Go Time?...Not so Fast
It typically takes 100 to 120 Growing Degree Days (GDDs) to accumulate from planting for corn to emerge. When we calculate GDDs early in the season, we should look at the soil temperatures rather than the air temperatures. The warmer the soils, the more GDDs we accumulate, and the faster emergence occurs. Current average soil temperatures around the state are around 50 F.
While the rule of thumb to start planting is that soil temperatures should be 50 F at the 4-inch depth and warming before we start planting, we also need to consider the conditions after planting.
How long until corn emerges - Soil temps in the 40s = ~3 weeks to emerge
- Soil temps in the 50s = ~2 weeks to emerge
- Soil temps in the 60s = ~1 week to emerge
The longer emergence takes, the risk for stand loss due to early season insect pests or seedling diseases increases. Additionally, crops in cold soils are more prone to cold injury while imbibing water and during early growth.
The short-term forecasts are showing the cooler conditions persisting for the next several days, with especially cold temperatures early this week.
Continue to be patient and wait for soil conditions to become ideal for planting. We are still within the optimum planting window for corn (April 11 to May 18) and soybeans (April 11 to May 20). The quicker germination and emergence occur, the more uniform and vigorous stands will be. | | Cover Crop Termination Challenges with the Cooler Temperatures
The cool temperatures we've been experiencing have been less than ideal for terminating cover crops like cereal rye this spring. While the cover crops continue to grow with these cooler temperatures, the activity of herbicides is reduced.
Glyphosate effectiveness made during less than optimum conditions is affected by many factors. In this field the sprayer tracks reduced rye control when applied during cool temperatures.
It is generally recommended to avoid applications when nighttime temperatures fall below 40 F, and we prefer temperatures at application to be at least in the mid-50s with clear skies. Read more on this topic in the ICM News article "To terminate or not to terminate?". ISU generally recommends terminating a rye cover crop with a herbicide 10 -14 days prior to planting corn to protect yield; however, that time frame is less critical for soybeans.
With the current weather conditions, the recommended 10-14 day window from terminating a rye cover crop to planting corn will likely either be narrowed or some may plant corn into the living cover crop and then terminate it (aka plant green). See the ICM Blog "Corn after a Cereal Rye Cover Crop in 2021" for some suggestions on how to minimize potential issues if planting green or sooner than the recommend 10 to 14 day window.
If you are considering or planning on planting green, I'd also recommend checking out the ICM Blog "Does planting green into a rye cover crop affect corn growth and yield?".
Finally, check with your crop insurance agent for any specific cover crop requirements that they may have prior to planting corn or soybeans. | | Check Alfalfa Stands for Winter Injury
While it seems like most of the alfalfa fields I've looked at are greening up quite nicely, there have been a few reports of winter injury in alfalfa. Now is the time to check alfalfa or other forage stands for any potential winter injury and determine if any action is warranted. See the ICM Blog "Check alfalfa stands for winter injury" for more information. | | Alfalfa Weevils Are Active Now
We recommend starting to scout for alfalfa weevils once we reach 200 Growing Degree Days (GDD) (base 48, from Jan. 1) on south-facing slopes south of I-80 and at 250 GDD on south-facing slopes north of I-80. You can monitor GDD (base 48) progress here.
We've reached the 200 GDD south of I-80, and I can confirm that weevils are active. Peak larval activity occurs around 574 GDD and they quit feeding around 900 GDD.
Adult alfalfa weevil found in an alfalfa field in Washington County on April 14, 2021.
Alfalfa weevil larvae feeding on an alfalfa plant. Mature alfalfa weevil larvae have a dark head and pale green body with a white stripe down the back. Photo taken May 2020.
The quickest and easiest way to initially scout for alfalfa weevil is to use a sweep net to survey the field. If you see some alfalfa weevils in the net, additional scouting details, thresholds, pictures and more can be found in the ICM News article "Alfalfa Weevils Active throughout Southern Iowa". | | Spring Forage Management - Fertilization and Weed Control
Pasture and forage stands have really started to green-up. Check out the ICM News article "Spring Forage Management Considerations" for tips on nutrient management and weed control to help make the most out of pasture and forage stands this year.
Also, I get questions about controlling summer annual grasses, like foxtail, in forages. The University of Nebraska recently published this article, "Controlling Summer Annual Grasses in Forages" that provides some good thoughts and considerations for managing annual grass weeds in alfalfa or an alfalfa-grass mix. | | Carbon Markets/Carbon Credits
Carbon markets/carbon credits have been getting a lot of attention recently, and this is an area I've received a lot of questions about. I wanted to share the article "How to approach carbon market opportunities" that the University of Minnesota put together.
The article includes a nice general discussion on carbon markets, what they can offer producers, and also what questions you should consider if you are looking into carbon credits. | | Join us for coffee and donuts at one of our upcoming field days looking at integrating annual forages for for either grazing or for using as stored feed. Wednesday, April 28 I 7:30 - 9 AM Jack Smith's Farm
26129 Tivoli Lane. Epworth, IA
Monday, May 3 I 7:30 - 9 AM
Bill Swanson's Farm
6077 100th St., Ottumwa
Tuesday, May 4 I 7:30 - 9 AM
Amana Farms
1 mile N of Main Amana on Hwy 151 More information found here. RSVP with your preferred location by emailing beefcenter@iastate.edu or by calling 515-294-2333.
| | May 18, June 15, July 13,
Aug. 10, and Sept. 14 5:30 to 7 PM Sessions will be held at various locations in Jones County Agronomy in the Field is a multi-session hands-on workshop for women designed to provide opportunities to learn more about forage and crop production practices, conservation practices and water quality impacts to help strengthen decision-making on the farm and to increase the comfort level when talking to landowners, tenants, ag retailers, and farming partners. Registration: $75 registration fee (includes all materials and resources). To register or for more information, please contact me at rka8@iastate.edu or by calling 319-653-4811. Note: Locations will vary but will be held in fields in Jones County. An email will be sent to those that register prior to each session with location information. | | |
June 3rd, 2021 I 8:30 - 9:30 AM
Join us for a virtual field day and forage plot tour highlighting our annual forage research where we will share data looking at different cool-season annual forage species, forage nutritional value, and yield potential.
How to participate: - Register at www.aep.iastate.edu/forage.
- Once you register, you'll receive a confirmation email with the link to join the virtual field day.
- Open to the public and no cost to participate, but pre-registration is required.
- If you aren't able to join us LIVE, the field day will be recorded and posted on the Iowa Beef Center's YouTube Channel.
Questions? Funding for this project provide by the Iowa Nutrient Research Center. | | Save the Dates! Virtual ISU Research Farms Spring Field Day Series June 7-11, 2021 I 8-9 AM (different topic each day) More to come soon! Southeast Research Farm Summer Workshop and CCA Training June 16 I 8 AM - NOON More to come soon! | | | | | |
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