Effect of Storage Temperatures on Potato Virus Infectivity Levels and Serological Detection by Enzyme-Linked Immunosorbent Assay. R. P. Singh, Research Scientist, Agriculture Canada, Research Branch, Research Station, Fredericton, New Brunswick, E3B 4Z7. T. H. Somerville, Technician, Agriculture Canada, Research Branch, Research Station, Fredericton, New Brunswick, E3B 4Z7. Plant Dis. 67:1133-1136. Accepted for publication 20 April 1983. Copyright 1983 Department of Agriculture, Government of Canada. DOI: 10.1094/PD-67-1133.

Leaves infected with potato leafroll virus or potato virus A, S, X, or Y stored at 25, 4, –20, or –70 C produced variable infectivity and serological readings. Freezing at –20 C lowered the A₄₀₅ values in ELISA for all potato viruses tested except PVX. Infectivity levels of PVA and PVY were also lowered at –20 C. Refrigeration of leaves at 4 C or freezing at –70 C preserved the infectivity and serological activity up to 12 days. The lower A₄₀₅ values at –20 C were not due to dilution effect, were not affected by host species, and were similar for stored leaves and expressed sap. Purification of PVY from leaves stored at 4, –20, and –70 C produced the lowest yield of virus at –20 C and the highest at –70 C. Pretreatment of leaves in solutions of 5% yeast extract, 5% bactotryptone, 5% bactopeptone, 10% sucrose, or 10% glycine followed by storage at –20 C partially retained both infectivity and serological activity.