Much has transpired since the last Agronomy Notes, Corn has put on 4-5 collars and is approaching V8 for a mid-April planting date and is 19” tall at that collar with total plant height knee high or 24-25” tall. Some of the early planted soybeans have put on 3-4 growth stages and are almost 8” tall with some of the replanted soybeans still poking through.
Corn plant development is from V4 on corn planted in early May to almost V8 for corn planted in mid-April. We are still seeing signs of slow emergence from the spring, either from slightly less than ideal planting conditions in certain areas of the field, poor seed to soil contact as well as germination differences within hybrids.
| 30-May | Planting Date | GDU’S | Plant Stage | Growth Stage | Plant Height |
| 15-Apr | 396 | Collar on Fourth Leaf | V4 | 5″ | |
| 23-Apr | 348 | Collar on Third Leaf | V3-V4 | 3-4″ | |
| 30-Apr | 314 | Collar on Third Leaf | V3 | 3″ | |
| 08-May | 216.5 | Collar on Second Leaf | V2 | 1.5-2″ | |
| 06-Jun | Planting Date | GDU’S | Plant Stage | Growth Stage | Plant Height |
| 15-Apr | 497 | Collar on Fifth Leaf | V5-V6 | 8-9″ | |
| 23-Apr | 449 | Collar on Fourth to Fifth Leaf | V4-V5 | 5-7″ | |
| 30-Apr | 415 | Collar on Fourth Leaf | V4 | 5″ | |
| 08-May | 317.5 | Collar on Third Leaf | V3 | 3″ | |
| 13-Jun | Planting Date | GDU’S | Plant Stage | Growth Stage | Plant Height |
| 15-Apr | 628 | Collar on Seventh Leaf | V7-V8 | 19″ | |
| 23-Apr | 580 | Collar on Sixth Leaf | V6-V7 | 12-14″ | |
| 30-Apr | 546 | Collar on Sixth Leaf | V6 | 10″ | |
| 08-May | 448.5 | Collar on Fourth to Fifth Leaf | V4-V5 | 5-7″ |
We have accumulated 325 Growing Degree Units (GDU’s) from May 24 to June 13, with the breakdown by week as follows:
- 93 GDU’s for the week of May 24 to May 30
- 101 GDU’s for the week of May 31 to June 6
- 131 GDU’s for the week of June 7 to June 13
The comparisons for GDU’s by day and week for this time frame is as follows:
| Dates | 2015 GDU | 30 Year GDU Average/Day | Difference/Day |
| May 24 - May 30 | 13.29 | 12.86 | 0.43 |
| May 31-June 6 | 14.43 | 14.86 | -0.43 |
| June 7- June 13 | 18.71 | 16.86 | 1.86 |
| June1-13 | 32.21 | 29.71 | 2.50 |
| Dates | 2015 GDU | 30 Year GDU Average/Week | Difference/Week |
| May 24 - May 30 | 93 | 90 | 3 |
| May 31-June 6 | 101 | 104 | -3 |
| June 7- June 13 | 131 | 118 | 13 |
| June1-13 | 225.5 | 208 | 17.5 |
With all of this data on GDU’s the take home message is that compared to a 30 year average we are very close “normal or average” on all planting dates at this point. Much can change and happen in a growing season but to say it is average or normal is a welcome relief compared to the last few years.
Once the corn plant reaches the V6 Growth stage the amount of GDU’s it takes to put on a new collar or growth stage reduces to 65-70 GDU’s.
| Growth Stage | GDU’s |
| Emergence to V6 | 85-90 |
| V6 to V14 | 65-70 |
| V14 to V18 | 55-60 |
In looking at the near future if everything stays “normal” we should be accumulating 19 GDU’s/day in the latter half of June. If we continue to have “normal” growing conditions we would be adding a collar or growth stage on the corn plants every 3-4 days.
Soybean plant development is from just emerging for some replanted soybeans to approaching V4 or 8” or more, for soybeans planted in late April.
| Planting Date | Plant Stage | Growth Stage | Plant Height |
| 28-Apr | Third to Fourth Trifoliate | V3-V4 | 8″ |
| 03-May | Third Trifoliate | V3 | 6″ |
| 10-May | Second to Third Trifoliate | V2-V3 | 3-4″ |
Harvest Progress: By in large the 1st crop of Alfalfa has been harvested and I started see trucks coming up from Iowa with peas that were combined starting about June 10th.
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