The Journey of Sweet Corn: From Seed to Table

By Gwen Anderson

Sweet corn, the iconic summer vegetable.  You can hardly drive a mile in the countryside without running into fields’ worth of corn of some kind (and probably not the tasty sweet corn type).  But you know right away what it is, with its tall stalks, long green leaves, and silky ears. Even in the city, farmers park their trucks, beds piled high with the golden goodness, off the shoulder of the highways and in busy parking lots to sell their crop to passersby (but the back of the truck is a hot place for corn, and allows the sugars to quickly convert to starch).  Everyone loves sweet corn, which is exactly why we grow it. Richard has a saying: “Some crops you grow for profit. Some you grow to make friends. We grow corn to make friends.” How do we make friends with sweet corn? By prudently selecting the right varieties, careful planning, vigilantly combating pests, and having an expert harvest crew.  If everything is done right, we will have the best sweet corn ever.

The process starts with selecting the best corn seed.  Like with all lifeforms, genetics plays a vital role in the characteristics that show up in corn.  All types of corn, whether field corn, decorative corn, popcorn, or sweet corn, are the same species: Zea mays.  The genes needed to make corn sweet instead of starchy are recessive genes.  The starchy gene is the dominant gene. Genes come in pairs, one from each “parent.”  If the genes passed down from the “parents” are the same, that is the characteristic that is displayed in the “child.”  However, if the genes in the pair don’t match, it is the dominant gene’s characteristic that is displayed. Take humans for example:  Brown eyes are a dominant trait, blue is recessive. If both parents have blue eyes, they will have children with blue eyes. If one parent has blue eyes and the other has brown eyes, the children could have either brown or blue eyes.  If both parents have brown eyes, the children could still have brown or blue eyes. It really just depends on what kind of genes the parents are carrying.

There are three recessive “sweet genes” in corn: sugary (su), sugary enhanced (se), and supersweet or shrunken-2 (sh2).  Su is the oldest of the sweet corn varieties to have been cultivated. It has around 9% sugar content which quickly converts to starch once it is harvested.  The short shelf life of this sweet corn is traded off for good corn flavor, mild sweetness, and a creamy texture. Se corn has between 16-18% sugar content and has a slower sugar to starch conversion rate than su corn, which means that sweet flavor is more stable.  The kernels on se corn are also extremely tender; so tender they are easily damaged. Sh2 corn has about 35% sugar and has a super slow rate of converting sugar to starch. The kernels are also thick, so it stores well. However, those thick kernels also make for a crunchy eating experience.  But remember how genes come in pairs? It turns out genetics isn’t exactly as cut and dry as recessive and dominant genes, and by mixing the recessive traits we can make new kinds of corn: Synergistic (su and sh2 mix) and Augmented (sh2 and se). Synergistic corn blends the sweetness of sh2 corn with the creamy texture and tenderness of su corn while giving it a long enough shelf life to do some traveling.  Augmented corn does basically the same thing, just with the se corn instead of the su corn.  All these hybrids were created by naturally crossbreeding the corn.  We do not use any GMO altered seeds of any kind, nor do we use seeds that have “seed treatments” that contain various poisons such as neonicotinoids.

With this lesson of genetics under our belts, we pick up a seed catalogue.  Farmer Richard has done plenty of trial and error, and has also learned to trust the advice of our experienced seed rep, Phil Timm.  We buy all of our corn seed from the same company because of the relationship we have built with Phil.  With his help, we try new corn varieties and also have been able to find our favorites: Nirvana, Sweetness, Kickoff, and Awesome.

Sweet corn in early July this year

During the winter, we plan which crops we are going to plant and where.  This helps us decide how much seed we are going to purchase. With the plans made and the seeds purchased, it is a waiting game for the right time to plant.  We normally plant corn, weather permitting, around May 1st.  For the first planting of sweet corn, it is essential to pick a variety that has “cold soil vigor.”  We also wait for the perfect time to plant it: a day with nice, bright sun that will be shining for the next 24 hours.  Depending on the soil temperature, we are able to play around a little with how deep we plant the seeds.  For example, we would plant the seeds more shallow if the soil was still too cool in order for the sun to warm the seeds better and encourage them to germinate. However, this can be risky because birds love corn seeds.  Last year, the red-winged blackbirds found our first shallow planted corn in the field, dug it up and ate a good portion of the crop before it could germinate!

