News Story

Agronomy Notes for the week ending June 10, 2017

Brian Weller, Lead Agronomist

The weather during the week was warm with several days in the 90°F’s, the high temperatures were also coupled with generally southerly winds, which caused most fields to dry rapidly and plants in lighter soil types showing drought stress. Issues that arose during the week were Armyworms found in fields with a grass cover crop, (in previous years we have found Army-worms on June 9th, this year we found them on June 6th) Black Cutworms found in high organic matter soils, and or soils that had manure applied, with manure that had straw or wood shavings showing more problems than other types.

Other issues that arose were, continued emergence issues for later planted corn and soybeans, Rootless Corn Syndrome, mainly with later planted corn. It is my believe that most of these issues will be of a concern later in the growing season. The southerly winds maybe more of an issue first, in that they bring us more insect and disease pressure. In my experience, it is more probable to have an insects issue, followed by a disease concern, than to have a disease concern followed by insects.

Soil temperatures at the 2” depth ranged from 66-90°F, and the 4” depth ranging from 68-84°F, with soil temperatures at the 8” depth ranging 67-77°F.


Soil Temperature




78° F



76° F







Soil Temperatures at the 20” depth were in the mid to upper 60°F’s, while soil temperatures at the 40” depth were in the mid to upper 50°F’s. (Soil temperature information is from both Central Farm Service and U of MN SROC in Waseca data.)

            Soil temperatures at the 8” depth this year, seemed to have fluctuated more than in previous years. At the 8” depth we typically see soil temperatures in 50°F’s roughly around April 25th, with 60°F’s around May 15th, and once temperatures hit these marks they tend to stay there and increase. This year we hit 50°F around April 15th but the temperature moved back and forth in the 40°F’s until May 4th. We hit the 60°F around May 9th but again fluctuated back into the 50°F’s until May 28th.

            By coupling a cooler soil temperature with a wetter environment, we normally see plant and root growth hindrance. If you place compaction in this mix whether it was from last fall or this spring, you further restrict root growth. I have seen more issues this growing season related to compaction issues than I have for the last few years. Which when you look at how wet we were during harvest and this spring makes sense. The take home from this information is regardless what nutrients we have placed in our soil, if the roots cannot intercept the nutrients, or the water that is moving them, odds are you are going to need a change in plan for the plants to have adequate nutrients to produce a 220-260 bu/acre corn crop this year. By taking a tissue sample or a Nitrate sample, you are measuring where your levels are at. By measuring where you are at, you are better able to manage what you have.

Corn plant development is from V1-V2 for corn planted early June, to V6 for corn planted in mid-April.

Planting Date


Growth Stage

Growth Stage

Plant Height



Collar on Sixth Leaf





Collar on Fifth Leaf





Collar on Fifth Leaf





Collar on Fourth Leaf





Collar on First or Second Leaf




We picked up 145 Growing Degree Units (GDU’S) during the week which is 32 GDU’s more the 30-year average. We averaged 20.71 GDU’s/day which is 4.57 GDU’s more than the 30-year average.


2017 GDU Average/Day

30 Year GDU Average/Day


June 4-10




June 1-10





2017 GDU

30 Year GDU Average


June 4-10




June 1-10





For the time frame of June 1-10th we have accumulated 206 GDU’s which is 52 GDU’s more than the average. Breaking it down further we averaged 20.6 GDU’s/day which is 5.2 GDU’s more than the 30-year average.

Corn plants grew rapidly during the week with some plants putting on 2 collars or growth stages and in some cases doubling in height. We did have corn plants that put on an inch of growth per day during the week, I couldn’t hear it grow but I could see it.

Some early planted narrow row corn (20-22”) with fast emerging hybrids reached canopy during the week. By reaching canopy faster these plants normally have better water and light utilization. We typically see 30” rows with the same hybrid and same planting date reach canopy 5-10 after narrow rows with the same hybrid.

Soybean plant development ranges from Germination and Emergence for beans planted in early June to V2-V3 (Second to Third Trifoliate) for beans planted in late April.

Planting Date

Plant Stage

Growth Stage

Plant Height


Second Trifoliate to Third Trifoliate




Second Trifoliate




Emergence to First Trifoliate




Germination to Emergence




Text Box: Nodules           

Lateral roots on soybeans at the V2-V3 growth stage are 4-6” across (as shown above and on the right), and by the V5-V6 growth stage, roots will grow across a 30” row.

 Nodules may form on the root system as early as V1 (first trifoliate) but will not start fix nitrogen until the beans hit V2. If you cut nodules and they are pink to red in color, they are actively fixing nitrogen, if the nodules are brown, green or white when you cut them, they are not actively fixing nitrogen.

Soybean plants will not produce nitrogen fixing nodules or will greatly reduce the number of nodules if there is excess nitrogen near the root system, or if the soil has experienced drought or water logged conditions prior to planting or the previous year. In either instance the soil bacteria will not support nodule formulation and a soybean inoculant will need to be added to help “rejuvenate” the population of bacteria that helps promote nitrogen producing nodules.

In the last few years I have seen more nodules on plants in fields that were sampled with NitrateNow for the corn crop the preceding year. I have also seen bean yields increase more on these fields that have had NitrateNow done on their corn crop. My conclusion is that by more actively managing the Nitrogen we have in our soils for our corn crop, our soybean crop is better able to produce more and better nodules, and subsequently, more yield.

Upcoming Events:

  • Central Advantage Field Technology Days September 6-7 Farm America Waseca


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