Jacques Fortin wrote:I don't have any direct experience with clubroot but this is from a pest/pathogen management guide for organic growers put out by cornell.
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It didn't list any treatment options, just cultural remediation.
Of course there are chemical poisons that can be used to try to asphyxiate the clubroot critter, but organic growers are wise enough to stay away from that solution and its concomitant side effects.
The real solution is
Good Permaculture Practices: healthy, diverse soil fungi, healthy, diverse soil biota, and a healthy, diverse plant community growing on top of it. I've broken all the rotation rules that are given for planting Brassicas, but I don't have any problems. And I started out with soil that was chock full of
Fusarium. What changed it was tilling in lots of wood chips. Moldy wood chips with all sorts of hyphae growing on them.
This is an exception to the rule that "no-till is best". When you are starting out with an unhealthy soil that is a breeding ground for a nasty pathogen, till it up and disturb those f$#@%rs. Solarize them. Put lime on them and raise the pH a couple, three points. It's probably best to do that around this time of year when everything is coming out of its winter dormancy. The last thing you want to do is to let it go on through another season.
Once you have thoroughly shaken up your plant pathogen breeding ground, till in lots of moldy wood chips. Not some fresh out of the chipper, but ones that have had a couple, three months to have spores land on them and get inoculated. If you can dig your hand into the pile of chips and pull out a handful that is full of white hyphae, then it is ready to do battle with the clubroot nasties. Till in the chips and seed the area with a cover crop as diverse as you can get. Skip the brassicas, but try chicory, alfalfa, dandelion to get some deep roots drilling into the soil horizon. Add some legumes to develop the nitrogen fixing bacteria population in the soil. When there is a mushroom flush after a heavy rain, go out and collect any you can find,put them through the blender and apply them as a soil drench. The whole point here is to overwhelm the clubroot with competition. Go to a healthy pond and collect some pond scum and use that to water your field.
What I have observed, when building hugelkultur beds, is that healthy soil is a magnet for soil gnats. When I am topping off a hugelbed with healthy soil, there must be a strong odor of fungal hyphae that draw the
soil gnats in to lay their eggs. You want all those eggs hatching into hungry larvae that will eat all sorts of microbes, including the ones that cause clubroot. If your soil has a healthy diversity of microscopic organisms in it, something will be eating the clubroot faster than it can reproduce.