Stressed soybean symptoms from drought include leaf flipping. (Photo by Leo Rocha in White County/ILSoyAdvisor.com)

As drought conditions worsened across Illinois last week, farmers and agronomists became concerned about potential ramifications of an extended drought. We’ve put together a collection of their thoughts and observations for this week’s column. Please read on …

Crops drying out; farmers begin to worry

URBANA — Crop conditions are deteriorating across Illinois due to drought as farmers and crop advisers become increasingly worried about whether some crop fields can hang on much longer. “Another week without a hint of precipitation in most of NE Illinois; soy has basically stopped growing and corn fields are struggling to canopy between rows,” reported Russ Higgins, University of Illinois Extension commercial ag educator, on June 23. “My thermometer is registering 99 degrees this afternoon. I truly hope to share a different story next week. There is concern on how long these crops can hang on before suffering significant yield consequences.”

Talon Becker, Extension ag educator, said both corn and soybean fields in Vermillion County are showing signs of heat-related stress, depending on recent rainfall amounts received. “In general, the larger corn looked healthier with less water stress, indicating there is some plant-available moisture at the deeper soil levels accessible to roots of these larger plants, but perhaps not by the corn closer to V6 (growth stage),” said Becker.

“Soybean fields also showed a good deal of variation in terms of overall growth (open trifoliates, nodes, branches, etc.), although most fields I stopped and walked into were showing at least some flowers, with several at R2. Although there was variation in the overall appearance of health in the soybean fields surveyed, there were flipped leaves and signs of water stress in all of them.”

According to Emerson Nafziger and Giovani Preza Fontes, Department of Crop Sciences
at the University of Illinois, “there is little we can do” besides wait and hope for rain before the potential for producing normal corn kernel numbers begins to slip. “Most fields are now at stages where dry soils will start restricting water uptake rates, and this will begin to limit leaf size and stem length,” the crop scientists stated.

As of June 20, Illinois corn condition was rated 4 percent very poor, 16 percent poor, 44 percent fair, 30 percent good and 6 percent excellent. Soybean condition was rated 4 percent very poor, 14 percent poor, 49 percent fair, 26 percent good and 7 percent excellent.

(“Dry Weather and Crop Conditions in Illinois.” Emerson Nafziger, Department of Crop Sciences, University of Illinois, June 22, 2023; Becker, T. “Illinois Crop Update – June 23, 2023.” Department of Crop Sciences, University of Illinois, June 23, 2023; USDA/NASS.)

Corn ‘weather rally’ fizzled out?

PEORIA — After a two-week rapid run-up of prices paid for corn fueled by speculation of a smaller than anticipated harvest due to the Midwest drought, values settled by around 30 cents per bushel last week. This caused market analyst Matt Bennett of AgMarket.net and Brian Grete of Pro Farmer to speculate on whether the crop “weather rally” is truly over.

“You have Illinois this week at 36 percent good to excellent,” Bennett said. “Obviously, that’s a massive drop. And when you start talking about the fact that last year, we were around 210 [bu. per acre yield] in Illinois, and then the national yield was in the low 170s. To me, you have to ask yourself what to do with the national yield if you start taking 30 to 40 bushels [per acre] out of the Illinois state-wide yield. And I think that that’s something that certainly is in the realm of possibilities at this stage of the game.”

While the weather forecast for last weekend included precipitation for much of the Midwest, Illinois was largely excluded from any significant rain events. However, Grete said, just the notion that rainfall could occur in some corn-producing areas was apparently enough to prod the market downward.

“If we do get a rain event, yeah, they’re going to take some of that premium back out of the market, and then if it turns dry, again, you’ll be back to adding in premium,” said Grete. “We are now at the point from a soil moisture standpoint, we’re hand to mouth, so to speak, on rains. We don’t have any subsoil moisture to pull from so to speak. And as a result, it is going to be forecast to forecast.” (AgWeb.com/Pro Farmer)

Agronomist: Soybeans fare best in drought

BLOOMINGTON — In times of drought stress, soybeans are most likely to flourish and produce yields closer to trend lines than corn. This is due to advances in drought-resistant hybrid soybean seed and soybean’s genetic basis of drought tolerance, according to Stephanie Porter, certified crop adviser with ILSoyAdvisor.com.

“Soybeans can better adapt in times of moisture stress. Indeterminate soybeans can handle moisture stress over a longer period and range of growth stages because they continue to grow during their reproductive stages and can compensate for drought if growth has been reduced at previous stages. We can easily see corn showing signs of drought or heat symptoms; however, signs of soybeans under drought stress aren’t as obvious,” Porter said.

Soybeans, however, can and will succumb to extreme drought conditions, regardless of hybrid.

“Drought stress impacts yield most during germination and later during reproductive seed development. Early season soybean stress may cause leaves to be smaller or limit vegetative growth; therefore, more energy and efforts may be given to root development. Ultimately, nitrogen fixation can be severely limited or completely halted by even moderate drought stress,” Porter wrote in her recent ILSoyAdvisor.com blog, The Fate of Soybeans During Drought.

“A more obvious sign of heat stress in soybeans may be leaf flipping, which is like corn rolling. Soybeans flip leaves to reflect more sunlight by exposing the silver-green leaf underside. This process can conserve water by reducing plant temperature stress and photosynthetic rates. Ultimately, the earlier and longer the leaf flipping occurs, the worse the severity. Lastly, extreme drought-stressed soybeans will exhibit leaf clamping. In other words, the leaves all fold in like a taco and this can occur anytime throughout the growing season when stress is severe enough,” Porter explained.

Illinois Farm Fact:

64 percent of the U.S. corn crop and 57 percent of the soybean crop is currently considered in drought conditions. (U.S. Drought Monitor; 6-22-23)