Epiphytotic Conditions Research Articles

Screening of Brinjal Varieties for Resistance Against Blight Disease Caused by Alternaria alternata (Fr.) Keissler in Konkan Region of Maharashtra, India

Brinjal (Solanum melongena L.) belonging to family solanaceae, is widely recognized around the globe as “eggplant” due to it’s resemblance to the shape of a chicken egg. The field experiment was carried out during Rabi, 2022-23 and 2023-24 at Central Experiment Station, Wakawali, Dr. Balasaheb sawant Konkan Krishi Vidyapeeth, Dapoli under natural epiphytotic conditions. Sixty six varieties / cultivars and germplasm lines of brinjal were screened to test their resistance reactions against blight disease of brinjal caused by Alternaria alternata. The results revealed that, all the entries of brinjal screened showed varied degree of per cent disease intensity. The highest per cent disease intensity was recorded in Konkan Prabha (41.92%) and was followed by NB-746 (37.91%), Dapoli local-1 (34.62%) and Dapoli local-3 (33.42%). Among 66 entries screened, three entries viz., D-79-19, RCMB-3 and Dapoli pandharivangi sel. were found highly resistant, seven entries viz., Khed local-41, DPL-BR-19, NBH-106, Suwarna Pratibha, DPL-BR-20, N-1007 and NBH-104 resistant, thirty eight entries moderately resistant and eighteen entries of brinjal were moderately susceptible to A. alternata incitant of brinjal blight disease.

Screening of Horsegram Genotypes for Resistance against Yellow Mosaic Disease

Aims: The present study aimed to evaluate the screening of horsegram genotypes for resistance to yellow mosaic disease. The disease causes decrease in number of seeds per pods, number of pods per plant. The disease may occur at any phase of plant development. Background: Horsegram crop suffers from yellow mosaic, powdery mildew, anthracnose, dry root rot, leaf spot, rust and cottony stem rot. Yellow Mosaic Disease (YMD) is recognized as the most detrimental viral affliction among the array of diseases induced by the Yellow Mosaic Virus. The occurrence of YMD in pulse crops has resulted in significant yield reductions, which can vary between 50 to 100 per cent. The best method to overcome YMD is the development of disease resistant varieties. Henceforth, an effort has been made to evaluate horsegram genotypes to obtain sources of resistance against YMD. Place and Duration of Study: Field experiment for screening was conducted at Main Agricultural Research Station, University of Agricultural Sciences, Dharwad, Karnataka, India, during summer 2023-24. Methodology: For screening, 148 genotypes were screened under natural epiphytotic conditions. Each genotype was sown in a 2 m row to test the resistance or susceptible reactions against YMD. A susceptible check (BGM-1) was planted after every 10 lines of test genotypes and all along the four sides of the field (infector row technique). Results: Out of 148 genotypes evaluated, none of them were immune or resistant, 12 were moderately resistant, 47 were moderately susceptible, 46 were susceptible and remaining 43 genotypes showed highly susceptible reaction. Conclusion: Identified moderately resistant genotypes can be utilized in YMD resistance breeding programme to develop YMD resistant varieties.

Screening Taro Germplasm against Bacterial Blight Incited by Xanthomonas axonopodis pv. dieffenbachia

Sixty-four Taro germplasm accessions from north east India along with two national released varieties were evaluated in natural epiphytotic field condition against bacterial blight incited by Xanthomonas axonopodis pv. dieffenbachia for two consecutive seasons during 2018 and 2019 at an Experimental Farm for Horticultural crops, Assam Agricultural University, Jorhat. The results obtained for the two growing seasons were pooled together. Per cent disease incidence and disease severity ranged from 23.81 (Nepali-2) to 78.57 % (SC-1) and 14.17 (Nepali-2) to 67.50 % (SC-1) respectively. The area under the disease progress curve (AUDPC) which directly corresponds to the bacterial disease infection with time resulting in more susceptibility to the disease ranged from 1612.5 (Sreekiran) to 9812.5 (SC-1). AUDPC was calculated from the per cent disease severity obtained from the first day of disease observation till the last day i.e. from 60 to 240 days after transplanting (DAT). The disease reactions of different germplasm to bacterial blight of colocasia were evaluated based on the disease severity (%) and disease rating scale whereby no cultivars were immune and highly susceptible to the disease. Four accessions viz. Sreekiran, Naga-2, Chandil Pin, Nepali-2 were resistant, twenty-one were moderately resistant, twenty-six were moderately susceptible and fifteen were susceptible. Variety/germplasm resistant to bacterial blight of Taro have not been reported till date. Proper selection of resistant varieties will be useful in breeding programmes and for further crop improvement.

