Factors affecting mechanical transmission of Tomato spotted wilt virus to peanut (Arachis hypogaea)

Evaluation of peanut germ plasm for Tomato spotted wilt virus (TSWV) resistance has been slowed by the difficulty in achieving a high rate of mechanical transmission of the virus to peanut. In this study, improvements were made and a highly efficient mechanical transmission protocol was developed. Several factors that affect the transmission efficiency were identified. Use of two antioxidants (sodium sulfite and mercaptoethanol) and two abrasives (Celite and Carborundum) and application of the inoculum by rubbing with a cotton swab dipped in the inoculum as well as pricking with an inoculation needle resulted in a significantly higher transmission rate. The most susceptible growth stage of peanut to TSWV inoculation was 2 to 3 days after germination (6 to 7 days after planting). The inoculation protocol consistently resulted in a higher percentage of infected plants from different sources of inoculum such as infected peanut, tobacco, and tomato.