Many soybean fields that Steve Gauck visited this season looked good nearly all year. Then during the end of August and into early September, some began to separate themselves from others.

“Where fields caught rains or could be irrigated, individual soybean seed size is still large,” says Gauck, a regional agronomy manager for Beck’s, sponsor of Soybean Watch ’24. Gauck is based near Greensburg, Ind. “However, fields where it turned very dry and which don’t have irrigation are a different story. Soybean seed size in those fields appears to be suffering. We could be looking at smaller-than-normal seed size in some cases at harvest.”

A drop in seed size in dry areas where there is no supplemental water available would not be a surprise, Gauck says. He notes that while the critical period for corn, pollination, is normally in mid-July, the crucial time for soybeans is during the reproductive stages of R5 to R6, when individual seeds fill within pods. That’s typically mid- to late August and into early September for soybeans, he notes.

Early-planted soybeans may have hit that period somewhat earlier than those dates. But Gauck says soybeans planted near the end of May or into early June because of wet May weather still may have been in this crucial stage in early September.

Related:Insects are out there — scout for them

Rainfall tailed off over the last few seasons in several areas. It appears to have done so again, Gauck observes, leaving soybeans without irrigation vulnerable to drought stress.

Noticeable difference with irrigation

Walking into the Soybean Watch ’24 field in early September, Gauck immediately noticed the difference versus most fields he had visited. Because part of the field is underlain with gravel at 3 feet, the entire field can be irrigated with a center-pivot system.

“Soybeans inside pods in this field are normal size,” he says. “They’re plump, even to the top of the plant. We even saw some four-bean pods in there. If moisture is short at key times, you seldom find four-bean pods.”

Access to irrigation doesn’t guarantee higher yields, but it certainly helps in years when Mother Nature turns the spicket off just when soybeans need it most. “It certainly appears irrigation will be the difference in yield in this field.” Gauck says. “There is good yield potential here.”

Ironically, Gauck believes the high yield potential was set up by a dry spell in June. “It promoted shorter distances between nodes, meaning more nodes and more pods per plant,” he says. “Rainfall came back in July, so plants kept most of the pods formed on those nodes. We saw some pod abortion even here — you will always see a certain amount of pod abortion.”

One secret to managing irrigation is not panicking and applying water too early. “These soybeans didn’t need as much water in June, and as noted, that dry spell likely worked in the grower’s favor, helping build shorter, node-filled plants,” Gauck explains. Once soybeans reached later reproductive stages in August and moisture became shorter, the grower irrigated as necessary.

“He continued irrigating even after leaves began to turn,” Gauck says. “That is important because plants can add to bean size and yield very late in the season. They need moisture to do it.”

From the field:
Up-and-down season heads toward curtain call

Reports across the Midwest all season have created a picture of a roller-coaster ride, with alternating stretches of too much and too little rain, and an overall nod toward warmer-than-normal temperatures.

Now it’s time to find out how yields will fare with this weather scheme as a backdrop. Over the next few weeks, Beck’s field agronomists who have monitored progress in their areas and field reports all season will summarize the 2024 season for soybeans as a whole.

Here are the first two reports:

In Missouri. The early wet pattern provided planting challenges and delayed farmers getting into the field to plant soybeans. The continued wet weather did not allow for timely post herbicide applications to happen, so it was not uncommon to see weed challenges across a wide geography this year. Where residuals were able to be overlapped, and in the few fields that farmers could get on within 20 to 28 days after planting with a post herbicide application, fields remained cleaner throughout the season.

There were favorable growing conditions early to mid-season, but in late season, we struggled to get any rainfall. Lack of rainfall and warm temperatures resulted in soybeans turning rapidly. Some later-season beans will likely struggle to fill top pods. It looks like the dry spell will likely lead to small seed size going into planting next spring.

Fungicide applications at R3 visually appear to have produced better overall plant health and pod retention through the environmental stressors. That is especially true if coupled with an insecticide to help knock down pesky stinkbugs that cause direct yield loss. For later-planted soybeans or double-crop beans, fungicide and insecticide at R3 appears to have helped with pod worm pressure.

As soybeans turned, numerous late-season pests showed up. It is common to see anthracnose, pod and stem blight, dectes stem borer, brown stem rot and charcoal rot in our more droughty areas.

Across the western side of Missouri, combines have not hit soybeans too hard yet, but early harvest reports seem like yields are fair. Earlier-planted soybeans could be the ticket to better soybeans this year. Hopefully, we can get a rainfall event soon to help later-season and late-planted soybeans finish out and settle some dust! — compiled by Celena Kipping, Beck’s field agronomist

In eastern Kansas. The 2024 growing season for soybeans across eastern Kansas was interesting for sure. From April through early June, we had ample rainfall, which caused both good and bad situations. Overall stands were OK. We did have some replant, but not as much replant as predicted. Much of the growing season through July was pretty low maintenance. Weed control was decent, and insects and diseases seemed nonexistent.

The overall outlook for soybeans was very positive through the middle of July. However, moods changed quickly by the end of August due to very dry, hot conditions for over a month. Eastern Kansas also began to experience plenty of disease and insect pressure. Bacterial leaf streak, brown stem rot, diaporthe and sudden death syndrome make up the bulk of diseases that can be found in nearly every field. We also had a big increase in dectes stem borer that led to plenty of discussions about identification. Leaf symptomology is very similar to SDS.

Now at mid-September, we are afraid yields will be all over the place. Many acres will likely yield much lower yield than originally predicted. Seed size is the main concern. Lots of soybeans are turning. On many acres, I feel like this is early due to stress over the last month. Harvest is still 10 to 14 days away on some April- to May-planted soybeans. — compiled by Brian Green, Beck’s field agronomist