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UBC Theses and Dissertations

Characterization of cranberry field decline syndrome in British Columbia Someya, Takuhiro


A condition called Cranberry Field Decline (CFD) has affected several cranberry beds in British Columbia, resulting in patches of severely reduced canopy density. To prevent the further expansion of declining patches, early diagnosis of CFD is critical. The symptoms of CFD were characterized by evaluating soil chemistry (pH and redox potential), plant growth (root health, upright density, canopy depth, and yield), and carbohydrate dynamics (Starch, glucose, fructose, and sucrose) in relation with the three levels of CFD development (declining, transitional, and normal) in four affected beds. For the carbohydrate analysis, it was hypothesized that starch content in stems (S_Sta) was different among the CFD development. Additionally, the effectiveness of sanding in beds for rehabilitating stressed vines was evaluated by measuring the growth characteristics under three levels of sand depth (0, 1.3, and 2.5 cm). The characterization of CFD showed no clear relationship between pH or redox potential and CFD development. Shoot density and growth did not change significantly, while lower canopy depth and root health constantly declined in the early phase of CFD development. However, all growth parameters sharply declined after the transitional condition. Starch content in stems declined from normal to declining areas, supporting the hypothesis. Hexose (sum of glucose and fructose) in uprights (U_Hex) to S_Sta ratio increased with the increasing severity of CFD. The results suggest that the stress-induced alteration of carbohydrate allocation under carbon deficiency may explain the changes in canopy structure in CFD-affected areas. Sanding at 2.5 cm significantly increased total upright density compared to control but slightly decreased yield. However, such impact was only seen in a bed with poor root health and deep brown canopy, suggesting the effect of sanding is influenced by bed condition.

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