Nutrients and Damage Agronomic Insights for Northeast Iowa May 16th, 2025
Well, we got the rain we needed to incorporate the herbicide and nitrogen that was applied the previous 2 weeks, and to get to germinate. Now a little cool down before we warm back up. This crop should really start to take off now with the current moisture and warmer temps coming next week.
Uneven Emergence
The corn and beans planted a couple weeks ago are emerging nicely for the most part. Some fields are a little uneven with seed that laid in dry soil. I did come across some corn this week that was coming unevenly, some was up one leaf already, but some had just begun to germinate. Some of the seed was laying in dry soil, I believe in this case due to uneven, cloddy soil, and planter units bouncing too much. Typically, we say if a corn plant is more than one leaf stage behind it is a weed, meaning that it will be a runt and have a hard time competing with its neighboring plants.
Sulfur Deficiency
It is not hard to find sulfur deficiency in young corn plants, especially in corn-on-corn situations or on lighter, low organic matter soils. The deficiency shows up as striping on the young plants on the newest leaves. Cool soils don’t mineralize sulfur as quickly, so we may see this go away as the soils warm up, if sufficient sulfur is present. We recommend applying gypsum in the fall, and/or using ATS with your 32% or AMS with Urea. Corn needs around 20-25 units sulfur for maximum yields.
Hail Damage
There was some hail Monday night further north, and some crops got damaged. Corn will just have some leaf damage as the growing point is well underground yet. But beans have all their growing points above ground. As long as one growing point remains, a bean can survive. I have seen frozen, hailed, or animal damaged beans come back well. The picture shows a bean plant that was cut off above the cotyledons, but each growing point is shooting a new branch.
Fungicide “Halo effect”
If you had soybeans treated with Ilevo for SDS and SCN this year, you may be noticing some “halo effect”. This is when the fungicide is taken into the seed, and shows some burn-like symptoms on the cotyledons and young roots. Saltro seed treatment doesn’t affect beans like that. You can see the comparison in the picture with Saltro on the left and llevo on the right .. Sometimes Authority or Valor herbicides applied pre emerge can make this llevo “burn” worse.
As always, reach out to me with questions or concerns you have or come across out in your fields. Everyone, Stay Safe! Connect with your agronomist >
Northeast Iowa Heat Units Accumulated
April 14 Plant Date: 322 (+9 to 30-year average)
May 7 Plant Date: 181 (+17 to 30-year average)
*It takes roughly 75 heat units for corn to sprout, and approximately 125 for emergence, so it was no surprise to see May planted corn emerging in a week.
Northeast Iowa Rainfall Data
April 2025: 4.8″ | 30-year average 4.2″ |
May 2025: 2.7″ | 30-year average 4.8″ |