Screening of Inbred Lines of Maize against Turcicum Leaf Blight (Exserohilum turcicum) under Artificial Epiphytotic Conditions

Aims: Turcicum Leaf Blight (TLB), caused by Exserohilum turcicum, significantly affects maize in Karnataka, leading to yield losses of up to 70% in severe cases. To develop tolerant genotypes against this disease, an experiment was conducted using 100 inbred lines collected from the IMIC maize field day in Hyderabad. Study Design: Investigation was carried using Randomized complete block design with two replication. Place and Duration of Study: Maize Research Centre and Seed Farm, Devihosur during kharif-2022. Methodology: One hundred inbred lines were screened against TLB disease. among them 10 resistant lines were selected based on their maturity, disease reaction, grain yield and per se performance. These inbreds along with the checks (Resistant check CI-4 and Susceptible Check CM-202) were sown in Kharif 2022 at Maize Research Centre and Seed Farm Devihosur, UAS, Dharwad. Artificial inoculation was performed 45 days after sowing in the leaf whorls using infected leaves with TLB and the results were evaluated at the silk drying stage. To assess the disease reaction to TLB, we used 1 to 9 scale as established by the Indian Institute of Maize Research, Ludhiana (Anon., 2016). Lines that received disease scores between 1.0 and 3.0 were classified as resistant (R), scores of 4 to 5 as moderately resistant (MR), scores of 6 to 7 as moderately susceptible (MS), and scores of 8 to 9 as susceptible (S). Results: The performance of these lines were compared with the resistant check CI-4 and susceptible check CM-202. Screening trial revealed that out of hundred inbred lines, eighteen lines Showed highly resistant reaction. This information can be useful for selection of parents and to develop tolerant hybrids in breeding programs or utilize them as source of resistance.

Identification of resistant sources against collar rot disease in groundnut (Arachis hypogaea) incited by Aspergillus niger

Collar rot disease incited by Aspergillus niger van Tiegham is one of the major constraint to groundnut (Arachis hypogaea L.) production in India. This fungus is ubiquitous, soil inhabitant causing severe reduction in seed germination. Infected seeds appear surrounded by black conidia and post-emergence infection occurs on collar region of plants leading to mortality of emerged seedlings at the seedling stage. Therefore, present study was carried out during rainy (kharif) seasons of 2022 and 2023 at Regional Research Station (CCS Haryana Agricultural University, Hisar, Haryana), Bawal, Haryana to identify the strategy of disease management by identification of new resistant lines which will be useful to develop introgression lines using marker-assisted backcrossing approach to improve disease resistance against soil-borne pathogens in popular groundnut varieties. A total of 245 groundnut genotypes were screened under natural epiphytotic field conditions in randomized block design (RBD) with three replications for their resistance against collar rot disease The results of the investigation indicated that 65 genotypes displayed resistant reactions among which ICGV-6285, GC-131-1, ICGV-06319, ICGV-02038, GC-100, GC-98, ICGV-02038, ICGV-7403, ICGV-7214, TG-37A and GC-133 exhibited the lowest collar rot incidence while, rest of the genotypes displayed moderately resistant, susceptible and highly susceptible reaction. Thus, these resistant genotypes could be utilized in the hybridization programme to develop high yielding groundnut variety with inbuilt resistance against collar rot of groundnut.

