Brown Spot Disease Research Articles

First Report of Leaf Brown Spot Caused by Diaporthe phoenicicola on Pachira glabra in China.

Pachira glabra is an increasingly important ornamental landscape tree in southern China. In August 2022, brown spots were observed on P. glabra leaves in Xiangtan City, Hunan Province, China (27.932°N, 113.020°E), affecting up to 40% of the 792 trees surveyed. On each diseased tree, nearly 30% leaves had symptoms, with an average severity of 21.2 ± 5.8% (n=100). The disease initially started as small yellow lesions along leaf margins, which later progressed to pale brown to brown with dark brown borders, eventually coalescing into large necrotic areas. Thirty symptomatic leaf samples (2 × 2 mm) were surfaced-sterilized in 75% ethanol for 10 s, 2% NaOCl for 30 s, rinsed in sterile water three times, placed on potato dextrose agar (PDA), and incubated at 25°C for 5 to 7 days in dark. Eight morphologically similar isolates were obtained from diseased leaf samples through single-spore isolation. On PDA, colonies initially appeared white, turning gray, while the reverse developed a pale yellowish hue. Aerial mycelia were white, cottony, and developed visible black pycnidia with oil droplets at maturity. The α-conidia were unicellular, hyaline, aseptate, oval or fusiform, usually with 1 or 2 guttule(s) and rounded at each end. These conidia were 5.3-8.6 × 1.7-2.5 μm (avg. 6.7 × 2.2 μm, n = 100) and present more frequently than β-conidia.The β-conidia were unicellular, hyaline, aseptate, filiform, straight or hamate, eguttulate, 14.6-23.3 × 0.4-1.3 μm (avg. 18.4 × 0.9 μm, n = 30). Morphologically, the fungi were identified as Diaporthe sp. (Udayanga et al. 2014). For molecular identification, the internal transcribed spacer region (ITS), translation elongation factor 1α (EF1-α), calmodulin (CAL), tubulin 2 (TUB2), and histone H3 (HIS3) sequences of all isolates were amplified from genomic DNA, using primers ITS4/ITS5 (White et al. 1990), TEF-2/728F and CALD-38F/CALD-752R (Carbone and Kohn 1999), Bt2a/Bt2b and H3-1a/H3-1b (Glass and Donaldson 1995; Crous et al. 2004), respectively. The GenBank accession numbers for a representative isolate gpg2023-1 were OR533573 (ITS), OR570887 (EF1-α), OR570888 (TUB2), OR570890 (CAL), and OR570889 (HIS3). BLAST results showed that the ITS, EF1-α, TUB2, HIS, and CAL sequences were 99%, 99%, 99%, 99%, and 98% identity, respectively, with those of Diaporthe phoenicicola (GenBank: KC343032.1, KC343758.1, KC344000.1, KC343516.1, and KC343274.1). To confirm the pathogen's identity, phylogenetic analysis using MEGA7.0 based on Maximum Likelihood was constructed. Isolate gpg2023-1 clustered with D. phoenicicola. Based on morphological and molecular data, the fungus was identified as D. phoenicicola. Next, pathogenicity tests were performed three times on one-year-old potted P. glabra plants. For each isolate, twelve healthy leaves on each of three plants were either wounded by a sterile needle or left unwounded, and then sprayed with a conidial suspension (1×106 conidia/ml) for each isolate. Control plants received with sterile water only. Plants were kept in a greenhouse at 25°C, 80% relative humidity, with a 12-h photoperiod. All wounded, inoculated leaves developed brown spot symptoms similar to those observed in the field with six days, while unwounded leaves and control plants remained symptom-free. The fungus was reisolated from all diseased leaves, fulfilling Koch's postulates and proving D. phoenicicola as the causative agent of this brown spot disease on P. glabra. While D. pachirae has been reported to cause leaf spot on P. glabra in Brazil (Milagres et al. 2018), this study marks the first report of D. phoenicicola causing leaf brown spot on P. glabra in China. This finding can help develop control strategies for this disease.

Bacillus amyloliquefaciens LM-1 Affects Multiple Cell Biological Processes in Magnaporthe oryzae to Suppress Rice Blast.

