Southern Rust

Iowa Farmer Battles Today's Pests While Eyeing Tomorrow's 'Mean Sixteen' Threats

Fri, 12 Dec 2025 18:52:50 GMT

For Worth County, Iowa, farmer Sarah Tweeten, the list of high-priority agronomic threats isn’t a political abstract — it’s a harsh reality she deals with every season.

Farming with her parents, Brian and Julie, and her uncle Roger, Tweeten has been steering the partnership toward more resilient cropping practices since joining the operation in 2021. This includes shifting from conventional tillage to strip tillage and splitting nitrogen applications.

The changes are part of a broader mindset: Protecting yields today from weeds, disease and insects while aggressively preparing for the next generation of agronomic threats. This forward-thinking approach is what led Tweeten to Washington, D.C., earlier this week as a Farm Journal Foundation farmer ambassador to help introduce a new report: “ The Mean Sixteen: Major Biosecurity Threats Facing U.S. Agriculture and How Policy Solutions Can Help. ”

Today’s Battles and Tomorrow’s Warnings
Researched and developed by Stephanie Mercier, PhD, the report takes an in-depth look at 16 significant pest issues U.S. farmers face now or could realistically in the future.

Tweeten is already battling a couple of the problems that underpin the urgency behind the research. For example, Palmer amaranth (pigweed) is gaining ground in her fields and across Iowa. The pervasive broadleaf weed can drastically reduce yields, with studies showing corn yield reductions between 11% and 91% and soybean yield reductions of 17% to 68%.

“We’ve struggled with pigweed as it continues to establish more resistance to our herbicides in our toolkit,” Tweeten says.

Two additional agronomic issues the report details include:

1. Asian Soybean Rust. First detected in the U.S. in Louisiana in 2004, this fungal disease has spread to southern states like Georgia and Mississippi. Scientists warn that warming winters could enable its migration to the Midwest, adding to existing disease pressures.

2. Corn Ear Rot. It can lead to aflatoxin production, making corn unmarketable and posing risks to humans and livestock. Aflatoxin is an issue Pickens County, Ala., farmer Annie Dee says is an ongoing problem for corn growers in her area.

“If we have aflatoxin, it can be impossible to sell the corn,” says Dee, also a Farm Journal Foundation Farmer ambassador.

A more recent threat she references is the impact of Highly Pathogenic Avian Influenza (bird flu) on local poultry farms.

Since January 2022, HPAI has been confirmed in a commercial or backyard poultry flock in all 50 states.

(USDA)

“An important market for us is poultry feed meal, so that’s a constant worry. The trickle-down effect is if we can’t move our corn then we can’t meet our financial obligations,” Dee adds.

Despite agricultural R&D offering a high ROI — $20 in benefits for every $1 spent — the Farm Journal Foundation report notes public funding for ag research has been declining over the past two decades.

“Farmers urgently need sustained support for aflatoxin research and prevention because these risks threaten our yields, our markets and the trust consumers place in American agriculture,” Dee says.

U.S. public spending on ag research and development has been falling for two decades.

(USDA-ERS)

African Swine Fever Has ‘Devastating Potential’
Looking to the future, Tweeten says she is concerned about African swine fever (ASF) and its potential to impact crop farmers as well as hog producers. The highly contagious swine disease hasn’t been detected in the U.S. mainland, but it isn’t far away. ASF has been confirmed in the Caribbean countries of Haiti and the Dominican Republic, roughly 700 miles from Miami, Fla.

“Being a farmer from Iowa, where we have probably eight times the amount of pigs as we do people, an outbreak of ASF would be just devastating to our state,” Tweeten says.

Hogs are among the biggest customers for the corn and soybeans Tweeten and her family grow. If African swine fever were to shut down hog production or exports, it wouldn’t just be a blow to livestock producers – it would hurt the entire agricultural community, she contends.

Read about 5 livestock diseases that could impact U.S. food security and economic stability.

Food Security Is National Security
When it comes to justifying funding for ag research, Tweeten knows there’s competition for every federal dollar. But she believes agriculture deserves a front-row seat — not only because of its economic weight and impact on farmers, but because of its role in national security.

“There’s that argument that food security is national security,” she says. “If there’s one thing COVID made us aware of, it’s that a disruption to our food chain can be terrifying, quite frankly.”

The pandemic made consumers and policymakers more aware of supply chain vulnerability. In 2020, the shock to the supply chain came from a human disease and logistical bottlenecks.

(Sarah Williams Photography)

Next time, Tweeten says, the disruption could just as easily come from animal or plant disease — whether African swine fever in hogs, Asian soybean rust or some other pathogen in crops. She worries about scenarios where farmers could face a fast-moving disease or crop pest while critical tools are still hung up in regulatory delays.

Her message: Farmers need a full toolbox, not one that’s half-built by the time a threat arrives.

“Ag needs to be in a good position when these sorts of emerging diseases and pests come into the country,” she says, “to have the tools in our toolbox ready for farmers to pull out.”

About the Farm Journal Foundation
The Farm Journal Foundation is a farmer-centered, non-profit, nonpartisan organization established in 2010. It works to advance agricultural innovation, food and nutrition security, conservation, and rural economic development.

Rust in the Ration: How to Combat Southern Rust’s Impact on Corn Silage

Thu, 04 Sep 2025 14:04:48 GMT

With the warm and wet conditions this season, southern rust is on the rise in Midwest corn crops. It may be time to start considering the impact that could have on corn silage and preparing to adjust rations accordingly. While southern rust is not a direct threat to herd health, it has been shown to lower the nutritional value of silage and can compromise feed quality.

Southern rust, a fast-developing fungal disease caused by Puccinia polysora, does not itself produce toxins, but it weakens the plant and provides the opportunity for other diseases to move in. These opportunists include various Furasium species, which produce mycotoxins (fumonisin and deoxynivalenol) that can be harmful in feed.

Southern Rust and Corn Silage Quality

Southern rust is known to impact corn silage quality. A study from the University of Florida showed increasing rust infestation resulted in increased dry matter and fiber fractions, but that dry matter digestibility decreased by 13%. Further, high rust silages had lower neutral detergent fiber digestibilities than medium and no rust silages. Southern rust also affected the concentrations of lactate and volatile fatty acids, causing both to decrease with increasing infestation. These results indicate decreased nutritive value.

The observed increased dry matter also reduced silo packing effectiveness. If moisture levels are too low at harvest, it is difficult to achieve adequate packing, which leads to poor fermentation and an increased risk of mold growth.

Because southern rust coverage reduces the photosynthetic area of the leaf, grain fill is often hindered, leading to a lower energy and protein content in the silage.

Southern Rust Silage Management

There are a handful of strategies producers can apply to counteract the effects of southern rust:

Adjust harvest time based on moisture content. Southern rust can cause corn to dry down faster than normal. Monitor moisture levels closely to ensure the proper fermentation of silage.
Consider a silage inoculant. Inoculants improve fermentation, and the rapid pH drop can inhibit mold and yeast growth.
Ensure good packing and storage. Pack silage well to limit oxygen exposure and prevent mold growth. Cover bunkers immediately and weigh down coverings thoroughly.

Feeding Southern Rust Silage

To counter the nutritional challenges of feeding southern rust-infected corn silage, dietary supplementation may be necessary.

Prior to inclusion, test all potentially infected silage for mycotoxins. This will allow you to determine the safety of the feed and avoid potential health issues. If mycotoxins are high, the incorporation of a mycotoxin binding agent into the ration will help reduce toxin absorption in the animal’s digestive tract. Additionally, supplementation with antioxidants, such as vitamin E and selenium, could help animals by countering oxidative stress caused by mycotoxins and supporting immune function.

