"Rommel's Asparagus" were poles placed in fields to keep Allied gliders from landing, particularly in the areas in Northern France prior to D-Day. I know of no usage of poles to keep Allied aircraft away from German airstrips.

You are probably asking about "Rommelspargel". These were wooden poles, sometimes connected with barbed wire. They are named after Erwin Rommel. The name "Spargel" (German for asparagus) comes from the visual appearance. This of course hasn't been the official name for these installations.