{"id":5818,"date":"2025-03-24T12:53:56","date_gmt":"2025-03-24T07:23:56","guid":{"rendered":"https:\/\/babrone.avfu.ac.in\/blog\/?p=5818"},"modified":"2025-06-16T11:53:05","modified_gmt":"2025-06-16T06:23:05","slug":"diseases-affecting-orchids-in-india-an-overview-with-insights-from-the-north-east-india","status":"publish","type":"post","link":"https:\/\/babrone.avfu.ac.in\/blog\/?p=5818","title":{"rendered":"Diseases Affecting Orchids in India: An Overview with Insights from the North-East India"},"content":{"rendered":"<p style=\"text-align: center;\"><span style=\"color: #000000;\"><strong>Dibya Sree Dutta<sup>1<\/sup>&amp; Pankaj Bharali<sup>1&amp;2<\/sup><\/strong><\/span><\/p>\n<p style=\"text-align: center;\"><span style=\"color: #000000;\"><sup>1<\/sup>Biological Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat 785006, Assam, India<\/span><\/p>\n<p style=\"text-align: center;\"><span style=\"color: #000000;\"><sup>2<\/sup>Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India<\/span><\/p>\n<p style=\"text-align: justify;\">&nbsp;<\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">*Corresponding author email: <a style=\"color: #000000;\" href=\"mailto:pbharali@neist.res.in\/pankajbharali98@gmail.com\">pbharali@neist.res.in\/pankajbharali98@gmail.com<\/a><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>Abstract<\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Orchids, a diverse and economically significant plant group, are highly susceptible to fungal, bacterial, and viral diseases, which adversely affect their cultivation and market value. Northeast India, renowned for its rich biodiversity, comprises the eight states of Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim, and Tripura. This region serves as a hotspot for orchid diversity; however, its humid subtropical climate also fosters the proliferation of various plant diseases. Major fungal pathogens such as <em>Colletotrichum, Fusarium,<\/em> and <em>Phytophthora<\/em>, bacterial soft rot caused by <em>Erwinia carotovora<\/em>, and viral infections including CMV, ORSV, and CymMV lead to severe plant damage. Despite the widespread occurrence of these diseases, research on orchid pathology, particularly in Assam, remains limited, posing challenges to effective management. This review provides a comprehensive overview of the major orchid diseases in India, with a special emphasis on the northeastern region.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>Keywords: <\/strong>Diseases, Northeast India, Orchids<\/span><\/p>\n<p style=\"text-align: center;\"><strong><u>GRAPHICAL ABSTRACT<\/u><\/strong><\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-5819\" src=\"https:\/\/babrone.avfu.ac.in\/blog\/wp-content\/uploads\/2025\/03\/Screenshot-2025-03-24-at-11.59.30-AM.png\" alt=\"Screenshot 2025-03-24 at 11.59.30 AM\" width=\"752\" height=\"356\" srcset=\"https:\/\/babrone.avfu.ac.in\/blog\/wp-content\/uploads\/2025\/03\/Screenshot-2025-03-24-at-11.59.30-AM.png 752w, https:\/\/babrone.avfu.ac.in\/blog\/wp-content\/uploads\/2025\/03\/Screenshot-2025-03-24-at-11.59.30-AM-300x142.png 300w, https:\/\/babrone.avfu.ac.in\/blog\/wp-content\/uploads\/2025\/03\/Screenshot-2025-03-24-at-11.59.30-AM-190x90.png 190w\" sizes=\"auto, (max-width: 752px) 100vw, 752px\" \/><\/p>\n<p style=\"text-align: center;\"><span style=\"color: #000000;\"><strong>Introduction<\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Orchids, classified under the family Orchidaceae, constitute one of the most diverse and widely distributed plant groups, comprising nearly 28,000 species and over 100,000 registered hybrids worldwide (Govaerts <em>et al<\/em>., 2017; Jangyukala and Hemanta, 2021). India hosts approximately 1,300 orchid species, with nearly 800 species found across the northeastern region, making it a significant biodiversity hotspot for these plants (Hinsley <em>et al<\/em>., 2018). The species distribution across the northeastern states includes Arunachal Pradesh (686), followed by Sikkim (501) and Assam (406), respectively. Globally, the orchid industry holds substantial economic value in floriculture, estimated at approximately $400 billion, with major producers including Thailand, Singapore, and Taiwan (DITP News, 2015).