| I planted my carrots 77 days ago and they take 70-80 days to mature according to the seed packet. We scattered the seeds in rows and seemed to have a very high germination rate. That meant we would need to do a LOT of thinning. Ultimately, the carrots need to have 2 inches of space in between them. We thinned the carrots a few months ago, giving them at least a half inch between them. Now we really need to finish thinning them so they have enough space to finish growing in the next week or so. I did some thinning over the weekend, but not all of it. I didn't want to pick more than I could eat (the carrots are small but they are certainly big enough to eat already) and I wanted to let the kids do some thinning so they could have the experience of picking carrots and eating them fresh out of the ground. (We've only got the kids half of the time and they were with their mom until today.) Today, the kids and I picked several carrots. Our three year old ate several of them. Our seven year old ate most of a carrot and decided she didn't like it much. The carrots are getting big and orange but they definitely aren't all of the way there yet. With another week in the ground, they'd get much bigger, oranger, and sweeter. In the next few days, I'd like to make carrot cake with the kids to celebrate our very first vegetable harvest from our garden.
So what do we do about the carrot fly? Clearly it was attracted by the smell of my carrot thinning. The advice I've found recommends doing carrot thinning in the evening, when you're less likely to attract carrot rust flies. For me, it's a little too late for that. And the fly probably laid its eggs, which will hatch in 6-10 days. The adult flies do no harm to the carrots, but the maggots do damage carrots. I would like to make sure that the resulting maggots find nothing to eat when they hatch. This is disappointing as it means I might have to pick all of my carrots slightly early, resulting in smaller carrots and a smaller yield. The alternative is to leave them in the ground and hope that the maggot damage is minimal.
Carrot rust fly maggots stick around for about a month, then they pupate. When they emerge as adults, they look for carrots so they can lay eggs and repeat the cycle. According to one website, carrot rust flies are known as weak fliers, so rotating your crops about 1000 meters away is a nice way to deter any larva that hatch now and survive to become adults from finding the next batch of carrots. However, that's not an option for me. We live on a small residential lot, not a farm. Another way to deter adult carrot rust flies can be to fool their sense of smell by interplanting carrots with a fragrant cover crop that is not related to carrots. That's possible. You can also set out traps for adult carrot rust flies. In my case, I don't think the threat posed by the single fly I saw today justifies that. The same can be said for row covers, which are another option.
To kill the larva - which are the actual problem to my carrots - I could use parasitic nematodes. This is really a great idea, because the nematodes can live in the soil for a while. However, they aren't active in low soil temperatures (below 60F), and so right now it's probably slightly cold for them to do any work.
From my internet research, it seems that carrot flies have about a 3 month life cycle. That means that an egg laid now would become an adult interested in laying eggs around June. One solution to the carrot fly problem would be planting no more carrots until then. That would be quite disappointing to me as our climate allows us to grow carrots year round and I've got some seeds I'm excited to plant for cosmic purple carrots. It's quite frustrating (but not surprising) that the carrot rust fly's life cycle so closely mimics the carrot's life cycle. After all, carrots take about 60-80 days to mature (depending on the variety you plant) and you can harvest them over a period of several weeks. Therefore, if the carrot flies play their cards right, they can make sure that all of the maggots hatch just in time to eat nearly-ripe carrots.
I've got a few carrots planted already but not very many. They are about 2 weeks old, so they will be ready to eat in 2 months. I was hoping to plant successive rounds of carrots so that there would always be ready to eat carrots around. Now that this stupid carrot rust fly has shown up, that seems like a bad idea. If I were growing carrots commercially on a larger scale, I'd use crop rotation, interplanting with a fragrant cover crop, row covers, and/or parasitic nematodes. As someone who just wants to plant and eat carrots without having some stupid larva eat them and poop on them, I'm not sure what I'm going to do. Perhaps the best way to go is to rotate my carrots between my yard and a friend's yard to break the cycle of carrot fly reproduction. I can be smarter about when and how I thin the carrots next time around, but if my yard doesn't have a steady supply of carrots, then it hopefully won't support an ever-growing carrot fly population either.
(Note: Also susceptible are any other plants in the same family as carrots. That means celery, parsnips, cilantro, parsley, fennel, and dill. Of that list, we're growing lots and lots and lots of cilantro, some parsley, and some fennel. I've got dill growing but it's not going to last long once the weather warms up. I was thinking that if it bolts I might let it hang around as a flower to attract bees for a while, but that's a less attractive option if it provides habitat for carrot fly maggots at the same time.) |
