Now is the time to conduct stand counts
By KRISS NELSON
AMES Many of the fields that have been planted are starting to show some growth poking through the ground. But do you know if the stand is uniform?
“You need to get out and make those stand assessments to start making the decision if we replant or not,” said Mark Licht, Iowa State University assistant professor and cropping systems specialist. “A part of that decision is what is the yield potential with the existing stand versus if we come back in and plant it.”
This discussion and more was part of a field scouting basics workshop held earlier last month at ISU’s Field Extension Education Lab.
“You have to be able to have some idea what yield potential difference is going to be,” he said. “You need to start factoring in time, fuel, labor, seed costs and whatever else you need to replant.”
How to evaluate a corn stand
According to ISU, to begin making a stand count, you start with measuring out 1/1,000 of an acre based on your row width. For example, a 30-inch row of corn you will measure out a length of 17 feet, five inches.
Then, count the number of plants in the measured area and repeat this in six representative locations across the field to get a more accurate picture of how things look. Randomly select these locations and do not intentionally avoid areas that have missing plants or gaps.
Dig up seedlings and check the plants for symptoms of the following:
- Seed rots and seedling blights.
- Anhydrous ammonia burn.
- Herbicide injury.
- Insect issues.
- Planter issues.
- If plants are missing entirely, check to see if you can even find any seeds where the plants should be.
The last step is average the counts and multiply the average number of plants by 1,000 to obtain the plant population per acre.
Licht said you will know shortly after the crop is coming up out of the ground if there are issues and hopefully find the cause.
Licht said if he finds stand counts 25,000 or below, he realizes there is a definite problem.
“I really want to know what is going on because now we are talking about replanting. We get into the replant zone on corn and we have to sit back and say if he replants is he going to end up with the same stand? That won’t go over well if he replants and has the same stand. We need to know what is going on so we can avoid it when we come back in a week.”
Sometimes it could be a mechanical issue, but either way, when checking stand counts, Licht says you have to be good at multitasking.
“You have to look at plant population, plant density – how many plants do I have out there? Then you have to do two to three things at the same time. Look at plant to plant spacing, do we have multiples? Do we have skips? Also, do we have even emergence? Meaning do we have a plant that is just emerging? Do we have stuff that is at V1 or V2 already? All of that will tell me what I need to do next,” he said.
Making those early stand counts, no matter what the conditions are is important.
“I come back to why do we really want to get out into these fields and what it really comes down to, is we need to know what a good stand looks like. What healthy plants look like and the best time to do that is when they are first coming out of the ground,” said Licht. “That is a critical thing to understand. That is setting you up for the rest of the year.”
Knowing what your stand count was at the beginning of the year will give you something to compare to.
“The growing season is long and we could have disease, insects or herbicide injuries, hail, wind, we have a lot of things that can impact that crop, so knowing what our stand was, what did it look like as we start out the growing season versus where we are at any given time,” he said.
In addition to surveying your stands, Licht said it is also time to be looking for early season insects.
“Army worms, black cutworms, those scouting dates are now,” he said. “We need to be thinking about where are they?”
Also, those first planted soybean fields need to be scouted for bean leaf beetles and seedling diseases should be checked for as well.
“You need to get out there and understand why some of these plants don’t look healthy. Is it a disease or not,” he said.
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