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Orchid cultivation, despite its economic value and global demand, is severely impacted by biotic and abiotic stresses, with diseases being a major constraint. Orchids are highly susceptible to fungal, bacterial, and viral infections, leading to reduced plant vigour, poor flower quality, and economic losses. Black rot is a major fungal threat, causing extensive tissue decay (Uchida, 1994; Erwin and Ribeiro, 1996). Other fungal diseases like anthracnose and blossom blight further affect production. Bacterial soft rot also causes severe damage to orchid crops (De <em>et al<\/em>., 2019).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">In addition to fungal and bacterial infections, viruses pose a major challenge to orchid cultivation. Cymbidium Mosaic Virus (CymMV) and Odontoglossum Ringspot Virus (ORSV) are among the most common viruses affecting orchids, causing mosaic patterns, necrosis, and floral deformations, thereby reducing plant vigour and commercial value (Varma and Ramachandran, 1994; Sherpa <em>et al<\/em>., 2003; Bhat <em>et al<\/em>., 2006; Sherpa <em>et al<\/em>., 2006a and 2006b). Once infected, viral diseases are difficult to control, as there are no effective chemical treatments available, making prevention and quarantine measures essential. In India, at least 10 viruses have been reported on cultivated orchids (Table 1).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">The northeastern region of India, with its humid subtropical climate and high rainfall, provides ideal conditions for the proliferation of pathogens, making orchids in this region particularly susceptible to various diseases. The lack of proper disease management strategies, along with limited awareness among growers, further exacerbates the problem. Therefore, understanding the pathology, distribution, and management of orchid diseases is crucial for sustainable orchid production and conservation. This review analyses major orchid diseases in India, focusing on the Northeast, highlighting symptoms and causal organisms to aid effective disease control for growers and researchers.<\/span><\/p>\n<ol style=\"text-align: justify;\">\n<li><span style=\"color: #000000;\"><strong> Important viruses of orchids<\/strong><\/span><\/li>\n<\/ol>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>1.1 Cucumber mosaic virus CMV<\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Cucumber Mosaic Virus (CMV), belonging to the <em>Bromoviridae<\/em> family and <em>Cucumovirus<\/em> genus, is a widely distributed pathogen affecting numerous plant species, including orchids. It was first identified in vanilla plants in French Polynesia, where it caused severe vine distortions (Farreyrol <em>et al<\/em>., 2001). Subsequent reports confirmed its presence in R\u00e9union and India (Madhubala <em>et al<\/em>., 2005; Sharma <em>et al<\/em>., 2005).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">The genome of CMV is tripartite and positive-sense RNA, encapsulated in isometric particles roughly 32 nm in diameter. Its genome encodes five key proteins, including two polymerase components, <em>i.e.<\/em>, RNA1 and RNA2, the 2b protein involved in viral movement and suppression of host defences, a 30K movement protein (MP), and a coat protein (CP) responsible for encapsidation. Some CMV strains also carry satellite RNAs (satRNAs), which can influence disease symptoms. With the ability to infect more than 1,000 plant species across 30 families and being transmitted in a non-persistent manner by over 80 aphid species, CMV is highly adaptable and poses a significant threat to global agriculture (Gallitelli, 2000).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>1.2 Groundnut Bud Necrosis Virus <\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Groundnut Bud Necrosis Virus (GBNV), belonging to the Tospovirus genus, has been identified as a pathogen affecting <em>Phalaenopsis orchids<\/em> in Sikkim, India. Infected plants displayed symptoms such as mild chlorotic spots, dark-green patches with chlorotic margins and mosaic patterns. Transmission Electron Microscopy (TEM) analysis of symptomatic leaf samples confirmed the presence of tospovirus-like particles ranging from 80 to 110 nm in diameter. This study marked the first global report of GBNV infecting Phalaenopsis orchids, including in India (Pant <em>et al<\/em>., 2019).