Sweet corn field during harvest time

Another thing we need to keep in mind when we are planting our sweet corn is what kind of sweet corn we are planting.  Because of sweet corn’s complicated genetics, it is important to keep sweet corn isolated from other types of corn; this is even true for different types of sweet corn!  Corn is wind pollinated, so we need to be cognizant of preventing cross-pollination.  It is recommended to keep at least a 250 foot distance between corn varieties that will be tasseling up at the same time to avoid cross-pollination between the varieties. Another option is to time the plantings to ensure at least 14 days between the estimated tassel dates to keep corn from cross-pollinating.  If we follow these guidelines, we are able to keep the true genetics of the variety of corn we plant which is then displayed in the characteristics of the corn we pick.  When Richard took me out to one of our corn fields last week, it was situated in a beautiful field next to our winter squash crop, surrounded by wildlife habitat, forest, and rolling hills. It was picturesque, to be sure, but it was also very far away from any other potential corn fields.

I mentioned the importance of knowing when the corn is going to be “tasseling up,” or getting ready to be pollinated to create the kernels.  The pollen of corn is in the tassels.  Corn takes 65 to 90 days to mature, and that range is broken into 3 different sub-seasons: early varieties (less than 70 days to mature), mid-season varieties (70-84 days to mature), and late varieties (more than 84 days to mature).  If we were going to be planting different types of corn together, we would want to make sure that they were in different sub-seasons. By planting corn from different sub-seasons, we can continue to deliver corn as long as possible throughout corn’s growing season, while also avoiding the potential for cross pollination between the varieties.

Richard explaining how the fake owls work

Earlier I had mentioned how the red-winged blackbirds had found our first crop of corn last year.  Birds are only one of the pests we have to combat when growing sweet corn. We have a couple different tactics we use to try to deter birds, but like all deterrents, they need to be in place before the animals figure out there is tasty corn to be had.  We hang “scare eye” balloons with long silver streamers on poles out in the field. These “scare eyes” work on the same principle that protects moths that camouflage themselves with large eye-like patterns on their wings: big eyes mean big predators. The silver streamers reflect light and move in the wind, also scaring the birds away.  We also have fake owls and hawks posted on the fence lines. These fake birds of prey are solar powered and have moving heads, keeping an ever-vigilant eye on the fields for us and keeping pesky corn eating birds at bay. The fence these sentinels sit on is plastic mesh tied to poles we place in the field that are 6 feet high.  This fence is a deterrent to deer, but again, only if they don’t know what is on the other side of it. Corn is a much tastier treat then grass and leaves, and sweet corn is so much better still than the field corn that is growing elsewhere.  The fence also doesn’t do much to keep raccoons out. So, in addition to the fence, we have an electrical ribbon running through the mesh near the bottom of it to surprise and deter any raccoons who try to pass through the fence.

Richard checking the pheromone trap for earworm moths

Now that we have the critters dealt with, there is one last pest we need to protect our corn from: Earworms.  Earworms are moth larvae that hatch from eggs that are laid on the silks of corn ears. When they hatch, they spend a few days on the silks before they eat their way down into the ear of corn.  To combat the earworms, we use an organic approved Bt spray, a naturally occurring bacteria that is toxic to the earworms. We have pheromone traps set up in the cornfields that attract the moths when they are ready to start laying eggs.  When we have moths in the traps, we know it is time to spray the corn. With the right timing, the newly hatched earworms eat the Bt we’ve applied to the corn silk and die before they can damage the sweet kernels inside.  Again, timing is everything and we only want to spray when necessary.

Richard harvesting sweet corn

With the pests dealt with and the corn crop mature, the next step is harvest.  At one time, we had a mechanical corn harvester. We would run it through the field, harvest all the corn at once, and then need to sort through the corn when we brought it back to the packing shed.  This lead to a lot of corn that would never be ripe and good, thus it was wasted. We decided we were going to go back to hand harvesting the corn. This allows us to pick only the best ears of corn at the right moment, leaving the unripe ears to grow up and become the best that they can be as well.  Every person on our corn harvest team was trained by Farmer Richard on how to look and feel for the best corn in the field. Ripe corn will have nice “shoulders” at the top of the ear, whereas an unripe ear will be pointy. If the corn looks like it has shoulders, the next step it to feel the tip, by where the silk is.  If the tip is soft, it is ready to be picked. If it is still a little stiff, it needs a few more days to let the kernels inside grow up and fill the rest of the ear. If the ear is ready to be picked, you grab the ear and twist it down, making sure you snap off as much of the stalk and leave it behind as you can. If you have too much stalk left on the ear, you’ll have to go back later and break it off before you pack it for shipping.  Once the ear is picked, you place it in your bag and move onto the next one. And all of this happens in a split second!

