This record is most useful in the logic updating process done by the expert as new knowledge is acquired. The pest management modules alone represent 135 dependency networks. For example, the 'severe' disease potential goal is described in a network as two situations which are shown as lines drawn from the 'and' statements. One situation which describes the 'severe' goal is shown by the darker lines. The network describing the severe goal is relatively simple, involving only two distinct situations.
Some networks have many individual situations to be displayed.
The difference in the number of goals for powdery mildew versus apple scab reflects the lower impact of powdery mildew as an apple pathogen in Pennsylvania orchards. The factors which describe the powdery mildew goals are phenology, cultivar susceptibility and disease severity this season or last. In the orchard profile the grower is asked to indicate the level of mildew in the orchard. The grower is asked for last year's severity if the current phenology is prior to pink and for this year's severity if it is later than the pink phenological stage. An example of a situation with a high powdery mildew potential would occur from the tight cluster to second cover phenological stage, high cultivar susceptibility and more than one terminal per tree showing mildew symptoms.