Sorry to hear about your tomatoes. I have given up growing them outdoors BUT if you can keep the leaves dry, with a cover as you suggest, then blight should be prevented from infecting plants. It only enters leaves and stems that are consistently wet, from about mid June when there is enough warmth. Good luck, let us know how it works! PS you can compost the blighted leaves and stems (I do always – and indoor toms & potatoes are all blight free this year)), the spores do not carry over through soil or compost, only arrive in humid air.
We will definitely try that method next year as we are not allowed greenhouses on our plots. I hadn’t realised that we could compost the infected plants as perceived wisdom always suggests burning or disposing off-site.
Have you contacted your local council for permission to erect a greenhouse on your plot? My wife and I had the same problem with growing tomatoes outdoors and so we contacted our local council and they agreed that we could erect a greenhouse so long as it was not permanently fixed ( i.e. no concrete base or foundations) and was not constructed of glass. We bought a lovely 8×6 polycarbonate traditional styled greenhouse for just under Â£200 and this has been on our plot for 2 seasons now and has given us a great crop of tomatoes and cucumbers.
Thanks for the advice Amac – great idea but our allotments are 200 years old and belong to a charity and no structures such as greenhouses or sheds are allowed so will try a smaller structure in plastic that I might be able to get away with.
I think some cover is going to be necessary next year.