VIEW ARTICLE

Factors Critical to Mechanical Transmissibility of Wheat Spindle Streak Mosaic Virus. J. T. Slykhuis, Research Scientist, Research Station, Research Branch, Agriculture Canada, Ottawa, Ontario K1A 0C6; Phytopathology 65:582-584. Accepted for publication 18 December 1974. DOI: 10.1094/Phyto-65-582.

The infectivity of wheat spindle streak mosaic virus in extracts prepared by grinding 1 g leaves of diseased wheat in 3 ml of water was lost in 1 hour at 20 C and in 8-24 hours at 10 C. Extracts similarly prepared in 0.5 M sodium borate (pH 9.0), 0.1 M potassium phosphate (pH 7.0), or 0.1 M Na₂SO₃ were still infectious after 1 hour at 35-40 C, or 3-4 days at 10 C. The virus was more readily transmitted from leaves than from roots of diseased wheat plants, and from the older, severely chlorotic leaves with islands of necrotic tissue than from the younger leaves with light green mosaic. Transmissibility from diseased plants was greatly reduced or lost in one week at temperatures of 20 C or higher, but diseased plants kept 6 weeks at 20 C or 25 C regained transmissible virus during a further 4 weeks at 10 C. Susceptibility to mechanically-transmitted virus was very low in wheat plants grown outdoors at Ottawa in September or October, and was reduced in greenhouse-grown plants by transplanting, rubbing with Carborundum, growing under very high or very low light intensity, or by allowing them to wilt from insufficient moisture before inoculating.