|Carter, John - UNIV. OF MINNESOTA|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 1999
Publication Date: N/A
Interpretive Summary: Black currant plants can be attacked by the gooseberry mite. Some plants can become heavily infested; others remain uninfested even though mites are nearby. We wanted to see if the mites decreased the ability of the black currants to survive cold winter temperatures. We froze some infested and non infested black currant branches in the laboratory. We visually rated the damage to the branches after this freezing.Two types of black currants 'Blackdown' and 'Risager' are usually less hardy than the cultivars 'Brodtorp' or 'StorKlas.' The lightly mite-infested 'Blackdown' and 'Risager,' however, survived lower temperatures than did the heavily mite- infested 'Brodtorp' or 'StorKlas.' Other sources of uninfested 'Brodtorp' and 'StorKlas' survived much colder temperatures than did the mite-infested counterparts. Our statistical procedure indicated that the heavy mite- infested plants were 10 degrees C (about 5 degrees F) less hardy than the uninfested plants.
Technical Abstract: Black currant, Ribes nigrum L., cultivars with heavy, light, and no gooseberry mite (Cecidophyopsis grossulariae Collinge) infestation levels (MIL) were tested for cold hardiness by visually determining the bud injury rating (BIR) after laboratory freezing in Jan., 1998. Lightly mite-infested R. nigrum L. cvs. Blackdown and Risager, usually thought of as less cold hardy than Nordic cultivars, survived -35oC while mite-infested buds of th Finnish R. nigrum cv. Brodtorp were injured at -35oC. Heavily mite- infested buds of the Swedish R. nigrum L. cv. StorKlas from Corvallis, OR, were injured at -20 while lightly infested buds were injured at -25oC. Uninfested 'StorKlas' buds from PA and B.C. survived laboratory freezing of -35oC. Heavy mite infestation lowered the bud cold hardiness of 'Brodtorp' and 'StorKlas' by 10oC, as estimated by a modified Spearman-Karber T50, in contrast to the hardiness of lightly mite-infested buds of these cultivars. .Black currant buds with heavy mite infestation contained unusual tissues forming what appeared to be spherical blisters or eruptions, about 100 microns in diameter. Other tissues in the region of heavy mite infestation appeared more turgid than their uninfested counterparts. Abiotic and biotic stresses can have a combined impact on field-grown black currants.