Follow the Field 2020 Update #7

It’s officially summer! The heat is great for the crops, but we could definitely use another rain soon – and hopefully the rain in the forecast pans out this week. We only ended up with a few tenths of an inch last weekend, while other parts of the state had a few inches of rain. But otherwise, everything is looking good!

June 26, 2020 Update:

Soybeans (65 days)

It’s hard to believe that it’s been more than two months since we planted these soybeans. Last week was a big week for the beans – they received their final herbicide application for the season and also entered into the reproductive growth stages.

See? Overall, they’re looking pretty good, even if they are a little short at the moment. I mentioned that they have now entered the reproductive stages. Even though these soybeans are beginning to flower and will begin to set pods, they’ll continue with their vegetative growth. Soybean varieties grown in central Illinois are what we consider, indeterminate – the vegetative and reproductive growth stages can happen concurrently.

Check out all of those new leaves! Like I mentioned a few weeks ago, soybeans set trifoliate leaves, so leaves in groups of three. You can see that there is one trifoliate in the left of the photo that are nearly completely unfurled, another on the right side that will be growing larger and opening very soon, and what looks like 2-3 more sets just about ready to make their appearance at the tip of the soybean stalk. With each set of leaves comes a new node, or connection from the leaf branch to the center stalk. Nodes are where the flowers will develop.

See were the flower is right next to the stem in this photo? That’s where the node is. The number of nodes, or sets of leaves, on a soybean plant determines approximately how many flowers will develop, which will eventually become soybean pods and then harvestable soybeans. This is what determines the yield potential of this plant and this entire field.

Last Saturday (June 20) was the summer solstice. It’s the longest day and shortest night of the year in the Northern Hemisphere. Soybean plants can detect night length and flowering is typically triggered around the summer solstice, or when nighttime begins to lengthen. Soybeans will continue to set flowers for several weeks (remember, the plant is still growing), but the reproductive growth stages are typically measured when the plant first enters the stage. R1 is “beginning bloom” and R2 is “full bloom”. This field is definitely in R1 and well on its way to R2 if it’s not there already. It will be in the R3 stage when pods begin to form where the flowers were.

As you can see in the above two photos, soybean flowers can be different colors. This is typically a trait of each variety. Our soybeans usually set white or purple flowers (I’ve most commonly seen purple). It’s possible that these two soybeans (just a few rows apart in the same field) are two different varieties.

 

Corn (44 days)

The corn grew a lot between last week and the week before and again from last week to this week!

You can see how the field is starting to fill out with the taller corn plants.

Looking at the ground, you can also tell that we need some rain. The straight line in the soil to the left of the photo is from sidedressing. The other cracks are because the ground is fairly dry (I get these in my yard where there’s no grass, too, so it’s not exclusive to crop fields). The ground is also pretty hard at the surface, which made it difficult to get the yard stick to stand up for the first photo. 🙂

I’ve talked a bunch about soybean leaves, but I’ve not talked much about corn leaves. Corn is considered a grass – sometimes called monocot – plant (as opposed to broadleaf/dicot) plant. If you remember from high school biology, one indicator that this is true is that the veins of the leaf run parallel to each other. On the other hand, soybeans are a broadleaf and the veins of the leaves do not run parallel to each other.

Corn leaves appear one at a time and are alternating. This photo is an overhead look at a corn plant. See how the leaves unfurl from the tip of the stalk in the center? Like soybeans, the point where each leaf is affixed to the center stalk is called a node, but nodes in corn do not determine yield since it only puts out one flower which then becomes the ear.

You can see how the leaves towards the top of the plant have increased in size. Larger plant means more energy demand, which means more leaf surface is needed.

Unlike soybeans, corn isn’t dependent on day/night length to decide when to enter reproductive stages. It pretty much has a set growth pattern and will reach full height before it sets the beginnings of the ear and the tassel. The timing of this depends on planting date, but will happen sometime in July in this field.

That’s all I’ve got for this week’s update. Expect lots of growing to happen this week!