If grain fill was affected and starch levels are low, you may need to incorporate an additional energy course to compensate. Further, poor grain fill could reduce the already low protein content of corn silage, and protein supplementation may be required.

When incorporating infected silage, ensure it is thoroughly mixed into the TMR to dilute potential ‘hot spots’. Inclusion levels of contaminated silage in the feed may need to be limited or removed entirely for sensitive animals, including lactating or breeding animals. Livestock should be monitored closely for symptoms of mycotoxin toxicity, such as reduced intake, weight loss, digestive issues or reproductive challenges. Be prepared to respond if issues arise.

When feeding corn silage infected with southern rust, caution is essential to protect livestock health and performance. The thoughtful use of compromised silage can help minimize risk while maintaining efficiency and animal well-being.

Your next read: Southern Rust Set To Take Big Bite Out Of Midwest Corn Crop?

Corn Disease Alert: Don’t Mistake Anthracnose Top Kill for Rust

Fri, 29 Aug 2025 12:39:17 GMT

The Midwest corn crop has endured a pressure cooker of disease problems this season.

Now, the aftermath of stress from disease and weather extremes in many areas are contributing to anthracnose top kill, according to Ken Ferrie, Farm Journal Field Agronomist.

“A lot of people think their corn is going through natural drydown at this point, but that’s not the case,” he says.

How To Tell The Difference
Ferrie explains the visual differences between the photo finish you want to see in corn and what happens when top kill sets into the crop:

The Desired Drydown Process: The husk should be ripening while the two leaves below the ear are green. In addition, above the ear the plant will be green all the way to the top of the plant. It should be dying slowly from the bottom up.

Anthracnose Top Kill: With this problem, you will see a green husk and the top two leaves will be dead or dying.

“Some farmers may confuse top kill with one of the rusts this year because the top of the plant could be yellow to orange in color. But rust comes from the ear zone and goes north to the top of the plant, while top kill shows up at the top of the plant and goes down,” Ferries explains.

Another clue to whether anthracnose was the cause of top kill (as opposed to high temperatures), Ferrie tells growers to look for black spores on the outside of the lower stalk of dead plants.

“When you split the top of the stalk, you’ll see discoloration. The more the hybrid is stressed, the quicker the problem shows up,” he says.

While fields that were sprayed with a fungicide later in the season tend to show the least amount of anthracnose top kill, fungicide does not stop it.

“We don’t have a fungicide for anthracnose top kill, but the healthier your plants are the less of the problem you’ll likely find,” Ferrie says.

Yield Loss Potential At This Point
“If your crop is at late R5 moving into R6, and the top of that plant is solid, it should finish strong,” Ferrie says.

But when top kill comes in 15 to 20 days before black layer, Ferrie says it hurts late-season kernel fill. This is particularly true in newer hybrids, which often build a lot of their yield late in the season.

Those hybrids will be pushed to black layer faster and at the cost of kernel depth.

Ferrie advises farmers to start conducting stalk push tests at 30- to 40-degree angles in their crop to see if the stalks will buckle, and to plan their harvest accordingly.

“With this stress from top kill, things will speed up and harvest will be here sooner than later for some growers and, unfortunately, with less yield,” he says.

Your next read: Southern Rust Set To Take Big Bite Out Of Midwest Corn Crop?

Southern Rust Set To Take Big Bite Out Of Midwest Corn Crop?

Wed, 27 Aug 2025 21:06:37 GMT

If one picture is worth a thousand words, then the video Iowa farmer Dan Striegel shot last week must be worth thousands more. In the video, Striegel is shown harvesting a field of emerald-green corn enveloped in a cloud of orangish-red southern rust.

“We were just getting that field opened up, and I looked over and saw that dust boiling up out of the chopper, so I shot the video,” Striegel says.

Southern Rust? Never heard of her.
What Cheer, Iowa. USA. #pftour25 #harvest25 pic.twitter.com/tiIsUc2CHl
— Dan Striegel (@djsinseia) August 21, 2025

To date, Striegel’s video has garnered more than 48,000 views on X, formerly Twitter.

“We’re in southeast Iowa, Keokuk County, and I think the southern rust is as bad here as it is anywhere,” Striegel adds. “Every field you walk in, if you’re wearing a white T-shirt, you’ll come out of there red.”

A Red Path Of Disease Mars The Midwest

Expect to see more red T-shirt-clad farmers walking out of cornfields across the upper Midwest, based on what the Crop Protection Network (CPN) southern rust map is showing.

The CPN continually updates its online, interactive map showing the counties by state where southern rust infections are confirmed. Now, in late August, the counties look like red steppingstones. They form a checkered path from southwest Michigan through northern Illinois and Indiana, into southern Wisconsin, across all of Iowa and nearly two-thirds of the way across Nebraska. Eastern South Dakota is also lit up with a string of red counties, as are parts of southern to central Minnesota.

The amount of southern rust present in the upper Midwest is worrisome to Ken Ferrie, Farm Journal Field Agronomist. In severe cases, the disease can wipe out 45% of the yield potential in a field, according to the CPN.

“At most, one in 10 growers in northern Iowa and Minnesota have seen the kind of southern rust some of them are seeing this year,” says Ferrie, who was working last week with corn growers in both states.

“It was a problem in probably eight out of every 10 fields I was in, and they’d all been sprayed at least once,” he says. “Minnesota has a corn crop that’ll knock your socks off – yield potential of 250, 270. I encouraged every grower to spray their field a second time except for two fields. One had been knocked down by hail, and the other had a hybrid that was clean.”

I spoke with a good friend of mine from Iowa yesterday that is an agronomist and farmer. He said the southern rust in corn across Iowa and much of the Midwest will take 9 to 12 bushel/acre off corn yields on average from what his team and himself are seeing. pic.twitter.com/Ad1VJ9oQBg
— Captain Cornelius1 (@ISU145) August 26, 2025

Hybrids Have Little To No Resistance To Southern Rust

A combination of early-season moisture, heat and wind formed the perfect storm for southern rust this season, allowing the disease-causing fungal spores (Puccinia polysora) to move from southern climes up to the Midwest, according to Kurt Maertens, BASF technical service representative for eastern Iowa and western Illinois.

“We’ve seen it all – southern rust, tar spot, northern corn leaf blight, gray leaf spot. Our corn has been inundated with all these fungal diseases, and we started seeing them early,” says Maertens.

If there’s a silver lining to southern rust, it’s that it does not overwinter in corn residue like tar spot does. But like tar spot, southern rust takes advantage of hybrids that have no built-in resistance. For many growers, that was an Achilles heel this season.

“When you’re dealing with a 117-day hybrid like they grow in southern Illinois, Tennessee, and Kentucky, you don’t grow corn that doesn’t have good southern rust resistance, because they deal with it every year,” Ferrie notes. “When you move to Minnesota, and you’re planting 102- to 95-day corn, you’re probably not going to find hybrids with southern rust resistance.”

Striegel says that was true for his neighbor’s cornfield, which he custom chopped for silage. “That field had two hybrids in it, one was worse than the other, and the field had been sprayed with a fungicide,” he says.

He adds that he also sprayed his own cornfields with fungicide, but they are still inundated with southern rust.

“We’ve had southern rust before, and it’s not usually something we have to worry about, but this is really bad,” Striegel says. “I’m standing on my deck looking at the cornfield next to my house, and you know, all of the leaves from the ears down in that field are covered with it.”

