Now the month of May has arrived and not much has changed weather-wise in the last week or two. Wet and cool conditions existed in the Sacramento area and in the state of Arkansas during the late winter/early spring time frames as harbingers of what we would expect to happen here during our spring. So far cool and wet have been the rule. I have not seen the NASS figures yet which give the planted percentages by state for the week. Seven days ago the estimates for the % planted in Iowa were at 21% with most of Northern Iowa and points north as 6 to 8% completed.
The operators who are sitting on the sidelines are feeling good about having a portion of their acres in the ground but wondering when the ground might warm up so the plants can start growing. Having so many days where the daily high temps in the high 40s or low 50s sure slow down the GDU accumulation. A week from now the farmers who will have had seed in the ground for three weeks or so will be checking the status of their small, unemerged seedlings to see if they remain green and healthy or if and seedling rots have become problems.
I was out in Nebraska for a few days last week. In much of the state growers are waiting for the ground to dry so they can plant. SW of Lincoln conditions are so dry the people are running their pivots to wet the ground enough to get the seeds to germinate.
Hybrid Maturity Choices
Looking at the calendar and recognizing that weekend rains arrived by Monday morning, that addition showers are expected to be passing thru the state thru Thursday, and that the ground will have to dry sufficiently before the planters can start running again, getting much of the seed corn in the ground by the May 10th deadline may not be accomplished. This is the case across tens of millions of acres across the entire Cornbelt. So far the markets have not wanted to correlate these delays to any reduction in yield because the larger planters and RTK allow so many acres to be planted in a long houred day or week.
For the seed dealers and companies who have spent two to three months on logistics getting the right seed in place, facing the prospect of having to redo a portion of the delivery process to reallocate and move seed supplies due to delayed planting is not something they want to do. Thus we see new pieces of advice become available for corn growers to use if their actual planting dates are two or three weeks later than planned. A good one that is available is from the Midwest Regional Climate Center at ISU. The information is available as U2U corn GDU Tool and was written by the team of Licht, Baum and Arahontoulis in Ames. The one thing that needs to be clarified if you begin using it is to clarify if the GDU figures on the seed bag tag refer to the date of planting or date of emergence.
In most cases the best corn yield results have been when the corn grower continued to plant their regular mix of early vs medium vs full season hybrids thru May 15th to 18th. After that time planting the very full season hybrids risks having much wetter grain at harvest could become a problem. Through experience it has become apparent that the GDU calculations can lie in that they do not take into account the hours of heat that can accumulate.
It might be good to recognize the trend so far seems to be for cooler than normal and expected temperatures, thus fewer total hours of heat. Any move to a package of five day earlier RM hybrids needs to recognize the need to still choose hybrids adapted to your expected disease challenges and the drying capacity of your grain handling system.
Field Scouting
As the corn already planted emerges or should have emerged there could well be fields where the stands appear thin. Cool and wet conditions can lead to problems with seedlings being affected by leafing out or emergence problems where ‘amide’ herbicides were used. In the past some of the most severe twisting or leafing out problems appeared the problems were attributed to cloddy soils with the light penetrating deeper than normal into the soil and the soil surfaced was compacted.
In one published Purdue IPM article the topic of what side of the kernel was pointing up as it was dropped into the seed trench was discussed. Germ side up was preferred as it allowed the hypocotyls to have the shortest distance to the soil surface.
Nitrogen Plans
In this year of guerrilla farming where the optimum planting windows appear quickly and for short time periods, the regular nitrogen application plan may need to be adjusted as to form of nitrogen material, method and timing. The use of a good stabilizer should also show great value. Having the ability to apply any liquid or dry into taller plants could also be valuable in a year where one needs to get the field planted as early as possible to start accumulating GDUs.
Corn and Soybean Insects
Based on black light trap catches in a number of surrounding states there were significant moth catches during mid to late April north even into N Iowa and S Minnesota. The moths are commonly attracted to fields where green cover crops covered the ground. It is when the cover crops are sprayed and killed after the eggs have been laid and the small corn plants offer the best choice of diet that measurable damage can be done. Be scouting for those larvae if your fields may have attracted moths during those days with SW winds.
As to insects affecting soybeans be aware the SB aphid eggs laid on buckthorn trees/shrubs in S Dakota and W Minnesota typically hatch as 150 GDUs based 50 accumulate. While that is the rule, the zone 3 winter temps experienced this past winter should have killed a high % of those eggs.
On Alfalfa
Due to the high demand for quality alfalfa, coupled with frequent winterkill and ice sheeting problems on established stands, hay producers stand to make good money where they can monitor and manage their crop acres using BMPs. Applying enough calcium, sulfur and micros are the top priority in the fertility program as are detecting and controlling alfalfa weevils. Further south as in Kansas and Missouri the weevil larvae had hatched and were starting their feeding one to two weeks ago. Growers in N Nebraska and S Iowa should be looking for those hungry green larvae as they feed on the soft tissue in the wrapped up leaves at the top of the plants. It is easy to shake the upside down plants over a while piece of paper to assess the population and take action if the larvae reach the published thresholds.
May the sunshine and soils warm for you this week and finish the field work needing to get done.
Bob Streit is an independent crop consultant and columnist for Farm News. He can be reached at (515) 709-0143 or www.CentralIowaAg.com.