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>1.3 Cymbidium ringspot virus<\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Cymbidium Ringspot Virus (CyRSV), first identified in <em>Cymbidium<\/em> orchids by Hollings and Stone in 1963, is classified under the <em>Tombusviridae<\/em> family and <em>Tombusvirus<\/em> genus, with Tomato Bushy Stunt Virus as its type species. This virus shares serological similarities with an isometric virus found in <em>Trifolium repens<\/em> (white clover) and was initially reported from southern England. Infected <em>Cymbidium<\/em> orchids typically develop chlorotic ring mottle and exhibit stunted growth, though these symptoms are not exclusively linked to CyRSV. The virus spreads through mechanical transmission and can infect over 60 plant species. Unlike many plant viruses, CyRSV is not transmitted via seeds or insect vectors but remains highly stable in the environment.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">In India, Cymbidium Ringspot Virus (CyRSV) has been detected in <em>Cymbidium elegans<\/em> and <em>Cymbidium longifolium<\/em> (Sharma <em>et al<\/em>., 2005). Structurally, CyRSV is a non-enveloped, icosahedral virus with a spherical shape and T=3 symmetry, measuring approximately 28\u201330 nm in diameter. Its genome comprises a single-stranded, positive-sense RNA (ssRNA) spanning 4,733 nucleotides and contains five major open reading frames (ORFs). The 33 kDa and 92 kDa proteins play a role in viral replication, the 41 kDa protein facilitates movement of virus within the host, while the 22 kDa and 19 kDa proteins contribute to capsid formation. Additionally, a small 4 kDa protein (ORF6) has been identified in the 3&#8242; non-coding region through computational analysis (Boyko and Karasev, 1992). The stability and wide host range of <em>CyRSV<\/em> makes it a significant pathogen affecting ornamental orchids (Hollings and Stone, 1963; Boyko and Karasev, 1992; Sharma <em>et al<\/em>., 2005).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>1.4 Potyviruses <\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Potyviruses constitute a significant group of plant viruses that impact a diverse range of crops, including orchids. In India, the Bean yellow mosaic virus (BYMV) has been identified in orchids such as vanilla, leading to symptoms such as mosaic and leaf malformations (Bhai <em>et al<\/em>., 2003; Bhat <em>et al<\/em>., 2004). Vanilla mosaic virus (VanMV), initially discovered in <em>Vanilla tahitensis<\/em>, shares a close genetic relationship with Dasheen mosaic virus (DsMV) and is spread by the aphid <em>Myzus persicae<\/em> (Farreyrol <em>et al<\/em>., 2006). Vanilla necrosis virus (VNV), first recorded in Tonga, was later classified as a strain of Watermelon mosaic virus (WMV-Tonga) (Pearson and Pone, 1988). Additionally, Calanthe mild mosaic virus (CalMMV) has been detected in orchids, causing mosaic and necrotic symptoms. Genomic analysis of VanMV has revealed a polyprotein structure characteristic of Potyviruses, with phylogenetic studies showing its close evolutionary link to South Pacific strains of DsMV (Puli\u2019uvea <em>et al<\/em>., 2017).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>1.5 Orchid fleck virus <\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Orchid fleck virus (OFV) was initially detected in <em>Cymbidium<\/em> orchids in Japan, where it was associated with chlorotic and necrotic flecks on leaves (Doi <em>et al.,<\/em> 1977). Since then, the virus has been documented in multiple countries, infecting a range of orchid species and leading to floral deformities (Blanchfield <em>et al<\/em>., 2001). OFV is transmitted persistently by <em>Brevipalpus<\/em> mites (Kondo <em>et al<\/em>., 2003) and belongs to the proposed genus <em>Dichorhabdovirus<\/em> within the <em>Rhabdoviridae<\/em> family (Dietzgen <em>et al<\/em>., 2014). Morphologically, the virus has a bacilliform shape and possesses a (bipartite) negative-sense RNA genome. In India, virus particles resembling OFV have been observed in <em>Coelogyne elata<\/em>, <em>C. flaccida<\/em>, and several <em>Cymbidium<\/em> species found in Sikkim and Darjeeling (Pant, 2008). Symptoms in infected plants include chlorotic flecks, necrotic rings, and yellow spotting.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>1.6 Odontoglossum ringspot virus<\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Odontoglossum ringspot virus (ORSV), a <em>Tobamovirus<\/em> from the family <em>Virgaviridae<\/em>, was first identified in <em>Odontoglossum grande<\/em> in the United States (Jenson and Gold, 1951). It later spread to <em>Cymbidium<\/em>, <em>Cattleya<\/em>, and other orchids, causing symptoms such as ringspots, chlorotic streaks, mosaicism, necrosis, and flower variegation (Lawson and Hsu, 1995). In India, the first report of ORSV was on <em>Cymbidium<\/em> species (Sherpa <em>et al<\/em>., 2004, 2006a, 2006b). It commonly co-infects orchids with <em>Cymbidium mosaic virus<\/em> (CymMV), leading to severe symptoms like necrosis and leaf cracking (Navalinskiene <em>et al<\/em>., 2005).