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Cashew (Anacardium occidentale) is an important commercial crop and highly prone to many biotic and abiotic stress. During March 2021, severe leaf blight symptoms were observed in Priyanka variety with 25-30% incidence grown under greenhouse nursery at ICAR–Directorate of Cashew Research (ICAR-DCR), Puttur (12º74ʹ08.92ʺN; 75º22ʹ97.22ʺE), Karnataka. Initial symptoms include small, irregular necrotic spots and later, the spots enlarged and covered major portion of the leaf lamina. In severe infection, leaves exhibited coalescing of spots leading to blight appearance. The infected leaves were randomly collected (n=5) and surface sterilized with 1% sodium hypochlorite for 1 min followed by three washes in sterile distilled water (SDW). Samples were plated on PDA plates amended with Rifampicin (40 mg/L) and kept for incubation at 25±2 oC for 5 days (12/12 h dark light period). A white-greyish, aerial, cottony mycelium on upper side with light yellow colour on the reverse side was consistently isolated. The black viscous acervuli were observed after 10-12 days of incubation. The conidia were fusiform, five-celled, versicoloured with three olivaceous brown median cells, two terminal hyaline cells, measured 23.3±2.12 – 28.33±2.7 x 3.6±0.8 – 4.28±0.78 µm (n=30). The apical cells had two to three flexuous, unbranched appendages, and basal appendage was solitary, tubular and unbranched. Morphological and cultural characteristics confirmed the pathogen as Neopestalotiopsis sp. (Maharachchikumbura et al. 2012). Further, two representative isolates (CLB_SCN1 & CLB_SCN2) were subjected for molecular characterization selected for molecular identification based on ITS-rDNA, tef-1α and tub2 gene sequences and phylogenetic analysis. Genomic DNA was isolated from 15 days old cultures and internal transcribed spacer (ITS) of ribosomal DNA (rDNA) (White et al. 1990), translation elongation factor 1α (tef-1α) gene (O’Donnell et al. 1998) and beta tubulin (tub2) using ITS1/ITS4, TEF1/TEF2 and Bt2a/Bt2b (Carbone and Kohn 1999; Glass and Donaldson 1995) were amplified using primer pairs respectively. PCR amplicons were sequenced, and the sequences were deposited in GenBank (accession numbers: ITS: OP880881.1, OP880882.1; tef-1α: OP882579.1, OP882580.1; and tub2: OP882581., OP882582.1). The phylogeny was constructed based on combined ITS, tef-1a, and tub2 regions. Neighbour-Joining (NJ) analysis was conducted and the tree was constructed with the substitution models (branch support was evaluated by 1,000 bootstrap replications). Combined phylogeny confirmed that the sequences shared a common clade with N. clavispora. Hence, morphological, microscopic and molecular characterization confirmed the pathogen as N. clavispora. The pathogenicity test was done on six months old healthy grafts of Priyanka variety (n=9) and repeated thrice. Conidial suspension (2×106 spores/ml) of N. clavispora CLB_SCN1 (15 days old culture) was sprayed on the healthy cashew seedlings, and kept in greenhouse by covering with polythene bags for 24 h (>80 % RH) and maintained under greenhouse condition. The control grafts were inoculated with SDW. The inoculated plants showed blight symptoms after 7-10-day post inoculation and control remained heathy. Re-isolation was done from the symptomatic leaves and identity was confirmed using cultural and molecular studies. Earlier reports showed that, N. clavispora has been reported to cause cardamom leaf blight (Biju et al 2018) and leaf spot disease of plum (Banerjee and Rana 2020). To best of our knowledge, this is the first report of cashew leaf blight disease caused by N. clavispora from India (Farr and Rossman, 2022). Early detection will help farmer in better management and avoiding economic loss caused by N. clavispora.

Coscinium fenestratum is a medicinally significant critically endangered plant found in Western Ghats of India. The leaf spot and blight was observed in Kerala during 2021 with disease incidence of 40% in 20 assessed plants in 0.6 hectare. The associated fungus was isolated on potato dextrose agar medium. A total of six morpho-culturally identical isolates were isolated and morphologically identified. Based on morpho-cultural features, the fungus was identified at genus level as Lasiodiplodia sp., which was further authentically confirmed as Lasiodiplodia theobromae by molecular identification with a representative isolate (KFRIMCC 089) using multigene (ITS, LSU, SSU, TEF1-α, and TUB2) sequence analysis and concatenated phylogenetic analysis (ITS-TEF1-α-TUB2). Pathogenicity tests were also assessed in vitro and in vivo using mycelial disc and spore suspension of L. theobromae, and the isolated fungus’s pathogenic behaviour was confirmed after re-isolation and morpho-cultural features. Literature survey reveals that there are no reports of L. theobromae on C. fenestratum from all over the world. Hence, C. fenestratum is being firstly reported as a new host record for L. theobromae from India.

Crossandra (Crossandra infundubuliformis (L.) Nees.) is one of the main floriculture crops in Karnataka. In 2020 (March-June), a characteristic leaf spot disease of unknown etiology with an incidence ranging from 10–12% (~30 ha area evaluated) was observed in Southern Karnataka (Mysore, Mandya). Initially, the symptoms developed as small specks (3 to 8 mm), characterized by circular to irregular shapes in the beginning and coalesced to form larger lesions. Ten samples were collected in polybags followed by the isolation of associated fungal pathogen on potato dextrose agar (PDA) medium amended with Chloramphenicol (60 mg/L). Briefly, small pieces of infected leaves were cut into small pieces and surface sterilized with 2% sodium hypochlorite (NaOCl) solution, rinsed three times with sterile distilled water (SDW), blot dried, then inoculated onto PDA medium, and incubated at room temperature (27 ± 2°C) for 3 – 5 days. Fungal colonies developed from the segments and were subcultured through hyphal tipping to fresh PDA plates to get pure cultures. A total of 12 pure cultures were obtained. Mycelia were initially white and eventually turned gray. The conidia were black, single-celled, smooth, spherical to subspherical, 9 to 18 μm in diameter (n=50), and borne singly on a hyaline vesicle at the tip of each conidiophore. The identity was initially established based on the cultural features and conidial morphology as Nigrospora sp. (Deepika et al., 2021). To confirm the identity of fungal isolates based on molecular sequence analysis was performed for two representative isolates (CIT1 & CIT2). ITS-rDNA, tub2 & EF-1α gene were amplified using primers ITS1/ITS4, T1/T22 & EF1-728F/986R (White et al., 1990; O’Donnel and Cigelnik, 1997; Carbone and Kohn, 1999), then purified and sequenced. The BLASTn analysis of ITS, tub2 and EF-1α gene showed 99-100% similarity with reference sequences from the GenBank database to Nigrospora sphaerica (ITS: 520bp, KX985935 – LC7312; MH854878 – CBS:166.26; tub2: 357bp, MZ032030 - WYR007, 350bp, KY019606 – LC7298, KY019522 – LC4278, KY019520 – LC4274; EF-1α: 472bp, KY019397 – LC7294, KY019331 – LC4241; MN864137 - HN-BH-3) and the sequences were deposited in GenBank (ITS: OL672271 & OL672272; tub2: OL782120 & OL782121; EF-1α: ON051604 & ON051605) (Wang et al., 2017). The associated fungal pathogen was identified as N. sphaerica (Sacc.) Mason (Chen et al. 2018; Deepika et al., 2021) based on the cultural, morphological, microscopic, and molecular characteristics. Further, pathogenicity tests were conducted on healthy plants (Crossandra cv. Arka; n=30) grown under greenhouse conditions (28±2 °C; 80% RH). Inoculations were made with conidial suspension (18 days old N. sphaerica isolate CIT1, 106 conidia/ml) prepared in SDW, and healthy plants sprayed with SDW (n=10) served as controls. All the plants were covered with polyethylene bags for 24–48 hr and observations were made at regular intervals. Typical necrotic lesions developed on 16 plants after 12 days after inoculation but no symptoms were observed on the control plants. The associated pathogen was re-isolated from diseased leaves and confirmed their identity based on morphology and cultural characteristics. Earlier, N. sphaerica was associated with various tree species as an endophyte, and recently several reports have appeared to cause disease on various crop plants (Deepika et al., 2021). However, there are no previous reports on the association of N. sphaerica causing leaf spot disease on C. infundibuliformis from India. Early diagnosis of this leaf spot disease will help the floriculturist adopt suitable management practices to avoid significant economic loss.

