Revitalizing the rice by using chemical fungicides and adjustment of date of sowing against false smut of rice disease

Efficacy of BAU-Biofungicide, Chemical Fungicides and Plant Extracts on Rice (Oryza Sativa L) Diseases and Yield Extract of garlic (Allium sativum L.), Neem (Azadirachta indica L.); BAU-Biofungicide (Trichoderma based preparation) and Bavistin DF (Carbandazim) and Potent 250 EC (Propiconazole) were tested in laboratory and field conditions for eco-friendly management of diseases of rice (Oryza sativa, L.) cv BRRI dhan28. BAUBiofungicide (2%) was found to have profound effect in inhibiting the mycelial growth of Bipolaris oryzae (brown spot), Cercospora oryzae (narrow brown leaf spot) and Rhizoctonia solani (sheath blight) in vitro and marked reduction of disease incidence of brown spot, narrow brown leaf spot and sheath blight in the field. It was noted that significantly low incidence of narrow brown leaf spot and sheath blight disease was observed in plots sprayed with Carbendazim (0.1%) in the field as well as mycelia growth inhibition of Cercospora oryzae and Rhizoctonia solani was found in Carbendazim (0.1%) under laboratory condition. Highest (20.20%) grain yield was increased in Propiconazole (0.1%), while (17.84%) higher increase grain was obtained with BAU-Biofungicide (3%). No statistical significant difference was observed between yield of BAU-Biofungicide and Propiconazole. Most of the detected seed borne pathogens were controlled by BAU-Biofungicide and Propiconazole. Maximum germination (%) was observed over control when seeds were treated with BAU-Biofungicide (2%). BAUBiofungicide (2%) exhibited (40.45%) higher increase in vigour index over control. Results indicated that the greatest antagonistic effect of BAU-Biofungicide was found in reducing disease incidence and increased grain yield as an alternative option of synthetic fungicide.

Rice production is severely affected by sheath blight disease in Bangladesh which is caused by a fungus Rhizoctonia solani that is still merely managed by synthetic chemical fungicides. In this study, different isolates of Pseudomonas fluorescens and Bacillus subtilis were evaluated to assess their inhibitory effects against R. solani both in- vitro and field condition following dual culture method in order to formulate technique for the management of sheath blight of rice. Among all the isolates, P. fluorescens (Pf- 7 and Pf- 8) and B. subtilis (Bs-17 and Bs-21) showed the highest in –vitro mycelial growth suppression of the pathogen. Based on the in-vitro mycelial growth suppression performance, fourteen treatments combinations, either single or in consortia of antagonistic bacteria in talc-based formulations were applied by root dipping. All the formulated bacterial isolates showed significant reduction in disease and severity compared to untreated control and chemical fungicide. At 90 DAT, both the disease incidence and severity were found lowest in T11 (31.67 % and 37.33 % respectively) where the seedlings were treated for 24 hours with consortium of Pf-7 + Pf- 8 formulated in talc followed by in T12 (32.00 % and 38.00 %) where the seedlings were treated for 24 hours with consortium of Bs-17 + Bs-21 formulated in talc respectively. Vegetative and yield parameters were also significantly increased in both T11 and T12. The highest yield as well as Benefit Cost Ratio (BCR) were found in T11 (2.50 kg/ m2 and 2.20) followed by T12 (2.49 kg/m2 and 2.18). Thus, the consortia of bacterial isolates (Pseudomonas fluorescens and Bacillus subtilis) with seedling dipping time for 24 hour represents a promising alternative to chemical fungicides for the management of sheath blight of rice in field condition. J Bangladesh Agril Univ 22(3): 342-351, 2024

Brown Leaf Spot of Rice, caused by the Pathogen Bipolaris oryzae, is one of the important rice diseases resulting in high yield reduction and poor grain quality. A field experiment was conducted to evaluate the efficacy of different doses of chemical fungicides against brown leaf spot in ‘SabhaMansuli’ variety of rice in the research field of Institute of Agriculture and Animal Sciences, Paklihawa Campus from July 15, 2015 to December 1, 2015. The experimental design was RCBD with three replications and ten treatments. Treatments comprised of three different chemical fungicides; SAAF® (Carbendazim 12% + Mancozeb 63%), Tilt® (Propiconazole 25 EC) & Bavistin® (Carbendazim 50% W.P.) at three different doses of 1.5, 2 & 2.5 g (or ml) and a control plot. Among the different fungicides, Tilt® at the rate of 2 ml/lit water showed significantly lowest AUDPC value (373.7) followed by SAAF® at 2 gm/lit (374.9) while the highest value was shown by Bavistin® at 2gm/lit (590.1).Similarly, highest economic yield was obtained in SAAF® at 2gm/lit (5.220 t/h) followed by Tilt® at 2ml/lit water (5.210t/ha) and the lowest in Bavistin® at 1.5gm/lit (3.320t/ha). So, among different chemical fungicides, SAAF® at 2gm/lit being efficient, economical and easily accessible, farmers could be suggested for reducing the disease severity and subsequent increase in the yield of rice.

