Clearing blight from a polytunnel?

Discussion in 'Poly-Tunnel Gardening' started by Frazzled, Nov 1, 2021.

  1. Frazzled

    Frazzled Gardener

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    The tomatoes and peppers in one of my polytunnels were affected by late blight this year. I've followed advice by trying to carefully remove the affected plants and dispose of them away from the garden. However, has the blight itself infected the polytunnel? Do I need to somehow disinfect the polytunnel soil and what not so it doesn't appear again?

    The polytunnels I manage are open to casual passers-by, so I can't really lock them down or practice very comprehensive hygiene. Given the recent blight tragedy, is it worth planning to grow more blight susceptible plants next year or should I focus more on blight resistant items?
     
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    • pete

      pete Growing a bit of this and a bit of that....

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      My personal thoughts are that blight is all around us, it's only when conditions are right it becomes a big problem.
      Having said that you could perhaps just water over the area of soil with diluted jayes fluid and perhaps spray the polythene with it.
      But I think you won't eradicate it.

      Just a thought, not sure if jayes is ok to use on polythene, you would need to check.
       
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      • JWK

        JWK Gardener Staff Member

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        I've used a bleach solution brushed onto all the glass and frame, then onto the soil with a watering can. I left that a few days then watered Jeyes into the soil. This is in my greenhouse. In past years I have dug out the soil and brought in fresh but it's a lot of work. Instead I plan to grow blight resistant varieties next year, the few susceptible heritage varieties I am going to grow in containers with new compost.
         
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        • Dave W

          Dave W Total Gardener

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          I don't think I'd chance Jeyes on the polythene, soapy water with a bit of bleach followed by a good rinse down with the hose is what I do.
          I'm about to skim off the top layer of soil before soaking with dilute Jeyes and then I'll cover the bed with polythene and leave it until I'm almost ready to replant in the tunnel. I have one or two potted plants that overwinter in the tunnel and covering the Jeyes soaked bed helps reduce the chance of the fumes from the Jeyes damaging them.
           
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          • noisette47

            noisette47 Total Gardener

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            It's interesting to consult the internet on this, because there are two completely opposite views. One is that, as long as all infected vegetable material is removed, the spores don't survive the winter, the other says that it persists for three or four years. I wonder if the difference is whether it's indoor or outdoor culture? There's less likely to be extreme cold in a greenhouse or polytunnel, so more likelihood of re-infection the following year. Frankly, I'd be more inclined to treat soil and surfaces with Bordeaux mixture which is just about the only effective fungicide left for non-professional use.
             
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            • Frazzled

              Frazzled Gardener

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              I'm told by some of the people casually associated with the garden over the years that they've never seen blight in the polytunnels before, nor have they seen it in outdoor raised beds. And this particular garden has been going for many years with good crops of tomatoes. Additionally, there's been a few noticeable mushrooms popping up, again haven't seen these before, including exotics like stinkhorns. And, we've had an overzealous volunteer who constantly overwatered during the summer.

              So my gut feel is this particular season we've had a combination of unlucky circumstances that have culminated in late blight. I'm thinking the bleach wash, Jeyes, and Bordeaux mixture in some combination will certainly not go amiss.

              Excellent information. Thanks to everyone.
               
            • pete

              pete Growing a bit of this and a bit of that....

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              I didn'y think you could get Bordeaux mixture anymore?
               
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              • pete

                pete Growing a bit of this and a bit of that....

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                Dave we had a look at Jayes a while back and found out its nothing like the stuff we used to use, its basically just soapy water and a bit of disinfectant now rather than the tar oil it used to be.
                 
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                • Dave W

                  Dave W Total Gardener

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                  Pete, I wonder if dilute creosote would do the job as long as it was applied earlier enough to be washed away before planting.
                   
                • pete

                  pete Growing a bit of this and a bit of that....

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                  Well I dont think creosote is what it was, and I'd be a bit wary of putting it on soil used for growing although I think it is probably very close to the old Jayes Fluid we used to use.

                  I can remember watering brassicas with dilute Jayes to help keep clubroot at bay in the 80s , it never did them any harm.

                  I dug out an old can of Jayes and I have a can of the new stuff and its a totally different product.
                   
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                  • noisette47

                    noisette47 Total Gardener

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                    I can. Not sure about UK?
                     
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                    • Dave W

                      Dave W Total Gardener

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                      Bordeaux mixture isn't legally available in the UK, though Vitax does advertise a very similar but less effective product.
                      You can make your own mixture with copper sulphate and lime and these are easily available on Amazon and probably elsewhere.

                      Copper (II) Sulphate has various uses, some of which are detailed below: It can be mixed with Lime to produce 'Bordeaux Mixture' which is used to control fungus on grapes, melons, and other berries. It can be mixed with ammonium carbonate to form a Cheshunt compound that is used in horticulture to prevent damping off in seedlings.
                       
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                      • pete

                        pete Growing a bit of this and a bit of that....

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                        Presumably if you don't live in Bordeaux you are not allowed to make it, the EU won't allow it. ;):biggrin:
                         
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                        • pete

                          pete Growing a bit of this and a bit of that....

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                          I've got this stuff, but its copper Oxychloride , not copper sulphate.:dunno: DSC02131.JPG
                           
                        • noisette47

                          noisette47 Total Gardener

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                          Pffft..you English! You never did twig about dealing with edicts from Brussels, did you? :biggrin: You just quietly carry on doing what you want, when you want....:roflol: ;):whistle:
                           
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