Improving Pepper Inbreds for Resistance to Pepper Yellow Leaf Curl Thailand Virus (PepYLCTHV) through Challenged Inoculations

Chili peppers (Capsicum annuum L.) are an economically important crop worldwide. Pepper yellow leaf curl Thailand virus (PepYLCTHV), a Begomovirus causing yellow leaf mosaic disease of chili pepper, has been reported to incur 95% economic loss under epiphytotic conditions. Thirty-one chili genotypes were screened for resistance to PepYLCTHV disease through inoculation using 10–15 viruliferous whiteflies per plant. We purified two resistant lines (PEP6 and PEP12) through four generations of selfing and selection. At 28 days after inoculations, two chili genotypes (PEP6 and PEP12) had low disease severity and percentage of disease incidence (DI) compared to four susceptible checks, viz., Yodsonkeam80, Homsupan, Huareau12, and Pong Charian, which had a disease severity score of 5 with 100% DI. Thirty initial plants of PEP6 showed an average disease severity of 3.64 with 69.33% DI, and PEP12 showed an average disease severity of 3.83 with 77.67% DI. From these populations, we selected nine highly resistant plant of PEP6 and seven plants of PEP12 having a disease severity of 0 through pure-line selection for four selfing generations. The ratio of resistance (R) to susceptibility (S) consequently decreased. In PEP6, the ratio decreased from 1R:2S to 1R:1S, while in PEP12 the ratio decreased from 1R:3S to 1R:1S. These lines have potential for release as resistant lines for improving chili pepper resistance to PepYLCTHV and for developing makers associated with the resistant trait.

Identification and confirmation of powdery mildew (Erysiphe polygoni) resistance in pea germplasm

Erysiphe polygoni DC, the causative agent of powdery mildew, poses a significant threat to pea crop, resulting in substantial yield and economic losses. To address this menace, an exploration of intrinsic resistance within pea germplasm becomes imperative for effective disease management. In our study, phenotyping of 1095 pea accessions, sourced from both indigenous and exotic origins, under natural epiphytotic conditions during Rabi 2021-22, revealed a prevailing susceptibility, with over 60 per cent disease severity in majority of accessions. Remarkably, only 22 accessions, including IC208327, IC220109, IC220378, IC258401, IC262762, IC262849, IC267140, IC267174, IC267727, IC274039, IC274040, IC310074, IC311066, IC345548, IC424898, IC552779, IC613133, IC629544, IC629687, NC57793, IC220193 and EC598669, exhibited resistance with a disease score of <1. Subsequent, pot screening of these 22 resistant accessions under artificial epiphytotic conditions during Rabi 2022-23 confirmed their resistance showing disease severity ranging from 5.83 - 17.50 per cent. Recognizing the pivotal role of resistant varieties in disease management, these identified accessions hold immense potential as resistant donors in crop improvement programs.. KEYWORDS :Germplasm, pea, powdery mildew, resistance

Correction: Identification of resistance sources for sesame phyllody under epiphytotic conditions in India

Correction: Identification of resistance sources for sesame phyllody under epiphytotic conditions in India

In Vivo Efficacy of Bioagents and Fungitoxicants against False Smut Disease of Rice Caused by Ustilaginoidea virens (Cooke) Takahashi

