We have grown some bought-in sweetcorn this year, the only thing that has grown with any vigour and hasn't been attached by rabbits and mice (yet!). The tassels have been brown for a couple of weeks now and we've been testing for ripeness. They just don't seem to be ripening and those that are, have patches throughout the cob where the kernals are small and totally unripened. The cobs are smaller than usual and some plants have a secondary small cob near the main one. Any ideas what the problem may be? They are on free draining soil and have been very well watered and grown in the usual block formation. Thanks in anticipation.