Rice is the most important cereal food crop in India, occupying one-fourth of the gross cropped area of the country (Pal et al. Agric Econ Res Rev 22:431–442, 2009). India is one of the largest producers of rice in world with 172.8 million metric tons in 2018 and is projected to register a CAGR of 2.7% during the forecast period, 2020–2025 (India Rice Market - Growth, Trends, Covid-19 Impact, and Forecasts (2021–2026). Modor Intelligence (2020) Available online: https://www.mordorintelligence.com/industry-reports/rice-market. Accessed 2 Mar 2021). A Global Agricultural Information Network (GAIN) report from the US Department of Agriculture (USDA) forecasted a record rice production in 2020–2021 for India due to favorable monsoons and climates this year (World-grain.com (2020) India’s rice production on the rise, available online: https://www.world-grain.com/articles/14450-indias-rice-production-on-the-rise. Accessed 20 Feb 2021). With increasing population of the world which is forecasted to be 9.7 billion by 2050 (World population prospects (2019) Ten key findings. United Nations Department of Economic and Social Affairs. Available online: www.population.un.org/wpp/Publications/Files/WPP2019_10KeyFindings.pdf. Accessed 6 Feb 2020), it is of great challenge to fulfil the growing demands of food not only in India but in the world (FAO Food and agriculture organization, FAOSTAT Database (2015) Available online: http://www.faostat.fao.org. Accessed 20 Feb 2021). There is a major drift in the urbanization in the world which results in depletion of land for cultivation which also affects the rice production (Satterthwaite et al. Philos Trans R SocLond B Biol Sci 365:2809–20, 2007). In India, rice is grown in two major seasons during kharif and rabi with 89% and 11% of total rice area (Kumar, et al. Popular Kheti 2:6–11, 2014). There are several other challenges involve which directly affect the rice productivity other than land availability. Water scarcity, soil quality deterioration, biotic and abiotic stress like disease and pest attack, climate change, etc. contribute to losses to a major extent (Kumar, et al. Popular Kheti 2:6–11, 2014). Rice disease is one of the prominent reasons for yield loss caused by pathogenic microorganisms and animal pests, which is estimated to be up to 38.2% (Oerke, J Agric Sci 144:31–43, 2019). Some of the major diseases like blast, sheath blight, and BLB contribute loss of 35, 25, and 20%, respectively (Kumar et al. 2014). Other rice diseases like leaf scald, sheath rot, brown spot, and grain discoloration are among the major diseases causing about 10–80 percent loss in paddy yield depending upon the location, variety infected, and severity of disease (Balgude, et al. 2017 J Rice Res 10:80–84, 2017). Sustainable agriculture system recommends minimizing chemical inputs in cultivation of crops. Uncontrolled and repeated use of chemical fungicide in rice not only develops chemo-resistance in pathogens but also causes severe problems to the human health and the environment (Asibi, et al. 2019 Agronomy 9:451, 2019). In present scenario, biological-based control method of diseases is now viewed as an eco-friendly and potent alternative for chemical methods for sustainable agriculture (Sharma, et al. International Journal of Biotechnology and Bioengineering Research 4:175–180, 2013). The chapter briefly explains the use of biological alternative approach for disease management in rice crops. Pseudomonas fluorescens are extensively used as an alternative to chemical fungicides for several plant pathogen controls (Sekar, et al. Agriculturally Important Microorganisms 107–132, 2016). The mode of actions and metabolites released by Pseudomonas plays a major role in disease suppression and spread (Bardin, et al. Front Plant Sci 6:566, 2015). The chapter also provides insight on several commercial overviews including ideal manufacturing practices and distributions. With increasing awareness of using biologicals as alternative tools, the present chapter also make aware of the regulatory guidelines and its implementation in Indian scenario.KeywordsRiceFungal disease managementBCA Pseudomonas