Magnaporthe oryzae, one of the most destructive rice pathogens, causes significant losses during the rice harvest every year. Bacillus amyloliquefaciens has been explored in many crops as a potential biocontrol agent. However, the mechanisms of B. amyloliquefaciens controled rice blast are not fully understood. Here, a biocontrol strain LM-1, isolated from a contaminated medium, was identified as B. amyloliquefaciens using morphological observation, physiological and biochemical tests, and 16S rDNA sequencing. LM-1 inhibited the growth and pathogenicity of M. oryzae and Bipolaris oryzae (Breda de Haan) Shoem. The mycelia of M. oryzae co-cultured with LM-1 were enlarged and broken by fluorescence microscopy using calcofluor white. LM-1 inhibited the mycelia of M. oryzae from producing conidia. Genes itu, srf, and fenB were detected in LM-1. Furthermore, the supernatant of LM-1 interfered with the appressorium formation of M. oryzae, blocked conidial cell death, and reduced autophagy degradation but did not affect the normal germination of rice seeds and seeding growth. Additionally, we observed hypersensitivity reactions, reactive oxygen species, and iron accumulation reduction in rice cells inoculated with supernatant. Our study reveals that LM-1 has a control effect on rice blast and affects cell wall integrity, sporulation, appressorium formation, cell death, and autophagy.

The interaction of fungicides and nitrogen dose under two crop establishment methods influences the severity of brown spot disease in rice

Brown spot (BS) disease poses a significant threat to rice cultivation globally, impacting millions of hectares annually. Research indicates that the severity of BS is closely linked to abiotic stresses and crop nutrition. A field experiment was conducted using transplanted (TP) and direct-seeded-rice (DSR) crop establishment methods to optimize the effective fungicide and nitrogen dose. The split-plot design was applied to study the effect of two factors (N-dose and fungicides) varying at different levels under two different crop establishment methods (TP and DSR) for two consecutive Kharif seasons (2021 and 2022). The BS severity was measured as the percent disease index (PDI), and the results of two seasons were pooled. The results indicated that all three factors significantly (p = 0.05) influenced the PDI and grain yield. The PDI under different fungicides was higher in DSR (30.20–88.90) than in TP rice (21.64–70.00). Similarly, increased N-dose altered the PDI negatively (p = 0.05) in both TP (32.16–46.12) and DSR (44.35–59.09) methods. The results indicated Tebuconazole 50% + Trifloxystrobin 25% WG (T7) at 125% recommended dose of nitrogen as the best combination, as it recorded the lowest PDI of 21.6 and 30.2 in the TP and DSR, respectively. Similarly, all three factors interacted significantly (p = 0.05) and affected the final grain yield. Overall, the BS is more severe in DSR, and a higher dose of N reduces the BS severity in both TP and DSR. Therefore, N fertilizer management, especially in the DSR, is essential, along with a fungicide, for effective management of the brown spot disease.

Antifungal potential of rhizospheric bacterial isolates of Daucus carota against brown spot fungus Cochliobolus miyabeanus

Cochliobolus miyabeanus is an important plant pathogen which causes a very common and widespread brown spot disease in rice, that may result in a severe reduction in the crop yield. The current studies were carried out to search out the antifungal potential of the bacterial isolates from the rhizospheric region of Daucus carota against brown spot fungus, C. miyabeanus. Isolation of rhizospheric bacterial isolates was done from carrot grown field of district Jaunpur in month of January, 2023. Experiment work has been done in Department of Biotechnology, Veer Bahadur Singh Purvanchal University, Jaunpur in 2023 from the month January to November. All bacterial isolates were tested for antifungal activity against brown spot fungi. Isolates were screened for their antifungal activities against brown spot fungus for further studying plant growth promoting, biochemical and morphological attributes. Isolates, CVO-7 and NBRI-O-2 showed efficient antifungal activity against test organism and also showed some plant growth promoting attributes that can further reduce the virulence of C. miyabeanus by enhancing availability of essential and trace elements for the plant. Both the isolates were characterized at a molecular level by using 16S rRNA gene sequencing and sequences of 16S rDNA segment were submitted to the NCBI GenBank database with the accession numbers OR775577 (Bacillus subtilis ss5cvo7) and OR775572 (Bacillus proteolyticus ss2nbrio2).

