Incidence Of Brown Spot Research Articles

Influence of cultivar selection on blast and brown spot diseases in rice: Molecular screening of blast resistance genes  

The prevalence of blast and brown spot diseases in rice is a substantial threat to national food security. This study investigated the distribution patterns of blast and brown spot, comparing their occurrence and distribution with respect to cultivar selection and conducting molecular screening for the identification of blast resistance genes. The research was conducted over five cultivating seasons from Yala 2017 to Yala 2019 in the Northern Province of Sri Lanka. Incidence percentages of the two diseases were calculated in 114 randomly selected fields across the five districts; Jaffna, Mullaitheevu, Kilinochchi, Mannar, and Vavuniya. Molecular markers were used to screen for nine major blast-resistant genes in 25 commonly cultivated rice cultivars. The results showed a significant shift in the disease over the period of study. While blast disease incidence declined after Maha 2017, brown spot incidence increased steadily from Yala 2017, peaking in Yala 2019. Interestingly, farmers’ cultivar preferences, often diverging from the Department of Agriculture recommendations, exhibited a strong correlation with disease occurrence. The cultivar Attakkari was identified as a highly susceptible cultivar, which had only three R genes and a major contributor to the progression of blast before Maha 2017. Despite higher brown spot incidence percentages observed in cultivars At362, Bw367, and Bg450, compared to Bg360, intensive post-Maha 2017 cultivation of Bg360 increased the average brown spot incidence to 43%. Cultivars grown after Maha 2017, with over five R genes, showed lower blast disease incidence, suggesting a genetic link to susceptibility. This lower incidence of blast was also observed in the disease evaluation test, where we used the same cultivars. Hence, this study highlights rice cultivar selection as a decisive factor influencing disease occurrence. Given Sri Lanka’s robust germplasm for blast-resistant genes, strategic cultivar selection has the potential for effective disease management.

Biological and Chemical Management Strategy to Control Brown Spot Disease in Rice Caused by Bipolaris oryzae

The main objective of this study was to assess the effectiveness of various fungicides in managing rice brown spot, a common fungal disease in India that can reduce crop yield and seed quality. During 2020-21 crop seasons, a research project was conducted in the experimental plot of the Department of Plant Pathology at the College of Agriculture in Rewa, Madhya Pradesh, India. Different treatments involving fungicide application at various rice growth stages were implemented. The results showed that all treatments involving fungicides significantly reduced the incidence of rice brown spot in-vitro condition and increased crop yield when compared to the control group. Among the fungicides, Difenoconazole 25% EC at a concentration of 200ppm proved to be highly effective in controlling the growth of the fungal mycelium. In in-vivo condition, the treatment involving T4, which includes seed treatment with the bio-control agent Trichoderma viride (10g/kg seeds), the application of Trichoderma viride (10g/l) at 15-20 days after transplanting, and the application of propiconazole (1g/l) at the booting exhibited the highest level of reduction in the incidence of brown spot disease, amounting to 13.6 per cent. The integrated management approach are very effective to control the brown spot disease in rice.

Comparative Study of the Co-Occurring Alternaria and Colletotrichum Species in the Production of Citrus Leaf Spot.

Both of the two citrus diseases, Alternaria brown spot (ABS) and Anthracnose, caused by Alternaria and Colletotrichum spp., respectively, can produce leaf lesions which are hard to differentiate. These two diseases have been confused as causal agents of brown spot for over a decade in China. In this study, citrus leaves with or without brown spot were collected from Zhaoqing, Guangdong and Wanzhou, Chongqing, and were further used for the taxonomic and functional comparisons between the co-occurring Alternaria and Colletotrichum species. In the amplicon sequencing, the average relative abundance and the composition of Alternaria, but not Colletotrichum, increased (from 0.1 to 9.9, p = 0.059; and to 0.7, p < 0.05) and significantly altered (p < 0.01) with the brown spot in Zhaoqing and Wanzhou, respectively. Two representative isolates Alternaria sp. F12A and Colletotrichum sp. F12C, from the same brown spot, were proved with different virulence and host response activation to citrus leaves. F12A caused typical symptoms of brown spot with the average spot length expanded to 5 and 6.1 cm, and also altered the citrus global gene expression 48 and 72 h after inoculation. In addition, F12A enriched the expression of genes that were most frequently involved in plant defense. In comparison, F12C caused leaf spot limited to the wounded site, and its milder activation of host response recovered 72 h after inoculation. Our study indicates that the incidence of brown spot in China is caused by Alternaria species, and the ABS should be a fungal disease of major concern on citrus.

