[Potty Plotty Lotty]

I have a new 3m x 2m PT which has a door at one end. The cover once fitted will have the excess buried in the ground.

Does anyone have any suggestions for reducing the risk of getting blight in the polytunnel. Some ideas I have come across as part of my research are:

a) Don't overfill the space to ensure air can circulate (this will be the hardest!!)
b) Bury a plastic bottle into the ground with multiple holes in it and water only into that to avoid surface evaporation and keep humidity down
b) Use weed suppressant membrane to reduce surface evaporation of water
c) Leave the door open all the time once blight is around to improve ventilation

Any thoughts or tips to share? On a practical note I don't have time or inclination to pop in before work to open the door!

[Plot94]

So far (fingers crossed) I have not had blight in the tunnel even when it is rampant outside. The main reason for this, I believe, is I am very careful during blight season not to cross contaminate. Change your footwear when entering the tunnel, I have a pair of crocs specifically for this. Never use tools outside then take them into the tunnel without cleaning them thoroughly etc. I have watering cans that I only use in the tunnel and do try not to splash too much but don't use bottles buried in the soil. The ground is heavily mulched with either straw or grass clippings to stop evaporation and this also helps avoid splashing the plants when watering.
Both the polytunnels are usually crammed with plants come mid summer and no sign of blight.
Hope this helps.

[mumofstig]

I've often thought that people assume they have 'blight', in a polytunnel/greenhouse when what they actually have is Botrytis. Still a fungal infection, but isn't blown into the polytunnel (as blight would have to be) it's caused by high humidity/inadequate ventilation. Leaving windows and doors open as much as possible makes it less likely.
It's also a good idea to give the greenhouse/polytunnel and good clean down before the growing season to remove mould spores or use a sulphur fumigator candle in a greenhouse (as long as there are no permanent plants inside.)

[snowdrops]

Yes I agree mum, I think it’s possibly botrytis I’ve had in my greenhouse the last couple of years, caused all my tomato plants to die prematurely but no effect to the tomatoes that I picked green & ripened in the conservatory,so definitely not blight.
Today I have just thoroughly disinfected the greenhouse house with snow foam (for car washing) & bleach added via the jet washer, & when the sun has gone down I’ll light the 2 sulphur candles in there ( all plants removed)

[JayG]

Bit of a conundrum - blight spores are airborne, so in theory the more airflow you provide, the greater the risk of copping it, although by doing so you would reduce the risk of botrytis which thrives on high humidity. 

In practice, in over 10 years I've never had blight in the GH, although botrytis seems to be inevitable towards the end of the season, but it doesn't greatly affect the crop.
Removing any manky tomato leaves helps reduce the chances of botrytis getting a hold too early, and avoiding wetting the leaves when watering helps avoid both problems.

[Potty Plotty Lotty]

Thanks all. Much appreciated. This year is certainly going to be a learning curve. 

Just waiting for the second order of hot spot tape to arrive as the 18m I ordered was insufficient. Ooops!