Blast disease caused by Pyricularia grisea, is one of the most devastating diseases of rice in most rice producing areas of the world. In Nepal, the disease causes 10%-20% yield reduction in susceptible varieties, but in severe case, it goes up to 80%. Chemicals are commonly applied for controlling rice blast disease, but when chemicals are used indiscriminately, they also pose a serious threat to the environment. An experiment was conducted to check the efficacy against neck blast disease of rice variety “DY-69” (a Chinese variety) with Hexaconazole 5 SC, Tricyclozole 76 WP and Kasugamycin 3% SL as chemical fungicides while with Trichoderma viridae as biological agent during June to November 2014 in experimental plot with four replications at Plant Pathology Division of Nepal Agricultural Research Council, Lalitpur. The treatments were applied two times in the field i.e. at tillering stage, i.e. 35 days after transplanting (DAT), and at booting stage, i.e. 65 DAT. Disease incidence, disease index, test weight and total yield were calculated and mean computed. Disease scoring of neck blast was done following the standard scoring system developed by SES (2002). Tricyclazole appeared better to control the neck blast disease followed by Hexaconazole determined in terms of disease incidence, disease index, test weight and total yield. However, T. viridae appeared quite comparable to tricyclazole. So, use of T. viridae as an option of bio-agent to control a disease will be ecofriendly measure and more study in its dose and application should be tested in field to verify the results and to control the blast of rice. Thus, using appropriate fungicide or bio-agents (alternative to fungicide) help in reducing health hazard by minimizing adverse impact on environment.

Brown spot of rice represents a globally important disease of rice, capable of inflicting severe yield losses under epidemic conditions. The historical relevance of this pathogen is exemplified by its major role in the Bengal Famine of 1943, highlighting its potential to cause large-scale crop failures which can be a threat to food security. Conventional disease management practices, including resistant varieties, use of disease-free seeds, hot water treatment, and chemical fungicides, remain the primary control measures. However, rising concerns over environmental impacts and the emergence of fungicide-resistant pathogen strains highlight the urgent need for sustainable alternatives. Endophytes, the beneficial microbes residing asymptomatically within plant tissues have emerged as promising bio control agents. They enhance plant health through nutrient acquisition, hormone modulation, and suppression of pathogens via multiple antagonistic mechanisms. They exhibit efficient root colonization, metabolic diversity, and competitive exclusion of pathogens, making them ideal for integrated disease management. Various studies have demonstrated the potential of endophytic strains in mitigating brown spot severity while promoting plant growth. Their eco-friendly nature and multifaceted interactions with the host make them effective tools for reducing chemical inputs in agriculture. This review explores the biology and epidemiology of brown spot disease, the current management strategies, and highlights the emerging role of endophytes in disease suppression and plant resilience. It also discusses future directions, including the application of multi-omics technology and genetic engineering to enhance the efficacy of endophytes. Overcoming regulatory hurdles and conducting large-scale field trials will be critical for transitioning from lab to field. Harnessing endophytes offers a sustainable, innovative pathway to combat brown spot of rice, reduce fungicide dependency, and build climate-resilient agricultural systems.

A field study was conducted during Kharif-2015 and 2016 on management of leaf and neck blast disease of rice caused by Magnaporthe oryzae under hill rice ecosystem. Different treatments including biological control agents like Trichoderma sp. and Pseudomonas sp. and chemical fungicides like tricyclozole, azoxystrobin and carbendazim were used at different growth stages of rice. Among the treatments, tricyclozole @ 0.06% was highly effective followed by azoxystrobin @ 0.1% with application immediately after appearance of disease. Trichoderma and Pseudomonas were not effective in reducing the disease pressure. Bangladesh J. Bot. 50(3): 713-716, 2021 (September)

Nanoemulsions in rice blast control: Biochemical and physiological mechanisms.

