In a written statement, the pilot reported that he was flying low over a grape vineyard to apply sulfur dust. After making two application runs, he began a third run, and observed that sulfur dust from the previous two runs had drifted into the area through which he would be flying. He continued the run, and lost all visual contact with the ground as the airplane entered the sulfur dust cloud. He felt the left wing hit a grape trellis, which pulled the airplane down and to the left. The airplane traveled 150 yards on top of the grape trellises before stopping inverted on the ground. The pilot indicated that the airplane and engine had no mechanical failures or malfunctions during the flight.