Indian Phytopathology a leading plant pathology research journal deals with the disciplines of Mycology, Fungal Pathology, Bacteriology, Virology, Phytopathology and Nematology. The journal is published quarterly in March, June, September, and December. The society has published the journal for over 69 years. The journal has national as well as global reach. ISSN : 0367-973X (Print version) ISSN : 2248-9800 (Electronic version ) Abstracting/Indexed in: CAB Abstracts, Indian Science Abstracts, RUNNERS, Indian Citation Index (ICI), Google Scholar, AGRIS (International Information System for the Agricultural Sciences and Technology),Chemical Abstracts Service (CAS), AGRICOLA, Directory of Open Access Journal (DOAJ), WorldCat, PASCAL database, RefDoc Indian Phytopathology offers online first publication upon acceptance Indian Phytopathology has instituted a feature called Online First Look. Within a few days of acceptance, papers by authors who choose to participate will be posted online. The papers have been peer reviewed and then revised as necessary by the authors but have not been copyedited, formatted, or assigned to an issue. The date on which each paper is posted is considered the publication date. This paper has been peer reviewed and accepted for publication but has not yet been copyedited or proofread. The final published version may differ Editorial Board
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Plant Viruses, Diseases and Their Management, ISBN: 978-93-84588-81-6, Author: Dr. Kajal Kumar Biswas, Principal Scientist, Division of Plant Pathology, ICAR-Indian Agricultural Research Institute, New Delhi by Publisher: IK International, N Delhi, 2017, 632 pp.
Copyright (c) 2018 Indian Phytopathology
A.P. Misra Memorial Lifetime Achievement Award (2016: B.B. Nagaich)
Rust resistance in Mucuna pruiens accessions
Mucuna is considered to be an important source of chemical which is useful in Parkinson’s disease and other neurological disorders. Mucuna accessions collected from various agroecological zones were screened for rust resistance at ICAR Research Complex for NEH region in Meghalaya. Only three accessions viz. WBN 3, WBN 6 and NGL 25 were identified as highly resistant. Seven accessions were found to be resistant and nineteen accessions were found to be moderately resistant. These accessions can be used in future breeding programs of this important crop.
P. BAISWAR*, K.P. MOHAPATRA, P. CHANDRA and S.V. NGACHAN
Identification of resistant sources and management of rice blast through fungicides
Surveys conducted during Kharif 2014 and 2015 in major Basmati rice growing areas of Haryana revealed that the neck blast (Pyricularia grisea) incidence ranged from traces to 20% in commercially grown Basmati varieties. The average disease incidence was highest in Basmati CSR 30 (1.20-2.12%) followed by Pusa Basmati 1121 (1.09-1.60%) while it was the lowest (traces) in Pusa Basmati 1509. Out of 88 scented genotypes, five genotypes viz. HKR 08-425, HKR 10-579, HKR 11-509, PAB 21-663 and Pusa 1485-06-8-10-5-15-11 showed consistent resistance to leaf blast under natural epiphytotic conditions of uniform blast nursery during kharif seasons 2014 and 2015. Amongst fungicides evaluated against neck blast, combination of tricyclazole 45% + hexaconazole 10% WG @ 1.0 g/l was found to be the most effective and statistically at par with standard fungicide tricyclazole @ 0.6 g/l in reducing the neck blast incidence and enhanced grain yield of paddy variety, Basmati CSR 30 followed by combination of tricyclazole 18% + mancozeb 62% @ 2.5 g/l.
