OCCURRENCE, ETIOLOGY AND EPIDEMIOLOGY OF ALTERNARIA LEAF BLOTCH OF APPLE IN HIMACHAL PRADESH

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dc.contributor.advisorNeelam Kumari
dc.contributor.authorOshin Saini
dc.date.accessioned2024-02-23T16:34:24Z
dc.date.available2024-02-23T16:34:24Z
dc.date.issued2023-11-29
dc.description.abstractThe present investigation titled, “Occurrence, Etiology and Epidemiology of Alternaria Leaf Blotch of apple in Himachal Pradesh" was carried out in laboratory and experimental farm of Department of Plant Pathology and Department of Fruit Science, Dr YS Parmar University of Horticulture and Forestry, Nauni, Solan (HP)-173 230 during 2022-2023. Periodic surveys were conducted in different apple growing areas of Kinnaur, Shimla, Mandi, Kullu and Solan districts of Himachal Pradesh. In the year 2022 and 2023, the disease incidence and severity was most prevalent in Jubbal of Shimla district. Symptoms of Alternaria leaf blotch appeared as reddish brown necrotic spots with dark purplish borders on the leaves. Dark brown to black lesions also appeared on petioles and mid ribs causing yellowing and defoliation. A total of 19 isolates were collected from different apple growing areas of Himachal Pradesh. Cultural characteristics revealed that isolates varied in colony type, colour, margin and pigmentation. Colony colour varied from light to dark olivaceous and colonies were velvety to cottony with regular to irregular margins. Morphological characteristics revealed that maximum conidial length was observed in Isolate 11 (32.95-51.54 μm) and minimum was observed in Isolate 16 (14.25-25.30 μm). Maximum conidial breadth was observed in Isolate 8 (8.65-14.55 μm) and minimum was observed in Isolate 12 (6.49-9.58 μm). Conidial septation varied from 1-9. Maximum conidiophore length was observed in Isolate 17 (22.17-50.46 μm) and minimum was observed in Isolate 7 (28.07-35.32 μm). Conidiophore breadth ranged from 3.73-5.62 μm to 2.97-3.15 μm. Conidiophore septation ranged from 0-9. Phylogenetic analysis revealed the homology of 13 isolated Alternaria sp. isolates with Alternaria alternata, A. tenuissima, A. arborescens, A. brassicae and A. alstroemeriae. Phylogenetic tree depicted that most isolates were closely clustered to Chinese isolates deposited earlier in the NCBI. Pathogenicity test for all isolates was carried out by ‘Detached leaf technique’ and all isolates were found pathogenic. From the screening of 11 apple cultivars, none of the cultivar was found to be moderately resistant or resistant to the disease. During epidemiological studies, relative humidity was found positively correlated with disease severity in the year 2022 and 2023. Temperature above 24℃, relative humidity 70-80 % and high rainfall favoured the disease development
dc.identifier.urihttps://krishikosh.egranth.ac.in/handle/1/5810207107
dc.keywordsETIOLOGY AND EPIDEMIOLOGY
dc.keywordsALTERNARIA LEAF BLOTCH OF APPLE
dc.language.isoEnglish
dc.pages53+iv
dc.subPlant Pathology
dc.themeOCCURRENCE, ETIOLOGY AND EPIDEMIOLOGY OF ALTERNARIA LEAF BLOTCH OF APPLE IN HIMACHAL PRADESH
dc.these.typeM.Sc
dc.titleOCCURRENCE, ETIOLOGY AND EPIDEMIOLOGY OF ALTERNARIA LEAF BLOTCH OF APPLE IN HIMACHAL PRADESH
dc.typeThesis
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