Manion spiral model

Chronic oak decline

1. 15/12/2017 1 Decline Spiral Model – evolving concepts Bacteria The Decline Spiral Model (Manion, 1981) Decline: Arises from factors that interact sequentially or simultaneously and have a cumulative effect over time. Certain factors may have key roles. Predisposition/altered host condition probably essential. Root health Secondary pests and diseases are of primary importance in causing tree mortality Wargo, 1996