Sweet corn being iced before being stored in the cooler

When your bag is full, you bring it to the wagon and get ice on it right away.  This is a crucial step because icing the corn and keeping it cold slows down the sugar to starch conversion, and lets you enjoy the corn for a longer time!  When harvest is done for the day, the wagon brings the corn home where we ice it again before putting it in the cooler so it can be completely cooled.  At this point, we have done everything we can to ensure that we have grown the best corn ever. It is now your job to make sure you keep your corn cold before you are ready to use it.  Always store sweet corn in the refrigerator and eat it within a few days of receiving it.

Did we achieve “the best corn ever” this year?  We hope you have enjoyed this article about the iconic summer vegetable and have learned a thing or two about how we bring it to your table.  With all the hard work we put into it, we sure hope we managed to make a few friends along the way by giving you a few sweet ears of our golden goodness this year!

Where's the Corn??!?!

By Farmer Richard

Before and after cultivating pictures. 

We have planted four different plantings of sweet corn, with the first on April 28.  With each planting we plant two different varieties of corn, each with different maturity dates so we can get two weeks of corn from each planting for a total harvest window of eight weeks!  Unfortunately, things don’t always work out as planned.  Corn needs warm soil to germinate and if you think back to April, it was a cold, wet spring.  We picked a warm day, 65°F, when the forecast was for a second warm, dry day to follow.   We planted varieties with good cold soil vigor and only planted the seeds about ½ inch deep with hopes that the sun would warm the top of the soil enough to get the seeds going.  The first 24 hours are the most important to start the germination process.  One variety germinated ok, the second variety produced very few sprouts and wasn’t enough of a crop to keep.  Well, the first planting didn’t go so well, so the second time out, still cool, we replanted part of the ground we had planted the first time and, again, planted shallow.  This time it turned dry and the seed germinated unevenly over the course of two weeks after a small rain.  Ok, well that’s better than nothing, but then we had a wet period that prevented cultivation and weeds became a problem!  Thankfully, the third planting came up nicely and we had dry weather to cultivate it, so no weeds!  We followed this one with our fourth and final planting.  We decided to make it a larger one to try to make up for the poor early ones.  Even though the first two plantings weren’t that great, we chose to fence them anyway to keep the critters out.  So then what happened?  Well, July 19^th happened and we had a severe weather event that sent water running across the middle of the field and took out the fence and much of the corn. 

After the rain, there wasn’t much left to do except clean up the fence.  We left the corn, fully exposed, for the raccoons as a sort of peace offering that they could have as much as they wanted from this field, but please stay out of the later plantings!  The last two plantings that are in a different field looked good initially, but after 8 plus inches of rain the plants started to yellow.  The excessive moisture rotted the main tap root leaving only shallow side roots, collaterals, supporting the plants!  The dry end of the field fared a little better and will produce some ears this week.  The remainder of the field is delayed and the quality of the corn is questionable as the ears haven’t filled out properly.  Nonetheless, we put up a 7-foot high fence with an electric tape running around the base of it.  The height of the fence will deter the deer and the low electric tape will keep the raccoons and other short, 4-legged creatures out of the field.  We also put up some owl and hawk decoys as well as bird scare eye balloons and reflective streamers to deter the birds.  Aside from playing some music and having a dance party, I’m not sure what else we can do!  Why have we gone to such extensive measures to protect our corn?  Well, it’s because we have a reputation amongst our local wildlife for having excellent sweet corn.  Unfortunately this is information that is passed on from generation to generation and thus, it is a never-ending, yet peaceful battle for us.

So our last field of corn is protected with all the bells and whistles to protect it from raccoons, deer, birds, and even bears!   But wait, there’s one more pest.   It’s the dreaded corn earworm!!  We monitor corn earworm presence by putting up a pheromone trap in the field to attract the corn earworm moths.   They migrate from the south and only arrive later in the season.  The female moths lay eggs on the new silk on the ears of corn and then 4-5 days later the eggs hatch and a worm emerges.  Conveniently, they are in perfect position to infiltrate the ear in their search for something to eat.  It is very difficult to combat this pest with any type of spray because you only have a small 2-day window of opportunity to kill the worm after it hatches and before it enters the ear of corn.  Once it’s in the ear, there’s nothing else that can be done.  So I use this pheromone trap to help me monitor the presence of the moths so we can try to time our spray applications with the best chance of killing the newly hatched worms.  I hadn’t found any moths up until last week when I found 12 corn earworm moths in the trap in one night!  That is the most I’ve ever caught in 40 years of using pheromone traps!  So where does that leave our last and best hope for sweet corn?  Only time will tell.