Novel Culture Media Made from Sago Pith Waste Used to Culture the Antagonistic Rhizobacterium Streptomyces angustmyceticus NR8-2

Sag o pith waste (SPW) is an agricultural by-product from the sago starch extraction process. Using SPW supports the bio-circular green economy and sustainable agriculture. Although many bacterial culture media are commercially available, using SPW as a carbon source to develop culture media is considered an alternative way to save costs and limit the import of commercial media. This research aimed to develop culture media from SPW to culture the antagonistic rhizobacterium Streptomyces angustmyceticus NR8-2 and test the antifungal activity of the cell-free culture filtrate (CF) of S. angustmyceticus NR8-2 against Curvularia pseudobrachyspora, the pathogen of brown spot disease in dragon fruit. S. angustmyceticus NR8-2 was cultured on glucose yeast malt agar (GYMA) and glucose yeast malt broth (GYMB) as general media, modified sago pith waste yeast agar (SPYA), and sago pith waste yeast broth (SPYB); then, the bacterial growth was measured. S. angustmyceticus NR8-2 grew on SPYA similarly to on GYMA, and there was no morphological change when it was cultured on SPYA. S. angustmyceticus NR8-2 could also be cultured on both GYMB and modified SPYB, as indicated by spherical pellet development, but the biomass of S. angustmyceticus NR8-2 cultured on SPYB was significantly higher than that on GYMB (p<0.05). The biofilm formation of S. angustmyceticus NR8-2 on the surface of SPYB or GYMB displayed no significant difference in dry or fresh weight (p>0.05). The cell-free CF of S. angustmyceticus NR8-2 was collected and tested against the antifungal ability of C. pseudobrachyspora via agar well diffusion. Cell-free CFs from GYMB and SPYB effectively inhibited the growth of C. pseudobrachyspora with percentage inhibitions of 60.95 and 58.99%, respectively, with no statistical difference (p>0.05). The cell-wall-degrading enzyme activity of chitinase and β-1,3-glucanase showed no significant differences when S. angustmyceticus NR8-2 was cultured on GYMB and SPYB. Furthermore, the solid-state cultivation of S. angustmyceticus NR8-2 on SPW + yeast extract and SPW + dextrose + yeast extract showed bacterial populations of 2.56±1.38 × 108 and 3.38±1.89 × 108 CFU/g, significantly higher than when cultured on SPW alone. The results of our study show that SPW is a novel source for the development of novel media that can be used to culture antagonistic rhizobacterium S. angustmyceticus NR8-2.

Impact of Cultural Practices and Nitrogenous Fertilizer on the Development of Brown Spot Disease of Rice

Among the diseases the brown spot disease of rice caused by Bipolaris oryzae is most dominant fungal disease of rice after blast (Pyricularia oryzae) which is causing losses in the yield which resulted in instability in rice production particularly in north Bihar. This disease was considered to be one of the most important facet of 1943 Bengal Famine. The losses in famine were accounted to 50-90 per cent (Ghose et al. 1960; Padmanabhan, 1973). The disease is a serious and has global distribution and it has been found in all rice growing countries in Asia, America and Africa. The studies mainly adhered to see the effect of various doses of nitrogen and different cultural practices on development of brown spot disease of rice. Among the various cultural practices, minimum (17.64%) disease seventy and maximum yield (3.13/ha) were found with application of FYM (5 t/ha) + line sowing of 60 kg seed/ha + 50% N application after 15 DAS 25 % N at maximum tillering + 25% N at panicle initiation + weed control. Doses of nitrogen were positively related with the disease development and negatively related with the grain yield indicating the maximum (38.30 % and 39.0 %) disease severity and minimum (1.86 and 1.97 t/ha) grain yield with nitrogen dose of 120 kg/ha. In respect of varietal response, the minimum (12.10 % and 16.40 %) disease severity and the maximum (4.34 t/ha and 4.58 t/ha) yield were recorded in the variety Rajshree receiving 80 kg N/ha.