Influence of production situation on the incidence of brown spot of rice (Oryza sativa) caused by Bipolaris oryzae in the Philippines

AbstractBrown spot, caused by Bipolaris oryzae, is becoming more prevalent and important in the Philippines but risk assessment is limited. Surveys of 2186 farmers' fields were conducted in the major rice‐growing areas in the country from 2015 to 2018 to analyse the components of production situation (PS) that contribute to the area under the progress curve of brown spot incidence (aBS). Based on lasso regression, the components of PS that influence aBS, in decreasing order, are ecosystem (irrigated vs. rainfed), crop establishment method (direct seeding vs. transplanting), variety type (hybrid vs. inbred), rate of phosphorus fertilizer, rate of potassium fertilizer, application of organic fertilizer (with vs. without organic fertilizer) and frequency of fungicide application. Pairwise comparisons showed that aBS is positively associated with direct‐seeded rice, rainfed ecosystem, hybrid rice, moderate to high P and K rates and spraying of fungicide. Correspondence analysis and chi‐squared tests showed that the class with highest aBS is closely associated with the production situation characterized by rainfed ecosystem, direct‐seeded rice, fungicide application, moderate nitrogen and moderate to high phosphorus and potassium rates; and weather pattern (temperature, relative humidity, solar radiation, rainfall and wind speed) that occurs during the wet season. These results confirm previous studies showing that increased adoption of water‐saving technologies and direct seeding for adaptation and mitigation to climate change and reduction of agricultural labour, will most probably favour brown spot. Strategies to manage the disease under these production situations should be implemented in government programmes and considered in future research agendas.

Effects of silica soil amendment against Exserohilum rostratum, the fungal pathogen of rice brown spot disease in Peninsular Malaysia

Rice brown spot (BS) exerts devastating agronomic effects on grain quality and overall productivity. In Peninsular Malaysia, BS disease incidence is fairly prevalent and little is known about the diversity of BS pathogens in the local granaries. Fifteen isolates from BS symptomatic rice plants were identified at five different rice granaries across Peninsular Malaysia. Based on the morphological and molecular analyses, two isolates were confirmed as Bipolaris oryzae while the rest were identified as Exserohilum rostratum. Phylogenetic tree analysis revealed that BS incidence in rice granaries in Peninsular Malaysia is caused by a pair of closely related fungal pathogens, E. rostratum and B. oryzae, with the former being more predominant. Cultural characterization of E. rostratum isolate KT831962 showed the best growth and sporulation activity on corn meal agar plates incubated in complete darkness. The effects of calcium silicate (CaSiO3) and rice husk ash (RHA) soil amendment against MR219 and MR253 rice varieties were evaluated during rice-E. rostratum interaction. Results showed that soil amelioration using CaSiO3 and RHA singly and in combination with manganese (Mn) significantly reduced rice BS disease severity. The BS disease index was reduced significantly to less than 31.6% in the silicon-treated rice plants relative to the control plants at 41.2%. Likewise, the grain yield at the harvest stage showed significantly higher yield in the Si-treated rice plants in comparison to the control, non-Si treated rice plants. The findings highlight the potential of RHA agro-waste as Si fertilizer in a sustainable rice production system.

In vivo Testing of Plant Extracts in Controlling Rice Brown Spot Disease Through Folia Application

Background: Rice brown spot disease is caused by the fungus Bipolaris oryzae (Breda de Haan), which is one of the most significantly devastating diseases in rice. Nowadays, biological control agents and plant extracts as botanical fungicides are used to develop an alternative method to control this disease and reduce the use of synthetic fungicides. Therefore, the efficacy levels of Hydnocarpus anthelminthicus Pierre ex Laness., Crateva magna (Lour.) DC., Caesalpinia sappan L., Xanthophyllum lanceatum J. J. Sm. and Carallia brachiata (Lour.) Merr. crude extracts were tested in vitro against B. oryzae and their control of rice brown spot disease under greenhouse conditions. Methods: Five plants namely; H. anthelminthicus, C. magna, C. sappan, X. lanceatum and C. brachiata were cleaned with tap water and air dried at 28±2°C then cut into small pieces and ground into fine powder and stored at 4°C until used. Plant crude extracts was prepared using ethanol as solvent. Result: The results showed that the H. anthelminthicus crude extract showed the best antifungal activity against B. oryzae at the highest dose tested, causing 93% mycelial growth inhibition. Under greenhouse testing, the application of the H. anthelminthicus, X. lanceatum, C. brachiata, C. magna and C. sappan crude extracts at a concentration of 50,000 ppm effectively suppressed and reduced rice brown spot incidence caused by B. oryzae when applied once 30 days after transplanting (DAT). Interestingly, the H. anthelminthicus crude extract at a concentration of 10,000 ppm displayed the greatest suppression of the development of rice brown spot disease in terms of disease incidence when applied twice 30 DAT and 45 DAT compared with unprotected control. The results of this study indicated that H. anthelminthicus could provide botanical fungicide protection against rice brown spot disease to reduce the use of synthetic fungicides.

