I do try with crop rotation - not always successfully by the book. However, I have a problem with potatoes. Over a third of my plot is taken up with potatoes and a third with legumes, brassicas, onions/leeks etc and the rest with the permanent beds - strawberries, other fruit and asparagus. This makes it difficult to rotate the spuds, as you can see. The maths just doesn`t work. This means that for the 2012 planting the beds overlap and I shall have no choice but to put potatoes partly where they were this year. Is this a total disaster? Is there anything I can do? I know that this will cause total shock and horror to the purists, but what about the pragmatists? I will welcome any advice.

You could try growing your potatoes in barrels/ bins, growing vertically would save you some space?

As you probably know (?) the problem is blight overwintering on any tubers you miss when harvesting, so that the resulting volunteers may spread blight to next year's crop. So if you must do it, take extra dig out all tubers, no matter how small. I wouldn't do it if you had any hint of late blight this year.

No Tony, I didn`t know what the main problem was. That`s the trouble with rules sometimes. The 'why' isn`t always obvious.
So thanks - I`ve had no blight at all but I`ll take extra care to get every tiny tuber out of the ground in the bit of the plot that`s overlapping.

I don't altogether agree that the persistence of blight in the soil is the main reason for rotating your spuds. Blight spores are airborne and can blow in from miles away. It is soil-borne nasties like cyst eelworm and wireworm that we need to keep one step ahead of.
Potatoes are problematic when it comes to planning a rotation. There's a discussion about it on another thread, here. As long as it can be seen that any soil-borne problems are not accumulating, you can get away with using the same piece of ground for a second year.

Thank you - I`ll be careful and risk it next year but I might have to look at my planting plans more carefully in future.

Not persistence in soil; specifically persistence on potato tubers. Yes there is always a risk of airborne blight spores, but they must overwinter and get into the air somehow.

Allegedly you can safely compost blighted potato tops (indeed burying them is one recommended way of disposing of them), but not the tubers, for this reason.

Agreed that I have probably overlooked other potential problems though.

Commercially you used not to plant main crop potatoes for 7 years (although some growers only leave 4 years) but in a garden situation I would not worry too much and if you are growing new potatoes I wouldn't worry at all. The crop may be a little smaller though.

Barney

I feel we get to hung up with rotation..if we are sensible and just move crops around the problem of any build ups should not happen..many of the rotations are so natural we just do them anyway.
Some allotments are not big enough for rotation, we have just started small starter plots, again no space for rotation .
Many plot holders grow runner beans in the same trench each year and just add compost..their results were fine.