium is present worldwide around hot and humid growing regions such as Southeast Asia. To understand if the gene coding for hemin transport protein (hem) is involved in virulence of the pathogen in soybean, we generated a hem mutant in Xag by overlapping PCR mutagenesis. Disruption of hem significantly reduced the population size and the disease incidence when sprayed on soybean but not when injected directly to soybean. The hem mutant caused the hypersensitive response induction on tobacco as an Xag wildtype. Interestingly, the hem expression was also reduced when the Xag wildtype grow in planta. The hemin transporter protein involved in the production of extracellular polysaccharide, biofilm formation, motility and attachment but not for extracellular enzymes. This confirmed that epiphytic fitness of Xag strongly required hem functions. These results suggest that hem gene is essential for virulence of Xag on soybean during the infection process.
The efficacy of two plant growth promoting rhizobacteria (PGPR) strains including Bacillus subtilis TUOrga1 and Pseudomonas fluorescens TU-Orga2 obtained from rice rhizosphere against naturally occurring diseases as well as their capacity to improve crop yield of sweet corn cv. Insee2 was studied. TU-Orga1 was significantly greater in inhibition of Acidovorax avenae subsp. avenae (Aaa) and Erwinia chrysanthemi pv. zeae (Ecz), caused bacterial leaf streak and stalk rot of corn, respectively by antibiosis. Greenhouse experiments using TU-Orga1 and TU-Orga2 treatments increased highest salicylic acid accumulation in corn leaves with 7.85 and 6.98 g g -1 fresh weight, respectively to protect Ecz infection. Each PGPR strain was single applied in the field through seed treatment and 3-foliar-spray-intervals at 14, 21, and 28 days after planting. Two PGPR treatments resulted in reduced severity of all diseases and increased yields when compared with the control treatment. There were differences among the treatments in that the highest level of disease suppression of bacterial stalk rot resulted with treatments TU-Orga1 (P = 0.05), whereas TU-Orga2 showed the highest level of disease suppression of bacterial leaf streak and sugarcane mosaic virus and provided significantly greater marketable yield increases than the other treatments. This illustrates the potential of these new biocontrol agents to suppress multiple diseases. They could become a component of an integrated program or an organic farming for corn disease management.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.