INVESTIGATION ON PREVALENCE OF RICE BROWN LEAF SPOT IN CAUVERY DELTA REGION OF TAMILNADU INDIA

Rice is the major food crop in India. Rice is affected by many fungal, bacterial and viral diseases. Among them, Rice brown leaf spot caused by Bipolaris oryze is a important disease which reduces the yield of the crop. The present investigation was carried out to study the prevalence and occurrence of Rice brown spot in Cauvery Delta Region of Tamilnadu. Among the five districts surveyed, the disease incidence was more in Sirkazhi of Mayiladuthurai district which recorded 35.5% incidence. Aananthathandavapuram from Mayiladuthurai recorded second maximum incidence (30.5%). Thiruparaithurai village of Trichy district has recorded lowest Brown leaf spot incidence (18.5%) compared to other areas. Brown spot disease incidence was more in cultivar BPT 5204 and ADT 43 compared to other cultivars. Brown spot incidence was more in milking and maturity stage compare to other stages of rice crop.

Integrated use of Propiconazole, Pseudomonas fluorescens and Bacillus subtilis for the management of rice brown leaf spot

The present investigation was carried out to study the effect of integrated use of propiconazole and bacterial bio control agents (Pseudomonas fluorescens and Bacillus subtilis) on the incidence of rice (Oryza sativa L) brown leaf spot during 2020-2021 at Annamalai University, Chidambaram. Among the various treatments tested in pot culture, seed treatment with consortia of P. fluorescens and B. subtilis + 1st foliar spray with Consortia of P. fluorescens and B. subtilis at 45 DAT + 2nd foliar spray with Propiconazole 25% EC at 60 DAT (T7) recorded minimum disease incidence (7.45%) and maximum number of productive tillers/ clump (17), grain (76.0 g/pot) and straw (127 g/pot) yield. In field studies also T7 treatment produced least disease incidence of brown spot (8.50%) and maximum growth parameters (17 productive tillers/clump) grain (74 qha-1) straw (86.30 qha-1) yield. Per cent disease incidence increased regularly with age of the crop, irrespective of treatments and maximum values were recorded at harvest. The maximum disease incidence and minimum values of growth and yield of rice recorded under control in both pot culture and field condition.

Integrated use of Propiconazole, Pseudomonas fluorescens and Bacillus subtilis for the management of rice brown leaf spot

The present investigation was carried out to study the effect of integrated use of propiconazole and bacterial bio control agents (Pseudomonas fluorescens and Bacillus subtilis) on the incidence of rice (Oryza sativa L) brown leaf spot during 2020-2021 at Annamalai University, Chidambaram. Among the various treatments tested in pot culture, seed treatment with consortia of P. fluorescens and B. subtilis + 1st foliar spray with Consortia of P. fluorescens and B. subtilis at 45 DAT + 2nd foliar spray with Propiconazole 25% EC at 60 DAT (T7) recorded minimum disease incidence (7.45%) and maximum number of productive tillers/ clump (17), grain (76.0 g/pot) and straw (127 g/pot) yield. In field studies also T7 treatment produced least disease incidence of brown spot (8.50%) and maximum growth parameters (17 productive tillers/clump) grain (74 qha-1) straw (86.30 qha-1) yield. Per cent disease incidence increased regularly with age of the crop, irrespective of treatments and maximum values were recorded at harvest. The maximum disease incidence and minimum values of growth and yield of rice recorded under control in both pot culture and field condition.

