[mumofstig]

I've just received this from our Allotment Assoc 

Dear Allotmenteers,

After careful observation and consulting the RHS, it is possible there is a problem with traces of broad-leaf (selective) weedkiller in some mushroom compost obtained this spring from Bilting Mushrooms. If you have compost from this source, please read the following cautionary notes. Please talk to your allotment neighbours who may not have registered their email address yet.

Plants in soil prepared with the mushroom compost on particular plots are showing classic signs of low level broad-leaf herbicide damage, while similar plants very close by, in soil without the compost, are free of damage. The plants seen to be affected are the pea family and tomatoes, both of which are particularly sensitive to this group of weedkillers. Affected plants are both outside and in a greenhouse. Spray drift is not a possible source of contamination. Please note potatoes could also potentially be affected.

No such problems have ever been encountered before with mushroom compost from Bilting Mushrooms.

Problems with these herbicides have been giving gardeners a headache for several years but new stuff should be free of trouble, since steps were taken to remove the source of contamination. Previously the herbicide was present in the straw used, or in the horse manure - the herbicide can pass harmlessly through the horse only to cause damage when the manure is used on plants. Old manure can still show traces of the herbicide for up to a maximum of 5 years.

Bilting Mushrooms have been contacted and are concerned, but do not understand how the compost can be at fault. They take great care in the preparation of the mushroom compost and all the horse manure they use is fresh - there is no way it should be contaminated. They cannot understand any way by which the traces could have got into the compost. The manager is sending samples for testing and checking his supply chain.

RHS advice is to feed and water the plants well and with care they will, in time, outgrow the problem. Soil which has been treated but not yet planted should be turned over to let the chemicals disperse and evaporate as fast as possible. Plants in other families - eg brassicas or courgettes - may well show no signs of trouble.

Please let me know if you have yourself experienced problems or would like more advice. Attached is a photo of sweet pea plant showing the type of damage seen, with curled, stunted shoots.

Is this Aminopyralid again? 

[Springlands]

I cannot remember where I read it but didn't John say somewhere that Aminopyralid had been cleared for use again.

[mumofstig]

Yes, it was, but the new rules are supposed to prevent it getting into composts 

[solway cropper]

Simple answer: make your own compost and feed. I got aminopyralid contamination in  supposedly 'organic' compost a few years ago and have been very wary of using anything I didn't know the full history of ever since. I'm lucky in having access to plenty of seaweed and manure from a truly organic source.

I'm not paranoid but I don't trust anyone