Brown spot of rice is a fungal disease caused by either Bipolaris oryzae, Helminthosporium oryzae or Drechslera oryzae species, which is found to be a major problem eventually causing sustainable losses both in quality and quantity. The pathogen after infection shows the symptoms on the leaves, panicles, glumes, and grain causing first as small, circular, and dark brown to purple-brown spots and fully developed lesions are circular to oval with a light brown to gray center, surrounded by a reddish-brown margin and ultimately killing the leaf. We have collected our information from secondary sources. In this review article, we have discussed the effects of bio-agents and chemicals and their comparative efficacy. Fungicides like: propiconazole, Carbendazim, Mancozeb, Hexaconazole, Cabendazim, Bion, Amistar, Tilt etc. are discussed which showed diverse performance on the diseases brown spot of rice. Extracts from the plant parts like roots, stem, leaves etc. are comparatively analyzed and studied that effected on mycelial growth and spore germination of Bipolaris pathogen. The plant components with phenolic structures like carvacrol, eugenol, and thymol are found to be highly active against the pathogen. The extracts of plants like Azadirachta indica, Nerium oleander, Curcuma longa, S. indicum, Cymbopogon citratus etc. are found suitable against brown spot in rice. Chemical fungicides were found to have more inhibition rate against the pathogen, even up to 100%. Although being eco-friendly, plant extracts were recorded to be less effective in comparison to chemical fungicides for suppressing plant pathogen. This article promotes the use of plant extracts for human health and environmental benefits over the use of chemicals for the control of plant diseases.

Rice blast disease caused by fungus Magnaporthe oryzae (syn. Pyricularia oryzae) is one of the most damaging diseases of rice, reducing plant production worldwide. In the present study, Bacillus subtilis strain GB519 was identified from the rhizosphere based on predicted signatures of 16S ribosomal DNA and gyrA gene and morphological, biochemical, and physiological characteristics. Treated with B. subtilis GB519, rice plants exhibited increased germination rate, vigor index, shoot length, shoot fresh weight, and root fresh weight coupled with more production of indole acetic acid, organic phosphorus, and inorganic phosphorus. In culture, GB519 inhibited growth of the following rice fungal pathogens (in order from most effective to least effective): M. oryzae, Ustilaginoidea virens, Fusarium graminearum, F. moniliforme, F. oxysporum, and Rhizoctonia solani. Three years of studies showed that, when rice was sprayed with GB519, there were significant reductions in rice blast incidence in both the greenhouse and fields: 70.3 and 62.1% in 2017, 69.9 and 71.6% in 2018, and 75.1 and 75.6% in 2019, respectively. Such reductions were correlated with accumulated hydrolytic enzymes, including amylases, proteases, chitinase, and lipases, and the defense enzyme activity of the total antioxidant capacity, catalase, and superoxide dismutase in rice. Field experiments showed that the biocontrol efficacy of GB519 was similar to that of other biological and chemical fungicides. Our results indicate that B. subtilis strain GB519 promoted plant growth and reduced blast disease and suggest that this strain has potential to be used as a biological control agent against rice blast. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Rice sheath blight (RSB) caused by Rhizoctonia solani is one of the most destructive diseases of rice (Oryza sativa). Although chemical fungicides are the most important control methods, their long-term unreasonable application has brought about problems such as environmental pollution, food risks, and non-target poisoning. Therefore, considering the extraction of fungistatic substances from plants may be an alternative in the future. In this study, we found that the Moutan cortex ethanol extract has excellent antifungal activity against R. solani, with a 100% inhibition rate at 1000 μg/mL, which aroused our great exploration interest. In-depth exploration found that the antifungal active ingredients of M. cortex were mainly concentrated in the petroleum ether extract of the M. cortex ethanol extract, which still maintained a 100% inhibition rate with 250 μg/mL, and its effective medium concentration (EC50) was 145.33 μg/mL against R. solani. Through the measurement of extracellular relative conductivity and OD260, the petroleum ether extract induced leakage of intracellular electrolytes and nucleic acids, indicating that the cell membrane was ruined. Therefore, we preliminarily determined that the cell membrane may be the target of the petroleum ether extract. Moreover, we found that petroleum ether extract reduced the content of ergosterol, a component of the cell membrane, which may be one of the reasons for the cell membrane destruction. Furthermore, the increase of MDA content would lead to membrane lipid peroxidation, further aggravating membrane damage, resulting in increased membrane permeability. Also, the destruction of the cell membrane was observed by the phenomenon of the mycelium being transparent and broken. In conclusion, this is the first report of the M. cortex petroleum ether extract exhibiting excellent antifungal activity against R. solani. The effect of the M. cortex petroleum ether extract on R. solani may be on the cell membrane, inducing the disorder of intracellular substances and metabolism, which may be one of the antifungal mechanisms against R. solani.

