Psa progression within orchards

Since December 2010, a month after Pseudomonas syringae pv. actinidiae (Psa) was first discovered in New Zealand, the development and progression of the disease has been closely monitored in selected kiwifruit orchards. Initially, little was known about how Psa would behave in the New Zealand environment. Through regular and detailed mapping and monitoring of symptom development within canopies, we aimed to determine whether disease incidence increased during the summer, and if leaf symptoms progressed to cane or trunk symptoms. Further aims included determination of carry-over of disease from one season to the next, assessment of relationships between orchard management practices and disease development, and understanding the relationship between disease progression and climatic conditions.