Isolation and Molecular Characterization of Rice Brown Spot Disease in Major Cauvery Delta Regions

Rice (Oryza sativa L.) is the second most important staple food among agricultural cereal crops, with over half of the world's population dependent on rice. 165.59 million hectares of land is used for rice production worldwide, yielding 518.1 million tonnes and a productivity of 4.68 t/ha (FAOSTAT 2022 - 2023). In India, the rice production is about 132 million tonnes which is produced in about 47 million hectares of land with a productivity of about 4.21 t/ha (Ministry of Agriculture & Farmers welfare, Government of India 2023). In Tamil Nadu, the rice production is about 6.8 million metric tonnes which is produced in about 2.21 million hectares of land with a productivity of about 3.76 t/ha (Department of Economics and Statistics, Government of Tamil Nadu 2022-23). One of the biotic stresses that accounts for about 15.6% of losses each year is rice disease. Of them, Bipolaris oryzae (Breda de haan) causing brown spots of rice is the most destructive disease which causes about 90% of yield loss. Ten isolates of brown spot pathogen were collected from the Cauvery delta regions and of them, the virulent isolate (Bo9) was characterized molecularly. All the isolates were studied based on their morphological characteristics. ITS primers were utilized to do the molecular characterization of the pathogen.

An Insight on Mycoflora Associated with Rice Grain Discolouration

Grain discolouration, a complex disease of rice is a new enemy to rice crops around the world, and it is becoming increasingly important due to the qualitative as well as quantitative loss of harvested crop. The present study was carried out on the ten different variety of rice (MEX-73, NLR-33892(Parthiva), MEX-48, MEX-61, PR-126, PR-128, PR-129, PR-130, Pusa-basmati -7 and Pusa basmati-1121). The incidence was calculated in one metre square quadrants randomly marked in the plot, where the highest incidence was observed in PR-126(36.23%) and the least was Pusa basmati-1121(19.77%). Several seed borne fungi were detected using blotter paper method. The Mycoflora observed were Curvularia sp., Fusarium sp., Bipolaris oryzae, Sarocladium sp., Aspergillus sp, Penicillium sp. The maximum frequency was observed for Aspergillus (25.73%) followed by Penicillum (24.53%), and the least observed was Bipolaris oryze(1.73%). The identity of the Aspergillus was confirmed using Inter transcribed Spacer primers (ITS1 & ITS4).

Interactive transcriptome analyses of Northern Wild Rice (Zizania palustris L.) and Bipolaris oryzae show convoluted communications during the early stages of fungal brown spot development.

Fungal diseases, caused mainly by Bipolaris spp., are past and current threats to Northern Wild Rice (NWR) grain production and germplasm preservation in both natural and cultivated settings. Genetic resistance against the pathogen is scarce. Toward expanding our understanding of the global gene communications of NWR and Bipolaris oryzae interaction, we designed an RNA sequencing study encompassing the first 12 h and 48 h of their encounter. NWR activated numerous plant recognition receptors after pathogen infection, followed by active transcriptional reprogramming of signaling mechanisms driven by Ca2+ and its sensors, mitogen-activated protein kinase cascades, activation of an oxidative burst, and phytohormone signaling-bound mechanisms. Several transcription factors associated with plant defense were found to be expressed. Importantly, evidence of diterpenoid phytoalexins, especially phytocassane biosynthesis, among expression of other defense genes was found. In B. oryzae, predicted genes associated with pathogenicity including secreted effectors that could target plant defense mechanisms were expressed. This study uncovered the early molecular communication between the NWR-B. oryzae pathosystem, which could guide selection for allele-specific genes to boost NWR defenses, and overall aid in the development of more efficient selection methods in NWR breeding through the use of the most virulent fungal isolates.

Characterization and evaluation of native Trichoderma harzianum P39 for biocontrol potentials against five seed-borne fungal pathogens of rice

Plant seeds can harbour pathogens that limits crop growth and productivity. This study isolated, characterised and evaluated native Trichoderma harzianum for antagonism against five (Alternaria alternata, Aspergillus oryzae, Bipolaris oryzae, Curvularia lunata and Fusarium verticillioides) fungal pathogens isolated from rice seeds. Evaluation was through simultaneous inoculation, a pathogen against the biocontrol agent, using the dual culture method in a PDA growth medium. Results confirmed the T. harzianum isolate had 98.27% pairwise identity with T. harzianum P39 (KX381171.1. accession number). The isolate showed increasing percentage inhibition, against all the pathogens, with increasing days after inoculation. The highest values ranged from 53.02%, A. oryzae to 70.06%, F. verticillioides (the least and most susceptible respectively). The overall inhibition percentages of A. alterata and B. oryzae (12th day after inoculation) were not significantly different from that of F. verticillioides. Trichoderma harzianum P39 can be formulated as biological seed dressing agent.

