Pensasmustikan viljelyä haittaavista tekijöistä Suomessa

Authors

• J. E. Hårdh Puutarhantutkimuslaitos, Piikkiö

DOI: https://doi.org/10.23986/afsci.71476

Abstract

Experiments on blueberry varieties have been carried out since 1947 at the Horticulture Research Institute. Rancocas has been proved to be the hardiest and the highest yielding variety in Finland, so far. June has some resistance against frost, while Pemberton seems to be easily killed by the early frosts (p. 132). In Finland blueberry culture is profitable only in the southernmost parts around the 60th latitude. Farther north the canes are often killed by winter frosts or, if overwintering is good, the berries do not ripen. Of the fungous diseases Blueberry canker (Fig. 1 and 2) is the most serious. Comparison with the Fusicoccum putrefaciens Shear (Godronia cassandrae Peck) isolate received from MCKEEN (1), London, Ont., and inoculation tests showed that in Finland the disease is caused by this fungus. Isolates obtained from the conidia (Fig. 3) and from ascospores produced similar cultures in 90 days on oatmeal agar, on both cultures the only fruiting formations in vitro being the sporodochia. Jersey is the most susceptible variety, Rancocas and Rubel have not shown symptoms of the disease. Leaf spots (Fig. 6) caused by Botrytis cinerea Pers. appear frequently in September, mostly on Burlington, HBS 109, June and Stanley varieties. Atlantic, Kengrape, Pemberton, Rancocas and Scammel do not show these symptoms. Leaf spot of this kind need not be serious because of its late appearance. A virus-like systemic disorder (Fig. 7) occurs on some June bushes. The leaves of a diseased plant show light green mosaic or light green or yellow stripes, the leaves being narrower than normal and often asymmetric. The symptoms are different from those described in the American literature for blueberry viruses. Inoculation tests, using the rubbing method, on young June plants did not produce visible symptoms. In 1957—58 some plants were killed by the vole Arvicola terrestris L. Often Doralis sp. aphids and larvae of Orgyia antiqua L. are seen on the growing tips and on the leaves of blueberry.