Lessons from the field
Farm News staff writer
FARNHAMVILLE – In the past three weeks, Randy Souder’s farms have only received sixth-tenths of an inch of rain. A lack of moisture has been common this spring and early summer in the Lake City and Lytton area where he farms.
“I can’t remember too many times it has been this dry, other than one year back in the 1950s and again in 1977,” said Souder, 61, who attended a field day Monday at FC Cooperative in Farnhamville.
These dry conditions are contributing to a number of complications in cornfields across west-central Iowa and beyond, said Steve Barnhart, a regional agronomist with Winfield Solutions, who spoke at the Answer Plots during the field day.
“The No. 1 problem I’m seeing across Iowa is rootless corn syndrome,” Barnhart said. “Even with as little moisture as we’ve had, the plants are trying to root. However, we had a dry soil surface and way too much wind this spring, which hasn’t been good.”
Iowa has also been far ahead of schedule with growing degree days from late-April to late-May. “We’re still about 10 days ahead of normal, in terms of GDDs, and this is huge,” Barnhart said, who noted that this has also accelerated insect development.
Entomologists at Iowa State University reported that the corn rootworm hatch this spring was the earliest on record. Even treated corn could be vulnerable.
“The pests need to chew the corn roots to die,” Barnhart said, “but there aren’t as many roots available this year, since the corn is struggling to get established.”
Next to rootless corn syndrome, emergence issues are the second biggest problem in Iowa fields this growing season.
In some cases, early-planted corn was nipped by frost. In other cases, crusted soil did the damage. “The crust didn’t have to be more than half an inch thick to start creating problems,” Barnhart said.
Unfavorable spring weather also complicated matters, Barnhart said. He said the worst time to plant turned out to be April 26 through April 28. Not only did the weather turn colder, but it rained in some areas, too. This led to imbibitional chilling, which occurs when seeds absorb water when soil temperatures are less than 55 degrees for an extended period of time.
The seedlings sometimes “corkscrew” or fail to emerge when exposed to the cold soil temperatures.
In late-April, the ice cold rain caused cell structure damage in seedlings, which started to leaf out underground and didn’t know which way to grow. Barnhart and his colleagues recorded daily air temperature swings of 40 to 50 degrees, followed by 15 to 25 degree temperature swings at a 4-inch soil depth.
“These temperature extremes were a big factor in corn seedling emergence problems,” Barnhart said, “and the extremes occurred because the soil was so dry.”
Ironically, corn that was planted in March avoided many of these problems, which is atypical since the odds are usually against farmers who plant corn that early.
“This year, the early-planted corn was able to establish roots down where the soils were still moist,” Barnhart said.
However, few fields were immune to the relentless winds that plagued many parts of Iowa this spring and caused sandblasting in some areas. Fortunately, damaged corn leaves won’t necessarily lead to an outbreak of Goss’ wilt, Barnhart said. “While Goss’ wilt needs an injured area to infect the plant, the bacteria also need moisture for an infection to occur.”
Whether Goss’ wilt develops or not, protecting the leaves as much as possible during the 2012 growing season will be important to yield potential, since more area for photosynthesis equals more grain fill.
Fungicides can be a good choice on some acres, Barnhart said. There are two situations where fungicides can be especially useful. Since corn residue provides a source of inoculum for gray leaf spot and other fungal diseases, fungicides can be beneficial for corn-on-corn or no-till acres. In addition, some crop genetics are more prone to fungal diseases than others, so treatment can work well with these vulnerable hybrids.
Soil, tissue testing
Since the 2012 crop is under stress in many areas, it may be wise to look into tissue sampling to help address any plant nutrient issues.
Tissue sampling is not infallible, but it’s another tool that can be useful, said Dan Bjorklund, a product manager with Winfield Solutions. “Always start with a good soil sample and use tissue sampling as a backup.”
If a tissue sample reveals low levels of boron, realize that weather conditions may be playing a role this year. “The main source of boron comes from the breakdown of organic matter in the soil, Barnhart said. “If conditions are dry, however, this process is disrupted.”
Bjorklund believes there’s still an opportunity for good yield potential for the 2012 crop, as long as timely rainfall arrives. “A lot of important things will be happening in the fields in the next few weeks. The quicker these crops’ roots get established, the better.”
Souder is still optimistic. “It seems like we always get rain about 10 minutes before it’s too late.”
You can contact Darcy Dougherty Maulsby by e-mail at firstname.lastname@example.org.
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