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">The virus is characterized by rod-shaped particles measuring 300\u2013318 nm in length and possesses a positive-sense single-stranded RNA genome of approximately 6609 nucleotides (Chang <em>et al<\/em>., 1996). It encodes four proteins: RNA-dependent RNA polymerase (126\/183 kDa), movement protein (33 kDa), and coat protein (18 kDa). ORSV spreads mechanically through contaminated tools and plant contact, with no known insect vectors. Studies indicate low genetic variability among global isolates, suggesting its stable genomic structure (Rao <em>et al<\/em>., 2015). &nbsp;<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>Table 1. List of orchid viruses reported across India and Northeast India<\/strong><\/span><\/p>\n<table width=\"100%\">\n<tbody>\n<tr>\n<td width=\"7%\"><span style=\"color: #000000;\"><strong>Sl. No. <\/strong><\/span><\/td>\n<td width=\"14%\"><span style=\"color: #000000;\"><strong>Family<\/strong><\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\"><strong>Genus<\/strong><\/span><\/td>\n<td width=\"9%\"><span style=\"color: #000000;\"><strong>Genome<\/strong><\/span><\/td>\n<td width=\"25%\"><span style=\"color: #000000;\"><strong>Virus name<\/strong><\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\"><strong>Distribution <\/strong><\/span><\/td>\n<td width=\"16%\"><span style=\"color: #000000;\"><strong>References<\/strong><\/span><\/td>\n<\/tr>\n<tr>\n<td width=\"7%\"><span style=\"color: #000000;\">1<\/span><\/td>\n<td width=\"14%\"><span style=\"color: #000000;\">Bromoviridae<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\"><em>Cucumovirus<\/em><\/span><\/td>\n<td width=\"9%\"><span style=\"color: #000000;\">RNA<\/span><\/td>\n<td width=\"25%\"><span style=\"color: #000000;\">Cucumber mosaic virus (CMV)<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\">Kerala, Sikkim Karnataka,<\/span><\/td>\n<td width=\"16%\"><span style=\"color: #000000;\">Bhat <em>et al<\/em>. (2004), Sharma et al (2005)<\/span><\/td>\n<\/tr>\n<tr>\n<td width=\"7%\"><span style=\"color: #000000;\">2<\/span><\/td>\n<td width=\"14%\"><span style=\"color: #000000;\">Bunyaviridae<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\"><em>Tospovirus<\/em><\/span><\/td>\n<td width=\"9%\"><span style=\"color: #000000;\">RNA<\/span><\/td>\n<td width=\"25%\"><span style=\"color: #000000;\">Groundnut bud necrosis virus (GBNV)<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\">Sikkim<\/span><\/td>\n<td width=\"16%\"><span style=\"color: #000000;\">Pant <em>et al.<\/em> (2019)<\/span><\/td>\n<\/tr>\n<tr>\n<td width=\"7%\"><span style=\"color: #000000;\">3<\/span><\/td>\n<td width=\"14%\"><span style=\"color: #000000;\">Flexiviridae<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\"><em>Potexvirus<\/em><\/span><\/td>\n<td width=\"9%\"><span style=\"color: #000000;\">RNA<\/span><\/td>\n<td width=\"25%\"><span style=\"color: #000000;\">Cymbidium mosaic virus (CymMV)<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\">Sikkim, Darjeeling hills Karnataka and Kerala<\/span><\/td>\n<td width=\"16%\"><span style=\"color: #000000;\">Varma and Ramachandran (1994), <em>Sherpa et al<\/em>. (2003), Bhat <em>et al<\/em>. (2006)<\/span><\/td>\n<\/tr>\n<tr>\n<td width=\"7%\"><span style=\"color: #000000;\">4<\/span><\/td>\n<td width=\"14%\"><span style=\"color: #000000;\">Potyviridae<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\"><em>Potyvirus<\/em><\/span><\/td>\n<td width=\"9%\"><span style=\"color: #000000;\">RNA<\/span><\/td>\n<td width=\"25%\"><span style=\"color: #000000;\">Bean yellow mosaic virus (BYMV)<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\">Kerala, Northeastern states<\/span><\/td>\n<td width=\"16%\"><span style=\"color: #000000;\">Sharma <em>et al.