There was a time when huge flocks of bats emerging from caves in the south intercepted the moth migration and devastated their numbers.  Any moths that did make it to our region would be taken care of by our local bat populations.  Sadly, bat populations are being decimated by “white nose syndrome” brought on by a compromised immune system from eating insects that are contaminated with neonicotinoid insecticides used extensively in modern, conventional agriculture.  This leaves us facing a potentially severe earworm invasion!  We do have two organically approved insecticides that we can use, BT (bacillus thuringiensis) and Entrust.  Alejandro has been very diligent working late on Saturday night to time the application just right and try to coat the silks and infect the worms before they enter the ear.  Neither of these insecticides are systemic.  Conventional growers use systemic insecticides, such as neonicotinoids and GMO traits, that poison all parts of the corn plant thereby killing the earworm no matter where it is on the plant or in the ear.  But I don’t want that in my ear of corn!  I do not care to eat systemically poisoned corn!  Our experience is that it is impossible to kill every earworm with organic sprays.  We are doing our best, but if you find a worm on the tip of the corn in a future week, we hope you will cut off the tip and enjoy the remainder of the ear which I guarantee will be delicious.  It may be the best corn you have ever eaten and will be the best we can do for this year!

Well, battling corn critters is not the only thing we’ve been doing around the farm, so I’d like to share a few other farm and crop updates.  Overall it has been a cool summer!  Beautiful weather to work in with highs around 75°F and just a few days creeping into the 80’s, but nothing higher than that and cool nights dipping down to 50-60°F.  The eggplant has done well and the peppers look great and are ripening to orange and red.  The tomatoes, on the other hand, have been slow to ripen and the second planting may not ripen at all before we see the first fall frost!  Yes, we are close to the first fall frost which is still predicted for around September 15.  It’s been a few years since we’ve picked green tomatoes before a frost, but this just might be the year.  Don’t worry, that’s not necessarily a bad thing.  Fried green tomato sandwiches are delicious!

Carnival Squash still on the vine.

The sweet potatoes look very good and have set on many tubers that just need some heat to “size-up.”  The jicama also has some nice roots and could be a good crop if the moisture stays steady to avoid growth cracks!  We will likely be harvesting some of the winter squash before too long, so we’ve been working diligently to get all of the onions and shallots trimmed and put into the cooler for long term storage so we can use our greenhouses for the squash! 

Salad Mix planting

While many farmers are done planting, we still have several more weeks of plantings remaining.  Earlier this week we beat the rain to do our final planting of fall turnips and daikon radish as well as our weekly plantings which included our first planting of lettuce for fall salad mix!  In addition to harvest, planting, etc, we are working on removing trees and repairing a major drainage ditch that dumped silt and rock onto one of our fields during the weather event at the end of July.  It’s quite an undertaking, but I think we’re making progress and we’re hopeful it will keep the water contained should we have another big weather event in the future.  

We believe climate change is real, so we’re not wondering “If” it will happen again but rather we are preparing for when it happens again!  We may not see the extended warm fall we have seen for several years, but we will do our best to respond to the extremes, both hot and cold!  We hope you will be understanding as crops continue to come in.  Like it or not, we’re in this together and these are the realities of farming this year.  Despite the challenges, we are reminded every day of the bounty of food our resilient fields continue to produce.  We are truly blessed and grateful for the opportunity to share this summer bounty of vegetables with you this week.   

Managing Weeds at Harmony Valley Farm

How do you manage weeds? That is a great question we’re often asked and it has a variety of answers depending on the crop, the stage of growth of the crop, the weather conditions, etc.  While conventional farmers often use chemical forces in their battle against weeds, we turn to non-chemical methods including mechanical cultivation and flaming. Richard and Rafael keep a close watch over our fields. Richard referred to Rafael as the “Weed Manager”. His observations have been extremely helpful in deciding when to cultivate and which implement to use on each crop. The goal is to reduce the weed seed, also known as the ‘seed bank’ in the soil. Weed seeds can live for 10 – 30 years in the soil, just waiting for the perfect time and conditions to grow. Our job is to remove weeds and not let them produce any more seeds. Below I will summarize some of our equipment, crew and processes that take on the task of keeping the weeds at bay!

Rafael flaming the cilantro
field before the crop sprouted.

