A declining pachysandra (Japanese Spurge) was submitted to the U of I Plant Clinic and examined for all problems. There were no signs of disease on the foliage and the roots.
After reading some of the information included with this sample, I suspected that the main problem was that this plant was receiving too much sun. According to the following website: http://counties.cce.cornell.edu/oneida/home%20garden/Annual%20&%20Perennial%20FLOWERS/perennials/Pachysandra.pdf
spurges are particular about their growing sites so select a good site
carefully. They will not grow well in full sun or in poorly drained
If too much sun is a problem, you may want to try to transplant it to a better location that suits its growing needs.
Unfortunately, a "stressed" plant can lead to disease and pests! I found some scale ( Oystershell Scale - Lepidosaphes) on
the stems of these plants, but I do not think this is the main problem.
When people see pests, they jump to conclusions and assume that they are the problem! Well, if the plant is stressed from not being planted in the proper site, pests like these scales, could become a full blown infestation.
the following website: http://landscapeipm.tamu.edu/ipm -for-ornamentals/susceptibles/
"The first line of defense against insect and mite pests of ornamental
landscape plants is to select adapted plants that are not known to
develop perpetual pest problems. Plant ornamental plants in suitable
locations and care for them properly to avoid plant stress conditions."