G1 Blackspot Manager model predicts the maturity and release of ascospores in relation to ascochyta blight on field pea

A simple model, G1 Blackspot Manager, has been developed to predict the seasonal pattern of release of ascospores in relation to ascochyta blight in field pea. The model considers a combination of two weather factors, daily mean temperature and daily total rainfall, to drive progress of maturity of pseudothecia on infested field pea stubble from past crops. Each day is categorised as suitable or not suitable for continuation of the maturation process. The onset of pseudothecial maturity has been found to take place when approximately ten suitable days have occurred. Following the onset of maturity, ascospore release is triggered when daily rainfall exceeds a threshold. The model was satisfactorily calibrated using three datasets from Western Australia. The calibrated model performed well when independently tested with 21 datasets, 17 from Western Australia and 4 from South Australia. It is concluded that G1 Blackspot Manager model has the potential to be used to formulate sowing guides for field pea in southern Australia that minimise the risk of ascochyta blight.