Hi, Anna, the first question that comes to mind is, Are you rotating the crop or planting sweets in the same soil/plot year after year? Planting the same thing in the same place year after year leads to reduced harvest over time. The “ant” might be the sweet potato weevil (it looks like an ant) and digs into the tubers (filling crevices with fecal matter—big yuck!) creating bacteria and decay. There are other sweet potato pests, too—banded cucumber beetle (yes, “cucumber”), wireworms, silverleaf whitefly…but they do not look like ants.
So it you want to grow sweets next year, make a new bed and fill it with new soil (we would put it several feet or as far away from the other bed as possible), plant something else in the old bed (see this page for suggestions, based on crop rotation http://www.almanac.com/video/how-rotate-your-vegetable-crops ) and, if you can (given how late it is in season) consider growing a cover crop now in the old/sweets bed (see advice for cover crops here: http://www.almanac.com/content/cover-crops-us)
Hi, Anna, the first question that comes to mind is, Are you rotating the crop or planting sweets in the same soil/plot year after year? Planting the same thing in the same place year after year leads to reduced harvest over time. The “ant” might be the sweet potato weevil (it looks like an ant) and digs into the tubers (filling crevices with fecal matter—big yuck!) creating bacteria and decay. There are other sweet potato pests, too—banded cucumber beetle (yes, “cucumber”), wireworms, silverleaf whitefly…but they do not look like ants.
So it you want to grow sweets next year, make a new bed and fill it with new soil (we would put it several feet or as far away from the other bed as possible), plant something else in the old bed (see this page for suggestions, based on crop rotation http://www.almanac.com/video/how-rotate-your-vegetable-crops ) and, if you can (given how late it is in season) consider growing a cover crop now in the old/sweets bed (see advice for cover crops here: http://www.almanac.com/content/cover-crops-us)
We hope this helps!