ABSTRACT
Plant virology is one of the most dynamic research areas in phytopathology. During the last quarter of the 20th century, our understanding of plant viruses and their pathogenic mechanisms has exceeded the imagination of early virologists. Today, new plant viruses are identified rapidly and our awareness of their pathological impact continues to increase. This impact is most clearly seen in yield and other economic losses. Plant viruses generate economic loss for farmers, producers, and consumers by adversely affecting plant growth and reproduction; causing death of host tissues and plants, sterility, reduction of yield or quality, crop failure, increased susceptibility to other stresses, loss of aesthetic value, quarantine and eradication of infected plants; and increasing the cost of control and detection programs (Waterworth and Hadidi, 1998). Viruses are also unique in the deceptive simplicity of their structure. However, this simplicity leads to a greater dependency on the host and a highly intricate relationship exists between the two. This complicates strategies for control of plant viruses and the losses caused by them. Control programs depend on our understanding of the virus-host relationship, and control remains one of the greatest challenges for the future of plant virology.
