By Councillor
Monmouthshire,
United Kingdom 
One of our allotment holders has had mixed results with his potatoes, some of which are flourishing but some are shrivelled with stunted growth (see pictures). The first shows a cutting from an effected plant, the other two show the problem on plants still in the ground.
The plotholder is saying he believes his potatoes have been sprayed which is obviously causing friction. Other allotment holders claim it is because he plants in the same piece of ground every year - possibly for 10-15 years! He says it's because he believes the ground has been sprayed and is poisoned and yet cannot explain why other plants are unaffected. If anyone has any ideas which can help sort out this problem, which he has had for 18 months, so I am told. The worrying thing is that a neighbouring plot also shows early signs of the same problem so ANY advice would be very welcome.
Thanks for your time.
Best wishes
Bob
30 May, 2011
It does look as if spray of some sort has got onto the damaged potato plants but would seem unlikely if the ones around them are doing fine. I wonder if it is potato blackleg... copy and paste the link below into your web browser
http://bit.ly/lvjI2z
and then compare with the photos which you will be able to see larger than we can.
It is not a good idea to grow any food crop on the same piece of ground year after year. This causes a build up of infection and diseases. The normal rule of thumb is to rotate the crops on a four year cycle. So year 1 potatoes, year 2 bassica family, year 3 roots, year 4 legumes.
30 May, 2011