A.P. Misra Memorial Lifetime Achievement Award (2015: A.N. Mukhopadhyay)
Pathogenicity of Sclerotium spp. on common weeds in Meghalaya, India
Sclerotium spp. are the major soil borne plant pathogens causing important plant diseases throughout the world. Two isolates SL 1 (Sclerotium rolfsii) and SU (S. delphinii) were used in pathogenicity test. Forty six common weeds (detached leaf and stem) were collected and used in pathogenicity test. Isolate SL1 (S. rolfsii) was pathogenic on both leaf and stem of all the common weeds except stem of Spilanthes paniculata. Isolate SU (S. delphinii) was pathogenic on both leaf and stem of all the common weeds. Incubation period on most of the common weeds was 1- 3 days except 6 days on Ageratum houstonianum and 4 days on Alternanthera philoxeroides, A. sessilis and Ischaemum rugosum with isolate SL1. Minimum days for sclerotia formation of SL1 isolate was 5 days on Emilia sonchifolia, maximum sclerotia production (38 nos.) was observed on Sonchus aspera. Incubation period on all the common weeds was 1- 3 days with SU isolate. Minimum days for sclerotia formation of SU isolate was 5 days on E. sonchifolia, Mikania micrantha and Urena lobata, maximum sclerotia production (46 nos.) was observed on Crassocephalum crepidioides. The weed A. sessilis was susceptible and U. lobata was most susceptible to isolate SL1 based on AUDPC. The weed A. houstonianum was susceptible and Commelina benghalensis was most susceptible to isolate SU.
PAMALA PRINCEJAYASIMHA, PANKAJ BAISWAR, RAJESH KUMAR , DIPALI MAJUMDER and SANDIP PATRA
Cultural characterization of Colletotrichum gloeosporioides causing anthracnose of pomegranate
Pomegranate is an important commercial fruit grown worldwide. The productivity of pomegranate is hampered by different diseases, among them anthracnose is one of the important disease caused by Colletotrichum gloeosporioides. Therefore, for better understanding of the nature of the pathogen cultural studies carried out. In cultural studies on different solid media, maximum radial growth of the fungus (87.5 mm) was recorded on malt extract agar, while sporulation was excellent in the case of malt extract agar which was at par with oat meal agar and potato dextrose agar medium. Colony growth varies from flat to fluffy with regular to irregular margin and pigmentation varies from white or yellow or orange. In growth phase study the maximum dry mycelial weight of C. gloeosporioides was observed on 12th days of incubation on potato dextrose broth (451.9 mg).
DEVANSHU DEV*, Y.M. SOMASEKHARA and M.K. PRASANNAKUMAR
Powdery mildew of Populus deltoids under temperate agro-climatic conditions of Kashmir, India
During August 2015 and 2016, white powdery colonies were found on the lower surface of the poplar (Populus deltoides) leaves in Kashmir province, India. White powdery patches were observed embedded with scattered, black fruiting bodies late in the growing season. The disease caused premature defoliation. The fungus associated with the white colonies was identified as Phyllactinia guttata (Wallr.) Lev. by morphological characterization. This is the first report of Phyllactinia guttata causing powdery mildew disease on Populus deltoides from Jammu and Kashmir, India.
M. ASHRAF AHANGAR*, Z.A. BHAT and Z.A. BADRI
Detection of 16Sr XI group of phytoplasma in non-symptomatic sugarcane cultivars in Eastern Uttar Pradesh, India
Twenty six non-symptomatic leaf samples from six different sugarcane varieties (CoS 07250, CoS 96268, CoS 91269, CoSe 01424, CoS 08272, CoS 08279) grown at Sugarcane Research Institute farm at Shahjahanpur were analyzed for phytoplasma presence by using P1/P6 and R16F2n/R2 primer pairs. The amplification product of 1.2 kb was obtained in 17 out of the 26 non-symptomatic leaf samples in nested PCR assays. The amplified products from 17 positive samples were directly sequenced, aligned and analyzed using BLASTn. The obtained 16SrRNA gene sequences of all the 17 nonsymptomatic sugarcane phytoplasma isolates were found identical (99-100%) among themselves and showed 99% sequence identity to member strains of a 16SrXI group of phytoplasma. The information of phytoplasma association with nonsymptomatic sugarcane varieties at early stage is important and needs immediate attention because at crop maturity the disease may become serious and responsible for major losses to yield and sugar recovery.
