On November 26, 2000, at 1000 central standard time, an Aerostar PA-60-601P, N713HM, owned and operated by a commercial pilot sustained substantial damage during an in-flight collision with trees during initial climb from runway 28 (4000 feet by 75 feet, ice-covered/asphalt) at the Fillmore County Airport, Preston, Minnesota. Instrument meteorological conditions prevailed at the time of the accident. The personal flight was operating under the provisions of 14 CFR Part 91 and was on an instrument flight rules (IFR) flight plan. The pilot and his sole passenger reported no injuries. The flight was originating at the time of the accident and the pilot performed a precautionary landing at the Quad City International Airport, Moline, Illinois, subsequent to the in-flight collision with the trees. According to the pilot's written statement, "I initiated the takeoff, on runway 28 accelerated to 100 MPH, rotated & lifted off. The gear and flaps were raised, and the aircraft stopped accelerating at about 112-115 MPH. I lowered the nose to pick up some speed, but it still wouldn't accelerate. I could see the trees approaching west of the airport & knew I didn't have climb speed, but also knew there was no choice but to pull up & hope I didn't stall." The pilot reported, "I pulled up sharply, but clipped the tops of the trees, the airspeed was still at 115 MPH IAS [Indicated Airspeed] with 12+ degrees nose up, and the airplane climbing rapidly. I then looked at the GPS [Global Positioning System] ground speed read out, and realized that it was at 140 KTS [Knots]. After assessing things, it became obvious that airspeed was not reading correctly." The pilot reported that he requested to divert from his IFR flight plan and land at the Quad City International Airport, Moline, Illinois, to determine the extent of damage to the airplane. The pilot stated, "During the trip to Moline, the airspeed indicator stayed at 115 MPH for about 15 minutes then pegged out at the back side of the "0" indication, and stayed there for a few minutes and came back to 160 KTS. My GPS was showing about 170 KTS at 7000 ft during the trip." The pilot reported, "I had a problem six weeks ago with a mud dauber wasp building a nest in the pitot tube, but this had been cleared out, and the aircraft flown several times since."