ASK THE AGRONOMIST BLOG

Japanese beetles are out in full force in crop production areas across the U.S. These small, metallic-green flying pests are problematic to corn and soybean growers, especially during pollination. And where there’s one, there are many. Here’s what we know about Japanese beetles — from their introduction to the U.S. to their features, vegetation preferences, patterns and best management strategies to combat them in the growing season.

1. They’ve been around for over a century. According to Iowa State University Extension and Outreach, Japanese beetles were first introduced to the U.S. in 1916 in New Jersey and have since moved westward.
2. They travel in packs. Japanese beetles come with friends. When feeding, they emit a pheromone that attracts hordes of other beetles. Growers may notice a group of beetles clustered together feeding on the vegetation of a plant.
3. They’re colorful and nimble. Adult Japanese beetles have a metallic-green head and shiny copper-colored wings. They are known to be excellent flyers, easily traveling from field to field as adults.
4. They overwinter in the soil. The beetles overwinter in the soil as grubs and start their path to emergence once spring soils have reached 50 degrees Fahrenheit. Their emergence starts south to north. For example, growers in the Midwest might notice their emergence as adults in late June and early July.
5. They prefer soybeans to corn, but both play host. Japanese beetles chew on foliage, including soybean leaves and some corn leaves. Experts say they prefer soybeans to corn. In soybeans, they feed on plant leaves, typically in the upper canopy, and cause skeletonization of the leaves. Essentially, they eat the tissue between the leaf veins forming heavy defoliation in fields. In corn, they typically eat silks. Unfortunately, silk clipping can lead to pollination issues and negatively impact grain fill. Adults may also feed on the grain.
6. Scouting is key. Japanese beetles are mostly found on the outside parameters of fields, but it’s important to check whole fields for their presence. There are Japanese beetle traps available that use a combination of pheromones and floral scents to attract the hordes, but scouting different regions of both corn and soybean fields is also an effective way to check thresholds. In soybeans, our experts recommend gathering 10 to 15 trifoliates from random plants, working your way from the bottom to the top of the plant, then repeating the process in three to four different areas of the field. In corn, Purdue Extension recommends checking five plants at random in five different areas of the field to record numbers of beetles found on each plant. Then, check the length of the silks on each plant and if pollen is still shedding from each plant.
7. Threshold calculations from scouting can help determine next steps. Iowa State University Extension recommends that treatment in soybeans be considered if 30% of the leaf is skeletonized before bloom and 20% defoliation after bloom. For corn, foliar insecticide should be considered at tasseling and silking if three or more beetles can be found per ear, if the beetles have clipped silks to less than half an inch in size, if pollination has not yet reached 50% complete or if three or more beetles are present per ear.

If you’ve reached these thresholds, our experts recommend applying a Lorsban-type insecticide over the canopy of affected corn and soybean fields. This will help control populations and further damage to the plants by the pests. 

To learn more about signs of Japanese beetles and how to protect your fields, contact your local Stine representative or university extension office.

This week’s crop progress report from the National Agricultural Statistics Service reports that of the 18 states that planted 92% of the 2021 corn acreage, 37% have corn at the silking stage and 6% at the dough stage. The corn crop is still looking strong for many growers, with 13% in excellent, 51% in good, 25% in fair and only 8% in poor and 3% in very poor condition. For soybeans, 48% are blooming and 14% are setting pods. Soybeans are also on the fair-to-good side, with 10% as excellent, 51% as good, 29% fair, 7% poor and 3% very poor condition. We have more reports coming in from our Stine^® regional sales agronomists (RSA) this week.

Dustin Ellis, Stine Region 4 RSA, central Iowa
“Just in the last few days, a large percentage of our Stine corn has started to tassel and, in most of my area, we had some timely rains ahead of it. The corn is looking really good and healthy. Virtually no disease is present in our corn this year. We have been very pleased with the emergence and stand counts from our new MX Series Corn by Stine lineup and the overall health of our products.   

“The Enlist chemical program is again doing an excellent job of controlling those hard-to-tackle weeds. One thing we need to remember is that even though the Enlist chemicals are working so well, we cannot start cutting back on our pre-emerge and post-emerge residual products. In order for this technology to stay strong for years to come, we have to continue using full rates and timely applications.    

“We are on track again for a great fall with some excellent yields on both Stine corn and soybeans.”  

Tony Pleggenkuhle, Stine Region 10 RSA, southeast and south-central Minnesota, northeast and north-central Iowa
“In Region 10, soybeans are currently in the R1/R2 stage. Corn started tasseling last week with some pollen being thrown this week. Soil moisture is adequate for most of the region with a few areas starting to experience some moisture stress. Chlorosis was prevalent this year in some areas due to wet planting conditions, but soybeans in these areas are beginning to develop a large enough root mass at this point to start pulling out of it. We have quite a bit of phytophthora showing up in these wetter-planted areas as well. 

“Preventive fungicide applications to combat tar spot have begun in the eastern part of the region. I haven't been called to view as many dicamba volatility-cupped soybean fields as last year, but I'm still seeing some cupping in fields bordered by Xtend soybeans and cornfields sprayed with dicamba-based products. Fortunately, the cupping hasn't persisted for as long as in prior years due to the excellent growing conditions in most of the region supported by adequate rainfall. Some rootworm larvae are present in cornfields as of last week. Rootworm feeding hasn't progressed to more than 1/2 node of damage to date. Japanese beetles are present in high numbers in a lot of fields, and I've also come across some surprisingly high aphid counts in southeast Minnesota.”

