ORCHARDIST-OBSERVED PREVALENCE OF SYMPTOMS OF KIWIFRUIT BACTERIAL CANKER DISEASE IN 'HAYWARD' KIWIFRUIT BLOCKS IN NEW ZEALAND
In November 2010 a virulent strain of Pseudomonas syringae pv. actinidiae (Psa) biovar 3, the cause of bacterial canker in kiwifruit, was first recorded in New Zealand. The disease caused by this pathogen is commonly referred to as Psa-V in New Zealand. Initially the impacts of Psa-V were most severe in the gold-fleshed kiwifruit cultivar Hort16A (Actinidia chinensis). More recently there have been reports of symptoms affecting the green-fleshed cultivar Hayward (A. deliciosa). In 2013 a study was undertaken of Psa-V in Hayward orchards to investigate relationships between disease expression observed by orchardists and environmental, management and vine-related factors. This paper presents initial results from that study on the Psa-V symptoms observed in the field by orchardists. Questionnaires sent to the owners of 1669 randomly selected Hayward blocks from different orchards were returned for 26.4% (442/1,669) of the blocks and 430 of these were suitable for analysis. Eighty-four percent (363/430) of respondents reported observing Psa-V symptoms in the selected block between March 2012 and February 2013. The most common symptom reported on female vines was leaf spot (76%), cane die-back (31%) and green shoot wilting (30%). In the same blocks the most common symptoms reported on male vines were leaf spot (70%), cane die-back (46%), red exudate (39%), and green shoot wilting (32%). Bud drop was reported from 41% of female vines and 33% of male vines, although this symptom can be caused by other pathogens. Although these results indicate a high prevalence of severe Psa-V symptoms in Hayward blocks, most growers reported low numbers of vines being affected within the blocks.
Froud, K., Cogger, N., Beresford, R. and Clark, G. (2015). ORCHARDIST-OBSERVED PREVALENCE OF SYMPTOMS OF KIWIFRUIT BACTERIAL CANKER DISEASE IN 'HAYWARD' KIWIFRUIT BLOCKS IN NEW ZEALAND. Acta Hortic. 1095, 45-48
Actinidia deliciosa, 'Hayward', cohort, questionnaire, observational study