Landrace Sweet Corn Project

Good afternoon all,

I have two ambitious corn projects in mind, and would like to bounce them off of you knowledgeable growers out there.  I'm planting in Illinois, which is the original home turf of many modern sweet corn varieties, so the potential for growing success is high.  However, my available space to plant is low (16'x16' square=~90-100 plants per crop).  At this point, I'm just viewing this as a delicious and educational hobby, but my eventual goal is to establish an early cold-season OP sweet corn, as well as an OP late mid-late season landrace sweet corn initially comprised of about a dozen F1 hybrids, with more added as new varieties are introduced to the market.  As if that's not demanding enough, I have some other constraints to work around.  

First, this is field corn country, so I can only plant my corn every other year when the field nearby is in soybeans, so naturally, this will be a long-term project.  In opposite years, the patch will be in beans to replenish the Nitrogen.  

Second, I have a 177 day growing season here, and yesterday I started the plot with an early cold-tolerant variety with harvest in 63-68 days (if all goes well).  As the years go on, I have plans to add some earlier types, as well as selecting the earliest/healthiest from each crop for seed saving.  I will be planting as many short pole beans (~4') as I can to help with the Nitrogen depletion as 2 of the 3 sisters.

Third, I plan to plant the later season crop immediately following fresh harvest of the early variety (excluding the ears marked for seed saving/drying).  This means I will have about 100 days, maybe a few more for the 2nd crop.  However, this will be about mid-July during the heat of our summer (I've never grown corn so late, so not sure what pests I'll encounter).

My main question is, has anyone out there intentionally staggered planting times of multiple varieties so that the listed "days to maturity" line up as close as you can get?  The idea is, to ensure maximum opportunity for maximum genetic "mingling" when all the silks are ready, and tassels are pollinating.  TIA  

What you plan on doing is absolutely correct in my opinion.  I do random staggered planting on all my corn breeding mixes/ landraces and I see wonderful results.  There is a fair amount of inherent failure but that is the byproduct of the intended goal and should be expected, negative selection is as important as positive selection as far as I am concerned.  

This year after much procrastination I am finally beginning a sweet corn breeding mix/landrace.  I have acquired over forty different varieties/strains, mostly open pollinated but some hybrids as well.  I will stagger the plantings by row.  By my method many will fail to pollinate but I do not care because enough random crossing always occurs to push the project along.  Be aware that some of your best seed genetically speaking might come from some of your ugliest ears, do not discount any seed based on human biases for "pretty" ears.

Be sure to always consider backcrossing in your strategy, it is a valuable tool for increasing genetic diversity at a faster pace.

Have fun, keep us updated.  Perhaps we could trade seeds in the future as this is also an excellent way to rapidly increase genetic diversity of a person's landrace mix.

Thank you for your response!  I've tried to do my homework, but there's no teacher like experience.  I'm glad you mentioned the bias toward a pretty ear part,  because I certainly would have.  I'd definitely be interested in trading seed down the road once I've got something going. Thanks for the advice!

Couple more things to consider that I neglected to mention.  Be aware of days to maturity (DTM) from a food harvest standpoint versus season length needed to get mature, viable seed (Seed to Seed).  I assume you have a longer growing season than I do so this may not be as critical to you, but it is very important to me in my short growing season.  My growing season is considered 90 day but I consider it to reliably be 100 day frost free, 110 day is realistic, 120 day happens but unreliable, 130 day in a rare and lucky year.  If I grow a corn that has a 120 DTM that means I might get ears mature at food stage and might not, and highly unlikely to get mature, viable seed (I do not play games with this, I expect my corn ears to mature and dry down on the plant before harvest for seed stock as it makes for the best seed).  

There obviously can be issues with crossing long DTM corns with shorter DTM corns because the longer DTM traits can increase the failure rate of the landrace plot in too short a growing season.  If I want to get 120 or 130 DTM corn into my landrace gene pool I choose to one-way cross corns with shorter DTM into those longer DTM corns, and I prefer to avoid the too-long DTM corns from crossing into my landrace.  I control this by detasseling the longer DTM plants.  It is simple to know which plants to detassle by observing the corn patch and noting the lagging development of the longer DTM plants.  Because my concerns generally go only one way I do not engage much in bagging of silks but I have done it for certain circumstances.

Sweet corn is a very unusual corn type to me, and I do not have too much experience with it.  Being that some sweet corns have as short as a 45 DTM it will be very interesting to me to cross those short DTM corns into the longer DTM corns.  I look forward to playing around with it.

For the foreseeable future I only want to include older hybrids, I do not want SE hybrids or any of the other modern supersweet hybrids as I find them overly sweet and incredibly bland, and thus utterly pointless to me.  

I have also engaged in intentional corn inbreeding, bottlenecking, and stressing, as well as experimenting with synthetics and composites, all to pry open the genie bottle of genetic diversity.  It is fascinating and I have had very interesting results, but those are subjects for another day.

