With rainfall several inches below normal, what should farmers of corn, soybeans or other grains do with their wilting crops?
The answer, according to experts at an information session on dealing with the drought Friday morning, is: nothing … yet.
In fact, according to experts in corn and soybeans, rain in the next week could salvage the 2012 crop.
Two information sessions were held Friday, at First National Bank in Platteville in the morning, and at the Bridges Restaurant in Darlington in the afternoon.
“I’ve had more desperate phone calls from producers the last couple weeks … just not knowing what to do,” said Kevin Raisbeck, vice president and agricultural lending officer at First National Bank.
Ted Bay, UW–Extension Office crops and farm management agent for Grant and Lafayette counties, started by giving results of tours of several farm fields. Alfalfa was “holding on really well until recently,” soybeans were “looking good for a long time visually from the windshield,” and corn was “uneven.”
“This year, 2012 is certainly the year this generation is going to remember as a drought year, especially in the corn area,” said UW Agronomy Prof. Joe Lauer. “This year, we’re all going to be humbled by the importance of water in the process.”
A similar drought took place in 2005 until breaking in mid-July, with record corn yields that fall. “This year the impact is going to be greater than 2005,” because of early planting due to the early spring and recent 100-degree temperatures.
The heat actually has hurt corn worse than the lack of moisture. “Leaves curl up and stomates close, so no photosynthesis goes on,” said Lauer. “Anything over 94 degrees Fahrenheit, basically corn stalks shut down.”
Pollen also dies above 86 degrees, which means pollination is only taking place in the morning.
Corn uses about one-third inch of rain now — either from rainfall or from accumulated moisture from winter show — and one-fourth inch per day by mid-August.
Lauer said the 1988 drought demonstrated best practices in drought years.
In 1988 the average yield of a central Grant County corn field was 71 bushels per acre, but “there were some hybrids that performed very well,” said Lauer.
High-population fields, with 35,000 to 36,000 plants, also had average or above yields.
The best results are likely to be in fields where corn and soybeans have been rotated. Lauer said yields increased 30 to 50 percent when corn was planted after beans.
Rotation “really helps in a drought-stressed year,” said Shawn Conley, UW state soybean and small grain specialist.
Now is a key period because pollination is taking place over the next week. Drought conditions make tassels speed up development, but silks slow down development. While pollination usually takes place over a 10-day period, in a drought that period drops to two to four days, Lauer said.
Corn fields need 1 inch of rain per week “to finish off everything that’s been pollinated,” he said.
Still, he added, “no management decision should be made until you determine how successful [pollination] was.” Even in fields with only 50 percent pollination, “it’s still better to let that 50 percent corn go for silage than cut it right now.
“There are some burned-up fields and they are not likely to grow back, but you never know. Corn is very resilient. … There are plots that still have hung in there pretty well, and there’s a lot that’s going to get pollinated.”
“The concern we hear is should we be chopping corn now?” said Bay. “And the answer is it’s too early; it’s still too wet.”
Lauer said the only reason to chop corn now is if no pollination took place, and that can’t be determined until around Aug. 1. “Even then, you’ve got to worry about moisture,” he said.
As far as predicting yields, he said, “I would expect quite a bit of variability this year,” he said.
Lauer said he’s not “expecting a lot of lodging issues” this year. Some corn is leaning because base roots don’t grow in dry soil.
He added that barren fields could be replanted with conventional corn (replanting transgenic corn is illegal under federal law).
“We’ve had years where we planted Aug. 1” and corn grew until the first killing frost, he said. “If you have a long fall you might get some production on some of those fields that are barren.”
Soybeans may be better off against the drought because of their “tremendous plasticity,” said Conley. “There are several fields out there that if we can catch some rain, there are easily 40 bushels per acre yields out there.”
Until two weeks ago, soybeans had only grown to one-fourth of their total biomass. At this stage, soybean plants are growing roots at the rate of 0.9 to 1.2 centimeters per day, which is why they still look relatively good, Conley said.
Soybeans’ critical growth period is within the next week, with rapid pod growth and the beginning of seed development.
“That’s when we can go from 40 [bushels per acre] to 20 in a hurry,” he said. “Beans this time of year need a quarter-inch [of rain] a day.”
Even if rains from now on are insignificant, Conley said the fields with “best-looking beans” could still get “low 30s” in bushels per acre, going down to 15 bushels per acre.
“I’m not a marketer, but if we don’t hit $18 beans I’ll be surprised,” he said.
Conley compared the current drought to the northern Wisconsin drought of 2007–08. After a dry 2007, soybean fields yielded 12 to 20 bushels per acre from plants 15 to 16 inches high. The drought continued into mid-2008, but after rain began in mid-July, soybean field yields increased to 40 bushels per acre.
“If we start catching rainfall, that yield potential is still out there,” he said.
The most common disease he sees in soybeans now is charcoal rot, while the most common pest he sees is spider mites.
“There is the one insect that can take the whole field,” he said.
Conley does not recommend spraying foliar fungicides on crops.
“Given the severity of our drought stress, I have not seen any research out there suggesting you spray foliar fungicide to mitigate drought stress,” he said, adding that “a good rain” can knock down spider mites and kill their eggs.
“It’s very rare even in a normal year to see a response to fungicides,” said Lauer.
Lauer said the biggest corn pest now was rootworm beatles, and “good-looking fields is where they seem to be congregating.”
Lauer also said dairy farmers and corn farmers need to work together to reach a mutually agreeable price on selling corn to dairy farmers who will need to buy feed for their cows.
“Right now is a good time for dairymen and grain farmers to be friends,” he said.