Chrysanthemum morifolium L. is an important flower crop grown in different parts of Karnataka for its striking cut flowers and international market value. During a field survey (Mysore district, Karnataka, February, 2022), chrysanthemum fields were found infected with foot rot disease. The presence of white mycelial structures with sclerotia were recorded near the stem-soil interface. The disease incidence ranged 10-12% measured in an area of approximately 10 hectares. The infected plants showed quick wilt, yellowing and toppling of the entire plant. Infected plants from Doddamaragowdanahally and Rayanahally (n=15) were collected and associated fungal pathogen isolated after surface sterilization with NaOCl (1%) on potato dextrose agar (PDA) amended with chloramphenicol (50 mg/L). Fungal mycelia developed from the infected tissues were inoculated on to fresh PDA plates to obtained pure cultures for further identification. Fungal colonies with dense, aerial whitish-cottony mycelia with uniformly globoid sclerotia (0.284.2 mm) were observed after 15 days of incubation (28 ± 2°C). Sclerotia were white in the beginning and turned brown at maturity. The average number of sclerotia produced per plate ranged from 240 to >480 (n = 10). To further to confirm the identity of the isolates, two representative isolates (CmSr1 and CmSr2) was subjected to molecular identification based on ITS-rDNA sequences. Briefly, genomic DNA was isolated from 12 day old cultures using the CTAB method and ITS-rDNA was amplified using ITS1-ITS4 primers (White et al., 1990). An expected amplicon of >650 bp (ITS) was obtained and later sequenced from both the directions. The consensus sequences were analysed through nBLAST search which revealed that 100% sequence similarity with reference sequences of Athelia rolfsii (S. rolfsii) from GenBank database (MT127465, MN974137, KC292637; identity 656/656; 0 gaps). A phylogenetic tree obtained by the neighbor-joining method using MEGAX shared a common clade with the reference sequences retrieved and computed, thus confirming the identification based on sequence analysis and molecular phylogeny. The representative sequence of A. rolfsii isolates CmSr1 and CmSr2 isolates deposited in GenBank with Accession nos. ON456153 and ON456154, respectively. Based on etiology, morphological, cultural and molecular data the pathogen was identified as Athelia rolfsii (Curzi) Tu & Kimbrough (Syn: Sclerotium rolfsii Sacc.) (Mordue, 1974; Mahadevakumar et al., 2016, 2018). Plants (n=60) were inoculated with sclerotial bodies (2 sclerotia/plant) near stem soil interface under green house and covered with polythene bags (at 27 ± 2°C and 80% RH). Non-inoculated plants (n=20) served as controls. The development of foot rot disease was observed eight days after inoculation. A total of 48 plants showed the foot rot symptoms and 12 inoculated plants and control plants remained healthy. The identity of the fungus was confirmed by morphological and cultural characters after re-isolation. C. morifolium is an important flower crop in Karnataka. S. rolfsii is known to be associated with blight and collar rot of Chrysanthemum spp. from Kerala (Beena et al., 2002) but no species (host) identity provided. Therefore, to the best of our knowledge, this is the first report of foot rot disease caused by Athelia rolfsii on C. morifolium in India. Early diagnosis of this disease will help the farmers to adopt suitable management practices to avoid loss.

Grape (Vitis vinefera L.) is a popular horticulture crop in Karnataka, India. A fungal pathogen caused panicle blight on panicles with immature fruit and severity increased subsequently in the grape growing regions of Devanahalli and Doddaballapur, Karnataka, between August and September 2019. The disease incidence varied from 15 to 18 percent in around 45 hectares of grape vineyards surveyed. The associated fungal pathogen was isolated on Potato Dextrose Agar (PDA) medium (HiMedia Laboratory, Mumbai, India) amended with Chloramphenicol. A total of 12 fungal isolates were obtained and identified based on morphology. Fungal cultures obtained from all the panicle blight affected samples were fluffy grayish to black with profuse, dense mycelium. Microscopic examinations revealed that the conidia ellipsoidal, two celled and hyaline when young, and developed dark brown pigments at maturity. Mature conidia measured 18.24±2.35 to 26.62±3.11 μm long and 10.32±1.08 to 12.57±1.82 μm width (n=30). The fungal pathogen was identified as a Lasiodiplodia sp. based on colony morphology and microscopic features. A total of three representative isolates L. theobromae (Vv12, Vv15, and Vv19) were selected for molecular identification based on ITS-rDNA, tub2 and EF-1α gene sequences and phylogenetic analysis. Genomic DNA was isolated from 12 day old cultures and ITS-rDNA, tub2 and EF-1α genes were amplified using ITS1/ITS4; Bt2a/Bt2b and EF1-728F/986R primer pairs, respectively (White et al., 1990; Glass and Donaldson, 1995, Carbone and Kohn, 1999). PCR amplicons were sequenced and the sequences were deposited in GenBank with the accession number ITS: MZ855866.1; MZ855867.1; MZ855868.1; tub2: MZ868708.1; MZ868709.1; MZ868710.1 and EF-1α: OM604750; OM604751; OM604752 respectively. The phylogeny was constructed based on combined ITS, EF-1α and the tub2 regions. Maximum Likelihood (ML) analysis was conducted and an ML tree was constructed with the substitution models (branch support was evaluated by 1,000 bootstrap replications). Combined phylogeny confirmed that the sequences shared a common clade with L. theobromae. Based on micro-morphological features and multi-locus sequence phylogeny, the associated fungal pathogen was identified as L. theobromae. There are no reports on the occurrence of L. theobromae causing panicle blight on grapes from India. Further, the pathogens association was confirmed through pathogenicity assay conducted on field harvested healthy bunches of grapes maintained under humid chamber. A total of 10 grape bunches were inoculated with a mycelial disc on the rachis of the panicle and incubated in a moist chamber for 5 days and control sets were inoculated with only agar plugs. The experiments were conducted in three replicates and repeated twice. A total of 21 panicle bunches developed typical rot symptoms 12-days post inoculation. The identity of the pathogen was confirmed based on micromorphology and cultural features after re-isolation (n=5), thus proving the Koch postulates and confirming the association of L. theobromae with panicle blight of grapes. Lasiodiplodia species are known to cause dieback, stem blight, leaf blights and spots on various crop plants. Mathur (1979) mentioned the occurrence of L. theobromae on grapes, however, no further details are available on the part associated, as well as morphological and molecular confirmation of L. theobromae. This is the first report of the L. theobromae causing panicle blight disease of grapes in India. Further, understanding the host range for L. theobromae and its variation will help to draw suitable disease management strategies.

