Corn is already under considerable pressure this year. Flooding in many areas, black cutworm, armyworm and the first hatch of rootworms increase the stress on your crop. Scout for the three Ws, water, worms and weeds to increase your awareness of what is going on and what possible steps you can take to preserve yield potential.
Thanks to the first W, water, many farmers’ fields may look more like a lake than what they depend on for profit. The question on many minds now is whether or not they need to replant, thanks to widespread heavy rainfall and ponding.
“Rule of thumb is the warmer it is the less likely a plant will survive,” says Brent Tharp, Wyffels Hybrids agronomy and product training manager. “Wait three to five days after the water recedes to check.”
Corn is a resilient plant and may be able to withstand flooding for a short amount of time if the plant isn’t growing rapidly. Wait a few days to check back to give the plant time to recover or provide indication it will not survive.
On warm June days you would typically see new growth three to five days after water recedes. It could be a bad sign if you don’t see growth. At that point, check the plants. Dig them up and split them down the middle to find the growing point. If you see creamy to white color in the growing point, you’re in luck. But, if it’s brown and mushy, the plant is dead and could require spot replanting.
“We should be switching to shorter season hybrids in June,” Tharp says. “Set and possibly lower expectations on replant, expect lower yield and wetter corn. Also, think about how much corn you are going to tear up to replant.”
A replant in June could mean you need to switch to shorter season hybrids to avoid frost this fall. Consider how many growing degree units each hybrid needs and pick one that will provide the greatest yield potential despite any planting date limitations. But don’t forget to do the math. Sometimes, replant doesn’t pay off. For example, if the patch you need to replant is smaller than the amount of crop that will be torn up while replanting it may be best to leave it.
Flooding isn’t the only threat corn encounters, the second W, worms, can cause as much or more damage. Many insect flights and hatches are in progress now and bring more risk to the plant. Many hybrids offer protection through Bt technology. Check labels or with your seed provider to find out what insects your crops are susceptible to.
Insect damage can cause stress to the plant and pests like western corn rootworm could completely kill the plant. As the plant moves into V8 stage it determines how many kernels around, girth, it will produce. Watch for insects at this time, says Andrew Ferrel, commercial agronomist, Mycogen Seeds.
“The growing point is out of the ground and makes the plant more vulnerable to death,” Ferrel says.
|Stinkbug damage caused while inside the whorl. Small holes, feeding around leaf ends and even root damage are signs of insect infestation. Check with your extension agent to learn locally recommended thresholds.
Watch for key insects like corn borer, rootworm larva, black cutworm, fall armyworm and others. A good indicator of rootworm hatch is when you start seeing lightning bugs. When they are out, rootworms are likely hatching and may begin feeding.
Here is a scouting calendar by DuPont Pioneer with some tips. https://www.pioneer.com/home/site/us/agronomy/crop-management/scouting/corn-scouting-calendar/
While scouting for insects, keep an eye out for the final W, weeds. At this stage, you might be able to come in with a post spray, but if it’s too late keep accurate notes to for next year. Stage your corn and check label instructions to determine if you can use a post herbicide.
“We need to be using multiple modes of action to fight resistance,” says Bob Springer, Channel Seedsman. “Get weed seeds destroyed.”
Identify what kind of weeds you are dealing with and check herbicide labels to see if it is labeled to kill your problem weeds. Also check weed height. In some cases, weeds taller than 4” could be too big to get consistent control, which makes early season scouting even more imperative.
“[There is] a pretty small window to check,” Springer says. “The main thing you learn is what you did wrong and learn for next year,”
Keep track of where you see water, worms and weeds to make plans for next year. Learn from this year’s misfortunes to avoid losing yield, and profit, in the future.