Bakanae disease is a destructive rice disease in South Korea caused by Fusarium fujikuroi infection. Chemical fungicides have been used to manage the disease, but the emergence of fungicide-resistant strains has gradually increased. Two chelating agents, chitosan oligosaccharides (COS) and ethylenediaminetetraacetatic acid (EDTA), are well known as biosafe and biocompatible antimicrobial agents. In this study, we compared the actions of COS and EDTA to gain a better understanding of the underlying antimicrobial activities and to evaluate them as eco-friendly fungicides against F. fujikuroi. While COS exhibited a rapid fungicidal effect on hyphal growing cells within 5 min, EDTA had a fungistatic effect on reversible growth inhibition. Scanning electron microscopy revealed that COS treatment resulted in pore-formation and cellular leakage along the growing hyphae, whereas EDTA caused no significant morphological changes. COS activity was greatly suppressed by the addition of Ca(2+) to the medium, and EDTA action was largely suppressed by Mn(2+) and slightly by Ca(2+), respectively. Taken together, these results indicated that two chelating agents, COS and EDTA, have different modes of antimicrobial action on F. fujikuroi. Thus, the combination of chelating agents having different modes of action might be an effective disease management strategy to prevent or delay the development of fungicide-resistant strains.

Rice blast disease caused by Pyricularia oryzae Cavara is the most destructive rice disease worldwide. Among the disease management options, the use of a fungicide is suitable for immediate action and remained an exclusive management method in the continents like Africa where agricultural technologies are not well advanced. The present study aimed to evaluate the effectiveness of seven chemical fungicides viz., Amistar Xtra 280 SC, Artea 330 EC, Contaf Max 350 SC, Fungozeb 80 WP, Matco, Rex® Deo and Tilt 250 EC for the control of rice blast disease under field condition at Pawe, northwest Ethiopia. The result revealed that all the test fungicides have significantly suppressed the disease development with 11.1 – 51.5% suppression of panicle blast severity and 18.9 – 67% suppression of neck blast severity compared to the control (Untreated plot). However, Contaf Max 350 SC had superior disease reduction by more than 60% and gave the maximum grain yield (5617.06 kg ha-1) among the fungicides while the lowest yield was obtained from the control (4324.73 kg ha-1) followed by Artea 330 EC (4639.35 kg ha-1). Therefore, the present results suggest that twice application of Contaf Max 350 SC fungicide at 1 Lha-1 is effective for managing rice blast disease in Pawe and other places with a similar condition.

Kernel smut, caused by Tilletia horrida, is a disease characterized by the replacement of rice grains with black sooty masses of teliospores or chlamydospores. Kernel smut differs from rice false smut, caused by Ustilaginoidea virens, in the color of chlamydospores. False smut is characterized by globose, velvety spore balls ranging from orangish yellow to greenish black in color. Both kernel smut and false smut have been persistent but are considered minor diseases in many countries since they were discovered in the late 1870s to the 1980s due to their sporadic outbreaks and limited economic impacts. In recent years, however, kernel smut and false smut have emerged as two of the most economically important diseases in rice, including organic rice, in many countries, especially in the United States. The increased use of susceptible rice cultivars, especially hybrids, excessive use of nitrogen fertilizer, and short crop rotations have resulted in an increase in kernel smut and false smut, causing significant losses in grain yield and quality. In this article, we provide a review of the distribution and economic importance of kernel smut; our current understanding of the taxonomy, biology, and epidemiology of kernel smut; and the genomics of the kernel smut fungus as compared with false smut and its causal agent. We also provide an update on the current management strategies of pathogen exclusion, cultivar resistance, fungicides, biological control, and cultural practices for kernel smut and false smut of rice.

False smut (Ustilaginoidea virens) and kernel smut (Neovossia horrida) are diseases of rice (Oryza sativa) that reduce both grain yield and quality. False smut is an emerging disease worldwide that is rapidly gaining in importance, whereas kernel smut has historically been a chronic minor disease with sporadic outbreaks that cause considerable losses. Highly effective disease control was obtained for susceptible cultivars by employing conservation tillage (69% reduction in false smut), continuous rice cropping (88% reduction in false smut), and moderate nitrogen fertility rates (34 and 60% reductions in false smut and kernel smut, respectively). Combining these treatments nearly eliminated smuts from cultivars that were fully susceptible under conventional cultivation practices. Furthermore, using a nursery designed to promote smut diseases, two rice hybrids were identified that possessed kernel smut resistance under the most favorable disease conditions. The genetic basis of the resistance is unknown. However, the utility for disease control is great because hybrids occupy significant portions of production rice acreage.