Radish is a member of the same family of plants as rape, cabbage, canola, ect. which can all be a hassle to harvest. I think the radish seed is larger that most of the others in the list. Problem is always getting the plant to dry down before the seed shatters out on its own. Swathing before harvest would probably be a good idea if it doen't shatter too bad. Getting it to feed is a major problem because the stuff wants to hang together and not feed, until a big slug comes in and bang your plugged up. If it is like rape it will be threshed out by the time it gets to the cylinder then you just need to get through the combine and separated. Small seed seive would probably help. You might try contacting Terry at St. John Welding because he has experience with setting up combines for various minor seed crops. http:__www.stjohnwelding.com_St_John_Weldin_Homex.h