Buy the 2015 Old Farmer's Almanac!
At potato harvest, they areAt potato harvest, they are killing the vines to terminate the growth of the tubers to control their size and set their skin which reduces bruising during harvest. This process also reduces insect issues and disease. They are probably applying an herbicide to help vine kill which is best applied at dusk with high volumes of water. This allows the product to penetrate the leaves and stems before being activated by the sunlight the following day. Hope this helps answer your questions!

2015 Garden Calendar2015 Weather Watcher's Calendar2015 Recipes Calendar2015 Engagement Calendar 2015 Everyday Calendar2015 Country CalendarNew Year Cross StitchLobster Rope Doormats