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Central Iowa Crop Update
Updates from an agronomist and weed nerd in central Iowa.
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In this issue:
- May 25 - Conservation on Tap, Waukee
- Weather forecast and planting considerations
- Insect round-up
- Soybean aphid fields for summer research - please help!
- Handy weather websites
- Check alfalfa stands
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May 25 - Conservation on Tap, Waukee
Iowa Learning Farms is hosting two Conservation on Tap events, including one at Kinship Brewing in Waukee, IA. Join Iowa Learning Farms, ISU Cropping Systems Agronomist Mark Licht, and Kinship Brewing Company Owner Zach Dobeck from 6-7pm on May 25. This informal meeting will be an opportunity for farmers, landowners, and interested Iowans to discuss conservation practices and ask questions. Learn more from the flyer and press release for this event.
Please RSVP by May 18 to 515-294-5429 or ilf@iastate.edu to ensure adequate food and space.
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Weather forecast and planting considerations
I'm sure all of our patience is wearing thin with this weather. The NOAA Climate Prediction Center has updated outlooks with continued above normal chance for rainfall through at least the next couple weeks. If you're keeping track, April 2022 went down as one of the top 10 coldest Aprils on record. Since April 1, we are running about 50-60% of average for growing degree day (GDD) accumulation. BRR. And in the last two weeks or so, parts of central Iowa are running nearly 200% of normal for rainfall.
Getting in the field has been slow going this year so far. Planter setup is going to be critical to setting the environment our seeds see in the field. Especially in wetter soil conditions, sidewall smearing and general compaction will take a toll on developing plants. This is exacerbated when we dry out after planting and can take the form of restricted root growth, "tomahawk" roots, and ultimately, crop yield loss. When you do get in the field, don't skip the important checks to make sure the seed is planted at the right depth and in good soil conditions.
Our optimum planting window is when soil and moisture conditions are correct in the spring, but yield potential for corn begins to drop off after mid-May. The optimum window for soybean planting is similar and yield begins to drop off after approximately May 20 in Iowa. Read this article from last spring for more information on planting date and yield.
If you've already planted, you'll want to be keeping an eye out for emergence when temperatures warm up over the next 7-10 days. If you planted corn in the April 10-12 timeframe, your crop should be emerging soon. Mark Licht wrote some thoughts on checking for emergence in a blog this week. The cool, wet conditions we've had also increases the risk for pest issues. Check out these blogs on soil-borne diseases and seed/seedling pest issues.
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Insect round-up
Moths are on the move in Iowa, but it seems like numbers in central Iowa remain fairly low. The black cutworm and true armyworm trapping network report from April 17 to 23 noted a couple significant flights of black cutworms but not in the central Iowa area. I have caught just a few of each moth in my traps in Polk County.
Check out the new Pest Forecasting page on the Iowa Environmental Mesonet Website! Ashley Dean worked with Daryl Herzmann to develop an interactive webpage to follow the GDD accumulation for different spring pests in Iowa. Access the webpage here and the article describing how to use the page here.
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Soybean aphid fields for summer research - please help!
ISU Extension Entomologist Erin Hodgson is wanting to survey Iowa aphid populations for insecticide resistance this summer. Ideally, she would come collect aphids before an insecticide application happens and would also like to come back and sample after an application happens (if it does).
It seems like aphids are a hit-or-miss issue in central Iowa, but if you are willing to participate by letting her team come sample prior to an insecticide application, please send me your cell phone number so I can reach out when we start to see soybean aphids!
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Handy weather websites
My colleague Joel DeJong worked with several 'weather gurus' (Daryl Herzmann, Justin Glisan, Dennis Todey) to write a blog that has some great weather-related websites that you might find useful. Check out the article here! It has information on where to find 4" soil temperatures, precipitation data, wind speed & direction forecasts, soil moisture information, and weather outlooks. Bookmark that blog to reference as you need!
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Check alfalfa stands
Alfalfa stands may be in tough shape this spring after the fall armyworm outbreak last fall, winter, and cool, wet conditions this spring. As alfalfa has been green for a few weeks now, take a moment to evaluate your stands for winter injury and see if the stand is valuable enough to keep for another year.
If you don't have a sweep net, it is a worthwhile investment to check stands for pests like alfalfa weevil. It may be difficult to sample alfalfa weevil this spring due to especially short stands, so Ashley Dean and Rebecca Vittetoe wrote some tips on this in a recent ICM Blog linked below.
- Check out this video on sweep net technique for soybean and alfalfa scouting!
- Alfalfa weevil resources:
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