A.K. TIWARI, KAVITA KUMARI, NISHTHA MISHRA, MADHUPRIYA, G.P. RAO* and B.L. SHARMA
Screening of tea cultivars tolerant to branch canker disease using histopathological studies
A glass house experiment was carried out for screening tea cultivars against Macrophoma theicola causing canker. One year old nursery plants viz. TRF-1, UPASI-3, Yabukita, UPASI-6, TRF-2, CR-6017, UPASI-9, UPASI-17, UPASI-26, TRF-4 and TRI- 2025 were selected. This study revealed that TRF-1 (19.67±1.20) and UPASI-3 (21.00±1.53) showed more number of pycnidiospores productions and bigger size of canker. The lesion size was bigger in clones UPASI-3 (2.57±0.09) and TRF-1 (2.03±0.09) followed by Yabukita. These clones were categorized as highly susceptible. In CR-6017 (3.00±0.58), TRF-2 (1.67±0.67) and UPASI-6 (1.33±0.33) noticed less number of spore production in the epidermis layer of cell. The canker size was also recorded small in size. The tolerant clones of UPASI-9, UPAS-17, UPASI-26, TRF-4 and TRI-2025 were characterized by the absence of spore formation and below 1.0 cm of canker size. These clones have been identified as tolerant varieties through histopathological studies and can be recommended for planting disease prone areas.
Occurrence of Groundnut bud necrosis virus on potato in North Western hills of India
Groundnut bud necrosis virus (GBNV) is a serious problem in many crops including potato where it causes potato stem necrosis disease. During a field visit in Shimla, potato plants showing clear symptoms of concentric necrotic rings along with necrosis on the stem were observed. The virus was sap inoculated onto cowpea followed by back inoculation on potato plants in insect-proof cages under glasshouse conditions. Characteristic chlorotic spots which later turned into necrotic local lesions were recorded on cowpea and necrotic spots on potato leaves. Samples were processed for RT-PCR based detection, wherein an amplicon of expected size i.e., 560 bp was visible indicating the presence of suspected GBNV in the field collected potato leaf samples and also in sap inoculated cowpea and back inoculated potato plants as well. Insect vector thrips were also examined by print capture RT-PCR based detection and found viruliferous i.e., carrying GBNV. The other host like tomato was also examined for the presence of GBNV and the RT-PCR assay revealed the presence of GBNV in tomato, serving as an important reservoir of inoculum in North western (NW) hills of India. It was also found that the virus under study was present in the majority of the potato growing areas. Hence, the above observations suggest that GBNV started appearing on potato, especially in the NW hills of India despite unfavourable conditions.
BASWARAJ RAIGOND*, PRIYA SHARMA, TARVINDER KOCHHAR, SHIVANI ROACH, AMBIKA VERMA, JEEVALATHA A, GAURAV VERMA, SANJEEV SHARMA and S.K. CHAKRABARTI
Bioactivity of various ethanolic plant extracts against Pectobacterium carotovorum subsp. carotovorum causing soft rot of potato tubers
Bacterial soft rot of potato caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) is the most destructive disease worldwide mainly during storage. The pathogen has a wide host range affecting a number of vegetable species. Use of various chemicals and antibiotics has been reported previously against this disease with variable degrees of success, besides, excessive use of antibiotics and chemicals causes various health hazards and also leads to the development of resistance to various other human pathogenic bacteria. In the present study various ethanolic plant extracts were evaluated against Pcc (syn. Erwinia carotovora subsp. carotovora) in-vitro by both disc and Agar well diffusion method. Among them seed extract of Datura stramonium gave highest inhibition zone of 26mm (agar well method) followed by leaf extract of Urtica dioica with 25.33mm. Other plant extracts with their decreasing order of efficacy were Datura stramonium (leaves), Trigonella foenumgraecum (seeds), Syzygium aromaticum (cloves), Salix alba (leaves), Hibiscus rosa-sinesis (leaves), Eucalyptus sp. (leaves), Azadirachta indica (leaves), Conyza canadensis (leaves), Cupressus torulosa (leaves), Morus alba (leaves), Ficuscarica (leaves), Polygonum hydropiper (leaves) and Juglans regia (leaves). Extracts which were found effective under in-vitro conditions were further evaluated on potato tubers. Among them, seed extract of Datura stramonium showed highest control (18.4% disease severity), when applied 12 hours prior to the inoculation of the pathogen and 20%, when applied simultaneously with the inoculation of the pathogen followed by Urtica dioica (leaves) with severity of 20.8% when applied 12 hours prior and 21.6% when applied simultaneously with the pathogen inoculation up to 6 days of storage as against 84.8% in case of inoculated control.