Cluster bean (Cyamopsis tetragonoloba (L.) Taub.) is an important vegetable crop cultivated widely in India. During a field survey in November 2021, about 60% of plants exhibited characteristic powdery mildew disease symptoms and signs in a 15 ha field in Northern Karnataka (Raichur), India. Initially, the symptoms and signs appeared as tan lesions, which later became small, circular and chlorotic. The abaxial surface turned yellow and was covered with white mycelial growth. As the disease progressed, white mycelia grew on the adaxial leaf surface, stems and pods as well. In severe infections, drying and premature defoliation of infected leaves were observed. Infected leaf samples with mycelia were collected (n=8) and the fungus was subjected to morphological and molecular observations. Mycelia on leaves was characterized as epiphytic, amphigenous, producing dense, white patches on the upper and lower leaf surfaces, stem and young pods. Hyphae were hyaline, thin-walled, 1.8 to 4.2 µm wide with erect conidiophores consisting of a cylindrical foot-cell, straight flexuous at the base and measured 20 to 36 × 6 to 9 μm (n=30), followed by 1 to 2 shorter cells. Ellipsoid conidia were produced singly and measured 28 to 42 × 12 to 20 μm (n=30) without fibrosin bodies. Chasmothecia were not observed. A reference specimen was deposited at the Institution of Excellence, University of Mysore Herbarium (UOM-IOE 2022_1). The morphology and other characteristics of conidia were consistent with an Erysiphe species (Braun and Cook 2012). Genomic DNA was isolated from a conidial suspension harvested from the powdery mildew affected cluster bean samples. The ITS region was amplified from three samples using powdery mildew-specific primer pair PN23/PN34 and sequenced directly (Chen et al. 2008). nBLAST analysis revealed that the ITS sequence shared 100% similarity with the reference sequence (E. diffusa vouchers HMJAU02177 - KM260363, BRIP 71013 - MW009058) of Erysiphe diffusa (CookePeck) U. BraunS. Takam. In addition to 100% match to voucher specimens of E. diffusa, there were no vouchers from other species that also had 100% match. The representative sequences were deposited in GenBank with accession numbers OM669776 - OM669778. Koch's postulates were conducted on healthy cluster bean plants grown under greenhouse conditions. Conidia were harvested from infected leaves, suspended in water and sprayed on 40 to 50-day-old cluster bean plants (28 ± 2°C and70% relative humidity). The development of powdery mildew symptoms was recorded on 22 plants after 10-14 days of post inoculation. Control plants inoculated with sterile water remained healthy without powdery mildew symptoms. Microscopic observation of spores from inoculated plants confirmed the pathogen as E. diffusa. The genus Erysiphe is known to infect many crop plants. E. diffusa has been reported to infect Vigna radiata, Glycine max and Phaseolus mungo in Australia (Kelly et al. 2021). No reports are available at USDA's host-fungus database for cluster bean and E. diffusa (Farr and Rossman 2022). To the best of our knowledge, this is the first report of E. diffusa associated with powdery mildew of cluster bean in India. Further comprehensive investigations will shed a light on the economic impact of powdery mildew disease on the cluster bean in India.

Cowpea is an important pulse crop cultivated in arid and semi-arid regions of the world. During field survey, a characteristic wilt was observed in around 45 ha of cowpea fields with incidence 17-25%. Infection was seen in pre-flowering stage and infected plants showed quick wilt symptoms with tan lesions near the stem-soil interface. Fungal pathogens associated were isolated on PDA, which produced dark to grey olivaceous colonies in the centre, and aerial mycelia were appressed with floccose and white to smoke-grey. Conidia are aseptate, initially hyaline, smooth-walled, broadly ellipsoidal with rounded ends becoming dark brown. Based on these morphological features, the fungal pathogen was identified as Aplosporella sp. The ITS-rDNA region was amplified using ITS1/ITS4 primers and sequenced. The nBLAST and phylogenetic analysis confirmed the pathogen as Aplosporella hesperidica. The Koch's postulates were performed on 45-days-old cowpea plants with mycelial disc of A. hesperidica. Development of typical necrotic lesions was observed after 28 days of post-inoculation and the pathogen's identity was confirmed based on re-isolation. Efficacy of fungicides evaluated in vitro showed that the pathogen is highly sensitive to systemic fungicides rather than the contact fungicides. The cowpea production was severely affected owing to the causative agent A. hesperidica. The collar rot disease of cowpea by A. hesperidica is the first report in India. SIGNIFICANCE AND IMPACT OF THE STUDY: A new collar rot disease of cowpea recorded from India has been investigated. The necrotic lesions were enlarged and eventually quick wilt and death of the host plant was observed with incidence ranged from 17 to 25%. Associated fungal pathogen was isolated and identified as Aplosporella hesperidica based on morphology and ITS-rDNA sequence analysis. Koch's postulates were performed under greenhouse conditions and in vitro evaluation of fungicides shows that the pathogen is sensitive to systemic fungicides. This is the first report of A. hesperidica causing collar rot disease of cowpea in India.

Salvia hispanica L. (Lamiaceae) commonly called 'chia' is an important food crop that has gained significance in recent times globally due to its nutritive value. During a field survey (Mysore district, Karnataka, October, 2021), chia fields were found associated with a characteristic foot rot disease. Further, the presence of mycelial structures along with sclerotial bodies was recorded near the stem-soil interface on the infected plants. The disease incidence ranged 15-21% in an area of approximately 15 hectares of chia fields. The symptoms initially appeared as tan lesions near the stem soil interface and the lesions were colonized by the fast growing mycelium. As the disease progressed, the plants toppled due to death of the stem-root interface region. Infected plants from KM Halli (12º20'90"N; 76º37'68"E) and DMG Halli (12º28'50"N; 76º51'66"E) (n=30) were sampled and associated fungal pathogen isolated on potato dextrose agar (PDA; HiMedia Lab, Mumbai). Fungal mycelia developing from the infected tissues were inoculated on to fresh PDA plates to obtained pure cultures for further identification. Fungal colonies with dense, aerial whitish-cottony mycelia with uniformly globoid sclerotia (0.52.9 mm) were observed after 1012 days of incubation at room temperature. Sclerotia were white at first and turned brown with age. The average number of sclerotia produced per plate ranged from 150 to280 (n = 10). To further to confirm the identity of the isolates, three representative isolates (SrSh1, SrSh5 and SrSh10) was subjected to molecular identification based on ITS-rDNA sequences. Briefly, genomic DNA was isolated from 12 day old cultures using the CTAB method and ITS-rDNA was amplified using ITS1-ITS4 primers (White et al., 1990). An expected amplicon of650 bp was obtained and later sequenced from both the directions. The consensus sequences were analysed through nBLAST search which revealed that 100% (643/643 bp) sequence similarity with reference sequences of Athelia rolfsii (S. rolfsii) from GenBank database (KY640622 and AB075298). A phylogenetic tree obtained by the neighbor-joining method using MEGAX shared a common clade with the reference sequences retrieved and computed, thus confirming the identification based on sequence analysis and molecular phylogeny. The representative sequence of A. rolfsii isolates SrSh1, SrSh4 and SrSh7 isolates deposited in GenBank with Accession no OM021878-OM021880. Based on etiology, morphological, cultural and molecular data the pathogen was identified as Athelia rolfsii (Curzi) TuKimbrough (Syn: Sclerotium rolfsii Sacc.) (Mordue, 1974; Mahadevakumar et al., 2016, 2018). Pathogenicity tests were conducted by inoculating the sclerotial bodies near stem soil interface of chia plants grown under green house (at 28 ± 2°C and 70% relative humidity). Briefly, a total of 60 healthy plants were inoculated with sclerotia and covered with polythene bags for 2 days and removed later. Plants (n=20) inoculated without any sclerotia were treated as controls. The development of characteristic foot rot disease was observed after 6-8 days post inoculation. A total of 38 plants showed the foot rot symptoms while control plants remained healthy. The identity of the fungus was confirmed by morphology and molecular sequence analysis after re-isolation. Chia is an important food crop and in recent times has been regarded as super food. Although S. rolfsii is known to be associated with many crops, this is the first report in chia. Therefore, to the best of our knowledge, this is the first report of foot rot disease caused by Sclerotium rolfsii on chia in India. Early diagnosis of this disease will help the farmers to adopt suitable management practices to avoid loss.

