ISHS Acta Horticulturae 472: XVII International Symposium Virus and Virus-Like Diseases of Temperate Fruit Crops
BUMPY FRUIT AND OTHER VIROID AND VIROID-LIKE DISEASES OF APPLE IN HP, INDIA |
| Authors: | M.K. Behl, D.B. Parakh, S.M.P. Khurana |
| DOI: | 10.17660/ActaHortic.1998.472.83 |
| Abstract:
Routine inspections at some of Kotgarh and Rohru apple orchards in Himachal Pradesh (H.P.) recently revealed the presence of a serious disease in some trees of cv. ‘Golden Delicious’. It was diagnosed as “bumpy fruit” (BF) on account of the bumps observed on the fruits. Perceptible symptoms of BF were also confined only to the fruits while the trees usually lacked vigor, bear scarce foliage and only fewer fruits on each branch. Initially the fruit surface developed depressions, at times including a “false-sting”, which became prominent with bumps upon fruit maturity even though the fruit neither gained much size nor changed in color as compared to the fruit on healthy trees. Infected trees also had some fruits which, at maturity, showed hard wart-like swellings with or without wedges or cracking of varying patterns. The fruits grew slowly in the latter part of the season. Apparently the fruit quality (sweetness and storage life) was also affected. The disease incidence is low at present (0.1–1.6%) yet some growers suggested it to be on the increase. The transmission appears mainly to be due to mechanical injury and grafting. A common symptom observed for both dapple apple and bumpy fruit diseases is the initial appearance of dark green spots on young fruits. There may be differences between symptoms on different cultivars yet occurrence of strains of the pathogen can not be ruled out. RT-PCR assays performed on the samples at Beltsville, using apple scar skin viroid (ASSVd) as a control, revealed that the pathogen associated with the disease is a variant of ASSVd. Further investigations are underway to determine the sequence homology of BF isolate vis-à-vis known strains of ASSVd. | |
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