There are lots of things that gardeners do which are totally unnecessary but we continue to do as the old books have always said that and it is copied for the next generation and so on. Many of the practices are for the commercial plantsman where disease and pests are likely to be more prevalent. I have been growing for decades and using our current polytunnel for over ten years. I NEVER sterilise the soil, the pots or anything else and yet never suffer any problems. I DO have a good tidy and clean in the spring and remove any rubbish and things in corners and under boards, but that is all.
Most of your problems with damping off would be more likely caused by poor ventilation and cool conditions. A slightly dirty seed tray is not likely to cause damping off, but a cheap compost or watering with dirty water from an old butt might well. You can even add a SMALL amount of copper fungicide to your watering water to prevent this disease.
Flea beetles and other bugs can be removed by allowing lots of natural predators into your greenhouse. If you are a 'sprayer' of pesticide, you have probably killed off most of your predators too, so try to use natural methods. When we arrived here we were plagued by flea beetles and no member of the brassica family would survive the seed leaf stage, but after a couple years of organic methods we no longer see any flea beetles at all, either in the tunnel or outside. Even the Colorado beetle on the potatoes disappeared after two years of integrated pest management.
I hope this doesn't sound too complacent and 'well, we're all right, Jack' but I do think that if you concentrated more on good composts, clean water, and plenty of ventilation, many of these problems would disappear. Don't try to make your greenhouse sterile, just concentrate on these other things
Most of your problems with damping off would be more likely caused by poor ventilation and cool conditions. A slightly dirty seed tray is not likely to cause damping off, but a cheap compost or watering with dirty water from an old butt might well. You can even add a SMALL amount of copper fungicide to your watering water to prevent this disease.
Flea beetles and other bugs can be removed by allowing lots of natural predators into your greenhouse. If you are a 'sprayer' of pesticide, you have probably killed off most of your predators too, so try to use natural methods. When we arrived here we were plagued by flea beetles and no member of the brassica family would survive the seed leaf stage, but after a couple years of organic methods we no longer see any flea beetles at all, either in the tunnel or outside. Even the Colorado beetle on the potatoes disappeared after two years of integrated pest management.
I hope this doesn't sound too complacent and 'well, we're all right, Jack' but I do think that if you concentrated more on good composts, clean water, and plenty of ventilation, many of these problems would disappear. Don't try to make your greenhouse sterile, just concentrate on these other things
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