ISHS Acta Horticulturae 472: XVII International Symposium Virus and Virus-Like Diseases of Temperate Fruit Crops
STATUS OF DAPPLE APPLE VIROID IN INDIA |
| Authors: | A. Handa, P.D. Thakur, S.V. Bhardwaj |
| Keywords: | dapple apple, India |
| Abstract:
Apple is cultivated in the provinces of Jammu, Kashmir, Himachal Pradesh, parts of Uttar Pradesh and Arunachal Pradesh of India with an annual production of around 1,000 MT. Among these, Himachal Pradesh has gained the lead in apple production and accounts for a sizeable cultivated area. Routine surveys conducted in apple orchards in the Shimla district revealed the presence of dappling symptoms on fruits with a 2 % incidence in a few orchards. Symptoms appear in mid-July as small circular spots which stand out against the background color on immature fruits. The surface of the spotted areas is somewhat flattened. Dappling symptoms were observed in apple cultivars Starking Delicious, Red Gold and Red Fuji. However, the fruits of Golden Delicious and Yellow Newton developed pigmented areas which turn brown, russetted and scarred with numerous tiny fissures, some of which turned into deep cracks. Affected fruits enlarged more slowly than unaffected ones. The percentage of affected fruits among diseased trees varies considerably. Polyacrylamide gel electrophoresis assay of nucleic acid extracts from the cultivar Starking Delicious showed circular RNA of the same size as that of apple scar skin viroid, which may substantiate the viroid etiology of the disease. However, based on symptomatology, other cultivars have been tentatively identified to be infected by a viroid. Further studies on these cultivars are in progress. | |
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