The scapes have corky lesions. Use rotenone or Sevin. Mites cause the leaves to turn yellow and have a dusty appearance. Heavy infestations form fine webbing. Applications of rotenone control the pest.
Slugs leave a slime trail which looks like part of the leaf was varnished.
Use baits containing Mesurol or metaldehyde. Japanese beetle can be controlled with sprays of methoxychlor, Sevin, or rotenone. This information is for educational purposes only. References to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned. This information becomes public property upon publication and may be printed verbatim with credit to MSU Extension.