Agronomic Update – September 5, 2020….how ‘low’ will temps go?…..

This should be the only ‘frost’ warning we should be seeing this time of year, and we don’t even get to experience this one….however, temps forecasted next week are too close for comfort!….2020 just keeps on giving….

Topics:

Growing Degree Day Update/Weather Update
Current Corn & Soybean Conditions….

As of September 4th, we have accumulated approximately the following for Growing Degree Days in 2020:

Planting Date GDD’s2020 Average GDD Departure from average

April 21 2610 2400 +210 (+10 days)

April 26 2557 2360 +197 (+9 days)

May 1 2506 2325 +181 (+8 days)

As you can see, we are way ‘ahead of the game’ on GDU accumulation for this year. We are 14-18 days ahead of 2019. However, a big cool down is on its way next week!

The above maps are the precipitation and temperature forecasts for the next 6-10 and 8-14 days. As one can see, we are looking at a dramatic cool down. It is amazing that we can go from 90’s to 40’s & 50’s in just two days. To put some perspective on this: this weekend and Monday will add approximately another 50-55 GDU’s to the above totals before GDU accumulation goes to zero after that for a few days. This will put us in the 2555 to 2660 range for GDU accumulation…..enough for 110 day and less, but still short 50-150 for 112 and higher depending upon hybrid and planting date. Will there be a potential for frost next week?….more on that below.

Current Corn & Soybean Conditions…..

Much of the corn crop is as follows: April 21 planting dates – 105-110 day hybrids 1/3-2/3 milk with some 3/4 milk lines – 112-118 day 1/4 to 1/3. Later planting dates are 1/4 to 1/2 for the most part. Majority of crop is 1/2 milk line.
So far staygreen in the irrigated is holding up for now, but starting to see more ears droop on the irrigated….this weekend’s heat will speed this process up. Having a good soil moisture profile will slow this process, but not stop it.
Sunlight: The last month has seen a 12% overall increase in sunlight versus normal. The last time we had this trend was 2012. In fact, sunlight this past month has been better than the same time frame in 2012. This should be a real positive to yield and late-season plant health. I can see the impact on this sunlight through the nice, dark grain color and the deep kernel depth. All of this should lead to high test weights and good grain quality.
However, the above cool temperatures will dramatically slow down crop development. What this means is most likely not as early of a harvest as we first thought. It appears that we will lose a week of growing season/crop maturing through next week’s weather. While we could sure use a rain, it will be better for grain quality (ear mold development, etc.) if we stay on the drier side through this cold front. However, due to the sunlight and extended grain fill period so far, I would expect overall grain quality to be better than the past couple of years even if conditions turned wet. An extended wet period (7-10 days of fog, drizzle, etc.) will still impact grain quality, especially if we do get a frost in this time frame.
Disease: relative humidity has been 8% below normal for the month. Last time this occurred at this time period was 2012. This has kept our disease pressure down, but increased the overall ET rates for both corn and soybeans over the past month. It is recommended that you still scout your corn fields over the next few weeks for southern rust to determine harvest priorities. This disease has continued to increase within fields over the past few weeks. If heavy enough, this disease could impact late-season plant health.
Ok, now to Frost….Current forecasts are showing low temps for Tuesday and Wednesday nights into the mid-to-upper 30’s. This is too close for comfort as even a 34 degree frost temperature can lead to leaf death in draws and bottoms. Hopefully temps won’t get this low, but if they do this will impact the above discussion on test weights and grain quality. Here is a link for more info on frost/freeze damage in corn that has not matured……https://www.agry.purdue.edu/ext/corn/news/timeless/FrostFreezeImmatureCorn.html#:~:text=Frost%20damage%20to%20immature%20corn,Maier%20%26%20Parsons%2C%201996).
Bottom line is…..whole plant death yield loss at 1/2 milk line corn is approximately 10-12%….whole plant death at 1/4 milk line is 20%….and 3/4 milk line is less than 5%. Just leaf loss would lower these numbers,…for instance, 1/2 milk line would be potentially just a 5% loss. One positive here is that our crop is mostly 1/3 to 1/2 milk line, so any impact will hopefully be on the light side. If we do see a frost, this will be the earliest in September that I have ever seen in my career…..just perfect for 2020, eh? Since many soybean fields still have a healthy canopy, damage from frost will be limited to the upper canopy, however, there will still be some loss regardless.
On a positive note, currently we are looking at a good quality irrigated corn crop….and, while dryland has suffered as of late, some fields, even here, will be surprising I think…..
Irrigated soybeans look good in the area as well…’lots and lots’ of 4 bean pods in many fields. However, this year we will see a bigger separation in irrigated vs. dryland yields. It takes rain in August to make soybeans and this was sorely lacking this year. SDS will be the disease that will have the biggest impact in our area on yields.

Let’s hope that Mother Nature gives another two weeks of grain-fill and we will have a heavy and good quality corn crop!

2020 Yield Data

Please check this website throughout harvest and this winter for local area yield data. We will continue to text yield results as they come out, but they will also get posted here for timely and organized viewing. The data will be under Ag Update – Harvest Data. Please contact us if you would like help calibrating your yield monitor and/or want a yield check!

Thanks for giving us the opportunity to be a part of your farming operation!

Starman Seed Service, Inc.