Seedcorn Maggots- S.O.S.

ARgardener · February 25, 2017

I had never heard of this pest. Now here I am, knee-deep in my first "Big" garden, and I have them.
I now know why I have them... I tilled in relatively fresh manures and leaves in late winter, so my soil is really rich with decaying organic matter. Which is what's drawing the little demons.
I've suffered huge losses on my germination rates and seedlings (especially in my carrots, spinach, and peas).
I really don't know what to do.. at all.
Should I desperately try a pyrethrin soil drench? Or is that a waste of $20?
Should I replant? Not sure if that would help either...
Should I do anything with the areas of the garden that aren't yet planted?
Are all of my summer crops now doomed as well??

It's pretty devastating, really... I just need some opinions on what to do.

brownrexx · February 25, 2017

I had never heard of them either so of course I Googled.

https://extension.entm.purdue.edu/fi...orn-maggot.php

They seem to be mostly a pest of corn and they look too large to be causing trouble with your carrot or spinach seeds. Many people have trouble with getting spinach seeds to germinate. they can be finicky.

Have you opened your pea seeds and found maggots inside? Why do you think that it's corn maggots?

Things may be different in Arkansas but I live in PA and I garden organically so I have way more organic matter than average in my garden. Average is 4% and I usually have about 10% according to my soil test. I have no germination issues.

Cole_Robbie · February 25, 2017

https://extension.entm.purdue.edu/pu...ions/E-219.pdf

In looking at the controls suggested in that link, other than pyrethrins they are all really nasty chemicals.

I wonder if gnatrol, or a BT product would help. Just a guess. Good luck.

ARgardener · February 25, 2017

Quote:

Originally Posted by brownrexx

I had never heard of them either so of course I Googled.

https://extension.entm.purdue.edu/fi...orn-maggot.php

They seem to be mostly a pest of corn and they look too large to be causing trouble with your carrot or spinach seeds. Many people have trouble with getting spinach seeds to germinate. they can be finicky.

Have you opened your pea seeds and found maggots inside? Why do you think that it's corn maggots?

Things may be different in Arkansas but I live in PA and I garden organically so I have way more organic matter than average in my garden. Average is 4% and I usually have about 10% according to my soil test. I have no germination issues.

My local entomologist confirmed it for me. They can effect over 40 vegetable crops. They don't just do inside of seeds, they eat on seeds, their sprouts, and roots.. so no crop is really safe just due to seed size, unfortunately.

The problem isn't just organic matter... it's under-composed organic matter... which is what I have a lot of. My horse manure really wasn't aged at all.

brownrexx · February 25, 2017

Did the entomologist have any suggestions?

ARgardener · February 25, 2017

Quote:

Originally Posted by brownrexx

Did the entomologist have any suggestions?

Didn't get to talk long, so I emailed him. He mentioned something about planting later as opposed to earlier

brownrexx · February 25, 2017

Yes, I was thinking that too. I also soak my peas either overnight or for 2 days to get them started to sprout before planting them. In my case I want to get them out of the soil sooner to prevent rot in cold soil but maybe this could help you too.

I also "prime" my spinach seeds to get better germination.

Google Priming spinach seeds to read about it. It really works.

Starlight · February 25, 2017

How terrible for you. I wonder if using b54red Bill's mixture of pyrethrin and especially DE would work?

Can you wait to replant when the weather warms up some and it may be a pain, but maybe starting seedlings indoors or a separate area with a row cover til they get big enough to transplant into the field.

If you go down to the section on Slurry .. about 3/4 of way down document, it tells you how to make a slurry seed treatment using an insecticide and a fungal treatment. It gives some chems to use, but I don't know anything about them, but there some good scientific , knowledgeable folks here on TV that might know if they safe to use on your crops or not.

https://archive.org/stream/seedcornm...lmo_0_djvu.txt

All I can find is let the soil warm up and top inch by dry with no cracks in it. The flies like to lay the eggs in cool, moist soil and fresh organic mixture. Fresh composted ground you should wait 6-8 weeks before planting in.

ARgardener · February 25, 2017

So here's what I've concluded..
I'm having this issue because I added 2 trailer loads of fresh manure.. in early January; as we know, processes are slow this time of year. This unaged material is now drawing in all those flies to lay their eggs. My fault, but I never had heard of seedcorn maggots.

Today I went out and ripped up alll my carrots (which were planted in a paper towel seed tape that has yet to decompose) so that made things simple!I figured since they're getting decimated, that to leave it would just enable the problem to grow and continue. May also end up doing this to my beets.
I very well may plant a little later. What's to lose? I'll get no crop if I don't replant, and I'll only be out a few bucks to buy the seeds

Also, I'm working on scalping the garden to try and get back to the original soil that isn't 50% unaged manure. I'm piling it up atop a stack of manure and I'm going to let it all age; then add it back to the soil in the fall.
Do you guys agree that this is wise?

