ASK THE AGRONOMIST BLOG

While a new season is just around the corner, many areas of the country have already enjoyed spring-like weather this winter. Warm, dry conditions persisted throughout much of February, which could greatly impact this year’s planting and growing seasons.

“Adverse winter conditions could spur herbicide carryover issues and affect insect mortality, especially with the rootworm population this year,” notes Tony Lenz, Stine^® technical agronomist.

To see how the warm weather has been impacting soil conditions, Tony and his colleagues did something you don’t typically do in February — soil sampling in our Product Development Plots (PDPs). In southern Minnesota, they measured soil temps at 41 degrees Fahrenheit in one field. In northern Missouri, soil temps were in the upper 50s.

“We saw a lot of 20–30-degree soils over the past two winters and 40–50-degree soils in February across the Midwest,” says Lenz. “Unfortunately, this means there hasn’t been enough killing freezes to eradicate insects such as corn rootworm. There’s also the potential for herbicide carryover as the dry conditions may have made it more difficult to break down last year’s applications, especially late post applications during the growing season.”

Corn Rootworm Concerns

Corn rootworm has been a growing concern across all of Stine’s territories, but especially in the Midwest, where growers are seeing more new variants of western and northern corn rootworm populations. 

We’re seeing variants of western corn rootworm pop up after consistent corn-soybean rotations versus corn-on-corn rotations. These variants typically have a one-year life cycle, except for the females that can lay their eggs outside of cornfields in adjacent soybean fields. When corn is planted the next year, the larvae hatch in the fields and cause root injury to the plants. Because of this, we’re even seeing damage to first-year corn. These variants have been observed in areas of Illinois, Iowa, Indiana, Michigan and Ohio.

Northern corn rootworm variants have extended diapause — or a lengthened growth cycle. Eggs can remain dormant in the soil for two winters and wait to hatch until corn is planted again. Like western corn rootworm, they are finding ways to survive the corn-soy rotation, but they have stronger overwintering survival rates and can adapt to longer rotations compared to western corn rootworm. These variants have been found in Minnesota, Nebraska, South Dakota and Wisconsin.

“It’s concerning that the northern corn rootworm variants can survive for two winter seasons, so they’re waiting for that next corn rotation to come back and feed on the crop,” says Lenz. “Also, the damage they are doing underground to the root system is very troubling.”

While people usually scout for rootworm beetles feeding on silks of mature corn plants, growers need to focus on looking underground this year. Western and northern corn rootworm begin feeding on roots as soon as they hatch into larvae.

“We’re seeing a lot of feeding on roots, which leads to hardening off,” says Lenz. “This causes stunted roots and becomes an even bigger problem when you get another drought cycle.”

University research demonstrates that, even at moderate levels, corn rootworm larvae feeding can cause yield losses between 15% to 45%. Fortunately, Stine can help. Tony and our agronomy team recommend leaning on genetics and traits, like Stine DuracadeViptera™, to help combat corn rootworm and other insects, as well as in-furrow insecticides or a combination of both. Stine agronomists are also testing new traits in their PDPs that protect against rootworm and other insects for growers’ consideration in the future.

“If growers are interested in viewing any of our PDP or other plot locations throughout the season, they can connect with their local sales reps to view some of these products in the field,” says Lenz.

Herbicide Carryover

The National Integrated Drought Information System indicates that root zone soil moisture in many parts of the South and Midwest is drier than normal. Dry conditions, combined with other factors such as soil pH, organic matter makeup, temps and timing of applications, can impact the half-life of herbicides.

“The half-life of a herbicide is what it takes for that herbicide to break down to 50%, where it’s not going to be as much of a problem for next year,” says Lenz.

According to the University of Nebraska-Lincoln Extension, chemical processes and microbes are needed to break down herbicides, and these processes require moisture. A lack of moisture can stop the breakdown clock.

“What growers must consider is how the herbicide they applied last summer could affect this year’s crop, especially in a corn-soybean rotation year,” says Lenz.

For example, growers who sprayed Atrazine, Group 27 HPPD or Clopyralid-based herbicides on corn last summer or Fomesafen herbicides like Flexstar in soybeans should be aware of potential herbicide carryover issues the next growing season.

Regardless of the crop, if growers note areas where emergence or stunted plants are an issue, they need to determine what lies beneath. 

“If you see an issue, it’s important that you take a sample of the soil and/or plant tissue and send it to the lab right away,” says Lenz. “You want to try and rule out what the issue isn’t and get to the root of the problem instead of guessing.”

No matter your concern heading into the 2024 planting and growing seasons, know that Stine sales reps and our agronomy team are available to help navigate any questions or issues.

On Jan. 2, Stine Seed Farm manager Steve Luther talked through takeaways from 2023 and how growers can plan ahead for the 2024 season on the Stine Seedcast. He discussed why developing a plan for the upcoming planting season is of the utmost importance to ensure crops have what they need to yield success come harvest. Here are Steve’s top four recommendations to incorporate into your plan to secure a smooth planting and growing season.

1. Weed control. While weeds may have not been a problem for some last year, with the drought-like conditions that plagued much of the country during the 2023 season, suppressing weeds that overwintered in the soil will be of top importance this growing season.

