AGRONOMIC UPDATE – AUGUST 14, 2023….Beautiful rains….

Topics:

  • Growing Degree Unit Update
  • Quick Crop Update/Water Use/Weather
  • Corn/Soybean Insect Update

TEMPERATURES & GDU ACCUMULATION:

As of August 13th, we have accumulated approximately the following for Growing Degree Units in 2023:

Planting Date     GDD’s2023          Average GDD     Departure from average

April 21                   2192                           2178                               +16 (+ .5 day)

April 28                  2148                            2119                               +29  (+1 day)

May 9                      2017                            2010                               +17  (+ .5 day)

Our trend for GDU accumulation has been very much like it has been over the past month or so.  From July to now we have had cooler temperatures, which has offset the warmer temps end of May through June, so that we currently are experiencing normal growth.  We can see this in the following two maps for departure from normal for average high and average low temperatures over the past two weeks:

Lower overall temperatures have meant less stress on the crop and lower ET rates (more on this below), however night time temps have stayed slightly above normal which has kept us from losing ground during these cooler temps.   The GDU numbers above are 1-2 days behind 2022 just for reference.    So, what is the upcoming forecast?:

 

The above maps are the 6-10 day and 8-14 day temperature and precipitation forecasts.  As you can see from the maps, it appears that temps are going to warm up significantly and precip will be normal….which is the best of both worlds considering the recent rains we have had.  Hopefully this forecast will give us more sun over the next two weeks as well…

CROP/WATER USE/WEATHER UPDATE
  • Crop conditions: Much of the Corn crop in the area is in the late-Dough to Beg. Dent stage, with some early maturity hybrids just showing the beginnings of a milk line.  Soybeans are in the R5(Beg. Seed) to late-R5 to almost R6(full seed).  These stages-of-growth track with the above GDU accumulation as average and very similar to 2022 at this time.
  • Relative Humidity – Over the past two weeks, RH has been running normal to above normal.   Average RH has been 72% which is slightly above normal.  For reference again, last year during this same time period, RH was averaging 61%   This has influenced a couple of things, both opposite of the past couple of years for August.  Higher RH has lead to increased disease in soybeans (though not so much yet in corn) and lowered average ET rates (see next bullet point).
  • ET rates – ET rates over the past 14 days have averaged .24″/day, or 3.3″ total for this period.   This figure is .03/day behind the average of .27/day.  Again, for reference, during this same time period in 2022, average ET rate was .285/day.  We are currently using 15% less water than last year at this time with a crop at the same stage-of-growth.  This has helped out with irrigation as well as increasing the efficiency of the recent rains.  However, temperatures are predicted to warm back up and humidity is forecasted to be lower which will increase ET rates again to more normal to slightly-above normal.  See tables below for Water Use for soybeans and corn as we head into the last half of grain fill.  Corn and soybean needs are still for 6-8″ to finish depending upon planting date and stage-of-growth.
  •          
  • Precipitation – After the last two years of very little to no rainfall, we are experiencing in our area some beautiful rains.   See map below:
  • As you can see from the map, our area has been blessed with significant rains that other areas to the west and south have not had….   August rains usually make dryland beans, we will see.  Some dryland areas have already been hurt from the dry conditions in June to where these later rains are not going to help them that much….it was just to hot and dry in June for the plant to recover fully with July/August rainfall…especially in tilled vs. no-tilled conditions.
  • Sunlight – As always sunlight becomes a huge player during grain-fill for both yield and late-season plant health.   Sunlight over the past 14 days and the past 28 days has been slightly below normal.  This is the first negative rend we have had over the past two years.  Sunlight over the past 10 days has been 5-8% below normal.  Last year at this time, we were running 5% above normal.  A lot of sunny days are forecasted over the next 10-14.  Hopefully that happens!  SUN MAKES CORN!!….
  • Diseases – So far corn diseases have not greatly increased in the area, which is a good thing considering the cool/wet conditions and higher RH as of late.  So far really just seeing Gray Leaf Spot starting to come in on lower leaves in some fields.  Also, we continue to see Northern Corn Leaf Blight lesions show up in hybrids that are not as tolerant to this disease…this bears watching if temps stay cool, but if temps rise like predicted, they should slow this disease down.  Also seeing Goss’s Wilt show up in the fields that experienced hail back in July.  Goss’s Wilt needs crop damage to occur for it to show up, which it did at the worst possible time for corn.  Mainly showing up in those hybrids not as tolerant to Goss’s Wilt.  Overall leaf disease pressure is currently low….For Soybeans, main diseases are White Mold and SDS.  Outbreaks of White Mold are the heaviest we have seen for a few years (so far heavier in sandier soils and more lodged plants), but are not at the levels we have experienced in past years.   I think this is attributable to increased fungicide treatments going on for this disease and Pioneer’s latest lineup of soybeans has greater tolerance to this disease.  Warmer temps and lower RH will greatly slow this disease down.   SDS continues to show up more and more each year.  We are seeing this disease show up in varieties that are not as tolerant to this disease and that were not treated with high-rate of Ilevo at planting….high-rate Ilevo does a nice job on this disease.
CORN/SOYBEAN INSECT UPDATE
  • Spider Mites – Currently we are finding very little in the way of this insect versus the past two years, which is due to the cooler/wet conditions.  However, if temps increase, precip falls off, and RH is drier, we could still see isolated spots of this insect make an impact towards the end of grain fill.  Main fields to watch are those that were corn/corn and treated for rootworm beetles….these would be the first fields to flare…
  • European Corn Borer – Moth flight has been a little heavier this year versus last few years.  It will be worth your time to scout popcorn/conventional corn acres to see if this pest is at treatment levels.  Treatment for this pest should be on, or NEEDS to be on, this week.
  • Soybean pests – so far, insect activity in soybeans continues to be very light.   Just not seeing much for soybean aphids or bean leaf beetles so far.  Expectations for major outbreaks of these pests are low, or anything else in soybeans at this stage, are quite low….

Reminder that the Pioneer Customer Appreciation Supper is this Sunday evening, August 20th.  Pioneer warehouse – Elgin, NE….5:30-8:30.   Bring the family!   See you there!

All for now!  Thanks for your time!

Starman Seed Service, Inc.

 

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