A great attempt. You got it framed. the problem with moving things is they like to get out of the focus range fast. Expecially an airplane. That is what this photo suffers from. It is soft on focus from just getting out of the DOF when locked on. Maybe a faster shutter speed would of helped?
good contrasting colors. i think that i would like to see some more negative space on the left to "lead" the object, a little too centered IMO. Also it looks a little on the grainy side, did you resize or use digital zoom?
Very vivid colors in the plane. Really helps to make it stand out. The propellor in motion really helps to give dynamic and sense of flight. The crop is a bit close. Showing more sky would give even more sense of flight. If you decide to keep the crop try sharpening it a bit. When you see a closeup like this your eyes tend to look for details.
Crop dusters are really fun to watch. Thanks for submitting this. The grain/noise is a bit of a bother but the blue and yellow are very nice. You really have flight here.