Pectobacterium carotovorum subsp. carotovorum
K.A. BHAT*, H.S. VISWANATH, N.A. BHAT and T.A. WANI
Enhancing sporulation and determination of virulence of Alternaria solani isolates infecting tomato
In order to study the effect of media, incubation condition and calcium carbonate (CaCO3) amendment on mycelial growth and sporulation in Alternaria solani, 13 different media were examined under different incubation conditions. Out of these, potato dextrose agar, phytone agar and Czapeck’s Dox agar supported maximum mycelial growth at 14 days after incubation at 25±1°C. Incubation condition T2 (One week continuous fluorescent light at 25±1°C followed by one week period dark at 21±1°C) supported sporulation in all isolates of A. solani. Moreover, pearl millet-CaCO3 agar media supported sporulation in all A. solani isolates and found to be the best medium supporting sporulation in A. solani. However, all the CaCO3 supplemented media (HPDA + CaCO3, CaCO3 agar and pearl millet - CaCO3) supported sporulation in A. solani. We further grew a random isolate As-4 under two growth condition viz., (i) subcultured on pearl millet + CaCO3 media and incubated under T2 incubation condition-denoted as isolate As-P and (ii) subcultured on PDA and incubated for 14 days under alternate light and dark condition at 25°C-designated as isolate As-Q. Effect of these growth conditions on virulence of A. solani were evaluated by inoculating both the isolate As-P and As-Q on different tomato germplasm/cultivars under glasshouse condition. Disease severity recorded on tomato germplasm indicated that EC-519795 and Pant bahar were highly susceptible and moderately susceptible to As-P and As-Q respectively. Germplasm Shalimar 2, Palam Pink and Arka Saurabh showed susceptible reaction against As-P while moderately susceptible reaction against As-Q. Disease reaction shown by Roma, Arka Vikas, EC-519770, Palam Pride and Arka Samrat appeared same against both the isolates. Results of glasshouse experiment indicated that A.solani isolate As-P, grown on pearl+CaCO3 under T2 incubation condition appeared more virulence than isolate As-Q, grown on PDA.
Crop-specific growth promoting effect of native Trichoderma species
The present study was conducted to explore the occurrence of crop specificity in the growth promoting effect of rhizosphere and rhizoplane resident Trichoderma spp. The isolates from rhizosphere and rhizoplane of healthy wheat, rice and chickpea plants collected from the diseased fields were evaluated for their growth promoting potential in vitro and in glasshouse. The isolates were tested by inoculation in their native crops and by cross-inoculation in other two crops as well. Results revealed that Trichoderma isolates, namely, TRS-R8 (rice), TRP-W8 (wheat) and TRP-C4 (chickpea), exhibited growth promoting effect in all the crops used in the study but performed significantly better in their native crops, measured as seedling vigour index (SVI) and plant vigour index (PVI) as compared to other isolates, standard check (PBAT-1, i.e. strain Th-14) and control. The SVI and PVI for the above isolates were 4115 and 6204, 3865 and 9919, and 5303 and 5212, respectively as compared to 3342 to 4402 and 4863 to 8770 for the standard check. The finally selected promising isolates (TRS-R8, TRPW8 and TRP-C4) were identified as Trichoderma asperellum (=T. viride) by using BiOLOG microstation system.
Identification of secondary metabolites produced by fluorescent Pseudomonads for controlling fungal pathogens of apple
Antibiosis is often implicated as an important mechanism of biological control and can be used for the suppression of many phytopathogens. Fluorescent Pseudomonas species viz., P. putida, P. fluorescens and P. aeruginosa isolated from apple rhizosphere were tested for their antifungal activity against Dematophora necatrix, Fusarium oxysporum, Phytophthora cactorum and Pythium ultimum. P. putida and P. aeruginosa inhibited the mycelia growth of all the four pathogens in dual culture tests (8.3-19.3 %I) while P. fluorescens inhibited growth of three pathogens viz., D. necatrix, F. oxysporum and P. ultimum (8.5-16.6 %I). In the present study three antifungal metabolites viz., phenazine, pyrrolnitrin and 2,4-diacetylphloroglucinol produced by P. putida, P. fluorescens and P. aeruginosa were isolated from apple rhizosphere using thin layer chromatography (TLC). The Rf value obtained by the ethyl acetate extracted metabolite of all the three Pseudomonas species ranged from 0.6 to 0.82 which is in accordance to the spot showed by standards. These extracted compounds were re-tested for antifungal activity against P. ultimum which showed inhibition in the range of 15.7 to 28.9 %. The results indicated that fluorescent Pseudomonas species used in this study produced a combination of diverse antifungal compounds and provided resistance against a broad spectrum of pathogens.