<\/em> (2005)<\/span><\/td>\n<\/tr>\n<tr>\n<td width=\"7%\"><span style=\"color: #000000;\">5<\/span><\/td>\n<td width=\"14%\"><span style=\"color: #000000;\">Potyviridae<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\"><em>Potyvirus<\/em><\/span><\/td>\n<td width=\"9%\"><span style=\"color: #000000;\">RNA<\/span><\/td>\n<td width=\"25%\"><span style=\"color: #000000;\">Vanilla mosaic virus (VanMV)<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\">Kerala and Karnataka<\/span><\/td>\n<td width=\"16%\"><span style=\"color: #000000;\">Bhat <em>et al. <\/em>(2004)<\/span><\/td>\n<\/tr>\n<tr>\n<td width=\"7%\"><span style=\"color: #000000;\">6<\/span><\/td>\n<td width=\"14%\"><span style=\"color: #000000;\">Potyviridae<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\"><em>Potyvirus<\/em><\/span><\/td>\n<td width=\"9%\"><span style=\"color: #000000;\">RNA<\/span><\/td>\n<td width=\"25%\"><span style=\"color: #000000;\">Vanilla necrosis virus (VNV)<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\">Kerala and Karnataka<\/span><\/td>\n<td width=\"16%\"><span style=\"color: #000000;\">Bhat <em>et al.<\/em> (2004)<\/span><\/td>\n<\/tr>\n<tr>\n<td width=\"7%\"><span style=\"color: #000000;\">7<\/span><\/td>\n<td width=\"14%\"><span style=\"color: #000000;\">Potyviridae<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\"><em>Potyvirus<\/em><\/span><\/td>\n<td width=\"9%\"><span style=\"color: #000000;\">RNA<\/span><\/td>\n<td width=\"25%\"><span style=\"color: #000000;\">Calanthe mild mosaic virus (CalMMV)<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\">Sikkim<\/span><\/td>\n<td width=\"16%\"><span style=\"color: #000000;\">Singh <em>et al.<\/em> (2007); Pant <em>et al<\/em>. (2017)<\/span><\/td>\n<\/tr>\n<tr>\n<td width=\"7%\"><span style=\"color: #000000;\">8<\/span><\/td>\n<td width=\"14%\"><span style=\"color: #000000;\">Rhabdoviridae<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\"><em>Rhabdovirus<\/em><\/span><\/td>\n<td width=\"9%\"><span style=\"color: #000000;\">RNA<\/span><\/td>\n<td width=\"25%\"><span style=\"color: #000000;\">Orchid fleck virus (OFV)<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\">Sikkim and Darjeeling<\/span><\/td>\n<td width=\"16%\"><span style=\"color: #000000;\">Pant (2008)<\/span><\/td>\n<\/tr>\n<tr>\n<td width=\"7%\"><span style=\"color: #000000;\">9<\/span><\/td>\n<td width=\"14%\"><span style=\"color: #000000;\">Tombusviridae<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\"><em>Tombusvirus<\/em><\/span><\/td>\n<td width=\"9%\"><span style=\"color: #000000;\">RNA<\/span><\/td>\n<td width=\"25%\"><span style=\"color: #000000;\">Cymbidium ring spot virus (CyRSV)<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\">Sikkim<\/span><\/td>\n<td width=\"16%\"><span style=\"color: #000000;\">Sharma <em>et al.<\/em> (2005)<\/span><\/td>\n<\/tr>\n<tr>\n<td width=\"7%\"><span style=\"color: #000000;\">10<\/span><\/td>\n<td width=\"14%\"><span style=\"color: #000000;\">Virgaviridae<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\"><em>Tobamovirus<\/em><\/span><\/td>\n<td width=\"9%\"><span style=\"color: #000000;\">RNA<\/span><\/td>\n<td width=\"25%\"><span style=\"color: #000000;\">Odontoglossum ring spot virus (ORSV)<\/span><\/td>\n<td width=\"13%\"><span style=\"color: #000000;\">Sikkim, Darjeeling hills<\/span><\/td>\n<td width=\"16%\"><span style=\"color: #000000;\">Sherpa <em>et al.<\/em> (2006a, 2006b)<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: justify;\">&nbsp;<\/p>\n<ol style=\"text-align: justify;\" start=\"2\">\n<li><span style=\"color: #000000;\"><strong> Fungal diseases of orchids: <\/strong>Several fungal pathogens infect orchids, leading to symptoms such as leaf spots, rots, and blights. The most common fungal diseases include:<\/span><\/li>\n<\/ol>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>2.1 Anthracnose<\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Anthracnose, caused by <em>Colletotrichum gloeosporioides<\/em> and <em>C. orchidacearum<\/em>, is a common fungal disease in orchids, characterized by sunken, oval lesions that range from reddish-brown to dark brown or grey. These lesions often appear on leaves, significantly affecting the plant&#8217;s aesthetic value and overall health. The disease thrives in warm, humid conditions, making orchids in greenhouse environments particularly susceptible. Effective management of anthracnose involves removing infected plant parts and enhancing air circulation to minimize moisture levels, which helps prevent the disease from spreading. Regular fungicidal applications of Carbendazim (Bavistin) at 1 g\/L at 10-day intervals have been found effective in controlling the disease and preventing its spread (De <em>et al<\/em>., 2019).