Genetic Studies and Response of Rice Germplasm (Oryza sativa L.) to Brown Spot Incidence in Aerobic Condition

The present investigation was carried out with 150 rice genotypes and three check varieties namely Rajshree, Pankaj and Rajendra Neelam with the view of assessing the variability in traits related to productivity and studying the response of these varieties towards brown spot resistance under the aerobic condition. These genotypes were evaluated for brown spot incidence and yield potential by recording observation for 11 quantitative traits by using augmented randomized complete block design at Rice research farm of RPCAU, Pusa, Bihar, during Kharif season of 2019. Analysis of variance revealed significant differences amongst the genotypes for all the eleven traits studied. Based on the mean performance, 14 genotypes out of 150 genotypes were significantly superior to the best check, Rajendra Neelam, for three traits viz., grain yield/ plant, Percent Disease Intensity (PDI) and area under disease progress curve (AUDPC), which are considered key traits for the assessment of brown spot incidence. The genotypes viz., VLD 16 entry no. -5, Udyagiri entry no.-9, and SKL 6 entry no.-94 significantly exhibited high mean for majority of the traits under study. Based on the AUDPC values, genotypes Satabdi, PS-4, Haryana Basmati and SKL6 were resistant for brown spot incidence. For most of the traits studied, moderate to low value of phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) was recorded. Higher magnitude of broad sense heritability and genetic advance as per cent of mean (GAM) were perceived for days to 50% flowering, plant height, no. of tillers per plant, no. of panicles per plant, filled grains per panicle, grain yield per plant, PDI, AUDPC signifying that direct selection by these traits can be rewarding for achieving yield improvisation and resistance to brown spot disease

Brown Spot and Stalk Rot Diseases of Maize (Zea Mays) and Susceptibility of Two Varieties to Physoderma Maydis in Far North Cameroon

Corn (Zea mays L.) is one of the most widely grown cereals in the world. However, in Cameroon, particularly in the Far North Region, yields remain low because of diseases increasing due to farming practices and climate change. This work aimed to characterize Brown Spot and Stalk Rot of corn and evaluate the susceptibility of two maize varieties to Physoderma maydis in field conditions. Two maize varieties, CMS9015, and CMS8704 were evaluated in a randomized block design. Disease symptoms were observed and described using identification keys. Microscopic characteristics of pathogens were performed using a microscope. Incidence, severity, and areas under disease curve progress (AUIPC and AUSiPC) were calculated. Brown spot occurred 3 or 4 weeks after sowing (WAS) at the growing stage in CMS8704 variety first, and stalk rot 7 WAS. Brown spot appeared in leaves and is characterized by oval yellowish spots in the leaf blade and brownish spots in the midrid. Stalk rot infects stem nodes and is characterized by brownish spots, leading to the broken stem. The incidence of brown spot increased with time and environmental conditions (rainfall). The highest incidence of Physoderma Brown Spot was recorded with CMS8704 variety 53.06 % against 51.72 % with CMS9015. Severity was respectively 54.40 % and 47.12 % with CMS8704 and CMS9015. The incidence and severity of stalk rot were almost identical in both varieties. AUIPC of PBS and PSR was higher in CMS9015 than in CMS 8704, 63 DAS. PBS and PSR infect maize production, and both varieties are susceptible to P. maydis.

Antifungal effect of glow discharge plasma and plasma activated water against brown spot disease of rice

The impact of atmospheric glow discharge plasma and plasma activated water on reducing rice seed-borne brown spot disease was investigated. It has been shown that the generation of reactive oxygen and nitrogen species by plasma containing electrons, positive or negative ions, and neutral species has antimicrobial activity. In this study, four plasmas were used for seed treatment viz., O2-air glow discharge plasma for 90 s, 120 s, air-plasma activated water for 9 and 12 min. Control (without treatment) and chemical treatment were used in order to compare the treatment effect. The plasma treatments used for this study showed a promising positive effect on seed germination and plant growth, and reduction of brown spot severity in the field. Among the plasmas, O2-air glow discharge plasma for 90s significantly increased seed germination (94.67%) compared to control (84.0%). Conidial suspension of Bipolaris oryzae treated with O2-air glow discharge plasma for 90 s and air-plasma activated water for 9 min successfully reduced the conidial germination ability of Bipolaris oryzae on Potato Dextrose Agar (PDA). The brown spot incidence and severity were significantly reduced in the plot which received seed treatment with O2-air glow discharge plasma for 90s and air-plasma activated water for 9 min. Interestingly, the same treatment remarkably enhances the plant growth parameters and yield of BRRI dhan28 compared to control treatment.

