Tobacco Mosaic Virus (TMV) is a plant disease that can infect over 300 different species of plants. This disease was recently reported to be causing severe problems in the U.S. greenhouse industry, specifically on petunias.
Like most plant viruses, TMV multiplies only in living plant hosts, but TMV can also survive in dead plant tissue, worker’s hands, and pruning tools. As a result, TMV can be spread very easily and become a serious problem for greenhouse growers. Unfortunately, TMV-infected plants cannot be cured; infected plants must be removed and destroyed along with tags, pots, potting soil and trays. Control for this disease depends on preventing transmission by discarding infested plants and disinfecting potentially-contaminated tools, equipment and surfaces such as bench tops.
TMV-infected petunias can be difficult to identify as symptoms caused by the virus can be very different. The most common symptom caused by TMV is yellow mottling or mosaic patterns on leaves, but infected plants can have less obvious symptoms such as stunted growth or yellowing leaves that could be confused with a nutrient deficiency. Other symptoms include distorted growth or lesions on leaves. For some great pictures showing some of TMV symptoms please see Michigan State University Extension news release from January 12, 2014.
Home gardeners are urged to use extreme caution when purchasing petunias this spring. Do not purchase plants that show symptoms of mottling or leaf deformation. Isolate newly purchased petunias from other susceptible hosts such as tomatoes, peppers, snapdragons and marigolds. Promptly remove all symptomatic plants from the garden to slow the spread of the disease and wash hands and decontaminate any tools used in the process.
Virus symptoms can vary with the species of plant affected and environmental conditions. However, avoid purchasing plants with yellow mosaic or mottling on the leaves as seen on this petunia.