1. How many corns did you plant?

2. Are they planted closely together?
(It looks as if the corns were not pollinated well).

3. Or did you pick them too early?
(Looks like they have been filled out well on the bottom side.)

4. Is that the first ear or second ear from a plant?
(Second ones seems to not fill out well as the first.)

Probably not enough water, too little nitrogen, and/or planted too thickly.

That looks a lot like it was picked too early! To me the ear was filled just fine.

I have raised Ambrosia for many years. I find it to be a very reliable variety. There is a small chance here that it was picked too early, If it is a second ear, that explains a lot. I tend to feel that the plant ran out of mineral nutrition or was planted way too thick.

That is pretty strange. I grow only Ambrosia (hard to beat). The kernels on the bottom half have well developed yellow ones which tells me that it's ripe. My best guess with limited info is incomplete pollination. The bigger the plot the better the coverage but you can hand pollinate. My corn plots measure 12'x12' which can be easily hand pollinated with a long stick raping the tassels daily during calm wind periods.
But for a more complete answer to your question we'd need to know your planting, care, & harvest methods such as spacing, fert used, lower ear? silk dry enough for mature ear? etc.

Thanks folks! A bit more info............. Planted 8, 30' rows, with row spacing of 30" & plants spaced at 8 - 10" apart....... Used drip irrigation & fertilized (side dressing) with urea 0-0-46 when corn was 6 - 10 " tall & again when it started to silk...... Ambrosia has a 75 day maturity & it had been well over that when I finally harvested. I'd waited for the ears to develop, but the bottom half was in the milk stage & the husks were starting to break down with no further development on the top..... This pic was of a main ear...... This is my first year growing Ambrosia, so I wasn't sure what to expect....

This post was edited by cugal on Thu, Aug 8, 13 at 21:39

From the look of the first ear you posted, you should wait for 5 more days before picking another ear to check for maturity, that is on 12 August. By that time the ear will most probably be matured. Harvesting corn at the right is something that comes with experience. To harvest at its sweetest and tenderest takes a lot of trial and error.

Planted 8, 30' rows, with row spacing of 30" & plants spaced at 8 - 10" apart...
..."fertilized (side dressing) with urea 0-0-46 when corn was 6 - 10 " tall & again when it started to silk..."

Well that sure seems like pollination should Not be a problem with 8 rows 30' long.
Your urea numbers are reversed, should be 46-0-0, the 46 being nitrogen of course. I use urea too but blend it with a 10-10-10 mix so that the developing plants also have adequate phosphorus and potassium with the nitrogen. Also, when side dressing the final time I do it as the first tassels start to just barely peek out, not when the ear silk shows as this may be too late to help.

As for the half mature ears, another "guess" would be if you had constant heavy rains right after the tassels started to produce pollen, the pollen could have been mostly washed out before getting to all the ear silks?

How do the other ears look?

Thanks folks! Lots of good info here! I've grown sweetcorn several years & I think I'm slowly getting the hang of this.....LOL GW has been a great help!

wayne_5, all the ears looked like the pic.....

You're correct vgkg, I had my Urea numbers backwards. Don't know if it's dyslexia or old age (both?) We have missed a lot of the heavy rain that fell just to our south, so rainfall shouldn't have affected the pollination. I will take your advice on fertilizing when the tassels emerge.

If the end of the ears continue to not develop, I have to wonder if they had enough phosphorus and potassium [in relation to N] to develop the grain. How are any other garden crops doing?

I am wondering if the problem is drought damage...see link.

Here is a link that might be useful: tip fill

This post was edited by wayne_5 on Fri, Aug 9, 13 at 22:05

Given the adequate spacing I'm inclined to agree with Wayne, probably not enough water. The bottom part of that ear is fully mature. The tip 40% indicates a lack of some factor most likely water.

Water deficit is easy to see on corn. The leaves wilt and curl at first during the hottest part of the day. When they are wilting most of the day you will get ears like that picture.

A picture of the plants might help if further assistance is needed.