Background

This data set is part of a suggested excercise from the APS Education Center Disease Progress Over Time case study on stripe rust (Sparks et al, 2008)

Description

Quoted directly from Sparks et al, 2008:

The effects of disease resistance and fungicide applications on wheat leaf rust disease progress can be evaluated using the AUDPC. Typically resistance is the best way to control foliar diseases in wheat such as stripe rust and leaf rust (caused by Puccinia triticina). The following example, based on field data from Kansas (Sparks and Stack, unpublished), illustrates the difference in disease severity for a variety susceptible to leaf rust, Jagger, and the resistant cultivars 2137 and Cutter. The last sample date was June 3, after which the plants were senescing. Using the methods from previous examples, create a way to compare disease levels on the three varieties of wheat.

Timing is critical if a fungicide application is used to control wheat leaf rust. Typically the assumption can be made that the fungicide will be effective for only two weeks after application, preventing new infections during that time. Label restrictions prohibit the application of a fungicide after flowering has occurred. The critical protection period for wheat is the two weeks after flowering when the head is filling. Loss of photosynthetic area at this time will result in the greatest yield losses. Once this two week period has passed, losses to any new infections are much less severe.