What type of soil do you have? or it could be something is eating your roots? If you are watering twice a week, how hot is it? if temps are cool and soil clay, could be too much water, what color are the leaves? any yellow ones? brown ones? deformed ones? any pics? pics would sure help.

Corn isn't a "thirsty" crop, sorry. The vast majority of corn in this country is grown on rainfall only. And over-watering produces the same wilting appearance because the roots are rotting.

Dave

It could be a pest like wireworm eating your corn's roots causing it to wilt.

Soil is basically a loam,heavy on the clay. It had clover as a cover crop this winter (I didnt incorporate the clover cus of burs it had), and I put in a ton of composted horse manure and some organic fertilizer. Soil is very fluffy and dries fast, its like a raised bed now.
They look great, nice and green and vigorous, until the wilting. I fed with some fish emulsion like 10 days ago.

Im in Southern Ca. We dont have rainfall except in winter, normal Ga/Ar rainfall probably isnt more then what Im doing... Is sweet corn grown without irrigation or just grain?

In my old garden (in a hotter area) I could see a big difference in corn that got more water in my patch, it was way bigger, so I always try and get a little extra water on them. Never heard of wireworm, looks like gopher damage almost but its not. We have cutworms I guess, but they've never concerned me.

bf:

My corn is doing the same. I think it's just that the roots can't take up water fast enough to fully keep the top turgid. The hotter and lower the humidity, the worse the wilting. One day was 96F, 67 mph peak wind gust, and 3% humidity. In weather like that corn will wilt with moist soil and probably uses 0.75 inch in one day.

I water about 2-3 times per week by flood in level basins. I'd say ~3-4 inches per week. Corn in Illinois grows pretty well with 1-1.5 inches per week rain. But that is much higher humidity and cooler with less wind and water use is about 0.25-0.33 inch per day.

You say your soil is very fluffy. That could be part of the problem. In a fluffy soil water movement thru the soil towards the root is reduced. Organic matter and loose airy soil is usually good. But to much of a good thing might limit water uptake by the corns roots.

It also sounds to me like you have gone a bit over-board on the fertilizer end. That could be having an effect on it too! Back off on that & let it take up what is already in the soil. More is not ALWAYS better.

Thank you so much for the replies, fruitnut, what do you mean water in loose soil has movement toward the root reduced? This is a new garden, I tore out half the lawn in the backyard for a garden. Thats why I wasnt shy on the amending. I had a hard time with my winter garden, and I did a soil test with some old soil test kit I had (I know might not be that accurate). Potash was ok but very phosphorus deficient(kinda suprised me) and needed N too.

bf:

Water has to move through the soil to reach the root surface. The roots aren't everywhere. As the roots withdraw water from the soil, at the root/soil interface, the water flows through the soil to replace the water that has moved into the root. A loose, fluffy soil will have a higher resistance to water movement than a moderately compacted soil. This resistance can be the limiting factor in supplying water to the plant. We're talking small distances around each root hair or root, say 0.1 to 0.25 inch but that is still critical for high water use periods.

You said your soil was fluffy and dries out fast. That sounds like the limiting factor to me on those high water use days. My plants, and I assume yours, only wilt when water use is at it's highest. My corn doesn't wilt on a day when there are some clouds and the humidity is higher. It only wilts midday on those days when water use is high to very high, say 0.4 inch per day or more.

You can get good sweetcorn growth and yield with some midday wilting. What really kills corn is prolonged periods of wilting just before and after tasseling.

Oh thanks Fruitnut, never heard or thought about that process. Maybe it will get better once my soil digests the compost more, I actually did wait a few weeks before planting, after incorporating it. Its weird to me that its happening so bad all of a sudden, after that one warm day. And nothing like the conditions your unfortunately having. It started when we had a few days in the 80s. And the past few days its been windy, but cool, 60s/70s.

I think its gonna be a failure, what a bummer, looked so good, was growing great. Doesnt seem to be growing much anymore, and corn is one of those plants that if you stunt it thats it, no second chances. Bet it will tassle soon. Maybe it was the feeding I did. Would expect leaf tip burn or something tho.

Does your corn perk up on its own (without watering or other action on your part) after experiencing direct sun exposure on a hot day?

Yes, my corn perks up in the evening and looks great by morning. That degree of stress isn't a crop buster. If your corn remains wilted overnight, yield is seriously hurt.

I haven't seen this mentioned yet so I'll just throw this in the mix.

Excess salt is a problem for some of us here in arid So Cal. Adding a ton of horse manure + fertilizer will certainly raise the salt content of your soil.

Excess salt will manifest itself by wilting plants (as you described), retarded growth, and scorched the leaf edges.

Have you seen any signs of a whitish crust on the surface of your soil when it dries out?

Did your soil test indicate moderate salinity before adding the manure + fert?

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I say you are overwatering it! I just drowned a pepper plant, bummer!!! I didnt realize it and then it just wilted altogether. Came back that night and then just wilted and is still wilted. Gave me 8 bell peppers before it croaked though. Now My corn is in a SWC and I water it day and night but I have no mulch or moisture barrier. It has never wilted, the leaves curled and turned brown once when I couldn't water it one day but never wilted. Mines silver queen.

dirtydan wow I hope thats not your yard! Looks like somewhere a bit inland, desert maybe?

I havent really let it perk up on its own, cant stand looking at it drying up so I eventually water towards the end of the day. Been about every other day I think. I dont think its overwatered because when I water it looks good again. I wonder if I caused shallow wimpy roots because I watered too frequently tho.

Unfortunately, those are indeed pictures of my yard. I am east of Ventura in the high desert. Since those picture were taken last year, I built raised beds and flushed the salt out of the root zone.

If you have high salinity the plant will begin to experience stress and wilt as the soil dries out since the salt in the remaining solution becomes more concentrated, inhibiting proper root function.. As soon as you hit it with water it will perk up because the salt is temporarily diluted.

In my garden, okra and bell peppers are the most sensitive to salt. Squash, tomatoes and corn are fairly tolerant.

Well its doing good now for awhile. I gave it a super good soaking. I had thought before I watered deep enough, but I guess it was still dry somehow further down. I think it also helped compact the soil a little so it didnt have to much air etc. Thank you!

bf:

My corn is doing better as well. We've gotten a little humidity. I water heavily and then wait until the first wilting starts during the heat of the day. This has been about two inches every 5 days lately. The first planting will be ready in about 10 days.

Corn takes a lot of water. For every case of drown corn roots in a garden situation there will be 1,000 cases of under watering.

Good to hear that things are going well!
Dan