PARUL SHARMA*, PANKAJ PRAKASH VERMA and MOHINDER KAUR
Identification of resistance sources against post flowering stalk rot in maize
Post-flowering stalk rot (PFSR) complex caused by Fusarium verticillioides (Sacc.) and Macrophomina phaseolina (Tassi) Goid, is among the important constraints that limits the productivity of maize (Zea mays L.). The absence of high levels of stable resistant sources to the pathogens has necessitated the continued search and identification of new sources of resistance. The principal goal of this work was once to identify new sources of resistance to PFSR and validate their stability across multi-environments by multi-year testing. A set of 80 elite inbred lines screened in the field against PFSR for three consecutive years at four hotspots in India (Hyderabad, Ludhiana, New Delhi and Udaipur) under artificially created disease epiphytotics. The scores on the scale of 1 to 9 based on the disease reaction were recorded by splitting the stems of each plant. Significant (p=<0.05) interactions of genotype, location and genotype x locations interaction were observed for PFSR resistance. Out of 80 elite inbreds, only 12 inbreds (PFSR/51016-1, CM144, HKI 193-1, PFSR-R2, PFSR-R9, JCY2-1-2-1-1B-1-2-3-1-1, CM117-3-4-1-2-5-2, 42048-2-2-1-1-1-2, JCY3-7-1-2-2-1-3-1-1-2-7-1-1-1, JCY2-7-1-2-1-B-1-2-1-1, LM13 and CM117-3-4-1-2-2-3) had mean disease incidence ≤ 3.0 on the 1-9 scale and the reactions were consistent across the environments. Thus, the identified 12 stable disease resistance sources could be used for developing promising maize hybrids with inbuilt resistance to PFSR disease for different maize agroecologies in India.
K.S. HOODA, M.K. KHOKHAR*, J.C. SEKHAR, P.K. BAGARIA, S.S. SHARMA, HARLEEN KAUR, R. GOGOI and R. RANGA REDDY
Morphological and molecular variability of Podosphaera pannosa causing rose powdery mildew in Himachal Pradesh, India
Rose powdery mildew caused by Podosphaera pannosa (Wallr.) de Bary is one of the most serious and devastating diseases of roses grown worldwide including Himachal Pradesh in natural as well as protected cultivation. Different isolates of six districts were morphologically distinguished from one another with respect of size of mycelium, conidia and conidiophores which ranged between 4.0 to 4.8, 22.8 × 12.4 and 72.0 to 78.0 μm, respectively. Molecular characterization of ten isolated from six districts were studied with seven RAPD markers. The dendrogram revealed similarity index among ten fungal isolates ranged between 19 to 73 per cent with an average of 46 per cent. Maximum similarity of 73 per cent was observed between isolate-5 and isolates-8 of district Mandi Himachal Pradesh. Least similar was isolate-7 which had 19 per cent similarity with other isolates.
Influence of weather parameters, nitrogen and potassium levels on foliar blight severity of barley under three different sowing dates
A field experiment was conducted to assess influence of ten weather parameters (maximum temperature, minimum temperature, maximum relative humidity, minimum relative humidity, wind velocity, bright sunshine hour, evaporation, total rainfall, soil temperature and vapour pressure) and three different levels of N (40,60,80 kg ha-1) and K (20, 40,60 kg ha-1) on the foliar blight severity of barley under three different dates of sowing (early: 30th Oct., timely: 15th Nov. and late: 15th Dec.). The experiment was conducted in Gangetic alluvial soil of West Bengal during rabi season at Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia in three consecutive years (2010-11, 2011-12 and 2012-13). Results showed minimum disease severity in high N and K combinations (N80 K60) irrespective of other treatment combinations in all the three dates of sowing. Whereas, late sown crop shows maximum disease severity irrespective of different N and K combinations. Timely and early sown crop recorded minimum foliar blight severity and maximum grain yield under maximum N and K combinations. Among the ten meteorological factors, maximum temperature, minimum temperature, minimum relative humidity, wind velocity, bright sunshine hour, evaporation were the influential to express disease severity under three different dates of sowing in different N and K combinations. Growth functions of disease severity were developed and based on correlation co-efficient (r) value and among the two growth functions (Logistic and Gompertz) Gompertz was found to be fit better for linearising the disease severity in comparison to Logistic growth model.
