There was absolutely no information in March and April warning against radioactive fallout in the countryside in Fukushima, where many residents ate the wild mountain vegetables - seasonal delicacy. On the contrary, as we all know now throughout the world (I hope), the national government and the Fukushima prefectural government were busily dispatching the two Nagasaki University professors (Yamashita and Takayama) to brainwash the residents.
Now the Fukushima prefectural government says it will test wild mushrooms. About the only reason I can think of is that the prefectural government just wants to make sure they are contaminated beyond 500 becquerels/kg level, so that they can send the bill to TEPCO for non-sales. If they are contaminated but with less than 500 becquerels/kg level and people still don't buy the mushrooms, they will send the bill to TEPCO anyway for damages from "baseless rumor", also known as "radiation".
The testing probably has nothing to do with safety for the consumers. Remember, they, and everyone in the government or with strong ties with the government have been saying all along that if you eat food that contains radioactive cesium well exceeding 500 becquerels/kg, it is safe.
From Yomiuri Shinbun (8/3/2011):
東京電力福島第一原発事故を受け、福島県は３日、これから収穫シーズンを迎える野生のキノコについて、放射性物質の検査を実施すると発表した。
Fukushima Prefecture announced on August 3 that it will test wild mushrooms in Fukushima for radioactive materials. The harvest season for wild mushrooms will start soon.
検査は週内から始める予定。
The testing will start within this week.
県農林水産部によると、検査対象は県内の直売所などで販売される４５種類。
According to the prefecture's Agriculture, Forestry and Fisheries Division, the testing will done on 45 types of mushrooms sold at shops within the prefecture including direct sales depots.
検査で放射性物質の規制値を上回った場合、そのキノコが属するタイプすべてについて、出荷自粛するよう、キノコが採れた市町村に要請する。
If radioactive materials exceeding the provisional safety limit are found in a mushroom, the prefectural government will ask the municipality where the mushroom was harvested to voluntarily stop the shipment of the same mushrooms.
Still no information as to what caused the hothouse mushrooms to become radioactive.