Can any one help? Last week my radishes were fine, but this week, many of my radishes had brownish tracks burrowed through the flesh.
It sounds like cabbage root fly, which attacks radishes as well as cabbages. Destroy your crop without composting it and sow your next batch in a different place, then cover it with fleece. The pest enjoys the cool wet conditions we had at the start of the month. Hopefully it's not enjoying the current heatwave!