I lost some of my broccoli to cabbage root fly. They were two good sized plants that I bought at the nursery as seedlings about a month ago. I also started broccoli from seed around that time (those are in a different part of my garden). Those plants are still very small, but seem healthy.
I have two brussels sprouts plants that I bought at the same time as the broccoli and were planted in the same row as the broccoli that are now dead from the maggots of the cabbage root fly. Should I assume the brussels sprouts are also infected with the maggots and pull them up even though they don't seem to be suffering yet?
I don't want my smaller broccoli plants suffering the same fate. So I don't want those maggots growing to maturity and laying eggs in my young broccoli plants (this is assuming they also aren't infected already).