SUNITA MAHAPATRA*, NITAI MUDI and SRIKANTA DAS
Virulence and genetic diversity of Puccinia striiformis f. sp. tritici isolates in Punjab, India
Virulence diversity was determined among 16 isolates of Puccinia striiformis f. sp. tritici was analyzed by inoculating isolates collected from diverse areas of Punjab on differential lines carrying known resistance genes. Pathotypes 78S84, 46S119 and 110S119 obtained from IIWBR, Regional Station, Flowerdale, Shimla were also included as check. All the Pst isolates were virulent on lines carrying genes Yr2, Yr3, Yr4, Yr6, Yr7, Yr8, Yr9 and were avirulent on genes Yr1, Yr5 and Yr10. Variation for virulence was recorded among isolates on lines having genes YrSD, YrSU and Yr9+. Genetic diversity of the isolates was studied using EST-derived SSR markers. Cluster analysis based on UPGMA algorithm and principal coordinate analysis (PCoA) classified these 19 isolates into three separate clusters which indicated genetic diversity among the isolates from Punjab.
HARMANDEEP KAUR, JASPAL KAUR*, RITU BALA ACHLA SHARMA, P.P.S. PANNU, PRAVEEN CHHUNEJA and N.S. BAINS
Implication of fungicide application regimes and post spray irrigation on late leaf spot and its residual impact on stem rot of groundnut
A field experiment was conducted during rabi season of 2015-16 and 2016-17 to study the efficacy of different protectant and systemic fungicides in different application regimes on late leaf spot disease of groundnut and to assess the impact of post spray irrigation timing on the severity of late leaf spot and as well as management of stem rot disease through deposition of foliar applied fungicides. Three sprays of chlorothalonil @ 2g/l (1th, 3rd, 5th) alternated with three sprays of pyraclostrobin @ 1g/l at 2nd, 4th and 6th spray (T8) reduced the highest disease severity (40.74%) as compared to seven spraying of chlorothalonil (T2) at 10 days interval (60.00%). The AUDPC values were significantly different among various treatments. Highest yield (28.89 q/ha) was also recorded in T8. The number of late leaf spot lesion decreased with the increase in gap between spraying and irrigation time. Irrigation after 96 h of fungicide spray caused only 2.02 leaf spot lesion per leaflet and highest pod colonization of 43.63% due to stem rot. Negative correlation was found between pod colonization and number of leaf spot lesion.
Detection of Xanthomonas campestris pv. campestris in imported germplasm of cabbage during post entry quarantine
Black rot is a devastating bacterial disease causing considerable yield losses in cabbage. Xanthomonas campestris pv. campestris (Xcc) is a regulated non-quarantine pest for India and detection of Xcc in imported germplasm is very important to prevent the introduction and spread of pathogen in the country. A total of 175 germplasm accessions of cabbage were imported by Syngenta India Pvt. Ltd. from China and grown in post entry quarantine (PEQ) growing area of Syngenta Farm, Karnal. During PEQ inspection of crop, 35 accessions showed typical black rot symptoms. Out of 35 accessions, eight representative accessions were used and found to be positive for Xcc based on mophological, cultural and biochemical assay. Xcc specific primers gave a specific band of 769 base pairs, which confirmed the presence of Xcc in the infected samples. 16S rRNA sequencing of one isolate (XccP1) was used to further confirm the presence of the pathogen. 16S rRNA sequence showed 100% sequence similarity with Xcc strains already deposited in NCBI database. Black rot infected germplasm accessions grown in PEQ area were up-rooted and incinerated to prevent further spread of disease.