Southern rust is real in eastern Nebraska. Fungicide 3 weeks ago, 2nd app today with some potassium acetate pic.twitter.com/WZubU6IBwz
— Trent Mastny (@TrentMastny) August 21, 2025

How Late Is A Fungicide Application Still Worthwhile?

Ferrie says the fields he scouted last week were at late R3 to early R4 and had already been sprayed with fungicide at least once, but the disease was rebuilding.

“Any field where farmers had sprayed two weeks previously, the southern rust and northern corn leaf blight, to a lesser degree, were coming back, especially the southern rust. It was resporating,” he says.

The intense disease pressure from southern rust, tar spot and others have kept fungicide use at high levels this season, despite poor commodity prices.

“Because of that [amount of disease pressure], we have seen increased demand for our fungicides this year,” says Maertens, who encouraged customers to get applications made at the beginning of tassel.

Maertens says he has fielded a lot of questions this summer from farmers, asking how late they could go with a fungicide application and still benefit.

“Our recommendation is to get in front of disease,” he says. “Generally, we stop applications before we get to dent (R5). That’s not to say a later application can’t have some benefit, but our best results have been before infection was able to take place.”

Southern rust is a yield enemy farmers routinely face in the Southeast, reports corn yield champion Randy Dowdy, Valdosta, Ga. He participated in the Pro Farmer Crop Tour last week and said on U.S. Farm Report he believes many Midwest farmers still have time to address disease.

“We need to implore the fungicides, the technologies out there and get after it and protect this crop, especially that crop that still has not reached dent,” he says.

Farm Journal Field Agronomist Missy Bauer likes to see farmers complete their fungicide applications on the front side of dough (early R4). “Once we get to early dent, I think it’s a little more challenging to get the payback consistently, though we’ve applied at early dent (R5), and seen a nice response,” says Bauer, who is based in south-central Michigan.

Under the tough disease pressure farmers are facing this year, Bauer is telling growers to scout fields and evaluate what growth stage their crop is in before they walk away or pull the fungicide trigger one last time.

She adds that farmers need to check the label to make sure the product used is able to address southern rust effectively. She describes these as “Cadillac” products containing the newest chemistry.

“When it comes to some of these diseases, especially southern rust and tar spot, I do believe a little bit of a Hail Mary pass can be effective,” she says. “Will it be as effective as an application you could have made on a more timely basis? Well, no, you could have made more money doing it timely, but you’re still protecting bushels and gaining ROI at the end.”

Ferrie adds that farmers might want to do the late-season fungicide application to keep their corn crop standing until they can put their harvest plan in place.

“Be doing the push test to check stalk quality,” he advises.

Southern Rust/Silage Alert!!

Southern Rust has been aggressively advancing in many fields, especially those without a fungicide treatment. In some situations the plants are shutting down prematurely and plant material is senescing rapidly.

While we typically want to get down… pic.twitter.com/aK3hGgZE19
— Pioneer Troy (@deutmeyer_troy) August 26, 2025

Striegel says some of the farmers around him are heading to fields to harvest their silage corn sooner than later, because of standability concerns. “Some of this corn got planted early, and we had a lot of heat. The crop matured quickly, and the diseases are kind of shutting it down. It’s just dying out, and guys are going to go get it,” he explains.

That’s the strategy Ferrie encourages farmers to use in regular production corn, too.

“Harvest the fields most at risk first. But if a field of corn goes down, go combine the fields where the corn is still standing and come back to that one later,” he recommends.

The reasoning is you don’t want to risk more corn going down while you’re harvesting the field of corn that already has.

“While I was driving through Iowa last week, I kept thinking that if I built corn reels to pick up down corn I’d bulk up my inventory, because I know where they’re going to get used,” Ferrie says, only half joking. “Yes, harvesting corn at 25% moisture is expensive, but down corn will kick your butt.”

Your next read: Revenge Applications: Why They Don’t Work, Cost You Money and Bushels, and Are Frankly Illegal

How Pro Farmer 2025 Crop Estimates Compare and Contrast With USDA Expectations

Fri, 22 Aug 2025 20:32:51 GMT

As more than 100 crop scouts traversed dirt roads and two-lane highways, stopping dozens of times to sample corn and soybeans in seven Midwest states, they gathered insights to answer the question on many farmers’ minds this week: How would the Pro Farmer estimates compare to the numbers USDA-NASS released August 12?

The answer: Pro Farmer found a big corn crop but one that’s currently positioned to average 182.7 bu. per acre – 6.1 bu. below USDA’s 188.8 bu. projection.

“When we put the yield estimate out, it comes with a plus or minus 1% for corn and a plus or minus 2% for soybeans, and that’s because we know things can change yet,” says Chip Flory, host of AgriTalk and lead scout on the western leg of the tour.

“The other thing is the yield models that we use give us a range, and then, based on conditions, we can move within that range with the yield estimate that we’re going to pull,” he adds.

With that perspective in play, here’s how the Pro Farmer and USDA estimates compare:

Pro Farmer Corn Estimate (+-1%): 16.042 to 16.366 billion bushels; 180.9 to 184.5 bu. per acre average
USDA Corn Estimate: 16.7 billion bushels; 188.8 bu. per acre average

(ProFarmer)

Disease Pressure Across The Midwest Is Concerning
The 2025 growing season has been marred by heavy disease pressure in many of the corn and soybean crops Pro Farmer scouts evaluated this week.

It was an issue Lane Akre says showed up repeatedly in corn and soybean fields from the get-go, as tour scouts fanned out to check 2,000-plus fields across seven states: Illinois, Indiana, Iowa, Minnesota, Nebraska, Ohio and South Dakota.

“We know disease can speed up the maturation of plants, making it difficult to keep them healthy long enough for optimal grain fill before harvest,” says Akre, Pro Farmer Economist and lead scout on the eastern leg of the tour. “We are concerned diseases like southern rust and tar spot could negatively impact corn yields in some of these states during the next few weeks.”

Soybeans Could Be the Star of the Season
USDA’s August estimate for the national soybean yield average is just slightly above what Pro Farmer scouts found in fields this week. Pro Farmer places the soybean yield average at 53.0 bu. per acre, with a total crop size of 4.246 billion bushels

By comparison, USDA expects soybeans to average a record high 53.6 bu. per acre, with a total crop of 4.29 billion bushels.

Pro Farmer Soybean Estimate (+-2%): 4.161 to 4.330 billion bushels; 51.9 to 54.1 bu. per acre

“One of the questions heading into the tour was whether the soybean crop could live up to the lofty expectations a lot of people have for it, and we found that it does,” Akre says. “There’s a massive crop out there in fields. We’re just hoping it can hold on until harvest – and outpace the disease pressure out there – to deliver on those big yields.”

Corn and Soybean Yield Summaries
Pro Farmer and AgWeb reported extensively throughout the tour — the highs and lows of each crop in each of the seven states. Here are summaries from each state. Click on the links to learn more details.

Illinois: Scouts reported an Illinois corn crop that looked lush from the road, but once they picked ears and pulled back husks, most described finding an average to above-average crop – not the record yield estimate USDA reported on August 12.

“The Illinois corn crop just wasn’t what we’d hoped,” Akre says. “USDA is anticipating a 1.7% jump from a year ago, and we’re actually down 2.2%.”

Indiana: Wet conditions from rain, fog and heavy due is causing some unevenness in Indiana corn and soybeans. Still, the state’s corn crop posted a yield number that came in 3.35% higher than its 2024 number.

From disease pressure to too much rain, some scouts found a solid soybean crop in Indiana, while other routes exposed extreme variability. Overall pod count numbers were down 2.30% from 2024.