Field biocontrol efficacy of Trichoderma spp. in fresh and dry formulations against rice blast and brown spot diseases and yield effect

Field biocontrol efficacy of Trichoderma spp. in fresh and dry formulations against rice blast and brown spot diseases and yield effect

Screening Plant Growth-Promoting Bacteria with Antimicrobial Properties for Upland Rice.

This study explores beneficial bacteria isolated from the roots and rhizosphere soil of Khao Rai Leum Pua Phetchabun rice plants. A total of 315 bacterial isolates (KK001 to KK315) were obtained. Plant growth-promoting traits (phosphate solubilization and indole-3-acetic acid (IAA) production), and antimicrobial activity against three rice pathogens (Curvularia lunata NUF001, Bipolaris oryzae 2464, and Xanthomonas oryzae pv. oryzae) were assessed. KK074 was the most prolific in IAA production, generating 362.6 ± 28.0 μg/ml, and KK007 excelled in tricalcium phosphate solubilization, achieving 714.2 ± 12.1 μg/ml. In antimicrobial assays using the dual culture method, KK024 and KK281 exhibited strong inhibitory activity against C. lunata, and KK269 was particularly effective against B. oryzae. In the evaluation of antimicrobial metabolite production, KK281 and KK288 exhibited strong antifungal activities in cell-free supernatants. Given the superior performance of KK281, taxonomically identified as Bacillus sp. KK281, it was investigated further. Lipopeptide extracts from KK281 had significant antimicrobial activity against C. lunata and a minimum inhibitory concentration (MIC) of 3.1 mg/ml against X. oryzae pv. oryzae. LC-ESI-MS/MS analysis revealed the presence of surfactin in the lipopeptide extract. The crude extract was non-cytotoxic to the L-929 cell line at tested concentrations. In conclusion, the in vitro plant growth-promoting and disease-controlling attributes of Bacillus sp. KK281 make it a strong candidate for field evaluation to boost plant growth and manage disease in upland rice.

Screening for brown-spot disease and drought stress response and identification of dual-stress responsive genes in rice cultivars of Northeast India.

The online version contains supplementary material available at 10.1007/s12298-024-01447-4.

Mycoflora associated with stored rice from storage facilities in Makassar and Maros, Indonesia

Abstract. Brugman E, Mario MB. 2024. Mycoflora associated with stored rice from storage facilities in Makassar and Maros, Indonesia. Biodiversitas 25: 1089-1096. Rice storage is a postharvest process that aims to maintain food availability, seed supply, and price stability. One of the main problems encountered in the storage process is the potential for fungal infection and contamination, leading to postharvest loss. This research aims to evaluate the mycoflora associated with stored rice from storage facilities in Makassar and Maros and their contamination level. Fungal isolation was done by spread plating with serial dilution and direct culture method. The fungal identification was made based on morphological characters, including colony, sexual, and asexual structures. The fungal contamination was determined by colony counting, contamination percentage, and species occurrence. The result showed that all samples tested positive for fungal contamination, with an average contamination level of 83.89% (Makassar) and 86.11% (Maros). The highest colony densities in the samples from Makassar and Maros were 9.0 × 103 CFU/g and 14.2 × 103 CFU/g, respectively. The average fungal contamination in the samples from Makassar was 3.67 × 103 CFU/g, and Maros was 8.32 × 103 CFU/g. The mycoflora associated with the rice grain samples from Makassar was Rhizoctonia solani (11.34%), Aspergillus spp. (52.18%), Fusarium spp. (10.87%), Rhizopus sp. (15.22%), and unidentified cultures (10.39%). Meanwhile, the mycoflora associated with the stored rice from Maros are Curvularia sp. (15.22%), Alternaria sp. (8.7%), Aspergillus spp. (17.39%), Fusarium spp. (32.61%), Rhizopus sp. (15.22%), and Bipolaris oryzae (10.87%).

