Just finished planting some corn, and have been a bit concerned at the time it is taking to germinate (up to 2weeks). Dug some seeds up and am finding a lot that have swollen but not germinated and have gone a bit dark and soft (pythium?) and quite a few that have germinated but seem to have brown discoloration around the lower shoot near the seed, with limited or no roots also (seed pics). Other plants are pushing out three leaves.
Planter runs that were sown two days earlier seem to be emerged and quite good. I know this would suggest soil temp, but I just didn't think it got that cold.
We had a warm start but was followed by three frosts in a row. Soil temp at 9.00am got down to 10 deg C for a couple of days, moisture is good. Could the cold snap knock the germinating seed? or could it be fert. burn.
I have never had fert problems in the past using the same system all on 26" rows (soild stand), even on skip row with the same fertiliser rates ( 12-13-12 @ 125kg/Ha + 46-0-0 (urea) @ 120kg/Ha) using cross-slot seeder that places it about 1" to the side of seed. Maybe in the past I've been lucky? Anyway I think it will be a replant, which i'm not really excited about, but if anyone has some suggestions it would be much appreciated.
Oh yeah, there wernt that many emerged plants that showed these symptoms (like in the pics) my main concern were the large amounts of ones that had only swollen and hadn't germinated at all, I just thought these could have been ones that had been injured and not killed off totally and may give you some clues to the underlying problem.
Posted 10/27/2008 07:20 (#491822 - in reply to #491800) Subject: Re: Corn Germination problems
Must be cold Jim, everything is viable, beautiful pictures of healthy cold seeds. I have seen it take 30 days, what year was that, late 80's early 90's, made a full yield. If the brown is dead tissue on the second pic, it may be injured, if it is the same seed as the other pics I think it will be OK. When the radicle or shoot turns yellow to brown then it is dying.
Posted 10/27/2008 07:36 (#491840 - in reply to #491822) Subject: Re: Corn Germination problems
I may be jumping the gun, we've got warm weather so I'll wait another week and check it out again. I'ts just if i'm going to re-plant then I only have a couple of weeks left to do so before it's getting late. It's a tough decision.
Posted 10/27/2008 07:46 (#491846 - in reply to #491840) Subject: Re: Corn Germination problems
Photo 003 is the only one that might be normal -- all the others are toast (002 might survive but won't be healthy). It appears to be classic chilling injury. The temps you cite aren't terribly cold, however. Maybe it was low-vigor seed (it's important to know the Cold Germ and AA scores when considering planting in marginal conditions).
It doesn't look like fertilizer injury. Is there any possibility of herbicide carryover from previous crops? And what was applied for the corn? (any 2,4-D in the burndown?)
Posted 10/27/2008 08:32 (#491876 - in reply to #491846) Subject: Re: Corn Germination problems
There wouldn't be any residual chem in these fields. No 2,4-D in the knockdown in this one either. Did have atrazine & 2,4-D for winter fallow 3mnth ago, but asume this is no problem. Only Glyphosate for knockdown, with Atrazine & Metolachlor PSPE, but this has only just been applied, and have had no rain.
There are quite a few seeds that havn't germinated at all.
What would the effects of fertilizer burn look like? If it was damage from the urea, how long until it would be no longer harmful( 3- 4 days?. the soil is moist), because I would re-plant on the same furrow.
Posted 10/27/2008 09:25 (#491916 - in reply to #491903) Subject: Re: Corn Germination problems
Do you mind if I ask you what brand and hybrid this is? We had a lot of corn that looked just like yours this past spring. We were also very wet and cold in central Nebraska. I noticed this problem was the worst in two particular hybrids. I have no idea what relative maturity you guys plant down there, so I could be way off thinking that it is the same corn we had. In our case 95% of the seed that had germinated survived. To my amazement a lot of the seed that was swollen and sitting in the ground actually came through when the rest of the corn was 4 or 5 inches tall. At that point I considered those plants more like a weed than a corn plant. We didn't replant, and I expect it to yield halfway decent compared to what a good stand would have been. I'm going to guess yield will be down 5% from its' full potential.