“The big thing for us and the Midwest, and I hear it time and time again, is how we’re going to deal with suppressing weeds,” says Luther. “They’re out there; I don’t think it’s any secret. It’s probably because it was hot and dry and a lot of the herbicides that we use in today’s age are very water soluble, so it takes a lot of rain to keep those activated in the soil.”

Many of the best post-emergent and pre-emergent herbicides on the market require rainfall to activate and move the herbicide within the soil profile. Unfortunately, 2023 was a dry year for many, so their in-season or post herbicide program last year may not be viable as a weed control method this season.

Luther suggests being proactive and planning ahead to modify and strengthen both soybean and corn preprograms to ensure your post program works as it should. “You don’t want to have rescue trips with your sprayer,” he adds. Talk to your local Stine agronomist or sales rep or crop protection specialist about an integrated weed management approach for 2024.

2. Nutrient program. Before hitting the field, growers should test their soil for nutrient shortages. The big three — nitrogen, phosphorus and potassium — are critical for plant production, but there are other inputs that should not go overlooked.

“Harry and I have always agreed, you’ve got to feed the crop. You can’t just put something on in the fall with your anhydrous and hope that’s going to be good enough,” says Luther. “This is even more important when you increase corn populations.”

Sulfur should be a foundational component of your nutrient program. The role of sulfur in corn plants is important to chlorophyll production and photosynthesis, which helps convert sunlight into energy and supports the plant’s nutrient uptake. Deficiency of sulfur can greatly impact the growth process and yield outcome of your crop.

To apply sulfur to plants, Luther recommends including it as part of your pre-plant and side-dressing program. “If you put pencil to paper, it’s one that returns.”

3. Fungicides and insecticides. Fungicides and insecticides are not just “insurance” in an unpredictable year; Luther says they should become a yearly practice. “There are affordable options that work really well out there,” he notes. Luther suggests taking a split-shot approach, applying fungicide as part of the post-program and then following it up over the top adding an insecticide to the pass.

4. Hybrid/variety selection. Stine has spent decades improving and expanding our genetic material to ensure growers have options. Luther does just that on the Stine Seed Farm, where he leads efforts to ensure our products perform and even exceed when paired with the right environment and best agronomic practices. Stine agronomists and sales reps are properly trained and well versed in how available products fit in their region. Setting up time to talk to our experts to place the right products on the right fields is a critical step to guaranteeing yield success in 2024.

Listen to Steve’s episode of the Stine Seedcast on your favorite podcast platform for more tips for the 2024 season and to learn about the evolution of the Stine Seed Farm.

Having subsoil moisture is pivotal to crop success. Lack of subsoil moisture can alter both farming practices and decisions. Most of the subsoil moisture is replenished in the spring when the ground thaws. Roughly 80% of rains in the late winter and early spring can infiltrate the soil and add to the subsoil moisture profile. Having a large amount of snow could help with depleted subsoil moisture levels, but only about 25% of melted water from snowpack will make its way into the subsoil. Iowa is not the only state struggling with depleted subsoil moisture levels; earlier this year, only about 30% of the acres in Nebraska had sufficient subsoil moisture levels.

Knowing your soil type and its moisture capacity can help when making agronomic decisions. Every soil type has different thresholds of water capacity, and some soils are more easily saturated than others. Tillage is known to dry out the soil while also decreasing rapid water infiltration, making it harder for water to move into the subsoil. Some fields could benefit from tillage to combat oversaturation, but in areas of depleted subsoil moisture, it could be detrimental. Obviously, no one knows how much rainfall you are going to have during the growing season, but having an idea of your subsoil moisture level is beneficial when making agronomic decisions.

Other than farming practices, hybrid and variety selection is key to maximizing your yield potential. Certain hybrids and varieties perform better in denser soils than they do in lighter ground. Knowing your subsoil moisture levels combined with your average environment will help you make an informed decision when consulting with your Stine^® independent sales rep and regional sales agronomist.

Connect with your local Stine sales rep or regional sales agronomist for a discussion on subsoil moisture and our 2024 corn and soybean lineup.

Article Sources:

Clipper-Herald, Brian Neben Lexington. “April 2022-March 2023 11th Driest Period on Nebraska Record.” Lexington Clipper-Herald, 13 Apr. 2023, https://lexch.com/news/april-2022-march-2023-11th-driest-period-on-nebraska-record/article_65bc8288-da0e-11ed-ab99-db8386c2c4cc.html. Accessed 16 Nov. 2023.

“Northwest Iowa Subsoil Moisture Survey Results Announced | Integrated Crop Management.” Crops.extension.iastate.edu, https://crops.extension.iastate.edu/blog/gentry-sorenson-leah-ten-napel/northwest-iowa-subsoil-moisture-survey-results-announced. Accessed 16 Nov. 2023.

“Frequent Tillage and Its Impact on Soil Quality | Integrated Crop Management.” https://crops.extension.iastate.edu/encyclopedia/frequent-tillage-and-its-impact-soil-quality#:~:text=The%20effect%20of%20tillage%20on%20soil&text=Since%20tillage%20fractures%20the%20soil,the%20force%20of%20pounding%20raindrops.  Accessed 16 Nov. 2023.