Sapota is an important horticultural crop grown in India, and Karnataka is a major producer of sapota. A characteristic leaf blight disease was observed in Southern Karnataka during field surveys conducted in 2019 with an incidence of 13-22% in approximately 45 ha of sapota field. The leaf blight-associated pathogen was isolated on the potato dextrose agar medium. A total of 12 isolates obtained from each location were identified culturally and morphologically. Based on the morphological and cultural features, the pathogen was identified as Pestalotiopsis or Neopestalotiopsis, which was further confirmed by molecular identification using a representative isolate (MZ03). The ITS rDNA and s-tubulin genes were amplified and sequenced using ITS1/ITS4 and T1/T22 primer pairs respectively. nBLAST search analysis and concatenated (ITS-rDNA and TUB2 loci) phylogenetic analysis confirmed the pathogen identity as Neopestalotiopsis vitis. Pathogenicity tests conducted on detached leaves by inoculation with a conidial suspension of N. vitis produced typical blight symptoms after 4-5 days and progressed to cover the entire leaf lamina after 10-12 days. The pathogen's identity was confirmed after re-isolation by cultural and morphological features. Although Pestalotiopsis clavispora and Pestalotiopsis versicolor causing diseases on sapota seedlings and trees have been reported, no reports are available for the occurrence of N. vitis to sapota from India. This is the first report of N. vitis associated with leaf blight disease of sapota from India.

Tuberose (Polianthes tuberosa) is an important commercial flower crop grown in Karnataka for its beautiful and fragrant cut flowers. Recently, an association of anthracnose disease (incidence ranged from 18 to 27%) characterized by the dark concentric sunken necrotic lesions with spore mass in the acervuli on leaves and peduncles of Tuberose was observed in a field survey conducted during October 2015 to March 2016. The pathogen was isolated on PDA medium. The fungal colony on PDA was grayish to dark gray. Conidia were falcate, one-celled, hyaline. Based on the micro-morphological, and cultural characteristics the pathogen was identified as Colletotrichum truncatum. The ITS-rDNA, GAPDH and s-tubulin sequences of the pathogen were sequenced using ITS1/ITS4, GDF1/GDR1, T1/Bt2b primer pairs. nBLAST search and phylogenetic analysis confirmed that the pathogen was C. truncatum. Koch's postulates were conducted on 45-day-old tuberose plants by foliar application of conidial suspension of C. truncatum. Development of typical anthracnose disease was recorded after 18 days of post-inoculation and the pathogen's identity was confirmed by re-isolation and identification. The anthracnose disease associated with Tuberose is a major constraint for the production of quality cut flowers. This is the first report of C. truncatum causing anthracnose on Tuberose in India.

Fungi constitute an important group of organisms that possess beneficial as well as negative traits against plants and animals. Association of fungi with plants is mostly saprotrophic and involves in decomposition. However, a multitude of fungal species are widely recognized as plant pathogens owing to many diseases in crops like potato, paddy, wheat, maize, pulses, oil-yielding plants, floricultural crops, horticultural crops, plantation crops, and so on. Over 70% percent of plant disease is due to fungal pathogens, and they are usually parasitic and exhibit disease symptoms. Biotrophic fungal pathogens exhibit long-term establishment by obtaining nutrients from live host tissues via specialized cells “haustoria” that develop inside the host. Necrotrophic pathogens fetch nutrients from the dead host tissues by killing the tissues with toxins or enzymes, whereas biotrophs have a narrow host range. However, necrotrophs are generalists with a wide host range or specialized with a narrow host range for their survival. Recent advances in molecular biology and sequencing platforms enable the exploration of diverse plant pathogenic fungi associated with crop plants. This chapter intends to summarize the diversity of plant pathogenic fungi on selected agriculturally important crops. It includes the detailed comprehension of plant disease concepts, classification of plant pathogenic fungi based on their lifestyle, fungal diseases of historical records, major fungal diseases of crop plants (rice, maize, and vegetables), and global perspectives of major pathogenic genera.

Rusts, being an important group of pathogenic fungi, are responsible for substantial economic losses and they are known to pass through five different spore stages in their life cycle. Diversity and documentation of rusts in India have been attempted in the pre-Butler’s, Butler’s, and post-Butler’s era. However, there has been a drastic decline in rust research in India in the recent past owing to possibly a lack of interest of few research groups. Historically, Butler laid the foundation for the study of rusts in India. The post-Butler’s era was ruled by several Indian scientists (Mehta, Prasada, Thirumalachar, Mundkur, Ramakrishna, Pavgi, Ramachar, Bagyanarayana, and others) through significant contribution towards the rust biodiversity. Several new rust genera and species new to science were discovered in this phase. However, with the advent of recent molecular tools and techniques, many countries have involved meticulously to document rich diversity of rusts and maintained their own catalogues for future pathological studies. From the Indian perspective, there is enormous scope for enhancing the knowledge on biodiversity of rusts on plant systems based on recent molecular tools and sequencing platforms. This review attempts to provide an overall picture of past and present scenario on rust research in India with future economic concern of these pathogens.

Linseed (Linum usitatissimum L.) is an important oil yielding crop cultivated widely in India. During the field survey, 2018-19 (Rabi season; January-February), characteristic powdery mildew diseas...

Rose (Rosa sp.) is an important floricultural crop largely cultivated in the Karnataka state of southern India. A field survey conducted in Devanahalli, Bangalore rural during October, 2019 revealed rose plants (cv. Arka Pride) showing die-back symptoms with a disease incidence of 7% in an area of 30 hectare rose field. Die-back was characterized by the development of necrotic lesions that started at the tip of shoots and progressed downwards leading to the death of young shoots. Pycnidia were found on young shoots showing necrotic lesions. Die-back affected shoots (n=10) were surface sterilized with 2% NaOCl for 2 min, rinsed thrice in sterile distilled water, and plated on potato dextrose agar (PDA) medium amended with chloramphenicol (40mg/L). The plates were incubated at 28±2 °C and pure cultures were obtained by hyphal tipping. Fungal colonies with white aerial mycelia along with pycnidia were observed on eight samples. Colony growth rate was at 4.2 ± 0.4 mm/day with an average colony diameter of 47.2 ± 3.8 mm after 7 days (12/12 h light and dark period). Pycnidia were solitary and globose. Conidia were hyaline, single celled ellipsoid to fusiform, measured 12.4 - 16.78 × 3.2 - 5.1 μm (n=50). Based on cultural and morphological features, the fungus was identified as Coniella granati (Van Niekerk et al., 2004; Mahadevakumar et al., 2019) (Figure S1). Further, two representative isolates (NLD-2021-1 & NLD-2021-2) were used for molecular identification based on barcoding of ITS-rDNA, LSU and tef1 regions amplified using primer pairs described in Alvarez et al., 2016. PCR amplified products were sequenced and the consensus sequence were analyzed through BLASTn search which showed ITS (NLD-2021-1: 611/611bp - MH860368 & NLD-2021-2: 573/573bp - KU147239), LSU (NLD-2021-1: 783/906bp - MH872113 & NLD-2021-2: 844/1172bp - KX833400) and tef1 (NLD-2021-1 & NLD-2021-2: 548/548bp -KX833682) sequences shared 100% sequence similarity with C. granati respectively. The nucleotide sequences were deposited in GenBank with the accession numbers ITS: MW898436, MW898437; LSU: MZ895475, MZ895476 and tef1 MW916275, MW916276 respectively. The phylogenetic tree constructed based on combined ITS-LSU-tef1 loci confirmed that the sequences shared a common clade with C. granati (Figure S2). Further, pathogenicity tests were conducted on conducted twice on healthy rose plants (Arka Pride; 60 days old after grafting) maintained in a greenhouse at 28±2°C and 70% relative humidity. Whole plant inoculation was followed by spraying the conidial suspension (10ml / plant) of C. granati (NLD-2021-1) (3 × 106 conidia/ml, amended with Tween20 at 2%) on 15 plants. A total of 10 healthy plants inoculated with sterile distilled water amended with Tween20 at 2% served as control. Inoculated plants were covered with polythene bags for 48 h to maintain relative humidity. Die-back symptoms were observed on young shoots after 15-18 days of post inoculation (DPI), and control plants remained disease free after 15 DPI. The pathogen was re-isolated on PDA from 10 diseased plants and identity was confirmed through morphological methods. Coniella granati is an important phytopathogen known to cause die-back and twig blight of pomegranate globally and other economically important crops (Cintora-Martinez et al. 2017). No reports are available on the association of C. granati with dieback of rose (Farr & Rossman, 2021), which should help in developing appropriate disease management strategies.

