Sweet Corn - Horrible Aphid Problem - Can I get your advice?


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Hey there guys. I've been gardening for a few years now with decent success haha. Our real bread winner has been Asparagus which seems to always do fantastic each year with minimal problems!

We decided to try Sweet Corn this year for the first time. It was going awesome, until the tasseling and silking started. Unfortunately, my corn started to tassel well before silks developed, so we didn't get any pollination and thus, no sweet corn... I definitely fertilized properly, so I think the heat wave and drought we experienced here is what caused this. I was watering my 8x4 ft bed with 2 gallons of water every other day - I did some rough calcs after the fact and found I probably should have been doing 4 gallons everyday, which would be 4x the amount of water than I was giving them... maybe that was my problem?

Regardless, I will try again next year! I've kept the corn stalks growing just for fun and so my wife can use them for fall decorating haha. But I've come across a major problem: Corn Leaf Aphids!

I wish I kept a better journal but I remember finding them on a single stalk around end of June. I sprayed them down with neem oil and moved on.

By end of July they had infested every single corn stalk. They have since covered every leaf underside, tassel, and silk. From a few feet away it looks like somebody has spray painted my stalks black...

I was getting desperate so resorted to my last resort, which is pesticides. I used some heavy stuff that has never let me down before: a mix of Permethrin and Bifenthrin, which should kill insects for up to 3 months. I sprayed the stalks down completely: top, bottom, from the bottom up to hit the undersides of leaves... No result. I've since sprayed the stalks down 6+ times over the last 4 weeks and they dont seem to die. Or maybe theyre dying, and more are just hatching at a faster rate...

Regardless, it's disgusting. The stalks are covered in the mold that results from the honeydew, and they are all sticky with goo and crawling with larvae and adults.

I don't want this to happen next year, at all. Can I get anyone's advice here on what to do next year? I am totally shocked the heavy duty pesticides did not take care of them on the first round. It makes me really nervous for next year - this would have been so heart breaking had I actually gotten my corn to pollenate! I'm also wondering, can these critters overwinter in Pennsylvania? I don't want them to stick around for next year.

Thank you guys so much. I tried posting on some gardening reddits and for whatever reason didn't get any responses. Also dont know anyone else growing corn who has ran into this problem. I appreciate the help.
 
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I didn't even realize aphids would attack corn leaves. I've never noticed them on my corn and I don't spray pesticides until they start to silk and then only spray the silks. I do usually have plenty on my tomatoes so maybe they just congregate over there instead.

I use 1 tbsp of Dawn Ultra per gallon of water on aphids. I have noticed though that when they dry up they are mostly still attached to the leaves so maybe that is what you are seeing. Most times they will turn white in a few days time. I have taken a magnifying glass and try to poke them with something to see if they move because they are hard to see any movement out of if they are just sitting there.
 
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Thanks for responding pal. Yes, I have noticed that when the pesticides do kill the ahpids, they all stick there but if poked are dead. However, there are still more groups alive than dead (poking them causes them to move around).

I should have mentioned i used soap too. First simple dish soap mix, then a neem oil / soap mix, then onto the big pesticides. It's been atrocious and I can't understand why!
 
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I don't think aphids can build up a resistance to dish soap so I'm not sure what the deal is. I have used 1.5 tablespoons of Dawn Ultra per gallon before also.

I don't think the insecticides kill the eggs. Maybe they are hatching that fast and appear to not be killed like you stated? If your infestation is that bad, it might be possible.
 
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I don't think aphids can build up a resistance to dish soap so I'm not sure what the deal is. I have used 1.5 tablespoons of Dawn Ultra per gallon before also.

I don't think the insecticides kill the eggs. Maybe they are hatching that fast and appear to not be killed like you stated? If your infestation is that bad, it might be possible.
I would agree with you about the soap, as I understand it blocks the breathing holes and suffocates them, though I use cheap, soft, soap rather than the detergent soap for dishes and apply it with an old shaving brush, which is pretty rough on them in itself.

As far as eggs hatching goes I don't think so. They produce eggs to over-winter, but during the Spring and Summer months they reproduce a-sexually. They say the young can contain the next generation before they are born, so you don't need many survivors to have a problem. Come Autumn they produce males and sexually active females that produce the eggs capable of overwintering. I don't think they would hatch before Spring.
 
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I don't want this to happen next year, at all.
Be really tidy, clear up every bit of fallen leaf and vegetable matter, then have a good hoe over and look to see if you have turned anything else up. Depending the eggs probably won't survive composting in a bin, they just might in an open compost heap. If you want to be extra careful chuck everything in the incinerator, they won't survive burning.
 

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