The present experiment was conducted from June to November 2017 at Crop Research Center, Chirodi, Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut (U.P.), India to assess the efficacy of six fungicides-propiconazole, strobin, flutolanil, copper oxychloride, azoxystrobin, flusilazol, and two bioagents viz., Trichoderma harzianum and Pseudomonas fluorescens-against false smut of rice under natural epiphytotic field conditions. Once panicle emergence reached 50%, each fungicide and bioagent was sprayed once. The findings of present investigation revealed that spray of propiconazole @ 0.1% reduced the false smut significantly and resulted in the lowest percentage of infected tillers (7.48%) and smutted grains (4.98%) along with maximum yield parameters like number of tillers (294), 10-ears weight (30.10 g), 1000-grain weight (24.50 g) and yield (4903 kg ha-1); it was followed by the spray application of either azoxystrobin @ 0.07% or strobin @ 0.06% with above respective parameters. Apart from the fungicides applied, the application of Trichoderma harzianum also reduced the false smut and increased the yield components significantly over the control plots. However, the lowest 10-ear weight (22.80 g), 1000-grain weight (17.50g), and yield (3100 kg ha-1) along with the highest percentage of infected tillers (23.93%) and smutted grains (21.47%) were recorded in unprotected plots. Therefore, growers can be advised to use a foliar spray of one of three fungicides-propiconazole @ 0.1%, azoxystrobin @ 0.07%, or strobin @ 0.06%–at 50% panicle emergence stage to fungicidal control of false smut of rice.

Identification of resistance sources for sesame phyllody under epiphytotic conditions in India

Identification of resistance sources for sesame phyllody under epiphytotic conditions in India

Morphological evaluation and yield performance of lentil genotypes against stemphylium blight

Experiment was designed to screen out lentil genotypes against Stemphylium blight (SB). Thirty-five test genotypes along with one moderately susceptible popular local control ‘Moitree’ were grown under natural epiphytotic condition in the farm of BCKV during 2020-21 and 2021-22. Genotypes wise crop phenological characters, yield and disease severity data were recorded. The result revealed, genotypes ILL10838/ILWL11/X2016S was resistant to SB with highest yield (1184.00 kg/ha) followed by 8114/10956/16-1 (1112.20 kg/ha) and IPL 220 (1072.90 kg/ha) with MR reaction. Pooled analysis of two years experimental data used to develop the model Y = 336.21 + 6.12x [R2 = 0.86] explained that there is an increase of yield 6.12 kg/ha with every 1 unit increase in the number of pods per plant. Correlation of determination value (R2 = 0.86) proved the feasibility of the model. Lentil genotypes ILL10838/ ILWL11/X2016S and 8114/10956/16-1 are the best suited for its cultivation and may scaled up for future breeding programme. Bangladesh J. Bot. 53(2): 381-389, 2024 (June)

Assessment of wheat genotypes for spot blotch (Bipolaris sorokiniana Sacc.) resistance under artificial epiphytotic conditions in the inner terai of Nepal

Spot blotch, caused by (Bipolaris sorokiniana Sacc.) is a significant fungal disease leading to economic losses in wheat (Triticum aestivum), especially in regions with low soil fertility and warm, humid climates, such as the inner Terai of Nepal. A field experiment was conducted at the National Maize Research Program (NMRP), Rampur, Chitwan, during winter of 2021/022 with an aim of identifying wheat genotypes with spot blotch resistance under artificial epiphytotic conditions. Each genotype was sown in a single 2-meter long row alongside susceptible check genotypes (Agra and Morocco) at every 20th row. Aqueous spore suspension of B. sorokiniana was applied twice in border rows during the booting stage at 15-day intervals. Disease severity was assessed four times at five-day intervals using a double-digit scale based on the percentage blighted area on the flag and penultimate leaf, and the area under the disease progress curve (AUDPC) was calculated. The results categorized 43 genotypes as resistant, 127 as moderately resistants, 135 as moderately susceptible, 66 as susceptible, and 7 as highly susceptible based on AUDPC. Cluster analysis identified cluster 3 comprising 17 genotypes as superior in terms of disease resistance as well as agronomic parameters. NRN-34 emerged as the top-ranked genotype within this cluster, followed by NAL-73, NAL-94, NAL-12, NRN-34, NAL-57, NAL-43, NAL-82, and NAL-35, exhibiting lower AUDPC values and higher yield-attributing character values. This study will aid breeders in developing spot blotch-resistant and high-yielding wheat varieties by incorporating the identified promising genotypes into further breeding programs.