Brian Burnell, Region 16, northern and central Indiana
“Crop conditions have been all over the board this growing season and currently are no different in Region 16 in the northern half of Indiana. In my travels, I have seen beautiful tasseling corn and I have seen some weak-looking corn barely knee high. Sometimes just miles from each other. We had been in a bad dry stretch for most of the region until a week or two ago when many areas got some much-needed rains for both corn and soybean crops. We will need a lot of timely rains for some later-planted corn and soybeans to catch up. MX Series Corn by Stine seems to be living up to the hype and looks great so far. And clean Enlist soybean fields are a great sight this summer considering how tough it was to get in some of the crop this year.”

Kevin Ryan, Stine Region 14 RSA, the mid-South
"We’ve had a lot of heat stress the last 30 days in Region 14. It’s been in the upper 90s and into the 100s every day. What’s surprising (in a good way) is that the cornfields have had pretty good grain fill. We’ve had good pollination, and grain fill continues to move along. Our hybrids look great, especially Stine 9817 and 9816.

"On the soybean side, we’re experiencing what looks like a lot of dicamba volatilization. It looks pretty widespread across the states in the mid-South, and it has really started to show up in the last week. The heat stress doesn’t help either. We recommend growers keep a close eye out for it. We’re running tests to confirm it’s dicamba. Stine growers can reach out to their local rep to help with testing as needed."

Paige Harris, Region 15 RSA, Michigan, New York
“As we approach mid-growing season, most corn has started tasseling and the soybeans have flowered. Most of the region is facing drought issues. There are a few pockets that have gotten an adequate amount of rain. With the drought, we will wait to see what happens to the corn as it is in a vital stage. Most of the region looked great when it was planted, so if we receive the rain soon, we should look forward to a good crop.”

Tanna Parrish, Stine Region 29 RSA, Georgia, Florida, Mississippi, Alabama
“It has been a challenging growing season. We’ve had little to no rain most of this summer. Some areas didn’t have any rainfall from April 2 until July 10, with record-setting heat on top of that. We have some corn being harvested now in north Florida and some silage throughout my region. We have some soybeans being shipped to south Georgia today to be planted after silage. Farming doesn’t ever seem to stop in the South! The positive we can take from this year so far is seeing how our products can handle such hot and dry climates. Luckily, our hybrids look to be able to handle these environments even when stressed to the max. Always try and find the good in difficult situations.”

To learn more about crop conditions in your region, contact your local Stine independent sales rep.

We’re well into the growing season, so it’s time for our annual crop progress update. According to the latest Crop Progress Report from National Agricultural Statistics Service (NASS), some of the nation’s corn crop is already silking. Current corn crop conditions include 3% very poor, 7% poor, 26% fair, 52% good and 12% excellent condition. Soybeans are beginning to reach blooming stage and are in good to fair condition. The NASS report indicates that 2% are listed in very poor, 7% poor, 29% fair, 52% good and 10% excellent condition. Here’s what our regional sales agronomists (RSA) are reporting from their territories.

Bethany Oland, Stine Region 7 RSA, northeast South Dakota
“Overall, crops in Region 7 look great. On the corn side, Stine 9320-20 has really stood out this year from emergence to mid-season plant health. We’ve had a few weather events throughout the region that have brought high winds and hail. MX442-20 and MX514-20 from our MX Series Corn by Stine line have stood out among competitor hybrids by handling the rough weather incredibly well.

"Soybeans across the region look great as well. It’s very clear that Stine’s breeding program is doing its job, as the EC and EE generations are standing out among previous generations.” 

Aaron Stockton, Stine Region 9 RSA, northern Texas, Oklahoma, southeast Kansas and southwest Missouri
“Portions of Region 9 have been dealing with weather extremes from when the first planter hit the field until now. Growers were able to get 90% of their corn planted and have all but finished with soybean planting at this point. We still have a few acres of double crop soybeans to go in but are ahead of schedule. The corn crop has been struggling in many places due to very hot, dry weather since the first of June. Some acres have already been slated for silage and many more are following suit. Soybeans look good for those that have received some moisture, but we could use some area-wide precipitation to get the rest back on track. In summer, southern Kansas and Missouri are typically hot and dry, but we are all praying for a break!” 

Kevin Krabel, Stine Region 13 RSA, central Illinois
“We are pretty much done with planting in Region 13. There are a few double crop soybeans being planted, but it’s the last of those acres. We had an extremely hot and dry June in most of my region, with most of the area north of I-70 getting almost no rain.. South of the interstate experienced more timely rains so pretty much everything down there looks good. I’m most concerned with the northern half of my region right now. Although we’ve had some good rains spread out over the past two weeks that have kept us from having a disaster on our hands, we need the rains to keep coming. If that happens, we’ll be in good shape.”

Ted Olson, Stine Region 19 RSA, northeast Missouri and southwest Illinois
“Some good rain showers have moved across Region 19 in the past week. This was welcomed greatly by the eastern side of the region, which had been on the moderate drought monitor. Despite the lack of moisture, corn and soybeans are in good shape. With wheat harvest done, growers are moving into fungicide application. The 10-day forecast looks favorable for pollination and has us excited for what this year’s crop will bring.”  

To learn more about crop conditions in your region, contact your local Stine independent sales rep.