See:
Greenhouse Plants, Ornamental - Impatiens Necrotic Spot
Cause Several viruses and virus-like diseases of unknown etiology are known on peony including tobacco rattle virus, (formerly known as peony ringspot virus or peony mosaic virus) nematode vectored by genera Trichodorus and Paratrichodorus and reported from Washington and Alaska and tomato spotted wilt virus, which is thrips vectored. Citrus leaf blotch virus has been found in peony grown in Oregon but was not associated with specific symptoms.
Alfalfa mosaic virus has been found Italy while cucumber mosaic virus has been reported in France.
The unknown or unspecified problems include peony leaf curl (graft transmissible and found by the OSU Plant Clinic), Le Moine disease, and crown elongation or witches' broom. Few if any works separate the various symptoms and possible viruses involved. Cycas necrotic stunt virus, lychnis mottle virus, and several other viruses have been found in plants with Le Moine disease but their association with the disease is still unknown. Le Moine disease may be the result of a combination of certain viruses.
Symptoms Both ringspot and tomato spotted wilt have a wide enough range of symptoms that they could easily be confused.
Ringspot-Circular areas consisting of concentric bands of alternating dark and light green develop on the leaves. At times, small necrotic spots also form. Yellow mosaic, mottling, banding, or blotching can also occur. Plants are not dwarfed. Cultivar and environmental conditions can influence symptom expression.
Leaf Curl-Plants are half normal height with crooked flower stalks and curled leaves.
Tomato Spotted Wilt-Both line patterns and yellow-green mosaics.
Le Moine-Dwarfed plants with spindly shoots, which fail to bloom. Roots are elongated and irregularly swollen with few feeder roots. Cross sections of the roots show yellow inclusions in the swollen portions.
Crown elongation-Numerous elongated crowns and slender weak shoots (witches' broom).
Cultural control
- Select and plant only virus-tested (and found to be free of all known viruses) stock.
- Control nematode vectors.
- Remove and destroy infected plants.
References Robertson, N.L., Brown, K.L., Winton, L.M., and Holloway, P.S. 2009. First report of tobacco rattle virus in peony in Alaska. Plant Disease 93:675.
Shaffer, C., Vakić, M. and Tzanetakis, I. E. 2021. First report of amazon lily mild mottle virus in peony in the United States. Plant Disease, 105:236.