Arbuscular Mycorrhizal Fungal (AMF) are dependent on the plant for their food, therefore, they die when the plant dies. Lucky for us before they die they form spores that can live a long time in the soil.
When we have looked at the soil from vineyards in winter it is filled with fungal spores. Pictured here of some of the types of AMF spores. The size of these spores can vary from microscopic to visible.