ISHS Acta Horticulturae 657: XIX International Symposium on Virus and Virus-like Diseases of Temperate Fruit Crops - Fruit Tree Diseases
STUDIES ON THE INFLUENCE OF APPLE STEM GROOVING VIRUS ON TREE GROWTH OF VARIOUS APPLE CULTIVARS IN THE NURSERY |
| Authors: | A. Maxim, L. Zagrai, I. Zagrai, M. Isac |
| Keywords: | cultivar, viral infections |
| Abstract:
The studies were conducted within 2001-2002 period and aimed at stressing the influence of Apple stem grooving virus (ASG) on the 2 year old trees in the nursery. The observations were taken with 14 apple cvs.: ‘Auriu de Bistritza’, ‘Dayton’, ‘Florina’, ‘Generos’, ‘Gloster’, ‘Golden delicious’, ‘Granny Smith’, ‘Idared’, ‘Jonathan’, ‘James, Grieve’, ‘Pionier’, ‘Prima’, ‘Starkrimson’ and ‘Wagner awarded’. The artificial inoculations were achieved by double budding in one year old tree field, with MM 106 layers, the upper bud belonging to the cultivar ("virus free" plants) and the lower bud being ASG infected. Each cultivar was included in two treatments: infected and healthy trees (10-16 trees / treatment). Only one ASG isolate from ‘Goldspur’ apple was used. The infections were acknowledged both by DAS-ELISA test and tests on the plant indicators (Chenopodium quinoa and ‘Virginia Crab’ cv.). At the end of growing season, the total tree height and diameter, 50 cm above the grafting union were measured. To compare the results, the data were statistically processed. Following our results one can see that the Apple stem grooving virus has negatively influenced the tree growth in the nursery. The average tree height of the 14 cultivars infected was 23.4% lower and the average diameter 13.7% smaller than in case of healthy trees. The most drastic reduction in tree growth were recorded with ‘Golden delicious’ cv. where the tree height was by 64.4% lower and the diameter by 42.9% smaller than the healthy control. Major reductions in tree height were observed with other varieties as well. ‘Dayton’ (38.5%), ‘Florina’ (36.6%), ‘Jonathan’ (34.9%), ‘Generos’ (33.7%). The most resistant variety to ASG artificial infections proved to be ‘Starkrimson’ cv. which did not show any reduction in tree height and diameter. The tree height was slightly affected in case of ‘James Grieve’ (-7.5%), ‘Prima’ (-9.1%) and ‘Idared’ (-9.3%) cvs. infected versus the healthy trees. All the varieties described have shown foliage symptoms of viral infections like: chlorosis, leaf distortion and a non-specific gloss to the cultivar. All the same the symptom intensity has varied from one cultivar to another. | |
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