PARDEEP KUMAR*, RAJ KIRAN, A. KANDAN, JAMEEL AKHTAR, BALESHWAR SINGH, KRISHNA NAIR and S.C. DUBEY
Integrated crop disease management in southern Rajasthan: ecofriendly practices in tune with biocontrol
The goal of integrated disease management is to reduce the economic and aesthetic damage caused by plant diseases. With the increasing environmental awareness, the focus has been shifted towards the search for viable alternatives of disease control methods. The various disease management practices like soil treatment with antagonistic fungus, organic manure, cakes; seed treatment with fungicides, Trichoderma spp., antagonistic bacteria like Bacillus subtilis, B. amyloliquefaciens and P. fluorescens, plant extracts; delivery methods like seed treatments, seedling root dip and spray of antagonistic bacteria and microclimatic manipulation to prevent disease causing spores, etc. were experimentally practiced. In case of tomato crop affected by early blight caused by Alternaria solani, Tomato-marigold intercropping-plastic mulching treatment (T+M+P) showed significant reduction in disease intensity by 35.4-38.9% as compared to tomato crop alone. Management practice for rhizome rot in ginger, caused by Pythium aphanidermatum, Fusarium spp and Rhizoctonia solani complex was studied and farmers were advised to do hot water treatment (50°C for 30 min) + seed treatment with Trichoderma viride + soil application with neem cake followed by drenching with suspension of neem oil or ridomil MZ. The role of weather parameters on incidence of parawilt and its management was assessed. In another study, we assessed the synergism in consortia application of Trichoderma harzianum and Pseudomonas fluorescens against rice blast and bacterial leaf blight of rice. Garlic extract (10%) against leaf spot diseases in groundnut was found very effective and at the same time stem and root rot complex in groundnut and wet root rot were also managed by application of T. harzianum Th3. The success of these ecofriendly measures essentially emphasised our research needs to reassess the ecofriendly system of plant disease management.
Genetic variability of multifunctional HC-Pro gene of Lettuce mosaic virus in northern region of India
Lettuce mosaic virus (LMV) is an economically important pathogen causing mosaic disease in lettuce like it causes in spinach (Spinacia oleracea). Isolates of LMV originating from different geographical regions in northern India were collected during the survey of 2013-2014. Lettuce mosaic virus (LMV) belongs to Potyviridae family (genus Potyvirus) and is mainly transmitted by aphids. This study covered the genetic variability of Helper component proteinase (HC-Pro) gene of LMV isolates. HC-Pro is multifunctional activity gene, which helps in transmission of virus. The amplified PCR products of ~1.3 kilo basepairs (kb) were obtained from five different isolates, sequenced and deposited in NCBI GenBank. Two isolates R4 and HR1 from Rajasthan (KJ558375, KM501033), isolate R5 from Haryana (KP635365), isolate R6 from Uttar Pradesh (KP635366) and isolate R4 from Delhi (KP635367)]. The phylogenetic analysis of LMV HC-Pro sequences is showed divergence with other isolates. These isolates showed two different clusters vis-a-vis diversity amongst each other.
RITESH MISHRA, RAKESH KUMAR VERMA and RAJARSHI KUMAR GAUR*
Copyright (c) 2017 Indian Phytopathology
Effect of β-amino butyric acid in induction of resistance against Xanthomonas campestris pv. campestris in cabbage
A defense activator chemical, β-aminobutyric acid (BABA) is capable of inducing local as well as systemic resistance against numerous plant pathogens. An experiment was conducted to evaluate induction of defense related enzyme peroxidase (POX) by BABA for imparting systemic resistance against Xanthomonas campestris pv. campestris (Xcc) inciting black rot disease of cabbage. Effect of BABA (1000 µg/ml) on the induction of POX activity in the leaves of cabbage resistant cv. Pusa Mukta and susceptible cv. Golden Acre in response to BABA and X. campestris pv.campestris revealed that the POX was found increasing in BABA + Xcc treated plants and reached maximum level at 5 days after inoculation, in comparision with BABA or Xcc treated alone. The bacterial population of X. campestris pv. campestris was also reduced significantly in both the cultivars of cabbage treated with BABA (1000 µg/ml) as compared to control (water) treated plants. The level POX activity was observed to be low in both uninoculated and inoculated susceptible cv. Golden Acre as compared to resistant seedlings during time course. Thus explaining the importance of POX activity in reducing population level of X. campestris pv. campestris, whose activity was enhanced with the application of BABA.
