Impatiens Necrotic Spot Virus

by Dr. Stephen Nameth
The OSU Plant Pathology Department

Impatiens necrotic spot virus (INSV) is the most economically important of the plant viruses associated with greenhouse flower production. The virus was first identified on New Guinea impatiens in the late 1980's and in spite of a variety of control practices implemented by growers, the virus continues to play havoc with the industry. The virus is moved about from plant to plant by the Western Flower Thrips. Symptoms expressed by plants infected with INSV are highly varied and host dependent. Some of the more common symptoms associated with INSV infection are, necrotic (dead) spots on the foliage, black lesions on the stem, ringspots, and oak leaf pattern. Since the symptoms are so varied and in some cases plants may be infected and not express symptoms, having the plant tested for the presence of the virus is necessary for positive identification.

Management practices include monitoring thrips populations with sticky traps and quarantining new or suspect plants material until it can be tested to confirm it's lack of infection.

Fig. 1. New Guinea showing necrotic spots associated with INSV infection.

Fig. 2. Gloxinia with oak leaf symptom.

Fig. 3. Dahlia with ringspot symptom.

Fig. 4. Cyclamen showing concentric rings often associated with INSV infection.

Fig. 5. Begonia infected with INSV.