Posted 10/27/2008 21:24 (#492222 - in reply to #492146) Subject: Re: Corn Germination problems
Was there a hint of sarcasm in there Ed? You've got to remember that this is Australia, we get the varieties you guys probably had several years ago. In Australia, this variety is about as short crm and drought tolerant as we get (which is what I need) I'm in winter crop wheat, Canola and Chickpeas country. The whole Australian corn crop at a guess would be only a few hundred thousand acres (mostly irrigated), so we rely on your non -GM mid west varieties.
By the way here is another shot of a seed, does cold make the actual root stunted and black?
Posted 10/28/2008 06:07 (#492479 - in reply to #492263) Subject: Re: Corn Germination problems
The reason I say it looks like chilling injury is that in the pics labelled 'scan0001' and 0002 (in original post at 03:59 server time), the roots are very distorted -- wrapped quite tightly around each other (and wrapped/distorted directly from their source inside the kernel in 0001), and abnormally truncated. Essentially the only other thing that causes distortions such as these is herbicide injury, which you have ruled out.
In the seedling that is sliced open, there is brown tissue inside the lowermost part of the shoot inside the kernel, which is due to disease invasion (a secondary problem that goes along with chilling injury). Chilling injury usually doesn't kill the tissue outright, but instead weakens it sufficiently for it to succumb to invasion by pathogens. This is likely what occurred to the kernel in 'scan0001' in your post at 20:24 -- the radicle [first root] was injured and became infected and died, although the secondary roots survived and look normal. (Incidentally, the coleoptile [shoot] is going the same direction as the secondary roots, a result of the 'confusion' created by the lateral slit of the cross-slot opener.)
Apparently the seed lot was low vigor, which greatly increases the susceptibility to outcomes such as these.
Fertilizer damage would look different -- there wouldn't be abnormalities (or very few), but there would be kernels that died soon after exserting a radicle or coleoptile, or before any sprout is visible. In a few cases, depending on how and where the fertilizer was applied, along with certain weather conditions, the seeds will germinate okay but will have some root die-back from fertilizer toxicity -- but there will be a distinct pattern (the roots only die back on the side where the fertilizer was located), and without any growth abnormalities.
Posted 10/27/2008 12:20 (#491989 - in reply to #491800) Subject: RE: Corn Germination problems
You didn't mention much about soil moisture at planting.
My math conversions could be wrong for Kg/ha from our pounds/acre but your fert rates do seem high for salt content placed 1" from the row. We were very very dry spring 2007 and had seeds lay dry from May 5 planting until a light rain germed them June 25. They stayed just perfectly dry, just like in the bag.
I don't like the looks of the radical roots from the seeds, this is abnormal development. Imbibitional chilling can cause abnormalities in seed however, 10C is not that cold and that is a normal temp for our area to experience at planting every year at some time or another. Seed genetics and seed quality will play a role, I would discuss with my supplier.
Posted 10/27/2008 16:52 (#492078 - in reply to #491989) Subject: RE: Corn Germination problems
The soil mosture is what I would call ideal for germination, nice and moist but far from wet.
I guess the one thing that puzzles me is that we've had a 10 deg c soil temp before and never had a problem.
My concern is how do you manage the ones that come up three weeks later in my replant. We are in a marginal yield area for corn (60bu/acre avg.) I guess I just take out the emerged ones at the end of the week and put up with the extra's later (mind you there isn't a lot of them that are going to come up).
Posted 10/27/2008 22:24 (#492276 - in reply to #492078) Subject: RE: Corn Germination problems
Have been planting 36bo8 for many a year. In this area in most years it still will rank in the top three or four across the plot.. Cold tolerance has been good along with early growth. That said it has been around quite awhile. Maybe the seed you got has lost some vigor. I heard that it is unavailable this year. Ours was froze off four times this year. Planted in cold wet conditions as most corn was.
Would think it was fertilizer damage but the ones that didn't germinate shouldn't have been burnt. as far as getting them all the same. a good frost will even them out.
Posted 10/28/2008 17:09 (#492829 - in reply to #492602) Subject: Re: Corn Germination problems
I think I will replant on the same drill rows, in an attempt to dislodge any germinated seeds to the surface. Then wait just before emergence and hit it with Gramoxone (Paraquat) to take out any survivors. That should give me an extra week to allow any more to come up. Tricky one to manage.
Hopefully any seeds that do make it through will be injured and weak and won't compete with the new crop