Iowa: Scouts spent two days in the state gathering dozens of samples to gain insights and project yield estimates. Despite challenges from disease pressure, scouts reported a big corn crop with significant potential. Their estimates put the Iowa crop up 2.93% over 2024, and up 6.4% versus the three-year average.

“This Iowa crop has a very, very strong ear count, great grain inches — just a very consistent equation putting that corn yield together,” reports Emily Flory Carolan, Pro Farmer Crop Tour data consultant.

For soybeans, scouts found a massive crop, up 5.49% in the number of pods as compared to the 2024 crop.

Minnesota: The corn crop in Minnesota is currently heading for a record yield this season, if it can outpace disease pressure. Scouts recorded the longest grain inches in the corn there that have ever been measured in the tour’s history.

“That’s definitely what pulled up that yield average for us,” Carolan says.

Soybeans also show tremendous yield potential in Minnesota. Pod counts were up 20.38% this week versus 2024 counts, and up 19.9% versus the three-year average.

Nebraska: Adequate moisture is pulling up corn yields in the state this season, with some tour routes reporting 8% to 10% increases compared to 2024 and 2023. The much-improved corn yield estimates were a welcomed change, scouts say, after seeing corn there struggle in two back-to-back years of drought.

Soybeans also are promising big yield results, with pod counts up 15.0% this week over the 2024 estimate.

Ohio: Heavy rains last spring meant many farmers either got a late start to the growing season or they had to replant fields. The moisture extremes early on have resulted in considerable variability in fields from one end of the state to the other. Still, scouts say the Ohio crop has solid corn yield potential overall, citing possible records along some Pro Farmer Crop Tour routes.

The soybean pod factory in Ohio is going strong – with numbers up 4.66% this season over 2024 – but scouts caution a lack of late-season moisture is concerning. More rain is needed for the soybean crop there to finish well.

South Dakota: Based on USDA’s August crop estimates, scouts knew the possibility was there to uncover a big crop in South Dakota. Field estimates show record yield potential is possible , especially due to ample moisture this year that’s supported growth and development.

Soybeans might be an even better story in South Dakota this year. Pod counts came in at 15.9% above last year’s tour and well above the three-year average of 970.1 pods.

For more insights from the 2025 Pro Farmer Crop Tour:

Watch On-Demand: Pro Farmer Crop Tour Day 4 Results from Iowa and Minnesota

Watch On-Demand: Pro Farmer Crop Tour Day 3 Results from Illinois and Iowa

Watch On-Demand: Pro Farmer Crop Tour Day 2 Results from Indiana and Nebraska

Watch On-Demand: Pro Farmer Crop Tour Day 1 Results from Ohio and South Dakota

Iowa Corn Has High Potential, Illinois Crop Looks Average and Soybeans Shine in Both States

Wed, 20 Aug 2025 23:58:02 GMT

Bright orange is a great color for pumpkins but not so much for corn. Nonetheless, that was the prevailing color Brent Judisch reports seeing as he evaluated crops Wednesday morning in northwest Iowa’s Harrison County.

“Our first six or seven samples were terrible with southern rust,” says Judisch, a Pro Farmer Crop Tour scout and Iowa farmer. “We saw three fields in a row that were actually gross. I walked out of them just covered with it. After that, while we’ve seen it all day, it’s been more in the lower leaves and not nearly as drastic.”

Chip Flory, lead scout for the western leg of the tour, says the northwest Iowa crop is the best and worst he’s ever seen.

“In the snapshot that we took of it, and the measurables we saw in the field today, it is the best corn crop,” Flory reported during the tour’s nightly live broadcast.

But the disease pressure in the Iowa crop has Flory spooked.

“Disease pressure is putting a lot of bushels — a huge number of bushels — at risk,” he adds. “You can take 20, 30 bushels off of corn yield with what southern rust can do to the crop, even at this late stage in the game. It’s a dangerous crop that we’re looking at out here right now.”

Chip Flory says he was surprised to see corn that was well into R5 (dent) in northwest Iowa. “I can’t tell if it was this mature because of pressure from the southern rust, or if it was because of higher nighttime temperatures at pollination,” he reports. “I am concerned about how much disease is out here, and what it’s going to look like in another week or two.”

(Chip Flory, Host of AgriTalk)

Can The Iowa Corn Crop Still Hit A Record?
The Iowa corn results were a big shocker on Wednesday, given the amount of disease pressure scouts saw, according to Emily Flory Carolan, Pro Farmer Crop Tour data consultant.

“I would say all three districts were setting new records. They were consistently high in all measurements for corn in ear count, inches long and kernels around,” she says.

Carolan’s summary of the results scouts tallied in Iowa revealed some high yield estimates, despite the disease pressure:

*District 1 was 197.89 bushels, up 12.06% versus 2024 and up 9.89% versus the three-year average.

*District 4 was 207.25 bushels, up 5.82% versus last year and up 14.01% versus the three-year average.

*District 7 came in at 195.03 bushels, up 1.80% versus 2024 and up 6.35% versus the three-year average.

(ProFarmer)

Flory is concerned southern rust will impact standability in the Iowa crop, which he says is starting to dent in areas, and cause some of it to go down.

“I’d want to keep an eye on the stalk condition of this crop, because if this disease pressure continues, farmers are going to want to get out and prioritize fields for harvest before we get there,” he adds.

Illinois Corn Crop Looks Average
Scouts report the Illinois corn crop appears lush from the road, but once they walked out into fields, picked ears and pulled back husks, most described finding an average crop.

“We’ve seen some good corn, we’ve seen some average corn and we’ve some stuff that’s got a long way to go,” tour scout Jake Guse told U.S. Farm Report’s Tyne Morgan on Wednesday morning.

That perspective played out in the total results tallied and shared during the nightly tour meeting. Illinois corn averaged 196.19 bushels per acre, down 2.24% from last year but up 1.72% from the three-year average.

(ProFarmer)

Ninth and final stop 4 miles North of Roseville, IL. Population was very good at 34,000. The yield is 213. Kernel depth is just under a 1/2 inch. Some disease was showing up here including tar spot! Soybeans had 1778 pods in 3X3 area. #oatt #pftour25 pic.twitter.com/xAcDSxJL0q
— Darren Frye (@Frye_WSS) August 20, 2025

USDA-NASS estimates released August 12 project the Illinois corn crop will come in averaging 221 bu. per acre for the state, up 4 bushels over 2024.

That’s outside what Guse’s expectations are for the state.

“As you’re driving along the road, you can see ears that are already tipped over. I just don’t see it reaching [USDA’s projection],” he says.

Lane Akre, Pro Farmer economist and host for the eastern leg of the tour, agrees with Guse. He reports pulling several samples of corn that exceeded 200-bu. per acre as well as one that only hit 143 bushels.

“The Illinois crop just wasn’t what we’d hoped,” Akre says. “USDA is anticipating a 1.7% jump from a year ago, and we’re actually down 2.2%.”

Akre’s leg of the tour went through three Illinois counties that are typically heavy hitters for corn yields: Bureau County, Henry County and Rock Island County.

“There’s really good dirt through that area, and the farmers there are very good at actively managing their crops and what they do with fertilizer, herbicide and fungicide,” Akre notes. “We saw some poor emergence and that might’ve weighed on the samples we took.”

Soybeans Could Be the Star of the Season
Soybeans offered a better yield picture for Illinois farmers than the corn crop, Akre notes.

“We didn’t have a single sample in the state that was south of 1,300 pods in a 3’x3' square. We saw a lot of pods and a lot of potential out there,” he says.