Tomato (Solanum lycopersicum L.) is an important vegetable crop and cultivated throughout India. During 2019-20, Karnataka produced 2163 tonnes of tomato, accounting for 10.51 percent of total prod...

Cowpea (Vigna unguiculata (L.) Walp) is one of the main legume crops grown in arid and semi-arid regions in the world. Brazil, Haiti, Myanmar, Nigeria, Sri Lanka, United States, and India contributes to the substantial production of cowpea at the global level (Mahadevakumar and Janardhana, 2012, 2014). Field surveys conducted during 2017-19 (August-September) in major cowpea growing regions of southern Karnataka revealed the occurrence of characteristic leaf spot disease of unknown etiology with an incidence ranging from 6 to 8%. Initially, the symptoms developed as small specks (1.5 to 3.5 mm), characterized by circular or irregular shape. These lesions began to develop from the leaf margin and regularly extended and coalesced to form larger lesions. After the successful manifestation of the symptoms on leaves, the associated fungal pathogen was isolated. In brief, the infected leaves were surface sterilized with 2% NaOCl for 2 min, rinsed thrice in sterile distilled water (SDW) and blotter dried. The leaf sections were placed on potato dextrose agar (PDA) in Petri plates and incubated at room temperature (27 ± 2°C) for 10 to 12 days. Mycelia developed from infected tissues were transferred to fresh PDA plates and pure cultures were obtained. Mycelia were initially white and eventually turned into gray. The conidia were black, single-celled, smooth, spherical to subspherical, 10 to 22 μm in diameter (n=30), and borne singly on a hyaline vesicle at the tip of each conidiophore. Based on the cultural features and conidial morphology, the fungus was identified as Nigrospora sp. Further, to identify the pathogen to the species level, the ITS region of the ribosomal RNA gene was amplified using primers ITS1 and ITS4 (White et al. 1990). The amplified PCR products were purified and sequenced. The nBLAST analysis showed 100% similarity with reference sequences from the GenBank database Nigrospora sphaerica (MT225783.1; MN795578.1), and the sequences were deposited in GenBank (Accession No. MT305812.1, MT305813.1, MT305814.1). Based on the cultural, morphological, microscopic and molecular characteristics, the associated fungal pathogen was identified as N. sphaerica (Sacc.) Mason (Chen et al. 2018; Wang et al. 2017) and a voucher specimen was deposited at University of Mysore Herbarium with accession No. UOM20-NS1. Further, pathogenicity tests were conducted on healthy cowpea plants grown under greenhouse conditions. Inoculations were made with conidial suspension (105 conidia/ml) prepared in SDW and healthy plants sprayed with SDW served as a standard control. All the plants were covered with polyethylene bags for 24-48 hr and observations were made at regular intervals. Typical necrotic lesions developed after 12 days of inoculation and no such symptoms were observed on the standard control set. The associated pathogen was re-isolated from diseased leaves and its identity confirmed based on morphology and cultural characteristics. Leaf spots are becoming a major problem in cowpea growing areas in recent years (Dactuliophora sp., Pestalotiopsis leaf spot, Alternaria leaf spot, and many others) (Mahadevakumar and Janardhana 2012, 2014). Recently, Aplosporella hesperidica causing collar rot on cowpea has been reported from the same region (Deepika et al. 2020). The seed borne occurrence N. sphaerica on cowpea is reported from Brazil (Rodrigues and Menezes 2002), there are no previous reports available on the occurrence of N. sphaerica on cowpea leaf spots, the present investigation is the first report of N. sphaerica causing leaf spot disease on cowpea from India.

Cowpea is an important pulse crop extensively grown in arid and semi-arid tropics which is affected by a number of diseases. Fungi belonging to mycelia sterilia are known to cause many diseases on cereals and pulses. During the cowpea field survey in Mysore District of Karnataka (India), Dactuliophora sp. was identified as the major pathogen causing zonate leaf spot (ZLS) disease. The fungal pathogen was isolated from naturally infected cowpea leaves and identified as a member belongs to the genus Dactuliophora, which was previously described by CLA Leakey in the year 1964 on Vigna unguiculata from Africa. However, detailed morphological and cultural examinations of the pathogen revealed striking differences from that of D. tarrii. Based on differences in morphology with D. tarrii, a new species Dactuliophora mysorensis sp. nov. is described herein. The disease incidence as well as disease index was estimated for 3 years (2016–2018). The severity of the disease was high during August–November. High incidence and disease index of ZLS was recorded in Doddamaragowdanahally region. The pathogenicity tests demonstrated similar symptoms of ZLS. The ITS barcoding revealed that the pathogen is closely related to Rhizoctonia bataticola and Macrophomina phaseolina. Further, in vitro evaluation of fungicides was carried out by poisoned food technique. Among the five fungicides examined, only two systemic fungicides (Benomyl and Carbendazim) were effective against D. mysorensis. Thus, the present study recommends Benomyl and Carbendazim for management of ZLS disease caused by D. mysorensis.

A severe outbreak of southern blight disease of China aster was observed during the post rainy season (September–November 2015) in the Mysore and Mandya Districts of Karnataka, Southern India. The disease incidence ranged between 12 and 47%. The typical disease symptoms include water-soaked lesions on leaves, stems and on the lower stem surfaces followed by quick wilting of the whole plant with abundant production of sclerotia near the stem-soil interface. The associated fungal pathogen was isolated on potato dextrose agar (PDA) medium, on which numerous reddish-brown sclerotia were seen. A total of 26 fungal isolates were isolated and studied for the mycelial compatibility. Isolate SrCCM 1 was used for pathogenicity analysis. The results of the study showed that, there was no variation among the isolates tested. Molecular identification of the pathogen by ITS-rDNA sequences of S. rolfsii showed 100% similarity with reference sequences. Based on the cultural, morphological and molecular characteristics, the fungal pathogen was identified as Sclerotium rolfsii Sacc. (Sexual morph: Athelia rolfsii (Curzi) C.C. Tu & Kimbr). Pathogenicity tests were performed on healthy leaves, roots and stems. Typical disease symptoms on leaves, stems and roots were evident after 5, 8 and 10 days of post-inoculation. Sclerotium rolfsii is known to cause diseases in economically important crop plants. However, no reports are available on the occurrence of S. rolfsii on China aster in India.

The distribution, prevalence and incidence of Phomopsis vexans in six major brinjal growing agro-climatic zones of southwest India is reported. P. vexans was isolated from diseased leaf and fruit samples from six zones and was studied for its morpho-cultural and molecular characteristics. Eighteen isolates were tested for their pathogenicity on 30-days old brinjal seedlings. The ITS regions of these fungal isolates were used for the molecular identification followed by phylogenetic analysis. The incidence of leaf blight and fruit rot disease was high in northern transition zone (NTZ: 10.625.3% and 2133.3%) followed by southern dry zone (SDZ: 8.318% and 22.362%) and central dry zone (CDZ: 1017% and 2939%). All the isolates exhibited similarities in colony morphology. Variation was observed with regard to number of pycnidia, colony growth and type. Among the 24 isolates, 18 belonged to G-type and the rest could not be ascertained to either colony type. The 18 G-type isolates produced leaf blight and fruit rot symptoms 2528 and 4555 days post inoculation, respectively. In the phylogenetic analysis, all the 24 isolates formed a single clade, thus confirming their close genetic relatedness, though they were isolated from different agro-climatic zones of southwest India. Phylogenetic analysis of complete ITS2 sequence showed the presence of two distinct groups based on substitutions and indels observed among the populations where six isolates from NDZ and CDZ formed a distinct group from the rest of the isolates.