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>2.2 Pythium Black Rot <\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Pythium Black Rot, caused by <em>Pythium ultimum<\/em>, is a destructive fungal disease in orchids, primarily affecting seedlings in humid conditions. The disease manifests as blackened leaves that eventually fall off, leading to severe plant deterioration. High moisture levels and poor drainage contribute to its rapid spread. Effective anthracnose management includes removing and destroying infected leaves, reducing irrigation, and relocating plants to a drier environment to limit fungal growth. Additionally, chemical control through fungicidal sprays of Metalaxyl (0.1%) or Mancozeb (0.2%) has been proven effective in managing the disease and preventing further infection (De <em>et al<\/em>., 2019).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>2.3 Heart Rot <\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Heart Rot, caused by <em>Phytophthora palmivora<\/em>, is a severe fungal disease affecting orchids, particularly <em>Cattleya<\/em>, <em>Phalaenopsis<\/em>, and <em>Vanda<\/em> species. The disease is characterized by yellowing of leaves, premature foliage drop, and rotting of pseudobulbs, leading to significant plant decline. High humidity and excessive moisture favour its development, making well-drained growing conditions essential for prevention. Management strategies include the prompt removal and destruction of infected plants (rouging) to prevent disease spread. Additionally, the application of Metalaxyl (0.1%) has been found effective in controlling the pathogen and limiting further infection (De <em>et al<\/em>., 2019).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong><br \/>\n<\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>&nbsp;<\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>2.4 Blossom Blight <\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Blossom Blight, caused by <em>Botrytis cinerea<\/em>, is a common fungal disease affecting orchids, particularly during cool and humid conditions. The disease manifests as numerous dark spots on flower petals, which may enlarge and create a shot-hole effect, reducing the aesthetic value of the blooms. Older flowers are more susceptible to infection, and high moisture levels exacerbate disease progression. Effective management includes maintaining proper air circulation and reducing excessive humidity. Chemical control measures such as spraying Bavistin at 1 g\/L or Indofil Z at 2 g\/L at 7-day intervals have been found to effectively control the disease and prevent further spread (De <em>et al<\/em>., 2019).<\/span><\/p>\n<ol style=\"text-align: justify;\" start=\"3\">\n<li><span style=\"color: #000000;\"><strong> Bacterial Diseases of Orchids: <\/strong>Bacterial infections in orchids often cause soft rots, affecting the pseudobulbs and leaves. The most prominent bacterial disease is:<\/span><\/li>\n<\/ol>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>3.1 Bacterial Soft Rot <\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><em>Erwinia carotovora <\/em>is the causal agent of bacterial soft rot, a highly destructive disease that affects orchids, leading to rapid tissue decay and plant deterioration. The infection begins as small, circular, blister-like dark green spots on the leaves, which rapidly progress into a soft, pulpy rot with a foul odour. High humidity and poor air circulation favour disease development, leading to severe tissue breakdown in the pseudobulbs. To manage the disease, infected plant parts should be removed promptly, and environmental conditions should be adjusted to reduce excess moisture. Chemical control through the application of Streptocycline (0.1%) has been found effective in suppressing bacterial growth and preventing further spread (De <em>et al<\/em>., 2019).