The average counts Illinois scouts recorded was even higher than what Akre found, with an average of 1,479.22 pods in a 3’x3' square area. That is up 4.24% versus 2024 and up 12.65% versus the three-year average.

(ProFarmer)

Iowa soybean results across the three districts were equally impressive.

“This year’s crop is better than last year by far,” Greg Lehenbauer, Pro Farmer crop scout, told AgDay’s Michelle Rook. “They’ve had adequate rain across this part of Iowa almost all summer long.”

#pftour25 Day 3. Stop 2 Plymouth Co. IA. #Soybean pod count 816. @AgDayTV @FarmJournal @USFarmReport pic.twitter.com/GgmulwJ8UI
— Michelle Rook (@michellerookag) August 20, 2025

Carolan’s data confirmed the excellent soybeans that crop scouts found on Wednesday in all three districts:

*District 1 soybeans: 1,279.25 pods, up 15.38% versus 2024 and up 15.05% versus the three-year average.

*District 4 soybeans: 1,376.15 pods, up 9.73% versus 2024 and up 13.63% versus the three-year average.

*District 7 soybeans: 1,562.54 pods, up 14.37% versus 2024, and up 24.66% versus the three-year average.

(ProFarmer)

While Flory is cautiously optimistic about the Iowa soybean crop, he says stem rot and sudden death syndrome is taking root in more fields and threatening yield outcomes.

“Some of the routes through southern and west-central Iowa have seen a tremendous amount of disease issue on the soybeans, so I’ve got a feeling it’s going to look a lot different in a week than what it does right now,” he predicts. “Now, if it was September 10, that’d be one thing. But it’s August 20, and there’s still time for those bean diseases to take some yield away.”

Flory’s sentiment about what fields revealed in Iowa was shared by scout Brent Judisch.

“What it’s going to come down to here in the corn and the beans is, does the crop mature faster than the disease moves, or will disease outpace the crop?” Judisch says. “We won’t know for sure for another two or three weeks.”

Watch On-Demand: Pro Farmer Crop Tour Day 3 Results from Illinois and Iowa

Watch On-Demand: Pro Farmer Crop Tour Day 2 Results from Indiana and Nebraska

Watch On-Demand: Pro Farmer Crop Tour Day 1 Results from Ohio and South Dakota

About the Pro Farmer Crop Tour
The Pro Farmer Crop Tour is taking place Aug. 18-21, 2025. Simultaneously, the tour follows an eastern and western route, with the two culminating in Rochester, Minn. Nightly meetings in each location review daily results, scouting observations and historical comparison data. Attend nightly meetings in person or watch the nightly broadcast online at AgWeb.com/croptour .

Southern Rust Has Infected Iowa Corn in ‘Likely Every County’

Mon, 11 Aug 2025 20:53:03 GMT

Alison Robertson says she has been at Iowa State University (ISU) for 21 years, and she’s never seen as widespread a problem southern rust is in Iowa this season. She believes the disease is present in every one of the state’s 99 counties.

She reports the disease moved into Iowa early, right at the beginning of grain fill.

“I’ve never seen this before…we’re just going to have to see how bad it gets,” Robertson, an ISU Extension field crops pathologist, told AgriTalk Host Chip Flory.

Corn yield losses from the disease can reach 30% and even more, depending on infection severity.

Karen Braun, chief market analyst at Zaner Ag Hedge and a Pro Farmer Crop Tour scout, says one of the fields she’s watching in western Iowa is “in pretty bad shape, disease-wise.”

“It’s really hard to get a feel for how widespread [southern rust] is, but I know a lot of people are talking about it, especially with how much moisture they’ve gotten out in the western belt,” she told Flory on AgriTalk.

Southern rust has infected corn in at least 18 states as of Monday, according to the Crop Protection Network (CPN). Along with Iowa, the CPN has confirmed the disease in other Midwest states, including Illinois, Kansas, Minnesota, Missouri, Nebraska and a “probable” finding in Michigan.

(Crop Protection Network)

“Southern rust loves wet, and the fact that we saw it early and we’ve been wet means the disease is really ramping up,” Robertson says.

What The Disease Looks Like On Plants
Southern corn rust, caused by the fungus Puccinia polysora, creates round, light brown to orange spots scattered mainly on the upper leaf surface. They might also appear on husks, stalks, lower leaf surface and ear shanks.

“We’re getting all these spots, pustules on those leaves that are producing spores,” Robertson says. “When the spores are produced, they burst through the leaf epidermis, and so because of that, those leaves are probably losing a little bit more moisture than they would do with something like Northern corn leaf blight, or gray leaf spot, or even tar spot.”

Tissue damaged by the disease is not able to photosynthesize. Corn kernels are then unable to fill with starch and build a heavy test weight.

“The plants are under a lot of stress trying to fill that grain, so that can lead to premature senescence and just death of those plants,” Robertson says.

Southern rust can be difficult to distinguish from common rust .

Many Farmers Still Have Time To Treat The Disease
Foliar fungicides can help farmers manage southern rust, but timing is critical. Research shows fungicide applications ideally go on the crop from tasseling through the milk stage (R3).

“And if you have a severe infection into dough, then a fungicide application could still be helpful. But once you get to R5, once that corn is denting, it’s too late, you can’t do anything,” Robertson notes.

The Crop Protection Network, a multi-state Extension resource, offers a new mapping tool called Crop Lookout farmers can reference to identify various diseases and their locations.

“If you just click on that, there’s a couple of hot links on that map for tar spot and southern rust. When we find new spots of disease, it’s updated in real time,” notes Daren Mueller, an ISU Extension pathologist.

Robertson has posted an article online with more information on Southern rust continues to develop across Iowa.

Fast Facts About Southern Rust
· Southern rust spores can travel miles on air currents.
· Once infected, symptoms can be observed within three to four days if the weather is favorable.
· Within seven to 10 days, spores are produced and can travel to other plants.
· Favorable southern rust conditions include hot temperatures and at least four hours of consecutive leaf wetness.
· Research shows southern rust can continue even with temperatures around 110°F.

The AgriTalk Segments with Robertson and Braun are available here:

Take Our Poll: What Problems Are Showing Up In Your Corn Fields?

Fri, 25 Jul 2025 17:32:30 GMT

‘Tis the time of year to be scouting for various diseases and pests and assessing how your corn crop is coming along. In addition to keeping a watchful eye for southern rust and tar spot, some farmers and agronomists have been surprised to find pollination issues. “ Overly tight tassel wrap ” went largely unnoticed until a couple weeks ago.

“It’s a situation where the tassels on some varieties, based on the growing conditions, were wrapped too tight. The pollen couldn’t get out of the wrap, which led to a poor start for the pollination cycle,” explains Ken Ferrie, Farm Journal field agronomist.

Farmers and agronomists have reported pollination issues due to tight tassel wrap in at least 10 states. Only time will tell how widespread the unusual problem impacted yields.

In addition to pollination problems, southern rust has now been confirmed in at least 15 states. With the recent heat, humidity and strong winds, agronomists are encouraging farmers to scout their corn fields, as conditions are ripe for the disease to spread.

Since late June, Ferrie has been closely monitoring tar spot reports in Illinois and working with growers to create and implement action plans for their specific fields to address the disease.

That’s why we want to hear from you. How is your corn crop faring? Click here to take our AgWeb poll , and let us know if you’re seeing pollination issues due to tight tassel wrap and/or if you’ve confirmed southern rust or tar spot this year. We only ask four questions, so it will take less than a minute to participate.

Southern Rust: Coming to a Field Near You?

