Herbicide injury to tomato.

Once affected, there is little you can do. You cannot wash the chemical off your plants. Once you see curling, the chemical has been absorbed into the plant, including the harvested portions.

Then you are faced with the inevitable question as to whether or not the produce is safe to eat.

There are no easy answers here. It depends on the concentration, toxicity and persistence of the chemical. As the summer progresses, the herbicide concentration may decline, but the chemical can still be there. Laboratory tests are valuable; however, these tests are very expensive and not readily available.

Acute poisoning from vegetables affected with herbicide drift is unlikely, but long-term effects such as developing cancer are difficult to assess (Masiunas, 2012). It makes sense to minimize our exposure to toxic chemicals and not to consume herbicide-tainted vegetables.

Avoid spraying herbicides when your garden is growing. 

Do not use lawn clippings or straw unless you know the history of their exposure to herbicide. In most cases, lawns should be mowed at least three times before using the clippings for mulch.

Written by Tom Kalb, Extension Horticulturist, North Dakota State University (NDSU). Photo courtesy of Julie Kramlich, Extension Agent, NDSU. 
Source: Masiunas, J. 2012. As cited in: What should you do with fruit and vegetables after pesticide drift? Penn State Extension: University Park.