My point is to continue to do your research and continue to learn all the different methods and strategies that can be used to achieve your goals, and even achieve your goals faster.  This stuff eventually becomes second nature and requires little to no extra effort or hassle on your part, so while it may sound complicated at first it soon becomes intuitive, interesting, and a lot of fun.  Some day soon you will have important and valuable corn strains that exist only in your collection.  I find this possibility to be a really cool thing, anyone could get such results with many of the different food plant types if they wanted it and were willing to make the effort.

Thank you for the insight! I'm enjoying myself already with the planning & contemplation of all the different possibilities. Now that I've got the ball rolling with my first planting of this series done,  I find myself ready to do more than just wait... but wait for germination is all I can do right now.

You mentioned intentionally stressing & bottlenecking your corn.  Can you elaborate on what you do to try to achieve a desired outcome?  About 11 years ago, I lived in a different area, and was on my way to developing a more shade tolerant sweet corn that could produce with closer planting distances (I always hate to cull planted seed that's growing well just because of spacing).  I know the general rule of thumb is 12" between plants, but I have seen some varieties specify 8-9" spacing, which is more attractive to me given my small space.  Alas, I tried germination tests on my old saved seed, but it seems 11 years is just too long for corn.  

I love reading about any and all corn projects, it is one of my favorite crops to work with. I'm in Southern IN so I also have plenty of growing season to work with and have on occasion been able to grow two crops in one year. That is to grow one to full maturity, about early July-ish and plant those seeds to mature again about late September-ish. DTM as indicated on packets is useful in adjusting your planting to get a faster one (plated a little later) to flower with a slower one. Actual maturity time in your climate will probably be controlled more by GDD (growing degree days) like described here. Purdue University GDD When I was working with sweet corn I found a lot of the really fast maturing ones did not do well here. They ended up tasseling at just a foot or two tall producing very small ears. I think it is because they got their required heat units too fast. If they were described as 60 DTM, it was closer to 45 here.

I had a lot of SE types in my mix along with bunches of SU but I also shied away form the so called synergistic and super sweet types. I think there a lot of good genetics in the  modern SE types as far as stalk strength, disease resistance and so on and it's fairly easy to select the SE back out if you want by culling the most shrunken and wrinkled seeds.

A problem I encountered with later plantings and two per season plantings is fall army worms which have increased in recent years. They can ruin a whole crop in short order if maturity happens to coincide with their arrival. I discovered an old Mexican variety called Zapalote Chico which has strong natural resistance to the worms. It is not a sweet corn, although if picked at the right stage is darned tasty. I'm crossing it this year with Aunt Mary's, an old SU white sweet corn that in my opinion is the best sweet corn in the world. It should might result in ears where some kernels are sweet, easily seen as shrunken or wrinkled kernels and some are more flour or dent. Since I'm not focusing on sweet corn anymore, I'll have no use for the sweet kernels. If either of you are interested in them send me a reminder about August or so.

I have read a bit about GDD, but will definitely read your Purdue reference.  I've heard similar about early tasseling in hot weather from other people's results. It's nice to hear about your projects since we're in similar areas climate-wise. I would surely be interested in some seed later on. I've considered adding limited outside (non-sweet) corn types if they bring useful genetics to the mix, which this does. My mix is planned to have resistance to multiple things, but fall army worm seems to be a difficult one to fight. Thanks for the info & kind offer!

Mark,

I've had field corn pollinate some of my sweet corn kernels in the past, & they were easy to tell once dried since they were the only ones smooth, rounded,  & not wrinkled.  I've never seen it the other way around since I haven't grown those types before.  Are the wrinkled "half" sweet corn seeds evident in the dried cobs, or does the flour/flint/dent take over until a second generation lines up recessive genes?  I'd think it would be evident the first year, but like I said, I've not tried it yet.

I'm not really sure of the dominant / recessive nature of the sweet genes. It may well be that (if it's recessive) a kernel not visually appearing sweet could produce some sweet kernels in future generations, especially depending on what pollinates it. In my experience, even though a smooth rounded kernel may be carrying a sweet gene it is easy to eliminate the sweet just by culling the wrinkled seeds for a couple of seasons.

I would guess the opposite would also be true. Cross anything you want in order to get diversity, strong stalks and so and then after a couple years start planting just the sweet, wrinkled kernels.  

I'm mixing the Aunt Mary's sweet into my mix because of how well it grows here but I actually want a flint corn, neither it nor the Zapalote Chico are flint. They just both have traits I want. Getting rid of the sweet will be easy in future seasons because of how easy it is to see; it would be just as easy to select for the sweet. The flour / dent nature of the ZC might be harder to get rid of but worth the effort for the worm resistance.

That sounds like a good plan. I look forward to hearing how your cross does. Thanks.

Mark Reed,

How's your Aunt Mary's x Zapalote Chico coming along this season?  I harvested my early, cold hardy sweet corn, and had more worm damage than I'd prefer, despite the early season.  I definitely want to add some worm resistance to my mix, & am just curious how yours is coming along?