Wed, 23 Jul 2025 19:21:56 GMT

It’s a corn disease issue creeping north and infiltrating fields earlier than it has in the past and one that thrives in high heat and humidity. With increasing reports of southern rust now being found as far north as Iowa , agronomists are encouraging farmers to scout early and often.

Southern rust is a fungal disease that affects corn crops. It’s trademark is small, orange-colored spots that look like rust.

And as Farm Journal’s Rhonda Brooks reported last week , southern rust can be difficult to distinguish from common rust .

The spots erupt on the upper surface of corn leaves. The disease likes warm and humid conditions, and once it spreads, it can be a major hit to yield, especially if it develops during the critical period of kernel development.

According to Crop Protection Network, southern rust was first reported in Florida and Georgia in mid-June, but the disease has quickly made its way to the Midwest. While the disease has been reported in Alabama, Florida, Georgia, Mississippi, southern Texas, it’s now been reported in a number of counties across the South and Midwest, including:

Arkansas: eight counties
Illinois: eight counties
Indiana: two counties confirmed, but three counties listed as probably cases
Iowa: 30 counties
Kansas: 16 counties
Kentucky: eight counties
Missouri: 12 counties
Nebraska: 27 counties
Oklahoma: three counties

“In addition to tar spot, there’s also been some reports of southern rust, depending on which area you’re in, as that stuff has blown up more from the south,” Missy Bauer told Farm Journal’s Rhonda Brooks during Corn College this week. “If the environment’s conducive for these things to continue, we could see some pretty big disease issues across the Corn Belt this year. We want to be prepared and make sure you’ve got plans in place to deal with this potential disease pressure.”

Dan Quinn, who is an assistant professor of agronomy and Extension corn specialist at Purdue University, says southern rust has been confirmed in southern Indiana, but he has also detected it in northern Indiana, which is early.

“We always track its movement from the south,” Quinn says. “That’s the key. Southern rust in a state like Indiana, we kind of get a clean slate every year. Tarspot is always here, it kind of hangs around, but southern rust we really have to track its movement as it moved up from the South.”

Quinn says Kentucky recently confirmed the disease, and then it appeared in Indiana.

“The thing with southern rust is, one, make sure it is southern rust. So we do have a lot of leaf rust out there. It’s always good to, you know, a lot of universities have diagnostic labs that can confirm that for you. So, first make that it is truly southern rust, but also be mindful of managing it. When it comes in this early, it can impact that crop pretty significantly. So a lot those areas are looking at a fungicide management for that disease.”

He says in his experience, southern rust can take 10% to 20% off yield.

“It’s like tar spot tar spot where I’ve seen 40% to 50% yield reductions. So any of those diseases that impact that green leaf area of that plant and really start to move into the ear, leaf and into the upper canopy, can have pretty severe impacts on yield.”

Quinn’s advice for farmers is to pay attention to where it’s moving. Farmers can track the disease here.

He says farmers need to pay attention to that map daily, which is tracked county by county, to see where the disease has popped up, but also be mindful of weather conditions.

Other advice for farmers includes:

1. Scout fields thoroughly and frequently

Southern rust can spread rapidly under favorable conditions (high temperatures and humidity), so early detection is critical
Inspect fields often, especially those that are late-planted or in low-lying areas, where humidity and moisture tend to linger
Focus on the upper leaves, looking for small, circular, light orange to cinnamon-colored pustules, primarily on the upper surface
Consult resources like the Corn ipmPIPE tool to monitor the disease’s progression in the region

2. Differentiate southern rust from common rust

While symptoms can be similar, common rust is generally less aggressive and causes less yield loss
Southern rust pustules are typically circular or oval, light cinnamon to orange, and primarily found on the upper leaf surfaces, while common rust pustules are more elongated, dark brown and can be found on both upper and lower leaf surfaces
The spores of southern rust will easily rub off on your fingers, unlike tar spot, which is a different disease that can initially look similar to southern rust

3. Consider fungicide application

If Southern rust is detected on multiple plants during the early dent stage or earlier, and hot, humid conditions are expected, a fungicide application might be warranted
Fungicide applications are most effective when applied at the onset of the disease and can help prevent further spread
The optimal timing for fungicide application is generally between the R1 (silking) and R3 (milk) growth stages of corn development
If conditions remain favorable for disease development, a second fungicide application might be necessary, especially for late-planted fields

4. Monitor stalk quality and consider early harvest

Southern rust can weaken stalks and increase susceptibility to stalk rot, potentially leading to lodging and harvest losses
As corn maturity progresses, regularly check stalks for signs of deterioration

Put On Your Scouting Hat: Check for Southern Rust in Corn and White Mold in Soybeans

Thu, 17 Jul 2025 19:37:08 GMT

Significant disease pressure is showing up in corn and soybeans earlier this summer than what Daren Mueller saw in 2024 crops. The Iowa State University plant pathologist says the early onset of disease pressure he has seen in Iowa – southern rust in corn, and sudden death syndrome (SDS) and white mold in soybeans – is concerning.

While he is closely tracking diseases in soybeans, he says there is “worse news” about the diseases showing up in corn.

“We actually are seeing a lot of southern rust in Iowa already. That is the one thing that I’m probably the most nervous about. I think we’ve found it in six or seven counties now,” he says.

Southern rust has been confirmed in at least 14 states. In Iowa, there’s a band of the disease that stretches east to west across the state, says Daren Mueller, Iowa State University pathologist.

(Crop Protection Network)

Along with Iowa, the Crop Protection Network (CPN) has confirmed southern rust in at least 13 other states – including Illinois, Kansas, Missouri, Nebraska – and a “probable” finding in Indiana.

Southern rust can be difficult to distinguish from common rust .

While both are fungal diseases that affect corn and share similar symptoms, they have distinct characteristics. Common rust tends to favor cooler, wetter conditions, while southern rust prefers warmer, humid weather.

Southern rust can also be more aggressive and potentially more yield-damaging than common rust, especially in later planted fields.

“Southern rust likes heat, and we don’t have good levels of resistance. And it can move very, very quickly through a cornfield,” Mueller told AgriTalk Host Chip Flory on Thursday. CPN reports yield losses up to 45% have been reported with severe infections.

“Last year was the first year in a long time where we really had to deal with southern rust, and we’re finding it about 10 days earlier than last year.”

The good news in Iowa, so far: the incidence (number of plants affected) and severity (area of leaf diseased) are low, adds Alison Robertson, Iowa State professor of plant pathology and microbiology in an online article she posted on Thursday.

Mueller is encouraging farmers to get out and scout for southern rust now, so they can take action to address the disease.

“In a year like this, if we catch a couple more rains like we’re supposed to in the next week or so, and this inoculum is out there, a timely fungicide application is going to be very beneficial,” he says.

The Crop Protection Network, a multi-state Extension resource, offers a new mapping tool called Crop Lookout farmers can reference to identify various diseases and their locations.

“If you just click on that, there’s a couple of hot links on that map for tar spot and southern rust. When we find new spots of disease, it’s updated in real time,” Mueller says.

Speaking of tar spot, Mueller says the disease can still take a huge toll on corn, but that farmers are learning how to deal more effectively with the disease.

“I think we’re getting more used to tar spot, and I think people aren’t panicking as much,” he says.

Soybean Diseases Showed Up Early This Season, Too

Mueller says he found SDS and white mold (also known as Sclerotinia stem rot) in soybeans in mid-July.

“That was about a month earlier than what we want,” says Mueller, who serves as the coordinator of the Iowa State integrated pest management program. “The fact that (SDS) was showing up a good month in advance, it has us a little nervous.”