The rice endophytic bacterium Bacillus velezensis LS123N provides protection against multiple pathogens and enhances rice resistance to wind with increase in yield

Rice (Oryza sativa) is a globally important staple food, but its production was influenced by various biotic and abiotic stresses. This study involved screening endophytic bacterial strains for their antagonistic activities and control efficacy against multiple rice pathogens in planta assays. Subsequent greenhouse investigations identified Bacillus velezensis LS123N as the most promising strain for effectively controlling various rice diseases, including bacterial blight, rice blast, bakanae disease, Pythium disease, and brown spot disease. Field trials further demonstrated that LS123N significantly reduced naturally occurring brown spot disease caused by Bipolaris oryzae in both seedlings and mature rice plants, and increased rice yields. For disease control against bacterial blight, Pythium disease, and brown spot, only a single treatment during seed germination resulted in significant disease control efficacy. The application of LS123N during seed germination aligns with common rice cultivation practices. Additionally, LS123N exhibited the capacity to improve rice resistance to wind stress and enhance rice growth during the seedling stage. Endophytic colonization of LS123N was evidenced from seed to mature rice plants after seed treatment. Interestingly, the expression of many rice defense genes was suppressed within 48 h of the LS123N introduction. In vitro assays showed that LS123N inhibited spore germination and normal growth of germ tubes of B. oryzae, produced multiple hydrolases, siderophores, and IAA, and had the ability to solubilize phosphorus compounds. In summary, these results indicate that B. velezensis LS123N is a promising biocontrol agent and has the potential to be developed into a biofungicide, biofertilizer, and biostimulator.

Rice disease segmentation method based on CBAM-CARAFE-DeepLabv3+

Rice is an important food crop, but it is susceptible to diseases during its growth process. Rapid, accurate, and effective identification of rice diseases is important for targeted measures to control disease spread. It is crucial for improving rice yield and quality. Therefore, this study proposes a CBAM-CARAFE-DeepLabv3+ rice disease segmentation method that combines attention mechanisms and feature recombination. This method focuses on three common diseases in rice growth: bacterial blight, blast, and brown spot disease. To enhance the extraction of favorable features, the algorithm adopts CBAM-RepViT as the backbone network. That is, the Squeeze-and-Excitation (SE) attention mechanism embedded in the efficient and lightweight RepViT network is replaced by the lightweight Convolutional Block Attention Module (CBAM). Compared to the SE attention mechanism, CBAM introduces a spatial attention module that focuses on important spatial positions in the feature map. It allows the model to extract more rich and detailed feature information by attending to both the channel and spatial dimensions of the feature map. Additionally, to further improve the feature extraction ability and image edge segmentation accuracy during upsampling, the lightweight Content-Aware ReAssembly of FEatures (CARAFE) operator is introduced into the decoding module for upsampling. Finally, to address the issue of imbalance between foreground and background pixel ratios in rice disease, a hybrid loss function composed of cross-entropy (CE) loss and Dice loss is proposed. Experimental results show that, compared to other networks such as DeepLabv3+, the proposed CBAM-CARAFE-DeepLabv3+ method achieves further improvement in segmentation accuracy, providing a new method for the development of rice disease segmentation technology.

Surveillance and management of brown spot of potato

A survey was conducted to assess the incidence of brown spot disease in three tehsils of District Okara. Maximum incidence was observed in Depalpur (44%) followed by Okara (33%) and Renala khurd (15%). During study, six chemicals (CabrioTop, Fossil, Axel, Forum Top, Kocide and Topsin M) and six phytochemicals (Nigella sativa, Azadirachta indica, Zingiber officinale, Cinnamomum verum, and Eucalyptus globulus) at three different concentrations were evaluated. Results indicated that maximum inhibition of mycellial growth was expressed by Fossil (5.24 mm) followed by Topsin M (7.13 mm), Axel (7.38 mm), Kocide (11.289 mm), Forum Top (18.79 mm), CabrioTop (25.01 mm). Among phyto-extracts, Datura stramonium (7.77 mm) showed maximum reduction in fungal growth followed by Nigella sativa (13.88 mm), Azadirachta indica (19.18 mm), Zingiber officinale (24.87 mm), Cinnamomum Verum (25.59 mm), and Eucalyptus globulus (36.13 mm) as compared to control (water). The current study, offers valuable insights into the prevalence and distribution of brown spot disease in District Okara, there by facilitating the development of focused management strategies to alleviate its impact on potato cultivation.

