There is an old saying- wait long enough by the river and the head of your enemy will float by. I think it is a perfect encapsulation of the “do nothing” impulse recommended by Fukuoka. Often problems will solve themselves given enough time better, and often far better than if you had intervened.
A great example of this principle happened with stable fly in my goat sheds. These insects suck blood from the animals then lay eggs in the manure. Under ideal conditions they can rapidly build up to damaging levels. For the first year or so they hadn’t discovered the herd, but then they arrived and we had a massive population explosion of biting flies. At the time the herd was on a concrete floor, so I tried cleaning up the manure regularly, though I soon noticed that the maggots did much better in a thin layer of fresh manure. Allowing a thicker manure layer to build up seemed to make life harder for them. I later found out there is a fairly common parasitic wasp that preys on the stable fly pupae, but it persists better under more undisturbed conditions compared to the maggots. I now make sure to leave a deep, well-aged manure pile in the corner to provide habitat for them (and having the animals on a dirt floor seems to also help). I cannot be completely sure my intuition is correct since the wasps are too tiny to observe, but since I changed my approach toward doing less I rarely see more than a couple of stable flies bothering my goats.
A second example of this principle is the blady grass/sword grass/cogon grass that has steadily spread in my goat pastures. It is a low palatability species, with high silica leaves with razor sharp edges. On the upside it produces a network of rhizomes that contain a modest amount of starch. This makes the plant easily controlled by pigs (though I would not tolerate the digging and erosion where it grows on my hills). It also means this plant is a potential famine food, so having a few large patches on hand is comforting when viewed the right way. That said, I was slightly concerned about it continuing to spread and dominate my goat paddocks, reducing feed quality.
Over the last two wet summers the blady grass population has exploded, growing taller and lusher than ever before. Then I noticed a particularly thick patch growing outside the goat paddocks looking strangely browned off and collapsed. I figured there was likely an unidentified pathogen taking out its root system. As an experiment I dug a bucket of soil from the worst affected spots, then transplanted it into the centre of the thriving blady grass clumps in the goat paddocks. I only did this to half the unaffected patches as a simple experiment to see if my method caused any effects. Fast forward a couple of months later and the deliberately “infected” blady grass patches are looking distinctly sick, while the untreated ones look pretty normal for this time of year. I won’t go out of my way to infect all of them- maintaining a stable population of the pathogen might depend on not killing all the patches at the same time. How far the effect will go to kill the blady grass I cannot tell, but if it slows them down enough to allow other species to grow then I will be happy. As it turns out, the inside of blady grass patches are the perfect place to establish wattle trees inside the goat paddocks since the girls normally graze around them. Spiny pioneer plants like brambles often serve a similar purpose. By the time the herd notices the trees they are past the vulnerable stage and ready to grow abundant, tasty goat fodder up and over the competition.