Response of mungbean genotypes for resistance against mungbean yellow mosaic virus

Mungbean yellow mosaic virus (MYMV) is an important viral disease across mungbean growing areas and causes severe yield loss in mungbean especially during the spring/summer season. The present study was envisaged to identify MYMV donors in mungbean. A total of 104 mungbean genotypes were evaluated for MYMV under natural field conditions during summer, 2019. The results revealed that MYMV severity ranged from 0% to 100% among mungbean genotypes. Out of 104 genotypes, 32 genotypes were completely free from MYMV, two genotypes exhibited resistant reaction (R), 22 genotypes were found moderately resistant (MR) and the remaining 48 genotypes were susceptible to highly susceptible reaction to MYMV. Thus, the identified 34 promising lines of mungbean were further evaluated against MYMV along with susceptible check DGGV-2 under epiphytotic conditions during the summer of 2020 and 2021. Pooled data of MYMV over the two years indicated that six genotypes namely, IPM-1205-2, IPM-2-14, IPM-410-3, IPM14-10, IPM-205-7 and IPM-1604-1 were showed stability for MYMV resistance. These identified stable resistant genotypes will serve as potential donors for the mungbean breeding program to develop resistance cultivars.

Identification of new stable resistant sources and assessing agro-morphological performance of sponge gourd germplasm against Tomato Leaf curl New Delhi Virus incidence.

Tomato leaf curl New Delhi virus (TolCNDV) causes yellow mosaic disease, which poses a significant biotic constraint for sponge gourd cultivation, potentially resulting in crop loss of up to 100%. In the present investigation, 50 diverse genotypes were screened for 3 years under natural epiphytotic conditions. A subset of 20 genotypes was further evaluated across four different environments. The combined analysis of variance revealed a significant genotype × environment interaction. Eight genotypes consistently exhibited high and stable resistance in the preliminary screening and multi-environment testing. Furthermore, genotype plus genotype × environment interaction biplot analysis identified DSG-29 (G-3), DSG-7 (G-2), DSG-6 (G-1), and DSGVRL-18 (G-6) as the desirable genotypes, which have stable resistance and better yield potential even under diseased conditions. The genotype by yield × trait biplot analysis and multi-trait genotype-ideotype distance index analysis further validated the potential of these genotypes for combining higher yield and other desirable traits with higher resistance levels. Additionally, resistant genotypes exhibited higher activities of defense-related enzymes as compared to susceptible genotypes. Thus, genotypes identified in our study will serve as a valuable genetic resource for carrying out future resistance breeding programs in sponge gourd against ToLCNDV.

Disease Reaction Studies for Turcicum Leaf Blight (Exserohilum Turcicum) Disease in Maize (Zea Mays L.) Under Artificial Epiphytotic Conditions

Maize is widely cultivated around the globe under varied climatic conditions. India is one of the major maize producing countries and stands fourth in terms of production. Turcicum leaf blight (TLB) disease caused by the pathogen, Exserohilum turcicum is one of the major diseases of maize causing varying extent of grain yield loss from 15 to 30%. To overcome the losses due to the disease, resistant cultivars needs to be developed. Hence, the identification of resistant sources is important in order to develop TLB resistant hybrids. Present investigation was conducted to identify TLB resistant inbreds and hybrids. Simplified Triple Test Cross (STTC) design was employed to develop 96 hybrids using twenty inbred lines. Further the hybrids and inbred lines along with two checks (Resistant –NAI 137; Susceptible – CM 202) were evaluated for TLB disease reaction under artificial epiphytotic condition during rabi 2019 in simple lattice design with two replications. Scoring was done from 60 to 80 days after sowing based on 1-9 TLB disease scale. Among the inbred lines V-86, MAI-295, V-70, MAI-214, V-85, 40375, V-72, V-39, 40061 were resistant and MAI-288, V-24 were susceptible. Among hybrids, 36 were resistant, 44 were moderately resistant. 14 were moderately susceptible and two hybrids were susceptible to TLB disease. Identified TLB resistant hybrids needs to be further evaluated to test their performance and stability across locations. These resistant sources can be used to transfer TLB disease resistance.

