If you want to put plants back in the same place, remove a few shovels of the contaminated soil and replace with new soil. If you use manure in peony beds, mix it thoroughly with the soil around the clumps. Lemoine Disease Lemoine disease is a root disease. Its cause is not known. Infected plants do not produce flowers.
Shoots are weak.
Small knobby swellings appear on the small roots, and soft yellow areas appear on the large roots. QDig up and burn infected plants. Root Knot Root knot, or root gall, is caused by nematodes. Nematodes are tiny worms that feed on many kinds of plants. They are most damaging where winters are mild, where the growing season is warm, and where the soil is light.