Lablab purpureus (L.) Sweet (Indian bean) is an important pulse crop grown in arid and semi-arid regions of India. It is one of the most widely cultivated legume species and has multiple uses. During a September 2010 survey, we recorded a new leaf spot disease on L. purpureus in and around Mysore district (Karnataka state) with 40 to 80% disease incidence in 130 ha of field crop studied, which accounted for 20 to 35% estimated yield loss. The symptoms appeared as small necrotic spots on the upper leaf surface. The leaf spots were persistent under mild infection throughout the season with production of conidia in clusters on abaxial leaf surface. A Dueteromyceteous fungus was isolated from affected leaf tissues that were surface sterilized with 2% NaOCl2 solution then washed thrice, dried, inoculated on potato dextrose agar (PDA) medium, and incubated at 28 ± 2°C at 12 h alternate light and dark period for 7 days. The fungal colony with aerial mycelia interspersed with dark cushion-shaped sporodochia consists of short, compact conidiophores bearing large isodiametric, solitary, muricate, brown, globular to pear shaped conidia (29.43 to 23.92 μm). Fungal isolate was identified as Epicoccum sp. based on micro-morphological and cultural features (1). Further authenticity of the fungus was confirmed by PCR amplification of the internal transcribed spacer (ITS) region using ITS1/ITS4 universal primer. The amplified PCR product was purified, sequenced directly, and BLASTn search revealed 100% homology to Epicoccum nigrum Link. (DQ093668.1 and JX914480.1). A representative sequence of E. nigrum was deposited in GenBank (Accession No. KC568289.1). The isolated fungus was further tested for its pathogenicity on 30-day-old healthy L. purpureus plants under greenhouse conditions. A conidial suspension (106 conidia/ml) was applied as foliar spray (three replicates of 15 plants each) along with suitable controls. The plants were kept under high humidity (80%) for 5 days and at ambient temperature (28 ± 2°C). The appearance of leaf spot symptoms were observed after 25 days post inoculation. Further, the pathogen was re-isolated and confirmed by micro-morphological characteristics. E. nigrum has been reported to cause post-harvest decay of cantaloupe in Oklahoma (2). It has also been reported as an endophyte (3). Occurrence as a pathogen on lablab bean has not been previously reported. To our knowledge, this is the first report of the occurrence of E. nigrum on L. purpureus in India causing leaf spot disease. References: (1) H. L. Barnet and B. B. Hunter. Page 150 in: Illustrated Genera of Imperfect Fungi, 1972. (2) B. D. Bruten et al. Plant Dis. 77:1060, 1993. (3) L. C. Fávaro et al. PLoS One 7(6):e36826, 2012.

Cowpea (Vigna unguiculata (L.) Walp) is an important legume crop cultivated in arid and semi-arid regions in underdeveloped and developing countries. India is a leading cowpea producer. In addition to India, Nigeria and Niger are the predominant producers of cowpea in the world. Brazil, Haiti, Myanmar, Sri Lanka, and the United States are also significant producers of cowpea. This is a drought-tolerant annual crop that thrives in warm weather (3), and is more well-adapted to the drier regions of the tropics than any other legume. Cowpea fields (190 ha) surveyed in Mysore district (Karnataka State) from 2010 to 2012 were found affected by a new leaf spot disease. Over 60% of surveyed fields were affected by this disease, with individual fields ranging from 30 to 75% disease incidence. Individual fields experienced an estimated 10 to 15% yield loss. Initially, leaf spot symptoms appeared as small, dark, necrotic lesions that increased to a diameter of 0.5 to 1.0 cm. These spots later enlarged to form brown, circular, elliptical, and irregular spots with halo margins. Symptoms persisted throughout the cropping season. Under severe infection, defoliation occurred. Black, sessile, discoid conidiomata were observed in lesions and exuded a pink spore mass that later turned brown. The fungus was isolated from affected leaf tissues that were surface sterilized with 2% NaOCl2 solution, washed thrice with sterile water, blotter dried, and inoculated onto potato dextrose agar (PDA). White mycelia produced black globular acervuli with conidia on PDA after 7 days of incubation at 28 ± 2°C with a 12-h alternate light and dark period. Conidia had 5-celled (21.37 to 24.89 × 6.3 to 6.9 μm) segmentation with darker median cells and hyaline end cells. The apical cell typically had three appendages (sometimes 2 to 4) measuring 22.0 to 27.3 μm long and the basal appendage was 3.47 to 6.2 μm long. Based on these morphological features, the fungal pathogen was identified as Pestalotiopsis species. The isolated fungus was tested for pathogenecity on 30-day-old healthy cowpea plants grown under greenhouse conditions. A conidial suspension was prepared from 7-day-old culture by flooding with 2 to 4 ml of sterile distilled water. Spores were collected with a sterile micropipette and spore concentration was adjusted to 3 × 106 conidia/ml and applied as foliar spray onto 15 plants each in three replicates. Non-inoculated control plants were sprayed with sterile water. The plants were kept under high humidity (80%) for 5 days and at ambient temperature (28 ± 2°C). After 10 to 12 days post-inoculation, leaf spot symptoms appeared on inoculated plants, and the fungal pathogen was re-isolated and no such symptoms were found on control plants. The pathogen was confirmed by micro-morphological features. The ITS region of the ribosomal RNA gene was amplified using primers ITS1 and ITS4 (2). The amplified PCR product was purified and sequenced. nBLAST search comparison of sequences revealed 99% homology to Pestalotiopsis photiniae (AY682946.1). A representative sequence was deposited in GenBank (KC568288.1). Pestalotiopsis is an important pathogen on many crop plants and has been recorded on a wide variety of hosts, primarily on leaves, fruits, and in the rhizosphere. In recent times, cowpea is susceptible to a wide range of fungal pathogens causing severe yield loss at all stages of growth and development (1). Leaf spot caused by Pestalotiopsis species are becoming a major constraint for cowpea production in India. No previous reports are available on Pestalotiopsis species causing leaf spot of cowpea in India. References: (1) S. Mahadevakumar and G. R. Janardhana. New Dis. Rep. 25:17, 2012. (2) T. J. White et al. PCR Protocols: A Guide to Methods and Applications, page 315. Academic Press, San Diego, 1990. (3) A. A. Zohri et al. Korean Mycol. 20:252, 1992.

Lemon (Citrus lemon (L.) Burm. f.) is an important fruit crop cultivated worldwide, and is grown practically in every state in India (3). During a survey conducted in 2013, a few small trees in a lemon orchard near Mysore city (Karnataka) (12°19.629′ N, 76°31.892′ E) were found affected by dieback disease. Approximately 10 to 20% of trees were affected as young shoots and branches showed progressive death from the apical region downward. Different samples were collected and diagnosed via morphological methods. The fungus was consistently isolated from the infected branches when they were surface sanitized with 1.5% NaOCl and plated on potato dextrose agar (PDA). Plates were incubated at 26 ± 2°C for 7 days at 12/12 h alternating light and dark period. Fungal colonies were whitish with pale brown stripes having an uneven margin and pycnidia were fully embedded in the culture plate. No sexual state was observed. Pycnidia were globose, dark, 158 to 320 μm in diameter, and scattered throughout the mycelial growth. Both alpha and beta conidia were present within pycnidia. Alpha conidia were single celled (5.3 to 8.7 × 2.28 to 3.96 μm) (n = 50), bigittulate, hyaline, with one end blunt and other truncated. Beta conidia (24.8 to 29.49 × 0.9 to 1.4 μm) (n = 50) were single celled, filiform, with one end rounded and the other acute and curved. Based on the morphological and cultural features, the fungal pathogen was identified as Phomopsis citri H.S. Fawc. Pathogenicity test was conducted on nine healthy 2-year-old lemon plants via foliar application of a conidial suspension (3 × 106); plants were covered with polythene bags for 6 days and maintained in the greenhouse. Sterile distilled water inoculated plants (in triplicate) served as controls and were symptomless. Development of dieback symptoms was observed after 25 days post inoculation and the fungal pathogen was re-isolated from the inoculated lemon trees. The internal transcribed spacer region (ITS) of the isolated fungal genomic DNA was amplified using universal-primer pair ITS1/ITS4 and sequenced to confirm the species-level diagnosis (4). The sequence data of the 558-bp amplicon was deposited in GenBank (Accession No. KJ477016.1) and nBLAST search showed 99% homology with Diaporthe citri (teleomorph) strain 199.39 (KC343051.1). P. citri is known for its association with melanose disease of citrus in India, the United States, and abroad. P. citri also causes stem end rot of citrus, which leads to yield loss and reduction in fruit quality (1,2). Dieback disease is of serious concern for lemon growers as it affects the overall productivity level of the tree. To the best of our knowledge, this is the first report of P. citri causing dieback of lemon in India. References: (1) I. H. Fischer et al. Sci. Agric. (Piracicaba). 66:210, 2009. (2) S. N. Mondal et al. Plant Dis. 91:387, 2007. (3) S. P. Raychaudhuri. Proc. Int. Soc. Citriculture 1:461, 1981. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

