From NPR:

The Japanese government is asking people not to eat spinach, parsley and other produce grown near the damaged power plant because some is tainted with radiation. Dairy farmers are also dumping their milk, and drinking water has been a problem in some locations, including — briefly — Tokyo.

But the biggest impact following the nuclear disaster has been in the region where these foods are produced. One might expect that reports of food contaminated with radiation would create panic in Japan, but step into the Ecos grocery store in Ibaraki prefecture, and nothing seems to be amiss.
Produce manager Kenki Utsuno is restocking the shelves with a leafy green called komatsuna. Even though this region has been hit with traces of radiation, the shelves here are full of cabbage, radishes, many different types of mushrooms, even spinach. But it's not from around here.

For more, see: Crisis Forces Japanese Farmers To Destroy Crops