Insidensi dan Keparahan Penyakit Bercak Daun Disebabkan oleh Curvularia sp. pada Pembibitan Kelapa Sawit di Kabupaten Banyuasin Sumatera Selatan

In Indonesia, there has been a notable expansion in the area and productivity of oil palm plantations. Oil palm is among the top seven plantation commodities prioritized for development. High-quality seedlings are essential for optimal plant production. However, several factors can impede oil palm productivity, including diseases that affect oil palm seedlings. One such disease is brown spot disease caused by the fungus Curvularia sp. The objective of this study was to determine the incidence and severity of brown spot disease in oil palm seedlings. The research was conducted from May 2023 to June 2023 in Banyuasin Regency using a purposive sampling survey method. Thirteen seedling locations were selected based on their adherence to good seedling criteria. Seedlings aged 6-12 months were used in this study. At each location, five plots were surveyed, with 30-32 seedlings sampled per plot. Supporting data, including fertilization, watering, and herbicide and fungicide application, were tabulated to supplement the research findings. Results indicated that brown spot disease can affect plants as young as two weeks old. Initial symptoms include brown spots that eventually widen and merge with other spots. The average incidence of the disease was 93.29 % (± 7.89), with an average severity of 47.13% (± 13.23).

Evaluation of the control efficacy of antagonistic bacteria from V-Ti magnetite mine tailings on kiwifruit brown spots in pot and field experiments.

Seemingly barren heavy-metal-polluted vanadium (V) and titanium (Ti) magnetite mine tailings contain various functional microbes, yet it is unclear whether this includes microbial resources relevant to the biological control of plant diseases. Kiwifruit brown leaf spot disease, caused by Corynespora cassiicola, can seriously reduce kiwifruit yield. To discover effective control measures for kiwifruit leaf spot, 18 bacteria strains among 136 tailing-isolated bacteria from V-Ti magnetite mine tailings were identified as inhibiting C. cassiicola by the confrontation plate method, indicating that antagonistic bacteria surviving in the V-Ti magnetite mine tailings were present at a low level. The 18 antagonistic strains could be divided into two BOX-A1R clusters. The 13 representative strains that were selected for phylogenetic tree construction based on their 16S rRNA sequences belonged to the Bacillus genus. Five predominant strains exhibited different toxin-production times and intensities, with four of them initiating toxin production at 32 h. Among them, Bacillus sp. KT-10 displayed the highest bacteriostatic rate (100%), with a 37.5% growth inhibition rate and an antagonistic band of 3.2 cm against C. cassiicola. Bacillus sp. KT10 also showed a significant inhibitory effect against the expansion speed of kiwifruit brown spots in the pot. The relative control effect was 78.48 and 83.89% at 7 days after the first and last spraying of KT-10 dilution, respectively, confirming a good effect of KT-10 on kiwifruit brown leaf spots in the field. This study demonstrated for the first time that there are some antagonistic bacteria to pathogenic C. cassiicola in V-Ti magnetite mine tailings, and Bacillus sp. KT10 was found to have a good control effect on kiwifruit brown leaf spots in pots and fields, which provided an effective biological control measurement for kiwifruit brown leaf spots.

Study on Major Disease-insect Incidence of Scented Gobindabhog Rice in New Alluvial Zone of West Bengal

A comprehensive study on “Improvement of production and storage system for Gobindabhog rice in West Bengal,” comprising two field and one laboratory experiment, was done at Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal, India, during the period of 2010–2012 to find out the optimum planting time, spacing, nutrients, disease, and pest management for scented Gobindabhog rice during the kharif season. Plant height, tiller production, and leaf area index increased consistently with the advancement of crop growth up to panicle exertion, panicle initiation (i.e., 56 DAT), and flowering (i.e., 84 DAT) stages, respectively. The planting date had a significant effect on the incidence of blast disease in Gobindabhog rice during both 2010 and 2011, except at 28 DAT. Delay in planting generally provided a favorable environment for the causal organism (Payricularia oryzae) during the vegetative and reproductive stages of Gobindabhog rice, thereby leading to a greater incidence of delayed crops (25 July, 10 August, and 25 August) than the earlier one (10 July). The susceptibility of the Gobindabhog rice crop to brown spot disease caused by Drechslera oryzae increased progressively with the advancement of crop age from 28 DAT (i.e., active tillering stage) to 84 DAT (i.e., flowering stage). The population of gundhi bug (Leptocorisa acuta) increased steadily from 84 DAT (i.e., 50% flowering) to 112 DAT (maturity stage), irrespective of main and sub-plot treatments as well as years of investigation.