Potential Application of Propolis Extracts to Control the Growth of Stemphylium vesicarium in “Rocha” Pear

Stemphylium vesicarium (Wallr.) E. G. Simmons is the pathogen responsible of brown spot disease in pear and has become one of the main concerns for European pear producers. In Portugal, S. vesicarium is responsible for significant yield reduction and economic losses in “Rocha” pear (Pyrus communis L. cv Rocha) production. Considering the antimicrobial potential of propolis, the high incidence of brown spot in pears and the emergence of fungicides resistance in S. vesicarium, this study aimed to evaluate the potential of Portuguese propolis as an alternative strategy to control brown spot disease in “Rocha” pear. In vitro assays showed that propolis extracts were able to inhibit up to 90% the S. vesicarium mycelial growth. In vivo assays in artificially wounded and inoculated “Rocha” pears showed that, compared to the control, the disease incidence decreased up to 25% and the lesions diameter up to 57%, in fruits treated with propolis. Moreover, propolis seems to be more efficient in reducing the disease incidence when applied after pathogen inoculation (curative assay) than when applied before pathogen inoculation (prophylactic assay). Thus, the results suggest that propolis extracts have potential to be applied as part of an integrated approach for the control of brown spot of pear.

Effect of Spraying Potassium Silicate at Different Crop Growth Stages on Brown Spot Incidence and Grain Yield of Rice

Effect of Spraying Potassium Silicate at Different Crop Growth Stages on Brown Spot Incidence and Grain Yield of Rice

Combining quince (Cydonia oblonga) rootstock with soil-applied calcium chloride solution as a strategy to control brown spot (Stemphylium vesicarium) incidence in Abbé Fétel pear fruits

Brown spot (Stemphylium vesicarium) is a fungal disease widespread in European pear industry. The high number of fungicide applications required to control the disease can promote strains with fungicide resistance. The aim of the present study was to assess the effectiveness of soil- applied water solution of calcium chloride in combination with rootstock to control the incidence of brown spot in Abbe Fetel pear. Soil salinity, stem water and osmotic potential, along with fruit fraction of calcium and defence-mechanism related-enzymes such as peroxidase, polyphenol oxidase, phenyl-alanine ammonia-lyase, and β-1,3-glucanase were investigate in tree grafted on Fox 11 (Pyrus communis L.) and Sydo®, a quince (Cydonia oblonga) rootstock. Both grafting combinations were fertigated or not with calcium chloride. Sydo® showed a positive effect in reducing brown spot severity on Abbe Fetel. Compared to Fox 11, fruits from trees grafted on Sydo® showed higher calcium concentrations, fraction of calcium pectate, fruit firmness, polyphenol oxidase, phenyl- alanine ammonia-lyase and β-1,3-glucanase levels. Fruit calcium concentration was positively correlated with disease fruit tolerance. However, soil calcium applications were ineffective in promoting fruit calcium partitioning. Calcium chloride applications decreased leaf osmotic and stem water potential in trees grafted onto Sydo®, but this wasn’t found in those grafted on Fox 11. In conclusion, Sydo® rootstock promoted Ca acquisition, osmotic adjustment at leaf and fruit level, fruit synthesis of defence-related enzymes that all together reduced brown spot severity in Abbe Fetel pear.

Efficacy of BAU-Biofungicide, Chemical Fungicides and Plant Extracts on Rice (Oryza Sativa L) Diseases and Yield

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.

Evaluation of Rice Varieties against Multiple Diseases Under Middle IGP of Bihar

An investigation was carried out to evaluate the susceptibility of rice cultivation to major field diseases like brown spot, sheath blight and bacterial leaf blight under middle Indo Gangetic Plain. The disease incidence and disease severity were observed at three different growth stages namely flowering, milk and maturity in boro seasons during 2015-16. The incidence of brown spot ranged from 8.93 to 17.83%, 16.67 to 25.67% and 18.33 to 28.33% at flowering, milk and maturity stages, respectively. The severity of brown spot in grade (0-9 scale) ranged from 5.13 to 10.33, 9.33 to 20.00 and 11.57 to 22.67, respectively at flowering, milk and maturity stages. The incidence of sheath blight of paddy ranged from 7. 03 to 16.50%, 13.13 to 22.67% and 19.67 to 35.67% at flowering, milk and maturity stages, respectively. The severity of sheath blight in grade (0-9 scale) ranged from 4.00 to 8.60, 8.33 to 13.93 and 18.33 to 34.33, respectively at flowering, milk and maturity stages. The incidence of bacterial leaf blight ranged from 5.00 to 14.00%, 11.43 to 21.00% and 17.00 to 34.00% at flowering, milk and maturity stages, respectively. The severity of bacterial leaf blight in grade (0-9 scale) ranged from 2.00 to 8.00%, 6.33 to 12.05% and 14.47 to 20.17%, respectively at flowering, milk and maturity stages. Among the varieties, the highest incidence and severity of Brown spot was recorded on Rajendra Bhagawati whereas it was lowest on 27P31 at all growth stages. In the case of Sheath blight, highest incidence and severity was recorded on Sambha Mahsuri whereas it was the lowest on CRL 193. Beside this in the case of Bacterial leaf blight, the highest incidence and severity was recorded on Kranti whereas the lowest was recorded on CRL 193. In general, it was observed that the incidence and severity of diseases increased gradually from flowering to maturity stage and the genotypes with the minimum incidence and severity of diseases gave the maximum yield.

