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Abstract
Fresh strawberries are currently a $9 million winter export crop from Israel. Strawberries occupy 400 ha, mainly along the coastal plain between Haifa and Tel Aviv. Following October planting on methyl-bromide-fumigated soil, fruit production begins in late November in plastic tunnel culture. Exports drop off after mid-April, and 75% of the 14,000 MT crop is then consumed locally, mostly in the fresh market, until the plants are plowed out, at the onset of hot weather in June. ‘Fresno’, ‘Tioga’, and an Israeli cultivar similar to ‘Aliso’ are the major cultivars. ‘Nurit’, a new, early Israeli cultivar, now occupies 10% of the crop area.
Abstract
Propagules of ‘Thornless Oregon Evergreen’ blackberry (Rubus laciniatus Willd.) were obtained from mother plants grown at 37°C for 3 to 8 months. Subsequent field performance indicated that the number of floricanes per plant and the number of fruit per fruiting lateral of these propagules were not influenced by the length of the heat-exposure period. A subclone of this cultivar that has been heat-treated for 245 days and is free of known viruses is being released as ‘Thornless Oregon Evergreen-80’.
Abstract
A sterility disorder (DSD) of ‘Darrow’ blackberry, a common problem in this cultivar in the eastern United States, causes partial to almost complete sterility without visible damage to other floral or vegetative parts. DSD withstands prolonged heat treatment in the plant, even when followed by shoot apex culture. DSD was not graft-transmissible by petiole insert leaflet grafting from known sterile ‘Darrow’ plants to healthy ‘Darrow’ or healthy ‘Marion’ blackberry plants. DSD is stable in symptom expression in varying environments and remains during various types of vegetative propagation. Therefore, the cause of DSD seems likely to be of genetic origin. A new disease agent, Alpine mosaic agent, was found in this study that is symptomless in ‘Darrow’ blackberry but causes mosaic symptoms in leaflets of Alpine strawberry leaflet-grafted from certain ‘Darrow’ clones, both sterile and fruitful. Its identity and economic importance are unknown.
Abstract
Small explants from four clones of red raspberry (Rubus idaeus L.) obtained from heat treatment (8 weeks at 37°C) to eliminate viruses were successfully regenerated in vitro using major Anderson’s medium with 1/4 strength levels of Murashige and Skoog major salts.
Abstract
The incidence of viruses in strawberry runner plants from 3 test plantings in Oregon varied by cultivar; incidence was greatest near the center of the major strawberry producing area of Oregon (Aurora) and was less in north-central Oregon (Hermiston) and in southern Oregon (Roseburg), where few strawberries are grown. Runner plants harvested from Aurora, Hermiston, and Roseburg plots in April 1970 were planted at Aurora in a comparative-yield trial with commercial nursery stocks from California, Oregon, and Washington. During the first year there were no significant differences in fruit production or in runner production among the sources of a particular cultivar planted at the same time at Aurora. However, during the second fruiting year, ‘Hood’ stock from Aurora yielded significantly less than some other ‘Hood’ stocks. We conclude that the Hermiston and Roseburg areas in Oregon can produce strawberry-nursery stock of the same quality with respect to virus incidence as other isolated areas now used for this purpose on the Pacific Coast.
During this study, virus incidence in daughter plants varied markedly from year to year in consecutive annual plantings of indexed plants at a given location. The number of runner plants produced, however, was not significantly correlated with the virus incidence in these runner plants over the 3-year period of the test.