What is eating my peonies?

Asked September 8, 2018, 2:25 PM EDT

I know what it is not. It is not slugs, as I have seen what slugs do to hostas, making them lacy and bare between veins. This is big chunks taken out of the edges of the leaves starting right after bloom is over. This is the second summer. How can I stop it from happening again?

Jefferson County Colorado

1 Response

The leaf notching damage that you see on the peonies is caused by a root weevil. At this time of year, treatment should be targeted at the larvae in the soil below the plants as described in http://extension.colostate.edu/docs/pubs/insect/05551.pdf:

Larvae develop in the soil and require different treatment. The systemic insecticide imidacloprid can provide some control and is used as a drench to the soil so that it moves to the root zone. A biological control alternative are insect parasitic nematodes of the genus Heterorhabditis. (See fact sheet 5.573, Insect Parasitic Nematodes.) Treatments should be made in late spring and early summer when adult feeding on leaves is observed and egg hatch usually begins. Both imidacloprid and Heterorhabditis nematodes require that the soil be kept moist following application and the site should be irrigated immediately after application

Best regards,