Genetic characterization of new source of resistance for tomato leaf curl New Delhi virus (ToLCNDV) from snapmelon (C. melo var. momordica)

AbstractThis study aimed to understand the genetics of tomato leaf curl New Delhi virus (ToLCNDV) in the identified novel source of resistance from Indian melon germplasm DSM-19 (Cucumis melo var. momordica) as viral diseases in muskmelon cause significant economic yield loss. To achieve this, a cross was made between the highly susceptible genotype Pusa Sarda (C. melo var. inodorus), known for its desirable fruit characters, and the resistant source DSM-19 to generate the suitable populations for inheritance study. These populations were screened under natural epiphytotic conditions and further validated through challenge inoculation with viruliferous whiteflies. The inheritance of ToLCNDV resistance in snapmelon germplasm DSM-19 was identified as monogenic recessive in both the screening methods. Moreover, a cleaved amplified polymorphic sequence (CAPS) marker named ‘CAPS 16 (2)’ was designed near to SNP marker D16 located on chromosome 11 of melon, and it was found to be linked to the ToLCNDV resistance gene in DSM-19. This is the first report on genetics of ToLCNDV resistance in snapmelon germplasm from India. Snapmelon line DSM-19 can be used as a source for fine mapping and introgression of the ToLCNDV resistance into susceptible muskmelon cultivars.

Upotreba bioloških i hemijskih fungicida i biostimulatora za zaštitu krompira od alternarije i kasne plamenjače

Ecological risks associated with chemical pesticides encourage application of biopesticides and integrated pest management. The study compared efficiency of the Manfil fungicide and Agat-25K biopreparation (single or combined with the ExelGrow biostimulator) against the late (LB) and early (EB) blights of potato. Field experiments were conducted with three potato cultivars (Arizona, Vektor, Aluett) of different resistance levels to the LB and EB diseases. Leaf blight development was registered as LB (Arizona), LB+EB (Vektor), and EB (Aluett). Agat25K delayed LB development under epiphytotic conditions on the susceptible cv. Arizona (biological efficiency 39%), though was inferior to Manfil (62%). On the contrary, for cv. Aluett, Agat-25K showed more significant EB suppression than Manfil (96 vs. 83%). Compared to the control, the yield increase of cv. Arizona was 15.8 t/ha for Agat-25K and 25.4 t/ha for Manfil. Tuber marketability increased by 28 and 13% for Agat-25K and Manfil, respectively. For moderately resistant and resistant cultivars (Vektor, Aluett), Agat-25K provided the highest yield increase compared to Manfil (19.1 vs. 16.7 t/ha for Vektor and 4.5 vs. 1.4 t/ha for Aluett, respectively), while the tuber marketability increased by 15% (Vektor) and 18% (Aluett). Agat-25K can be recommended for use on moderately-resistant cultivars under sporadic LB epiphytoties and for the EB control. ExelGrow application with Manfil and Agat-25K was first shown to improve their biological efficiency on moderately LB-resistant and LB-resistant cultivars (up to 12%).

Identification Sources of Resistance from rice Germplasm Against Sheath Rot Disease under Artificial Epiphytotic Conditions

Twenty nine entries along with three checks were screened against sheath rot disease under artificial epiphytotic conditions during Kharif 2018 and 2019 to identify sources of disease resistance under field condition. Four entries designated viz., NVSR-317, NVSR-411, NVSR-405 and Sambha mahsuri exhibited resistant reaction whereas, 23 entries viz., NVSR-348, NVSR-350, NVSR-355, NVSR-2101, NVSR-2103, NVSR328, NVSR-329, NVSR-2528, NVSR-2565, NVSR-2566, NVSR-330, NVSR-331, NVSR-335, NVSR-338, NVSR360, NVSR-364, NVSR-365, NVSR-370, NVSR-374, NVSR-384, NVSR-389, NVSR-2435 and NVSR-406 showed the moderately resistant reaction and rest of the entries were recorded moderately susceptible and susceptible in their reactions against the sheath rot disease under artificial inoculation. Both susceptible checks GR-11 and TN-1 had scale-7 indicated much disease pressure with susceptible reaction. These resistant germplasm may be further utilized as donor for further breeding programs to evolve new resistant variety against sheath rot.

