Potato vine killing methods as related to rate of kill, vascular discoloration, and virus disease spread

Summary

The effect of various vine-killing methods on five varieties of potatoes was studied over the 1948–1950 period.

All varieties were killed more easily as they matured. Later-maturing varieties were more difficult to kill than the earlier-maturing.

Of the chemicals used, the dinitros and tar acids gave the most rapid rate of kill, the arsenicals an intermediate rate, and cyanamid a relatively slow rate of kill.

The greatest amount of discoloration occurred in the early-maturing varieties. With the exception of the rotobeater and hand-pulling, those materials or methods that killed the vines most rapidly tended to produce the greatest amount of vascular discoloration. The amount of vascular discoloration produced by vine-killing tended to increase with age of the plants until the plants were maturing rapidly, at which time there was a decline in the amount of discoloration. No appreciable fading or increase in vascular discoloration was detected in tubers during storage of 5 varieties at 37° and 50°F. when examined in November and February. The amount of discoloration did not appear to increase or fade in Irish Cobbler tubers when examined at intervals of one and two weeks after application of the material.

Rotobeating potato vines followed by a chemical spray reduced the spread of the leafroll virus, as compared with rotobeating alone or chemical vine-killing alone.