Characterisation of phytopathogenic fungi in nursery seedlings of Tectona grandis L.F, Swietenia macrophylla King and Cassia fistula L. In Central Kerala
| dc.contributor.advisor | Gopakumar, S | |
| dc.contributor.author | Kiran Mohan | |
| dc.contributor.author | KAU | |
| dc.date.accessioned | 2020-02-27T10:06:20Z | |
| dc.date.available | 2020-02-27T10:06:20Z | |
| dc.date.issued | 2017 | |
| dc.description | PG | en_US |
| dc.description.abstract | Disease free planting stock significantly ensures a better field survival while at the same time reducing the burden of economic loss. Teak, mahogany and Indian laburnum which are extensively used for afforestation programmes in India are attacked by several fungal pathogens at nursery stage. Hence an investigation was undertaken to identify the fungal diseases associated with above mentioned seedlings in Kerala and also to assess the efficacy of selected fungicides and bio-control agents against these pathogens through in vitro studies. Purposive sampling survey was conducted in eighteen Government tree nurseries of Thrissur (10 nos.) and Palakkad (8 nos.) districts during the summer (February-May), monsoon (June- September) and post monsoon (October-January) seasons for monitoring the occurrence of fungal diseases and collection of diseased samples. Out of the fifteen fungal diseases observed, nine was from teak, two was from mahogany and four was from Indian laburnum seedlings. Fungal diseases observed from teak seedlings included teak leaf blight (TLB), teak leaf spot-1 (TLS-1), teak leaf spot-2 (TLS-2), teak leaf spot-3 (TLS-3), teak leaf spot-4 (TLS-4), teak collar rot, teak root rot-1 and teak root rot-2. In the case of mahogany, mahogany leaf blight-1 (MLB-1) and mahogany leaf blight- 2 (MLB-2) were noticed. Four foliar diseases were observed from Indian laburnum viz., Indian laburnum leaf blight-1 (ILB-1), Indian laburnum leaf blight-2 (ILB-2), Indian laburnum leaf spot-1 (ILS-1) and Indian laburnum leaf spot-2 (ILS-2). TLB was found to be most severe foliar disease in teak and maximum Percent Disease Index (PDI) and Percent Disease Severity (PDS) of 63.50 and 18.72 per cent respectively were recorded from Vellanikkara in Thrissur district. Collar rot (PDI 18%) was observed only from Chettikkulam in Thrissur district. Chittur (Teak root rot-1) recorded maximum PDI of 34.5 per cent. In mahogany, MLB-1 observed from Aatoor recorded maximum PDI (57.50 %) while maximum PDS (10.4%) was recorded from Vellanikkara. In Indian laburnum, ILS-2 observed from Vellanikkara recorded maximum PDI (38.50%) as well as PDS (5.76%). TLB showed positive correlation with temperature while it showed a negative correlation with relative humidity. TLB symptoms originated as small irregular grey to blackish spots surrounded by yellow halo scattered over the lamina. Symptoms of teak leaf spot (TLS-1, TLS-2, TLS-3 and TLS-4) started as small necrotic spots and were generally observed in old, mature leaves. Leaf blights in mahogany (MLB-1 and MLB-2) was characterized by necrotic regions with definite black margin. Leaf blight diseases of Indian laburnum (ILB-1 and ILB-2) were observed as necrotic regions in the tip as well as base of the leaf. Leaf spots (ILS-1, ILS-2) occurred as medium sized spots on the upper surface of the leaf. Pathogenicity of the thirteen isolates was proved by Mycelial Bit Inoculation Method (MBIM) as well as Micro Droplet Inoculation Technique (MDIT). Spore suspension method was adopted for collar and root disease. Cultural as well as morphological characters of pathogens were studied and morphological identification done with the expert advice of National Centre for Fungal Taxonomy (NCFT), New Delhi. Molecular identification of selected pathogen was done at Rajiv Gandhi Centre for Biotechnology (RGCB), Thiruvananthapuram. The causative pathogen in TLB was identified as Curvularia eragrostidis, in TLS-1 as Alternaria alternata, in TLS-2 as Macrophomina phaseolina, in TLS-3 as Botryodiplodia theobromae, in TLS-4 as Colletotrichum gloeosporioides, collar rot pathogen as Alternaria alternata, root rot-1 pathogen as Fusarium solani and root rot-2 pathogen as Fusarium oxysporum. Olevea tectonae was confirmed as the pathogen of teak rust fungus. MLB-1 and MLB-2 were caused by Curvularia geniculata and Alternaria alternata respectively. In Indian laburnum, Alternaria alternata (ILB-1), Colletotrichum gloeosporioides (ILS-1) and Phoma cassiocarpa (ILS-2) were the disease causing pathogens. The identity of obligate parasite causing ILB-2 was also confirmed as Cercospora sp. in vitro evaluation studies revealed that carbendazim 12% + mancozeb 63%, difenoconazole 25EC, carbendazim 50WP to beefficient against teak foliar diseases. Similarly carbendazim 12% + mancozeb 63%, carbendazim 50WP, hexaconazole 5EC showed promising results against collar and root diseases of teak. Carbendazim 12% + mancozeb 63%, hexaconazole 5EC, cymoxanil 8% + mancozeb 64%, propineb 70WP, carbendazim 50WP were observed to be efficient against foliar diseases of mahogany. In Indian laburnum, hexaconazole 5EC, difenoconazole 25EC, carbendazim 50WP, carbendazim 12% + mancozeb 63% were found to be efficient. The fungal antagonist Trichoderma asperellum showed promising results compared to the bacterial antagonist Pseudomonas fluorescens. | en_US |
| dc.identifier.uri | http://krishikosh.egranth.ac.in/handle/1/5810143808 | |
| dc.keywords | Fungal pathogens, TLB(Teak Leaf Blight), Fusarium solani, Phoma cassiocarpa, Curvularia eragrostidis, Alternaria alternata, Macrophomina phaseolina, Botryodiplodia theobromae, Colletotrichum gloeosporioides | en_US |
| dc.language.iso | en | en_US |
| dc.pages | 134 | en_US |
| dc.publisher | Department of Forest Management and Utilisation, College of Forestry, Vellanikkara | en_US |
| dc.sub | Forestry | en_US |
| dc.subject | null | en_US |
| dc.theme | Phytopathogenic fungi in nursery seedlings | en_US |
| dc.these.type | M.Sc | en_US |
| dc.title | Characterisation of phytopathogenic fungi in nursery seedlings of Tectona grandis L.F, Swietenia macrophylla King and Cassia fistula L. In Central Kerala | en_US |
| dc.type | Thesis | en_US |