Screening of blackgram genotypes for molecular variability in reaction to Mungbean yellow mosaic disease
Sixteen blackgram genotypes were tested for yellow mosaic disease under field conditions and identified nine genotypes as resistant, one as moderately resistant, four as susceptible and two as highly susceptible. No genotypes were found to be immune or highly resistant against yellow mosaic disease. Polymerase Chain reaction (PCR) of DNAs from sixteen genotypes using Sequence Characterized Amplified Region (SCAR) markers namely, SCAR 20F/20R resulted in specific amplification in nine genotypes indicating resistant nature of these genotypes. There was no amplification in six genotypes while faint amplification could be observed in the genotype LBG-752 that recorded 14.47% incidence of the disease along with moderately phenotypic reaction.
H. CHANDRAJINI DEVI*, V. PRASANNA KUMARI PH. SOBITA DEVI and BIRESWAR SINHA
Use of NCM based DNA extraction method for simultaneous detection of citrus mosaic badnavirus and Candidatus Liberibacter asiaticus by duplex PCR
Candidatus Liberibactor asiaticus (Ca. Las), a phloem limited, gram negative bacterium is the causal organism of citrus greening disease (Huanglongbing/HLB) whereas citrus yellow mosaic disease is caused by Citrus mosaic badnavirus (CMBV). Both the diseases, singly or as mixed infection in the grove are considered as serious threat to Indian citrus industry. Early diagnosis for these systemic pathogens are essential in order to prevent the spread of these diseases and finally to devise their integrated management strategies. In the present study, a method of simultaneous detection of CMBV and ‘Ca. Las’ was developed using a simple nitrocellulose membrane (NCM) based DNA isolation protocol in three commercially grown citrus cultivars in India, viz. mandarin (Citrus reticulata), sweet orange (Citrus sinensis), and acid lime (Citrus aurantifolia) infected with these pathogens. Citrus tissues were crushed in extraction buffer containing NaOH and EDTA. The crude extract was spotted on NCM and incubation elution was done in nuclease-free water after 30 minute of NCM spotting. Eluted products were taken for simultaneous detection of CMBV and ‘Ca. Las’ using duplex PCR with newly designed primers. The developed protocol was found to be equally sensitive as multistep DNA isolation method and commercially available kit. The protocol is simple, rapid and inexpensive thus can be used for large-scale pathogen indexing of citrus plant samples in orchards and nurseries.
MANALI MOTGHARE, PRADEEP KUMAR SHUKLA, P.W. RAMTEKE and DILIP GHOSH*
Woody veins: A disease of Peepal (Ficus religiosa)?
Ficus religiosa or Peepal is a sacred tree native to Nepal, India, Bangladesh, Myanmar, Pakistan, Sri Lanka, south-west China and Indochina. It is also known as the bodhi tree, pippala tree, peepal tree or ashwattha tree (in India and Nepal). Ficus religiosa is a large dry season-deciduous or semi-evergreen tree up to 30 meters (98 ft) tall and with a trunk diameter of up to 3 meters (9.8 ft). As an interesting fact, the leaves of this tree move continuously even when the air around is still and no wind is blowing. This phenomenon can be explained due to the long leaf stalk and the broad leaf structure. However, religious minded people in Hindu/Buddhist religion attribute this movement of the leaves to the fact that “devasâ€ or “godsâ€ reside on these leaves and make it move continuously. This fact is also mentioned in the Bhagavad Gita as a verse “O Ashvatha, I honour you whose leaves are always movingâ€ Ficus religiosa is used in traditional medicine for about 50 types of disorders including asthma, diabetes, diarrhea, epilepsy, gastric problems and inflammatory disorders. Several peepal trees in Dwarka, New Delhi have been observed with woody vein of leaves (Fig. 1). Up to 60% of leaves of infected trees showed woody vein. Such leaves also showed mosaic mottling. Some leaves showed vein woodyness only one or two veins while other showed all the veins with woody symptoms. I am reporting this disorder as it appears concern to our religious tree with the hope that working scientists will investigate the etiology of this disease.