I use Power Soil DNA Isolation Kit (Mobio Laboratories.

I use the Mecherey-Nagel kit.

 Hyphae (P.infestans, Ps.cubensis, Alternarias) collected (medium/water pipetted out) are -32C frozen with glass beads, vortexed 2x3min in Kit's lysis buffer, and processed. Works like a charm in genereal PCR, SSR, and mtDNA PCR.

For grinding we use the FastPrep system with Matrix A tubes, which is really very efficient, either starting from pure fungal culture or from plant tissue (even hard). For DNA extraction, we use plant DNA extraction kits (Qiagen DNeasy Plant mini kit, or Macherey Nagel, Nucleospin Plant). They both works very well with a wide spectrum of fungal genus or oomycetes, are easy to use, and allow you to work in a standardized way. No harmful chemical required. 

If you just want a quick DNA extraction (but unsuitable for long term storage of the DNA), just transfer a pellet of fungal material in a PCR tube containing 100 µL TE buffer, then heat at 95°C for 3 min, then on ice for 1 min, twice. Then, you just sample 2µL of the supernatant for your PCR or qPCR test.

@ Renaud, how long can the DNA be stable if I decide to use the quick simple method for extraction?