SDS is most severe when soybeans are planted in cool, wet soils and has delayed emergence – conditions that were prevalent this past spring in parts of Iowa and further into the East and Southeast.

Severe SDS can result in yield losses greater than 50%, according to University of Minnesota Extension.

To address SDS, there’s no curative action farmers can take, but Mueller offers one action farmers can take to address the problem.

“You get your pad and paper out and you take notes in the field. Record what varieties you selected, what seed treatments you put down. That’s all valuable information for the next time you plant soybeans,” he says.

This is an important action because key soybean planting states, like Iowa, have had three or more years of fairly dry weather in the latter half of the summer, so crop advisers and farmers have little data on which of the newer varieties perform best in the face of SDS.

“Use it to your advantage to just collect the data,” Mueller advises.

For white mold, Mueller says farmers can still apply a fungicide in many cases and get enough of a response to warrant the cost of treatment.

“We’re still, early enough, you can get a fungicide out there if you feel like the risk is staying high. You could spray all the way up to R3 and still get some money back on your fungicide,” he says.

“You’ve got to get some penetration through the canopy [for white mold],” he adds. “All the activity is done in that lower canopy. Anything you can do to get the fungicide as deep into that canopy as you can, that’s what we want.”

Unlike SDS, white mold is fairly easy to pinpoint definitively in the field. At this point in the season, Mueller says to look for individual dead plants “here and there” in the field.

“Then just peel back the canopy, and look for the white powder, it’s called mycelia, the fungal growth. You know that’s a telltale sign that you have white mold,” he says.

Mueller’s complete conversation on AgriTalk is available here:

Your next read: ‘Overly Tight Tassel Wrap’ Is Affecting Pollination In Corn

Triple-Action Foliar Fungicide Targets Tar Spot, Southern Rust and Frogeye Leaf Spot

Thu, 05 Jun 2025 19:36:46 GMT

Farmers will have a new foliar fungicide, Corteva Forcivo, to include in their disease management plans for the 2026 season, pending registration from the U.S. Environmental Protection Agency (EPA).

Forcivo will feature three modes of action – flutriafol, azoxystrobin and fluindapyr – to address foliar diseases in corn and soybeans via overlapping preventive and curative activity.

Key diseases targeted include tar spot, southern rust and frogeye leaf spot, among others, according to Mike Eiberger, U.S. marketing leader for Corteva.

The fungicide will offer farmers these key benefits:

Triple-action foliar disease control. Forcivo fungicide will be available in a convenient premix that growers can apply at a use rate of 7 to 9 fluid ounces per acre. The multiple modes of action will help ensure that if a disease is less controlled by one key ingredient, others will help manage the threat, notes Eiberger in a press release.

Multiple row crop disease flexibility. In addition to addressing disease issues in corn and soybeans, Forcivo will provide broad-spectrum disease control in wheat, barley, sorghum and triticale.

Bolster plant health and yield potential. Forcivo will provide up to 30 days of residual activity to protect crops and maximize return on investment all the way through harvest – even from late-season, yield-robbing diseases – according to Eiberger.

Corteva reports farmers will be able to take advantage of the upfront savings with its TruChoiceoffer and save on their purchase of Forcivofungicide by bundling it with other Corteva crop protection and seed products, such as herbicides, nitrogen stabilizers and Pioneer brand seed. With the TruChoice offer, farmers will be able to save money when funding a prepay account online or through a participating retailer, according to the press release.

Pending registration approvals, Forcivo fungicide will be available for growers to include in their 2026 disease management plans. To learn more about Forcivo fungicide, visit Corteva.us/Forcivo or contact a local Corteva representative.

Your next read: Ferrie: Unravel The Mystery Of Ugly Corn Syndrome To Reduce Yield Losses

Timely Fungicide Use Safeguards Corn Yield Potential

Fri, 18 Apr 2025 14:48:02 GMT

Applying a foliar fungicide in corn is a go-to practice every year for Chad Eitmann, who grows corn and soybeans in southwest Iowa, near Treynor.

“It wasn’t that way 15 years or so ago, but it is now,” says Eitmann, who says he takes a proactive approach to foliar fungicide use, applying product before he can see any disease show up in the crop.

“The scout and spray method just doesn’t seem to work as well,” he says. “By the time you see any disease, there’s so much that already happened in the plant that you’re over the curve.”

Eitmann says he is particularly concerned about tar spot this year, as the disease is moving into his area. Here’s a look at where tar spot and southern rust were confirmed in the U.S. during the 2024 season. The northern reach of the latter was particularly surprising to the plant science community last year.

Tar spot is on the move in the U.S. The map shows confirmed locations for the disease during the 2024 growing season.

(ipmPIPE)

Southern rust surprised a lot of agronomists and farmers by how far it spread in the northern Midwest during 2024.

(ipm PIPE)

Eitmann says he saw corn crops in his area last year that weren’t treated soon enough for tar spot, and the yield outcomes were affected significantly.

“Some guys [held off] using a fungicide because of the commodity prices and emotion. They were like, ‘No, we’re not going to spend any more money.’ It looked to me like that decision cost them 40 to 50 bushels an acre – maybe more,” Eitmann recalls.

Address Environmental Stressors
Kim Tutor, a technical marketing manager with BASF, says using a preventive application of a premium quality fungicide helps with environmental stress mitigation and optimizes growth efficiency.

A proactive application keeps stomatal conductance working efficiently in corn plants. Essentially, stomates function like small vents on the leaf surface of corn plants, helping with respiration and photosynthesis.

Along with stress reduction, a foliar fungicide application can address diseases in the latent stage of development in the plant — that period between initial infection and reproduction.

Essentially, you can’t see the disease yet with the naked eye, but it is present, invading crop tissue and producing toxins that wreak havoc inside the plant, decreasing productivity and, ultimately, yield outcomes.

Every Disease Is Different
Tutor says a latent period exists for all diseases in corn and soybean crops. Some of the latent periods for economically concerning diseases include:

• Frogeye leaf spot – 7 to 10 days

• Target spot – 8 days

• Southern rust – 7 to 10 days

• Tar spot – 14 to 20 days

The increased risk from tar spot has Eitmann trying to decide how to time his foliar applications this season to get the most residual control possible.

University of Nebraska Extension says most FRAC Group 11 QoI (formerly called strobilurins) and FRAC Group 7 SDHI fungicides are expected to provide between 21 and 28 days of protection of leaves from infection by some fungi.

“Group 3 triazoles can provide some systemic or locally systemic curative activity, but only for infections that have just occurred in recent hours or couple of days,” Extension reports. “Thus, fungicides applied a day or more after infection will not stop all lesion development and some disease development may still be observed.”

Tutor encourages growers to think through their fungicide application timing in order to maximize results for as long as possible. Here is the strategy she recommends, which includes three options, specific to BASF products:

Option 1
BASF commonly recommends farmers use a planned, preventive application of a fungicide with multiple active ingredients and a long residual – at least once per season – to protect corn and soybeans from disease before its presence can be seen on the plants.

“Generally speaking, if I take all the data I have access to and summarize it, the sweet spot for fungicide applications in corn is going to be right around VT R1,” Tutor says. “That’s going to give you the best bang for your buck in terms of a return on your investment with one application.” Tutor recommends a 7 oz. per acre application rate of Veltyma.

Option 2
For growers who have the tar spot inoculum in fields or know it’s in nearby fields, Tutor advises going with a higher product rate rather than assuming two fungicide applications are needed.

“We’re going to recommend you optimize that rate and you take Veltyma up to 10 oz. per acre, again at the VT R1 timing. “Those additional 3 oz. are going to provide a good bit more residual control, and that has the potential to carry you through the rest of the season,” she adds.