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>Conclusion<\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Orchids are among the most economically and ecologically significant flowering plants, with India, particularly the northeastern region, serving as a crucial biodiversity hotspot. Despite their ornamental and commercial value, orchid cultivation faces severe challenges due to various fungal, bacterial, and viral diseases that impact plant health, flower quality, and overall marketability. While numerous studies have documented orchid diseases globally, research efforts in India, especially in Assam, remain limited. A significant research gap exists in Assam, where no comprehensive studies have been conducted on the pathological aspects of orchids. Although diseases affecting orchids have been frequently observed in the region, systematic investigations into their causal agents, epidemiology, and management strategies remain scarce. This lack of detailed research hinders the development of effective disease control measures, leaving orchid growers vulnerable to recurring infections and potential economic losses. Addressing this research gap through systematic investigations and disease management studies is essential for ensuring the sustainable growth of the orchid industry in India.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><strong>References<\/strong><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Bhai, R.S., Thomas, J., Potty, S.N., Geetha, L. and Solomon, J.J. (2003). Mosaic disease of vanilla (<em>Vanilla plantifolia<\/em> Andrews) &#8211; the first report from India. <em>Journal of Spices and Aromatic Crops<\/em>, <strong>12<\/strong>: 80\u201382.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Bhat, A.I., Bhadramurthy, V., Saju, S. and Hareesh, P.S. (2006). Detection and identification of <em>Cymbidium mosaic virus<\/em> infecting vanilla (<em>Vanilla plantifolia<\/em> Andrews) in India based on coat protein gene sequence relationships. <em>Journal of Plant Biochemistry and Biotechnology<\/em>, <strong>15<\/strong>: 33\u201337.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Bhat, A.I., Venugopal, M.N., Pant, R.P. and Bhai, R.S. (2004). Occurrence and distribution of viral diseases of vanilla (<em>Vanilla plantifolia<\/em> Andrews) in India. <em>Journal of Spices and Aromatic Crops<\/em>, <strong>13<\/strong>: 143\u2013148.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Blanchfield, A.L., Mackenzie, A.M., Gibbs, A., Kondo, H., Tamada, T. and Wilson, C.R. (2001). Identification of <em>Orchid fleck virus<\/em> by reverse transcriptase polymerase chain reaction and analysis of isolate relationships. <em>Journal of Phytopathology<\/em>, <strong>149<\/strong>: 713\u2013718.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Boyko, V.P. and Karasev, A.V. (1992). Tombusvirus genome may encode the sixth small protein near its 3\u2019 terminus. <em>Virus Genes<\/em>, <strong>6<\/strong>: 143\u2013148.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Chang, C.C., Wong, S.M., Mahtani, P.H., Loh, C.S., Goh, C.J., Kao, M.C.C., <em>et al<\/em>. (1996). The complete sequence of a Singapore isolate of <em>Odontoglossum ringspot virus<\/em> and comparison with other tobamoviruses. <em>Gene<\/em>, <strong>171<\/strong>: 155\u2013161.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">De, T., De, L.C., Singh, D.R., Roy, A. and Chowdhury, A.K. (2019). Diseases in orchids [Poster]. <em>North Bengal Agricultural University &amp; ICAR-NRC for Orchids.<\/em> Available at: <a style=\"color: #000000;\" href=\"https:\/\/www.researchgate.net\/publication\/338208475\">https:\/\/www.researchgate.net\/publication\/338208475<\/a>.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Dietzgen, R.G., Kuhn, J.H., Clawson, A.N., Freitas-Ast\u00faa, J., Goodin, M.M., Kitajima, E.W., <em>et al<\/em>. (2014). <em>Dichorhavirus<\/em>: a proposed new genus for <em>Brevipalpus<\/em> mite-transmitted, nuclear, bacilliform, bipartite, negative-strand RNA plant viruses. <em>Archives of Virology<\/em>, <strong>159<\/strong>: 607\u2013619.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">DITP News (2015). Tropical Thai orchids are in high demand around the world. <em>Thai Trade Center Los Angeles.<\/em> Available at: <a style=\"color: #000000;\" href=\"https:\/\/chatgpt.com\/c\/www.thailandhorizon.com\">www.thailandhorizon.com<\/a>.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Doi, Y., Chang, M.U. and Yora, K. (1977). <em>Orchid fleck virus<\/em>. CMI\/AAB Descriptions of Plant Viruses (183).<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Erwin, D.C. and Ribeiro, O.K. (1996). <em>Phytophthora diseases worldwide.<\/em> American Phytopathological Society, St. Paul, MN.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Farreyrol, K., Pearson, M.N., Grisoni, M., Cohen, D. and Beck, D.L. (2006). <em>Vanilla mosaic virus<\/em> isolates from French Polynesia and the Cook Islands are <em>Dasheen mosaic virus<\/em> strains that exclusively infect vanilla. <em>Archives of Virology<\/em>, <strong>151<\/strong>: 905\u2013919.