There has been news about a possible widespread contamination of compost containg manure; contaminated because of the use of the  persistent herbicide aminopyralid on grassland - which passes on via silage and feed through to farmyard and horse manure.  This led me to wonder if mushrooms and spent mushroom compost are affected.
The answer was:-

From: "UKHotline@dow.com" <UKHOTLINE@dow.com>

Subject: FW: Contamintaed manure: aminopyralid
Date: 07 July 2008 10:25

I have no data on this, but aminopyralid has no microbial activity, so I
think it unlikely that it would affect mushrooms.  I would think it
likely that any mushroom compost which originally contained aminopyralid
would still contain it when it was spent.  I would not expect all the
lignin to have been broken down during the mushroom growing period.
Best Wishes
Jim Butchart
Technical Services Specialist

Mobile 07764 268196
www.dowagro.com/uk

So! It would be worth writing to your MP (try: www.writetothem.com) to urge the banning of this product.  The only advice I have read is that if the soil is rotovated or thoroughly dug this helps break up the contaminated plant material and clears it perhaps for next year.

It spoils vegetable growth, giving disappointing crops as is widely reported, and is not licensed for food products. Best of luck!

BUT NOW BETTER NEWS! (August 2008)

The Lib-Dem MP for Sefton (Mr.John Pugh) has taken this matter up for us with DEFRA. DEFRA sent a self-justification  of which he writes "It sounds rather complacent and I believe foolish and unrealistic to rely on 'label precautions' being followed at all times".
But there is welcome news: he reports that Dow AgroScience are withdrawing the product and that the Pesticides Safety Directorate is suspending authorisation at least temporarily while the problem is investigated.  So many thanks to Mr Pugh MP!

The advice remains to rotavate or dig several times ensuring the used manure is turned readily. Do not replant till next year. Unused manure (if you suspect it contains the herbicide) should be left to rot down fully for several years before use. Or disposed of as waste. It appears these products do not affect consumer health and any vegetables should be safe to eat, says DEFRA.  

--Last edited by michael on 2008-08-10 14:07:44 --