I have a small backyard veggie garden that I manage organically, although I'm not a fanatic about it. Last fall my turnips were destroyed by root maggots. This year I have carrots planted in that bed; they are just starting to come up. Do I need to worry that the larvae will switch species of preferred plant and decimate my carrots? What could I do to prevent that? Thank you.
Kent County Michigan
Yes, you need to worry. If you have root maggots that affect turnips they will affect carrots, too. When you follow one target crop with another, you have a good opportunity of having probems. But do a bit of internet searching and make sure that you have had root maggots. You can also have wire worms that will create similar damage but do not look the same. I am hoping you saw the insect that did the damage. Otherwise, you are guessing at the bad guy.
So I will continue with root maggots because this is what you said. There is virtually no control, organically or traditionally, for root maggots. One possibility is to plant a different crop in the area where the root maggots were. This gives them nothing to feed on. Crops like lettuce, onions, alfalfa, sunflowers or buckwheat are not bothered. Those are recommended to follow an area that has had root maggots.
Control grassy weeds in the garden and it is always good to avoid severely infested fields with another tasty crop. You can read about bilogical control but this hinges on having the correct identification for your pest and then finding an insect that is sold by a biological control business that matches up.
In the fall of the year, rough till the soil and leave like that for birds to pick through.
But if your damagers were wire worms, other control measures are needed.