[glallotments]

Some potatoes on a neighbouring plot are showing very similar symptoms of hormonal herbicide poisoning – just one of the varieties planted – Picasso. The plot holder is new and hasn’t added anything to his soil – only water and the plot was fallow before he used it and no-one dumped any manure onto it.

This was a puzzle and so I sent photographs of his potatoes to the RHS and to DOW asking the following.

Is it possible that the seed potatoes that he bought had been grown in contaminated manure and the seed potatoes absorbed some of the residue which is causing this problem or could the symptoms be caused by something else. I have attached photos of the affected potatoes taken yesterday.

I received the following response from the RHS:

Many thanks for your most interesting email.
As just one of your neighbour’s spuds is showing symptoms it is almost certainly something that has affected the tuber.  It seems unlikely that the seed crop was grown on land manured with contaminated manure as the mother crop would have been badly injured and the crop scrapped.  Other causes include being stored or chitted in the same environment as hormone weedkillers, including lawn weedkillers, which can have a vapour action. 

No herbicide or manure has been used on this plot as the previous plot owner just ploughed over the soil for a couple of years or so and before then it was fallow for years. The plot holder is going to try the broad beans treatment.

Has anyone else had this sort of problem?

[Goosegirl]

Was the fallow land treated with some longer lasting herbicide before he got it? Could someone have been spraying a herbicide nearby on a hot day as the warm air currents can spread the herbicide droplets over quite an area? Is anyone else experiencing the same problem and is it just potatoes that are affected?

[glallotments]

No chance of any herbicide getting on the land prior to him taking it over. For about three years the previous plot holder practised ploughing and that was it until he was given a notice to quit.

These potatoes are very close to our plot only and we haven't used anything.
It is just one variety of potatoes - Picasso. These are being grown in a small raised bed and are in the midst of other beds. His other variety of potatoes are growing well.

The reason my mind drifted to a tuber/seed potato problem is because potatoes that we accidentally left in where last year we had a problem showed symptoms of contamination when they  grew. The chemical company said that these daughter tubers could have absorbed the residues last year. So I wondered if someone growing seed potatoes could have had the same problem and ended up with affected tubers.

The RHS think this unlikely as they say the grower would have discarded his crop. However, our potatoes grew through the problem and at the end of the season looked just fine. How often would a grower visit his crops - could he/she possible miss the problem? I just don't know.

[Yabba]

Silly question alert :

raised bed, I assume that's been filled with soil from their own plot?

¥

[glallotments]

Yes although some did come from a neighbouring plot that didn't have any affected manure used  and no symptoms of anything untoward last year - we went down that route too.

We even thought his shed could be at fault as he bought it from someone who was affected last year but on checking he hadn't stored anything that was affected in his shed.

[Yabba]

I knew it was a silly question, but had to ask huh?

¥

[glallotments]

As a teacher I always told my pupils - no question was stupid if you didn't know the answer!!

[Iain@JBA]

In practice all crops that are put forward for certification in Scotland are inspected throughout the growing season at least twice by trained inspectors. It shouldn't happen. Some picasso is grown in England and they have different methods so I couldn't say for sure what their procedures are. I have not heard from anyone else about bad seed this year so you could just be unlucky.