Option 3
In those areas where farmers expect heavy disease pressure this season, Tutor does advise going with a two-pass program.

“With that first application, we’re going to recommend you put your best foot forward and go out with the 7 oz. rate of Veltyma at that tassel timing. Then, follow it up a couple of weeks later at the R3 timing, again with a 7 oz. rate of Veltyma or another good product like Headline Amp at 10 or 14.4 oz. per acre.”

Evaluate Results To Determine ROI
Mike Pellett, a farmer near Atlantic, Iowa, says he routinely makes at least one foliar fungicide application in corn, as the payoff has been consistent across acres for multiple years.

“We’re big data people, and the proof is in the results that come off the field,” Pellet says. “We’ve got years and years of data that show a benefit, some years more than others, but as a whole, we definitely know it’s a better decision to spray than to not spray, and sometimes by a big amount.”

Pellett, Eitmann and Tutor discussed fungicide use as part of the BASF media program at the 2025 Commodity Classic.

Your next read: Soybean Farmer Fine-Tunes Seeding Rates For Higher Profits

Ferrie: Is Your Corn Crop Running Out of Nitrogen? Why That Matters Now

Tue, 03 Sep 2024 20:47:48 GMT

This week in the Boots In The Field podcast, Ken Ferrie addresses a variety of agronomic issues impacting late-season corn and soybeans across parts of the Midwest.

Here are three of his key takeaways:

1. Nitrogen deficiency is showing up in corn fields, and is extreme in some areas. In many cases, the N deficiencies are enough that Ferrie is able to see them from the road, as plants have yellowed all the way up to the tassels. He recommends checking fields to consider what an insufficient amount of N at this point in the season will mean to yield results.

“Plants running out of N at R4 run the risk of tip abortion,” he notes, as a for instance. “At R5, tip kernels are going to get light, and if it’s a D hybrid, it’s going to cost you in late fill.”

Reflecting on the two nitrogen-friendly years of 2022 and 2023, Ferrie notes that 2024 nitrate samples indicated farmers had lost some nitrogen and needed to replace it.

On top of that, many growers also bumped up yield goals this season, which given yield projections for this fall, that looks like it was a good decision.

“We can see now that bumping those N rates was the right thing to do,” says Ferrie, Farm Journal Field Agronomist. “The more N you had on last fall or early this spring (some of which was lost), the more we had to bump those rates.”

In some cases where farmers bumped up their N applications, they could have been pushed even higher.

“Going through R5, we could see some of these big ears wanting to tip early due to the weight of the ear and long ear shanks. The heat this week will make this even more visible,” he says.

If temperatures drop and some rain comes through for farmers, many of those affected ears will straighten back up. But if the ears tip over due to weight before black layer occurs, that will affect kernel fill and final yield results.

“Many fields have top kill in the corn plants, and it is more evident with stress,” Ferrie says. “The later it shows up, the less damage it’ll do to yield. But if we lose those top three leaves too early, it’ll lighten up the kernels on the top one-third of the ear.

“If you’re running out of nitrogen, you will become a victim of top kill,” he contends. “If you’re deep into R5, the effect will be a lot lighter on you.”

2. More variation is showing up in soybeans: Across parts of Illinois, Ferrie says he is seeing more sudden death syndrome (SDS) along with dry weather stress. The combination is impacting soybeans now in the reproductive stages and is speeding up their maturity.

“We’re seeing the early-planted beans in the drier areas showing some stress and starting to actually change color,” says Ferrie, adding that some of the stress is compaction related and some is a pH issue.

“In some of the higher pH pockets, how far along the soybeans are will play a big role in how much the stress affects the yield,” he says.

3. Pest problems and some disease issues need immediate attention:

Stink bugs: Ferrie says to be on the outlook for stink bug populations. He says to be vigilant in checking soybean seed acres.

Impacted seeds may be smaller, shriveled, and/or discolored, he notes. Damaged seeds may also produce stunted seedlings.

Tar spot: More corn growers are seeing tar spot popping up in their crop.

“Most corn I’ve been in looks like it’s going to make it the black layer, but the plants may be trashed by that time,” Ferrie says.

“Other areas seem to be somewhat clean of tar spot. I do expect that to continue to change as we’re finding tar spot in the upper portions of the plant, indicating that it’s on the move,” he adds.

Southern rust: The disease is becoming more of a problem in the Midwest this year. Temperatures that reach 80°F-plus during the day in combination with warm nights and high humidity will kick up the amount growers will see in affected crops.

Efficacy ratings for corn fungicide management of southern rust have been compiled by a working group of corn researchers and can be found here: Fungicide Efficacy for Control of Corn Foliar Diseases

You can listen to the Boots In The Field podcast for this week here: Episode 341: Boots In The Field Report

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Ferrie: Corn Is Going Into The Home Stretch, Do You Need To Make A Second Fungicide Application?

Tue, 20 Aug 2024 15:16:30 GMT

Ken Ferrie is hearing from farmers across the Midwest who are trying to decide whether to make a second fungicide application to hybrids affected by heavy disease pressure. In southern Indiana, he is seeing many fields of corn at R5 that are fighting tar spot, which is particularly concerning because of how quickly the disease can take down a corn crop.

“There, many fields have been sprayed twice, and farmers are entertaining a third application,” says Ferrie, Farm Journal Field Agronomist, based in Heyworth, Ill.

At this point in the season, Ferrie recommends corn growers scout fields with tar spot to identify where it is located on the plants. Look to see if the disease is moving around and can be found higher in the plants, and not just along the base of the stalks.

“With corn prices expected to lead with a three in the front, it does make it hard for growers to decide what to do next,” Ferrie acknowledges. “We have corn stretched out here in Illinois from R3.5 to R5, and at R5 we still have 30 days to go in this growing season.”

Another consideration farmers need to think through is how long they will need tar spot infected corn to stand in the field before harvesting it.

“Many of you guys have indicated you’re going to let corn dry in the field, and you don’t care if that takes until December,” he says. “In corn with tar spot in the midway up in the plants at R4 and with the plan to dry corn in the field, you may need to help that crop out with a second fungicide pass.”

Don’t Over-Estimate Yield Counts

2024 will go down as the year of the aphid for many growers. Some hybrids are giving up 15 to 35 bushels per acre to the pest, which is adding insult to injury by contributing to green snap.

“In some fields, aphids have caused the plants to abort one-third to all of the ear. Green snap below the ear means a complete loss, and green snap above the ears is resulting in about a third of an ear, which is probably going to go through the stripper plates,” Ferrie says.

As you do yield checks in these fields, he says to start with all the non-affected corn ears and calculate the yield on them first. Then, make a yield estimate on the poor ears, divide this number by 90, and then add that number to your unaffected ear yield estimate to arrive at your final yield estimate.

“These aphid-affected plants often have uniform stalk diameters, which can be missed when you’re checking your ear counts out there,” Ferrie cautions. “Growers who disregard poor ears and calculate the yield on good ears and use uniform plants as their ear count are going to over-estimate yields.”

Ferrie notes that the impact of aphids is worse on some hybrids than on others, but to not simply resort to pulling those hybrids out of your lineup for 2025, because many of them are high-yielding.

“We just need to be aware if aphids are an issue in certain hybrids as we plan for next season,” he says. “For now, those affected hybrids need to be watched for harvest loss this fall. Don’t let them get through the stripper plate, and get as much corn off aborted tips as possible,” he adds.

Listen here for this week’s complete Boots In The Field podcast: https://www.croptechinc.com/bifr-8-19-2024/