Psychotria nervosa, commonly called “wild coffee” (Rubiaceae), is an important ethno-medicinal plant in India. In 2010, a new rust disease of P. nervosa was observed in three regions of Mysore District, Karnataka (India), with disease incidence ranging from 58 to 63%.Typical symptoms of the rust disease on wild coffee were prominently visible during the early monsoon season (May to June), with chlorotic spots on the adaxial and black pustules (telia) on the abaxial leaf surface. Telia produced abundant teliospores, which were bicelled, pedicillate, and measured 33 to 45 by 19 to 30 μm. The germination of teliospores produced a typical metabasidium bearing four basidiospores, each containing two haploid nuclei. Spore stages of the wild coffee rust pathogen were studied using artificially inoculated healthy wild coffee plants with germinated teliospores. Only telia were observed on the inoculated plants, indicating that this rust fungus has an abbreviated microcyclic life cycle that includes only teliospores and basidiospores. Phylogenetic analysis based on internal transcribed spacer and partial large subunit (LSU) sequence data showed that the wild coffee rust pathogen is related to Macruropyxis fraxini, Puccinia bartholomaei, P. choridis, and P. sparganioidis. The herbarium sample of P. psychotriae was examined and was shown to be different with respect to telium size and teliospore dimensions (24 to 32 by 13 to 18 μm). Therefore, the rust pathogen causing wild coffee rust is a new species, P. mysuruensis sp. nov.

Maize (Zea mays L.) is one of the important cereal crops in the world and is the third largest grown cereal crop in India. Field surveys conducted in 2013-15 recorded stalk rot incidence of 28–35% in southern states of India. The typical symptoms were observed after pollination with the drying of the lower leaves and eventually entire plant wilted prematurely, lower internodes turned in to grey-green color and stalks are hollow and weak leading to the lodging of the plant. Stalk rot associated pathogen was isolated on PDA medium. Out of 219 Fusarium isolates, 19 were distinct and the fungal colonies on PDA medium showed the development of pale brown to dark brown pigment. Macro conidia were produced in orange sporodochia from monophialides on branched conidiophores with apical cells tapered and elongated. Chlamydospores were solitary and intercalary. All 19 isolates were morphologically identical, and a representative isolate was used for molecular identification. The ITS rDNA and TEF gene were amplified and sequenced using ITS1/ITS4, TEF1/TEF2primer pairs. The nBLAST search and phylogenetic analysis confirmed that the pathogen was Fusarium equiseti. Pathogenicity tests conducted on 50-day-old maize plants by injecting conidial suspension of F. equiseti produced typical stalk rot symptoms after 15 days of post-inoculation and the pathogen's identity was confirmed by cultural and morphological features after re-isolation. Association of F. equiseti as the causal agent of sheath rot of maize was reported from China. The association of F. equiseti with stalk rot of maize is the first report in India.

In the present study, fruit rot disease of Cucurbita maxima observed in many crop fields of Southern Karnataka, India is reported. The fruit rot disease on Pumpkin appears as water soaked lesion on the surface of the fruit followed by the development of large rotten areas with abundant white mycelial growth. The fungal pathogen was isolated on potato dextrose agar (PDA) medium and development of whitish fast-growing mycelia with numerous reddish brown sclerotia was observed. The sclerotia were initially white and turned dark brown upon maturation. Genomic DNA was isolated and internal transcribed region of ribosomal DNA was amplified using ITS1-ITS4 universal primers. Based on cultural, morphological and molecular characteristics, the fungal pathogen was identified as Sclerotium rolfsii. The rDNA sequence results also showed 99–100 % similarity with reference sequence AB075298.1 and JF966208.1 confirming pathogen identity. The pathogenicity test conducted on healthy detached fruits produced fruit rot symptoms after 6–8 days of post inoculation. S. rolfsii is known to infect many economically important crop plants at various stages of its growth and development. To the best of our knowledge, this is the first report on the association of S. rolfsii with fruit rot of C. maxima in India.

rinjal is an important vegetable crop grown worldwide. A field survey conducted during 2012 in Kerala state of South India, the little leaf disease affected brinjal plant was observed in one of the home gardens located at Nemmara (Palakkad district). The diseased and healthy samples were collected; genomic DNA was isolated and 16SrRNA gene amplified by performing nested PCR using universal primers pairs P1/P7 and R16F2n/R2 respectively. The association of Phytoplasma was detected in all the three symptomatic brinjal samples and in Phytoplasma affected Periwinkle used as positive control. An expected amplicon size of 1250bp from nested PCR was purified and sequenced. The nucleotide sequence analysis (nBLAST) of 1250bp fragment of sequence KL-50(KP027530) revealed 97% similarity with Candidatus phytoplasma trifolii (JX104336). Phylogenetic analysis and study of virtual RFLP gel pattern of the sequence also revealed the association of Candidatus phytoplasma trifolii.

Leaf blight and fruit rot disease of brinjal ( Solanum melongena ) caused by the fungal pathogen Phomopsis vexans is the most prevailing diseases responsible for the significant yield loss in many Brinjal growing regions of India. The survey conducted during 2008-2010, seven (07) isolates of Phomopsis vexans causing leaf blight and fruit rot disease in different areas of Karnataka were isolated, identified and confirmed by Koch’s postulates. Identification of Phomopsis vexans by conventional culture method was time consuming and laborious. Hence, PCR based detection assay was used to detect the pathogen from DNA samples obtained from fungal isolates. Universal primer pairs designed from internal transcribed spacer regions ITS1 (5'-CGGATCTCTTGGTTCTGGCA-3') and ITS4 (5'-GACGCTCGAACAGGCATGCC-3') of the ribosomal DNA (rDNA) of the genus Phomopsis were used for PCR. The study revealed the amplification of expected 553bp PCR products in all the DNA samples isolated from different isolates of Phomopsis vexans confirming their association in leaf blight and fruit rot disease of Brinjal. DOI: http://dx.doi.org/10.3126/ijls.v7i1.8173 International Journal of Life Sciences 7(1): 2013; 17-20

Summary The multi-use tree Canthium dicoccum (Rubiaceae) growing in shrub forests of Mysore, Mandya and Chamarajanagar (India) was severely affected by a leaf blight disease. The ascomycete Pestalotiopsis mangiferae was consistently isolated from symptomatic leaves and identified by micromorphology and ITS rDNA sequencing analysis. Pathogenicity test was performed and Koch's postulates were fulfilled. This is the first report of P. mangiferae causing leaf blight of C. dicoccum in India.