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Gallitelli, D. (2000). The ecology of <em>Cucumber mosaic virus<\/em> and sustainable agriculture. <em>Virus Research<\/em>, <strong>71<\/strong>: 9\u201321.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Govaerts, R., Bernet, P., Kratochvil, K., Gerlach, G., Carr, G., Alrich, P., <em>et al<\/em>. (2017). <em>World checklist of Orchidaceae.<\/em> Kew: Facilitated by the Royal Botanic Gardens. 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Occurrence of <em>Cucumber mosaic virus<\/em> on vanilla (<em>Vanilla plantifolia<\/em> Andrews) in India. <em>Journal of Biosciences<\/em>, <strong>30<\/strong>: 339\u2013350.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Navalinskiene, M., Rougalas, J. and Samuitiene, M. (2005). Viral diseases of flower plants 16. Identification of viruses affecting orchids (<em>Cymbidium Sw.<\/em>). <em>Biologia (Lahore, Pakistan)<\/em>, <strong>2<\/strong>: 29\u201334.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Pant, R.P. (2008). Association of <em>Rhabdovirus<\/em>-like particles from <em>Coelogyne<\/em> species from Sikkim and Kalimpong. Annual Report, National Research Centre for Orchids, Pakyong, Sikkim, India, p. 28.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Pant, R.P., Basavaraj, Y.B., Srivastava, N., Bhattarai, A., Kumar, A., Baranwal, V.K., <em>et al<\/em>. (2019). First report of <em>Groundnut bud necrosis virus<\/em> infecting <em>Phalaenopsis<\/em> in India. <em>New Disease Reports<\/em>, <strong>39<\/strong>: 17.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Singh, M.K., Sherpa, A.R., Hallan, V. and Zaidi, A.A. (2007). A potyvirus in <em>Cymbidium s&nbsp; <\/em>&nbsp;in Northern India. <em>Australasian Plant Disease Notes<\/em>, <strong>2<\/strong>(1): 11\u201313.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Uchida, J.Y. (1994). Diseases of orchids in Hawaii. <em>Plant Disease<\/em>, <strong>78<\/strong>: 220\u2013224. doi: 10.1094\/PD-78-0220.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Varma, A. and Ramachandran, P. (1994). Viral diseases of orchids. <em>Journal of Orchid Society of India<\/em>, <strong>8<\/strong>: 15\u201318.<\/span><\/p>\n<p style=\"text-align: center;\"><a href=\"https:\/\/babrone.avfu.ac.in\/blog\/wp-content\/uploads\/2025\/03\/Research-article_Pankaj-Bharali_edited.pdf\">Download PDF<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Dibya Sree Dutta1&amp; Pankaj Bharali1&amp;2 1Biological Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat 785006, Assam, India 2Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India &nbsp; *Corresponding author email: pbharali@neist.res.in\/pankajbharali98@gmail.com Abstract Orchids, a diverse and economically significant plant group, are highly susceptible to fungal, bacterial, and viral diseases, which&#8230;<\/p>\n","protected":false},"author":2,"featured_media":5820,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"footnotes":""},"categories":[1,445],"tags":[],"class_list":["post-5818","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-articles","category-articles32th-issue"],"_links":{"self":[{"href":"https:\/\/babrone.avfu.ac.in\/blog\/index.php?rest_route=\/wp\/v2\/posts\/5818","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/babrone.avfu.ac.in\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/babrone.avfu.ac.in\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/babrone.avfu.ac.in\/blog\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/babrone.avfu.ac.in\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5818"}],"version-history":[{"count":3,"href":"https:\/\/babrone.avfu.ac.in\/blog\/index.php?rest_route=\/wp\/v2\/posts\/5818\/revisions"}],"predecessor-version":[{"id":5824,"href":"https:\/\/babrone.avfu.ac.in\/blog\/index.php?rest_route=\/wp\/v2\/posts\/5818\/revisions\/5824"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/babrone.avfu.ac.in\/blog\/index.php?rest_route=\/wp\/v2\/media\/5820"}],"wp:attachment":[{"href":"https:\/\/babrone.avfu.ac.in\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5818"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/babrone.avfu.ac.in\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5818"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/babrone.avfu.ac.in\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5818"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}