Hi Ed..

 Interesting to see some similarities and some differences between our two environments for the same problem.

I was interested to see the other posts that mentioned eliminating the "green bridge". Tho' we consider that important for other reasons, it was never considered here to be of any consequence to  Takeall/Haydie.    Rotation of a non host in the previous year was the big thing.  

Light, high pH soils of low fertility R US !!!!!.       Of course one major difference  is that after harvest, we normally have  hot, dry conditions through to the following autumn,when hopefully we would get rains to allow us to start the cropping cycle again.. So there is usually very little chance of breakdown of the wheat crowns and the fungus, between  the finish of one crop in Nov.Dec, and the start of the next in May or June.     It was considered that  summer or early autumn rain if it occurred gave some breakdown, and  helped with the crop that normally would be sown  late autumn/early winter.

Unless  we were digging up the plants and washing the roots out to see the blackened crown and roots, there was usually no outwardly visible sign of the disease until the dead heads appeared.   Also,  we didnt tend to get them in the circles as suggested in  your link. They were simply scattered throughout the crop, and  the worse the infection  was, the less  scattered  they were.

Also interesting to note that we refer to Fusarium  as Crown Rot,  not  Hayde/Takeall.  This being the pink  crown disease, rather than the head scab.    I dont know if they are the same, I have no experience of head scab.