Role of potassium on insect pests and diseases of puddled transplanted rice cv. Lalat in Odisha

Potassium (K) is one of the most important essential nutrients for rice crop. The role of K in enhancing rice productivity is well established. It also imparts resistance against diseases and insect-pests. A field study was conducted to evaluate the effect of different levels of K application on the disease and insect pest incidence of puddled transplanted rice during dry season (DS) 2013–14 and wet season (WS) 2014 involving 9 potash management options in 3 replications. The experimental soil was highly deficient in exchangeable K (25.85 mg/kg). Increase in K dose from recommended 40 kg/ha to 80 kg/ha significantly reduced all insect pest and disease incidence. Recommended dose of K 40 kg/ha along with one foliar spray of 1% KNO 3 at flowering was also effective than other treatments. Reducing fertiliser K to 50% and adding straw (3 t/ha) was not as effective as full dose of K, but had moderate effect on pest incidence. Both blast and brown spot incidence correlated negatively with K content in leaf at maximum tillering (MT) and panicle initiation (PI) stages with more correlation at MT stage (r= -0.59, -0.69) than PI stage (r= -0.48, -0.37) in dry season and PI stage (r=-0.51, -0.73*) than MT stage (r= -0.48, -0.37) in wet season. Insect attack in both dry and wet seasons negatively correlated with K content in leaf at MT and PI stages with wet season having stronger correlation than dry season for all the major insects. From the study, it is also evident that not only the leaf K content, but K-N balance is also important for making the plant resistant to insect pest and disease attack. Thus, K nutrition is important for control of most common insect pests (stem borer, leaf folder, whorl maggot and Gundhi bug) and diseases (blast and brown spot) in rice.

Application of Wood Vinegar for Fungal Disease Controls in Paddy Rice

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.

An Investigation on Disease Incidence, Grain Yield and Quality of BRRI Dhan29 in Bangladesh

Rice crops are susceptible to disease, which causes large yield losses in many Asian countries. The influence of disease incidence and severity on grain yield and quality of the rice (Oryza sativa L., cv. BRRI dhan29) was investigated in three different locations of Chief Farm Superintendent’s (CFS) farm viz. Near Weather Yard (location-1), Near Agronomy Farm (location-2) and Near CFS farm office (location-3), Bangladesh Agricultural University (BAU), mymensingh, Bangladesh during boro season. In location-1, both brown spot and sheath blight were recorded whereas in location-2 and in location-3 only brown spot was recorded. Severity of brown spot was lowest at the location-1 and the highest at the location-3. Combined incidence of brown spot and sheath blight decreased the yield considerably whereas brown spot did not alone. Maximum severity of sheath blight was observed both in flowering and soft dough stage and minimum at maximum tillering stage. The lowest infection index of brown spot was obtained at maximum tillering stage and the highest infection index was obtained at soft dough stage whereas maximum and minimum infection index of sheath blight of rice were recorded at soft dough stage and maximum tillering stage, respectively. Aparently healthy seeds, spotted seeds, discoloured seeds, deformed seeds and chaffy grains were found among the three locations. Germination percentage was highest in healthy seeds compared to other category seeds. Alternaria padwickii, Alternaria tenuis, Bipolaris oryzae, Curvularia lunata and Fusarium semitectum were found to be associated with the seed. The highest and lowest occurrence of A. padwickii, A. tenuis, B. oryzae, C. lunata were recorded from chaffy grains and from healthy seeds, respectively. It is suggest that disease incidence and severity was gradually increased with the age of the plant and reduced yield and quality of BRRI dhan29. Int J Appl Sci Biotechnol, Vol 4(3): 311-317