STUDIES ON POTATO VIRUS DISEASES
Authors: SMITH KENNETH M. 
Published: February 2008

Summary.

Experiments are described on the transmission by different methods of two potato viruses, crinkle on Myatt's Ashleaf potato, and interveinal mosaic on President potato.
The virus of potato crinkle was transmitted by needle scratch to President, Arran Victory and Great Scot potatoes. President developed a mosaic mottling, Arran Victory a crinkle similar to that shown by the source of infection, while Great Scot developed crinkle, together with numbers of streak lesions on the leaves. Negative results were obtained with Big Ben and Up‐to‐Date.
Attempted transmission of the crinkle virus by means of the aphis M. persicae to potato varieties, President, Arran Victory, Great Scot and Kerr's Pink, was successful only with President, which developed a crinkle of a mild type.
Crinkle scions were grafted on to healthy President, Arran Victory, Great Scot and Kerr's Pink. The first two developed crinkle in a form comparable to the source of infection; Great Scot developed a severe streak which attacked the growing points; there was little or no crinkling; Kerr's Pink showed streak lesions accompanied by mottling.
Needle inoculation of tobacco with the crinkle virus produced a severe necrotic disease, which increased in virulence by progressive needle inoculation through tobacco. When this virus was returned to healthy potatoes of nine different varieties, including Up‐to‐Date which is capable of “carrying” streak, all nine varieties developed a severe crinkle and leaf‐drop streak. Big Ben was the most‘ susceptible and was killed in very case.
Aphis (M. persicae) inoculation of tobacco with the same crinkle virus produced different symptoms from those of the needle; these consisted of spots and faint green lines. When this virus was returned to healthy potato by aphis or needle, crinkle and leaf‐drop streak resulted.
Needle inoculation of Datura stramonium with the crinkle virus produced a well‐marked mottling of light and darker green; when this disease was returned by needle to President potato, a mosaic mottling only resulted.
The virus of interveinal mosaic on President potato was transmitted by M. persicae to healthy President; negative results were obtained with Arran Victory.
The virus of interveinal mosaic was found to be transmissible by the needle to healthy President.
Interveinal mosaic was transmitted by grafting to President, Arran Victory and Great Scot. President showed interveinal mosaic only. Arran Victory showed interveinal mosaic together with numerous streak lesions, while Great Scot developed a form of leaf‐drop streak.
The virus of interveinal mosaic, when transmitted to tobacco by the needle, produced a well‐marked ringspot. When this was returned to potato by needle, interveinal mosaic developed, with the addition of streak lesions and marked curling and distortion of the leaves. Progressive inoculation through tobacco of the ringspot induced by interveinal mosaic gave an increased virulence. When this virulent virus was returned to healthy potato by needle, a severe form of streak resulted, which obscured the symptoms of interveinal mosaic.