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It's been eight days since we planted and if you look down the rows you can
see some seedlings that have emerged. We've had some rain and things
are looking pretty good. I'm a little concerned that the rains caused some
soil surface crusting. That will cause the seedlings to work a little harder
to emerge. It would have been better if this field had not been
tilled prior to planted. There would have been crop residues to
protect the soil and we could have planted no-till into the residues.
This is a closeup of a seedling. The two green leaves are the cotyledons. The cotyledons are modified storage leaves. They provide nutrients for the young seedling for about 10 days. The stem below the cotyledons is called the hypocotyl. Sunflower is a dicotyledon plant, which means it has two cotyledons and the growing point is above the soil surface. That's different from grassy plants where the growing point initially remains below the soil surface.
Not all the seedlings emerged as well as the ones we were just looking at. This one is having some problems emerging through the soil crust. You can see it has pushed the soil up. The part that you see is the hypocotyl and it is pulling the cotyledons to the surface. The cotyledons are almost ready to open. This is called the crookneck stage of emergence. Let's take a closer look at this seedling.
Here's our seedling that was having a little problem emerging. You can see the hypocotyl is bent. That's a good indication there was surface crusting. The seedling was pushing upward and it met resistance from the soil crust. When there's hard rains or with clay type soils, we tend to see more soil crusting. Crusting can be severe enough that seedlings die before they break through the surface. Also, crusting causes differences in time of seedling emergence and while that doesn't appear to be a big problem, it causes the late-emerged plants to flower later than the plants that didn't have problems emerging. We'll see if that's a problem later in the growing season.
It appears that our herbicide application is doing its job. These venice mallow seedlings are chlorotic (yellowing) and will be gone before too long. If we hadn't used a herbicide, our field would be covered with weeds by now.
You don't see this every day. A golf ball in a sunflower field! It would appear that our neighbors across the street are using our sunflower field as a driving range. But that's not the important item in this picture. If you look directly above the golf ball you can see two seedlings next to each other-- that's not good. We call that a double- when two or more seeds are planted at the same time. Do you remember looking at the notches in the planter plate? In this case, two seeds were in the notch of the planter plate, they dropped into the soil and germinated and emerged. It appears that I'll have to do a little hand thinning, otherwise these two plants will not grow well nor have very big flower heads.