Hi Gillian,
Thanks for the question. Bokashi can help prevent plant disease in two key ways. Firstly, plants grown in bokashi-rich soil are shown to have stronger root systems and, in turn, are more resistant and resilient to diseases. Secondly, the bokashi microbes have been shown to reduce unwanted fungi including those causing Fusarium wilt and blight.
We don’t have first-hand experience of using bokashi to reduce Fusarium wilt but we would recommend mixing about a cup of bokashi bran to every cubic foot of affected soil. This will give your soil a boost of the beneficial bokashi microbes. Alternatively, start composting your food waste with bokashi and regularly add bokashi pre-compost to your raised beds. This will give the soil all the great benefits of the bokashi microbes and valuable organic compost.
Happy composting 🙂

So, our garden has about 100 cubic feet of garden soil. By weight, how much bokashi bran is 100 cups? (Seems like…. a lot!)
Would I be better off with the EM-1 solution to distribute in the garden? (Is it the liquid form of microbes??) 
Would you point me towards where you have read that bokashi has been shown to “reduce unwanted fungi, including fusarium.” I want to keep researching!
 
thank you!

Yes, it may be easier to treat with the EM-1 solution. Our EM should be diluted 1 part EM with 120 parts water so a 500ml (17oz) bottle will give you around 17 gallons of usable EM solution).
This is the most commonly referred to article about using effective microorganisms and bokashi to treat fusarium fungi (https://www.cabdirect.org/cabdirect/abstract/19961006335)
Happy composting 🙂