How to Manage Pests
UC Pest Management Guidelines
SYMPTOMS AND SIGNS
Symptoms on plants infected with Tobacco mosaic tobamoviruses and other tobamoviruses vary with specific viruses or strains, and depend on the temperature, light intensity, day length, and age of the plant. Symptoms can include necrosis on any plant part, defoliation, leaf distortion, and mosaic symptoms on leaves, stems, and fruit.
COMMENTS ON THE DISEASE
An important source of primary inoculum is contaminated seed. The virus is carried on the seed coat, and thus can be removed from contaminated seeds by washing seed with dilute solutions of tri-sodium phosphate. The tobamoviruses on pepper are readily spread mechanically within the field by handling and mechanical damage to plants, but not by insect, nematode or fungal vectors.
The tobamoviruses are very stable viruses. They can survive in plant debris for many years.
The best control is to use seed that has been treated to eliminate the seedborne inoculum. Minimizing plant handling and damage also is important for reducing field spread of tobacco mosaic virus. Good sources of plant resistance genes (L1-L4 genes) to various tobamoviruses also exist and are present in commercially available cultivars. No chemical strategies are effective.
UC IPM Pest Management Guidelines:
S. T. Koike, UC Cooperative Extension, Monterey County
Acknowledgment for contributions to Diseases:B. W. Falk, Plant Pathology, UC Davis