Cotton (Gossypium hirsutum) is the most important fiber-yielding crop grown in India and worldwide. In India, during 2012-2013, 1.16 million ha were under cotton cultivation, with an average production of 480 kg/ha. As production of cotton has increased in areas, so has the occurrence of various pests and diseases. During a field survey conducted in the cotton-growing areas of Devalapura Village of the Mysore District during August and September 2013, a boll rot disease was observed with distinctive symptoms and signs of a fungal pathogen observed in 27% of fields. Incidence of the boll rot within fields ranged from 8 to 12%, while 3 to 5% stem rot was observed on boll rot-affected plants in about 15 to 18 ha of total cotton fields surveyed. White mycelial strands with spherical, dark-brown sclerotial bodies were found on the surface of infected bolls near the ground and the affected bolls were completely decayed. The disease-affected bolls were disinfested with 2% sodium hypochlorite solution for 3 min, and 5-mm samples were placed on potato dextrose agar (PDA) medium and incubated at 28 ± 2°C. The fungal colonies that grew from infected tissues were whitish with cottony aerial mycelium and abundant globoid sclerotia observed after 10 to 12 days of incubation. Sclerotial bodies were initially pale whitish, becoming dark brown over time. Based on morphological and cultural characteristics, the associated fungal pathogen was identified as Sclerotium rolfsii Sacc. The identity of the pathogen was further confirmed through PCR amplification of internally transcribed spacer (ITS) region using ITS1/ITS4 universal primer. The amplified PCR product (550 to 570 bp) was sequenced and BLASTn search comparison revealed 100% homology with Sclerotium rolfsii (Accession Nos. JF966208 and JX914480). A representative sequence of S. rolfsii was deposited in GenBank (KP412471.1 and KP412472.1). Further, pathogenicity tests were conducted on 30 healthy cotton bolls in vivo by inoculating the bolls with sclerotia obtained from 12-day-old cultures; noninoculated bolls served as controls. Characteristic boll rot symptoms were observed on 60% of total inoculated cotton bolls 7 days after inoculation and S. rolfsii was reisolated from the infected bolls and the identity of the pathogen was confirmed. S. rolfsii is a serious soil-borne fungal pathogen with a wide host range (Mullen 2001) and prevalent in tropical and subtropical regions, where high temperature and moisture are sufficient to permit growth and survival of the fungal pathogen (Punja 1985). The association of S. rolfsii with boll rot of cotton has been reported from Bangladesh (Shamsi et al. 2008). In India, major diseases of cotton include wilt (Fusarium oxysporum f. vasinfectum), anthracnose (Colletotrichum capsici), and areolate mildew (Ramularia areola) (Rangaswamy and Mahadevan 2002). S. rolfsii infect bolls on branches near ground level, causing boll decay. Numerous sclerotia produced on the affected bolls are the source of secondary inoculum and are dispersed by rain splash during the late monsoon, thus resulting in new infections on the basal stem and leaves of the cotton plant. The disease has resulted in reduced yield and market value of the crop. To the best of our knowledge, this is the first report on the occurrence of S. rolfsii causing boll rot of cotton in India.

Chrysanthemum (Chrysanthemum indicum L.) is an important floriculture crop grown in different parts of Karnataka, India for its beautiful cut flowers. Recently, there has been a decline in flower quality due to major pests and diseases. A field survey conducted during 2012-2013 in chrysanthemum-growing areas revealed the occurrence of virescence with an incidence of 5 to 10% in nearly 6 to 8 ha of chrysanthemum fields in Mandya and Mysore districts. Symptoms including malformed flowers with greenish florets and reduced flower size and floral virescence with sepaloidy were observed. Diseased leaves and flower parts were collected and used for identification of the causative agent. Ten samples (6 symptomatic, 2 healthy, and 2 phytoplasma-associated with phyllody of Catheranthus roseus as positive control) were used for total genomic DNA isolation using GenElute Plant Genomic DNA Miniprep Kit (Sigma-Aldrich, St. Louis, MO) and the DNA was used as template to amplify the phytoplasma-specific 16SrDNA gene using P1/P7 primers followed by nested PCR using R16F2n/R16R2 primers (Gundersen and Lee 1996). The expected 1.25-kb amplicon was detected only with DNA from symptomatic and positive control samples. Nested PCR products of all six phytoplasma-associated samples were purified and sequenced from both the directions using a ABIx370 Genetic Analyzer (Applied Biosystems, Waltham, MA). The 16SrDNA sequences were aligned using CodonCode Aligner (Centerville, MA) and analyzed by BLASTn. The analysis revealed that all six sequences shared 100% identity with Cassava witches broom (KM280680.1) and Peanut witches broom (JX403944.1) phytoplasma. The in-silico RFLP pattern of F2n/R2 primed region of 16SrDNA gene analyzed by using iPhyClassifier (Zhao et al. 2009) revealed that the sequence shared 99.8% nucleotide sequence similarity with coefficient value of 1.00 to the reference strain RFLP pattern of 16Sr group II, subgroup A (Peanut witches broom phytoplasma; Accession No. L33765.1). Based on 16SrDNA sequences and in-silico RFLP analysis, the phytoplasma associated with the chrysanthemum virescence was identified as a member of 16SrII-A group. The representative sequence was deposited in GenBank with Accession Number KP027534.1. Phytoplasma associated with little leaf and witches broom of chrysanthemum have been reported earlier from India and were assigned to groups 16SrI-A and 16SrII, respectively (Kumar et al. 2012; Raj et al. 2007). Chrysanthemum virescence phytoplasma belonging to Candidatus phytoplasma aurantifolia has been reported from Japan and has not been assigned to any group (Naito et al. 2007). The occurrence of virescence is of great importance as it affects the overall productivity and quality of flowers, which reduces the market value of chrysanthemum. To our knowledge, this is the first report of a group 16SrII-A phytoplasma associated with chrysanthemum virescence in India.

Common bean (Phaseolus vulgaris L.) is an economically important crop grown worldwide. In India, it is grown for both green bean and dry pods (seeds). During 2012-2014, sudden wilt and leaf spots were observed during early growth to preflowering stage in the Mysore and Mandya districts of Karnataka State. The disease incidence was 30 to 35% in nearly 45 to 48 ha. Symptoms include wilting of foliage, tan lesions on stems at ground level, and gradually drying of the whole plant. Leaf spot symptoms on 30- to 45-day-old plants were water-soaked lesions with concentric necrotic spots (5 to 12 mm). White mycelial strands with spherical dark brown sclerotial bodies at the stem-soil interface were observed. Infected tissues were disinfected with 2% sodium hypochlorite solution for 3 min, and plated on potato dextrose agar and incubated at 28 ± 2°C. A single associated fungal pathogen was consistently isolated. It was characterized by dense, aerial, whitish cottony mycelium. Uniformly globoid sclerotia were observed after 10 to 12 days of incubation. Whitish sclerotia (1 to 3 mm) turned to dark brown at maturation. Based on etiology, and morphological and cultural characteristics, the pathogen was identified as Sclerotium rolfsii Sacc. (syn. Athelia rolfsii (Curzi) Tu & Kimbrough) (Mordue, 1974). Identity was further confirmed through PCR amplification of internally transcribed spacer (ITS) region using ITS1/ITS4 universal primer. Amplified PCR product (550 to 570 bp) was sequenced and BLASTn search comparison revealed 99% homology to Sclerotium rolfsii (GenBank Accession Nos. DQ093668 and JX914480). Representative sequence of S. rolfsii was deposited in GenBank as KP412468.1 and KP412469.1. Pathogenicity tests were conducted on 15-day-old common bean plants (cv. S-9) by soil infestation and foliar inoculation of sclerotial bodies obtained from a 12-day-old culture of S. rolfsii. The experiment was conducted on 30 plants along with control plants. Soil infestation with sclerotia resulted in wilting and crown rot symptoms with 90% disease and 100% leaf spot incidence and no such symptoms were observed on control plants. The fungal pathogen was reisolated from inoculated plants and the identity was confirmed through morphological and cultural characteristics. Southern blight and leaf spot diseases of common bean are a major constraint for its production in India. To our knowledge, this is the first report on the occurrence of S. rolfsii causing southern blight and leaf spot of common bean in India.

Cowpea ( Vigna unguiculata ) is an important legume crop in developing countries and is cultivated throughout the arid and semiarid tropics (Zohri et al., 1992; Singh et al ., 1997). India is a leading cowpea producer (Asiwe et al ., 2009). …