ARgardener · February 25, 2017

Avoiding Seed Maggots

1. Avoid under-composed materials (especially manures), these attract adults
2. Avoid keeping the seedbed too moist- this stimulates females to lay eggs
3. Don't plant as early as possible.. The first planting weather is also the first life-cycle for many pests. Wait a few weeks to dodge things
4. If an outbreak happens, efforts are basically futile. Instead, replant later to catch a break in the bugs' reproduction cycle.
5. Till-in organic mature early in the fall.
6. Rotate crops

Cole_Robbie · February 25, 2017

I don't know the size of your garden, but I would wonder about solarizing as an option. Cover the ground in clear plastic, and in the hot sun, it should get hot enough to kill whatever bugs you have. I would think the hot temps would also speed up organic matter decomposition.

ARgardener · February 25, 2017

1,200 square feet...
Also not sure that the sun is intense enough to accomplish that yet. Good thoughts, though.
There will be enough residual organic matter from prior tillings, so once I scalp my raised rows things should be looking up. Should.

BigVanVader · February 25, 2017

Horse manure is bad if not aged. I've seen this in my piles before but I never used it until it smelled like dirt. I've not had issues with alpaca or rabbit though.

brownrexx · February 25, 2017

If you just added the manure in January then yes, it is definitely too soon. You should never grow root crops in manure until it has aged at least 4 months. This is not to avoid flies but to avoid pathogens from the manure that can infect humans.

Using manure is good, you just need to age it first, either in a compost pile or tilled into the soil for several months before planting.

I think that your idea of trying to remove it and let it compost sounds like a reasonable idea.

Then by waiting a bit to replant, hopefully any larvae in the ground now will have hatched into flies and then they will move on to the compost pile where the manure will attract them away from your garden.

It's probably the best you can do for this year.

ARgardener · February 25, 2017

Quote:

Originally Posted by BigVanVader

Horse manure is bad if not aged. I've seen this in my piles before but I never used it until it smelled like dirt. I've not had issues with alpaca or rabbit though.

What have you seen in your piles? Seed maggots?

Unfortunately there's no rabbit or alpaca source I'm aware of nearby

February 25, 2017	#1
ARgardener Tomatovillian™ Join Date: Dec 2016 Location: steamy southern Arkansas Posts: 155	Seedcorn Maggots- S.O.S. I had never heard of this pest. Now here I am, knee-deep in my first "Big" garden, and I have them. I now know why I have them... I tilled in relatively fresh manures and leaves in late winter, so my soil is really rich with decaying organic matter. Which is what's drawing the little demons. I've suffered huge losses on my germination rates and seedlings (especially in my carrots, spinach, and peas). I really don't know what to do.. at all. Should I desperately try a pyrethrin soil drench? Or is that a waste of $20? Should I replant? Not sure if that would help either... Should I do anything with the areas of the garden that aren't yet planted? Are all of my summer crops now doomed as well?? It's pretty devastating, really... I just need some opinions on what to do.

February 25, 2017	#2
brownrexx Tomatovillian™ Join Date: Feb 2016 Location: Southeastern PA Posts: 1,420	I had never heard of them either so of course I Googled. https://extension.entm.purdue.edu/fi...orn-maggot.php They seem to be mostly a pest of corn and they look too large to be causing trouble with your carrot or spinach seeds. Many people have trouble with getting spinach seeds to germinate. they can be finicky. Have you opened your pea seeds and found maggots inside? Why do you think that it's corn maggots? Things may be different in Arkansas but I live in PA and I garden organically so I have way more organic matter than average in my garden. Average is 4% and I usually have about 10% according to my soil test. I have no germination issues.

February 25, 2017	#3
Cole_Robbie Tomatovillian™ Join Date: Jun 2012 Location: Illinois, zone 6 Posts: 8,407	https://extension.entm.purdue.edu/pu...ions/E-219.pdf In looking at the controls suggested in that link, other than pyrethrins they are all really nasty chemicals. I wonder if gnatrol, or a BT product would help. Just a guess. Good luck.

February 25, 2017	#8
Starlight Tomatovillian™ Join Date: Jan 2015 Location: AL Posts: 1,993	How terrible for you. I wonder if using b54red Bill's mixture of pyrethrin and especially DE would work? Can you wait to replant when the weather warms up some and it may be a pain, but maybe starting seedlings indoors or a separate area with a row cover til they get big enough to transplant into the field. If you go down to the section on Slurry .. about 3/4 of way down document, it tells you how to make a slurry seed treatment using an insecticide and a fungal treatment. It gives some chems to use, but I don't know anything about them, but there some good scientific , knowledgeable folks here on TV that might know if they safe to use on your crops or not. https://archive.org/stream/seedcornm...lmo_0_djvu.txt All I can find is let the soil warm up and top inch by dry with no cracks in it. The flies like to lay the eggs in cool, moist soil and fresh organic mixture. Fresh composted ground you should wait 6-8 weeks before planting in.

February 25, 2017	#13
BigVanVader Tomatovillian™ Join Date: Mar 2014 Location: Greenville, South Carolina Posts: 3,099	Horse manure is bad if not aged. I've seen this in my piles before but I never used it until it smelled like dirt. I've not had issues with alpaca or rabbit though.