Efficacy of Fungicides and Optimization of Application Timing for the Management of Sclerotinia Rot of Mustard Caused by Sclerotinia sclerotiorum

Sclerotinia rot of rapeseed-mustard caused by Sclerotinia sclerotiorum (Lib.) de Bary has gained significant importance in Rajasthan, Punjab, Haryana and other major rapeseed-mustard growing areas of India in recent years. Fungicides are extensively used for the control of this disease since no commercial cultivars have been found resistant to S. sclerotiorum and other management practices have not been found very effective. Therefore, the present investigations were carried out to evaluate the efficacy of fungicides and to optimize application timing for the effective management of Sclerotinia rot of mustard. Among 08 fungicides tested in vitro, Carbendazim 50% WP and Propiconazole 25% EC were found most efficient at completely inhibiting the mycelial growth of S. sclerotiorum at all the concentrations tested. In an in vitro sclerotial (carpogenic) germination test, Carbendazim 50% WP completely inhibited sclerotial germination at 100, 250 and 500 ppm. Under artificial inoculation conditions in the field, Propiconazole 25% EC @0.1% was found most effective in reducing Sclerotinia rot incidence (87.04%) followed by Carbendazim 50% WP (83.33%) and Tebuconazole 25.9% EC (75.93%). Similarly, under natural epiphytotic conditions in field, Propiconazole 25% EC @0.1% was found best in disease incidence reduction (85.34%) with increased yield (40.00%) followed by Carbendazim 50% WP (81.25% & 38.09%) and Tebuconazole 25.9% EC (79.72% & 35.24%) in disease reduction and increased yield respectively. Differential time and frequency of application of Propiconazole @0.1% were tested and found that 02 applications i.e. 1st spray at 4.2 flowering stage i.e. 30% bloom stage (70 DAS) and 2nd spray at 4.3 flowering stage i.e. 50% bloom stage (85 DAS) was equally effective in disease incidence reduction (82.70%) with 03 applications i.e. 1st spray at 4.1 flowering stage i.e. 10-20% bloom stage (55 DAS), 2nd at 4.2 flowering stage (70 DAS) and 3rd at 4.3 flowering stage (85 DAS). Therefore, the optimization of fungicide application timing and the number of sprays with adequate concentrations is advisable to increase the cost-effectiveness of crop production while controlling the disease.

Screening of Rice Genotypes for Resistance Against Bacterial Blight Disease

A study was undertaken at V. C. Farm, Mandya, Karnataka, India during 2020 to screen the genotypes against BLB under natural field conditions. Host Plant resistance is an important component of an integrated management program for this disease. Among the 102 rice genotypes screened under natural epiphytotic condition at Zonal Agricultural Station, V. C. Farm, Mandya, none of them were found immune against bacterial leaf blight. So, in the study, plants were assessed by measuring disease severity (% of leaf diseased) and area under the disease progress curve (AUDPC). The pathogenicity of Xoo was tested on IRRI rice cultivars, inoculation was conducted at the maximum tillering stage, and the lesion length was measured after 14 days of inoculation. An attempt was made to phenotypically characterize a set of 102 Genotypes from IRRI for BLB resistance by artificially inoculaton using clipping method. Out of the 102 genotypes and two checks tested, it was observed that five entries viz., IRGC 125853, IRGC 126264, IRGC 132357, IRGC 122088 IRGC 125658 and Improved Samba Mahsuri were highly resistant with score of 1. Only one entry (IRGC 125754) was resistant with score of 3, 33 lines being moderately resistant with score of 5 and 43 lines were susceptible with score of 7. 20 lines and also the susceptible check Jyothi-PTB 39, had the highest susceptibility with a phenotypic score of 9.