If you have ever been to our farm or seen field pictures, you have seen our raised bed fields. Our first line of defense is to reduce the weed seed in the top 2 inches of soil before planting a crop. We try, but do not always have the perfect weather conditions or enough time, to make the beds 2 weeks prior to planting, thus giving the weeds time to sprout. If that happens, we can use the ‘Flamer’ to burn off the weeds that have sprouted prior to planting. Juan or Rafael have been Richard’s go to guys when it comes to flaming our fields. The ‘Flamer’ is a piece of equipment that takes the propane from the large tank mounted on the implement and through the pipes to create, in essence a flame thrower.  Sounds pretty cool right!  No, there is no big ball of flames; it is really just enough heat/flames close to the ground to burn the weeds that are already growing, but can save a huge amount of time and manpower.  We can also use the ‘Flamer’ after the crop is                                                          planted but before the plants push through the ground to                                                                  burn the weeds that are already growing.

Rafael cultivating the cilantro field
with the 5 Row Basket Weeder

A closer look at Rafael basketing the
cilantro field!

Once the crop is out of the ground we lose the option to flame. Now we have to turn to a variety of different cultivating implements for help. This will depend on the crop and how big it is in the field. A good example is our cilantro. It is planted on raised beds in rows of 5 on top of each raised bed.  We use the 5 row ‘basket weeder’ to loosen the soil and pull out any small weeds that are already growing in the top inch of soil. Rafael has done an excellent job with perfecting his basketing procedures.  Rogelio, Ramon and Jose Manuel have also done a great job with the basket weeder.

Oscar (driving the tractor) and Luis operating 'The Kult'
to take care of those pesky weeds in our beautiful parsnip field.

A closer look at the fingers of 'The Kult' working!

Last year we purchased an awesome German made K.U.L.T. Kress Cultivator. We refer to this as ‘The Kult’. Rafael learned how to operate this implement and has now taught Oscar and Luis how to use it. Weeds growing in the row are a huge problem as they are hard to get to without damaging the crop. This implement, when conditions are good, will help to reduce those pesky weeds in the row. There is one person (Oscar) driving the tractor and another (Luis) steering the implement to make sure the crop does not get pulled out. The Kult has little fingers that come close to weaving together near the base of the crop loosening the soil and ‘stirring’ out the small weeds. We use this machine with our transplanted brassicas (broccoli, cauliflower, etc). We transplant our brassicas to give them a head start on the weeds, giving them the advantage of being larger than the sprouting weeds.  It is way easier to get rid of smaller weeds when our crop is larger and easier to see in the row and the Kult works very well with these crops.    

Vicente using the 2 row Lilliston
cultivator in the corn field.

Vicente using the disc Lilliston
to bury the weeds in the potato field.

For other larger crops, it makes more sense to bury the weeds with dirt. This is a great option for crops like potatoes or corn.
 Vicente has learned how to use the Lilliston cultivator with ease. The open steel fingers on this implement pull up the soil between each crop row and push the loose soil around the plant, essentially burying the weeds.
       

Corn row before (top) and
after (bottom) the Lilliston.

When all mechanical attempts have been applied,
we have one more tool: our hands to do hand weeding. This is very time consuming but also necessary in some cases.  With carrots or parsnips, both of which have longer germination rates, the weeds generally pop up before the crop. After the field is flamed with the flame weeder and the crop starts coming up, we need to make sure the hand weeding gets started soon.  This takes very good eye-hand coordination as well as knowing the difference between the crop and a weed.
I can’t stress this enough, but extreme precision while using any of these implements makes the difference between a well weeded crop and not having any crop at all because it was all pulled out or buried.   You have to watch the front of the tractor to see where you are going, but also the back to make sure you are not pulling up any plants.  Even the hand weeders need to be careful.

Picture of the tool room where we
store the hand weeding tools.

Here are some parting thoughts on weeds.  Richard estimates that we kill 90 -95% of the weeds in our fields with the mechanical weeding techniques, leaving only a smaller amount for the hand weeders. Did you know that 1 weed that has gone to seed can produce up to 20,000 seeds and that these seeds can and will be carried by birds, water and the wind? This means that even though we remove most of the weeds, we will always have some weeds to deal with on the farm. Did you also know that Mother Nature does not like bare ground? Turns out she doesn’t like to be naked!  We use cover crops to help with the weeds (and other reasons) since if we don’t cover it, she will use the weed seeds in her seed bank to cover herself up. I know we have only touched briefly on the weed subject and there is a lot of information out there we didn’t discuss.  Rest assured that Richard and Rafael are on top of the weed battle. Discussing when to cultivate, which crops, upcoming weather, which implements to use, should they use fingers, discs, knives or how deep to go when cultivating are just some of the conversions that they have on a daily basis. In the end, we are grateful to all of our cultivating crew for their attention to detail, which allows us to have healthy crops to harvest and eat!