Agronomic Update – July 28, 2020…..possible cool down here we come….

Corn Fun Fact:  One acre of corn eliminates 8 tons of carbon dioxide from the air.

Topics:

– Growing Degree Day Update

– What’s going on in my fields?…..Corn Development, Disease, Crop Water Use….

– Corn/Soybean Insect Update

– Soybean Development – Disease and more…

As of July 28th, we have accumulated approximately the following for Growing Degree Days in 2020:

Planting Date     GDD’s2020          Average GDD     Departure from average

April 21               1760                        1625                      +135 (+5.5 days)

April 26               1707                       1586                       +84 (+5 days)

May 1                  1656                        1550                        +78 (+4 days)

Since the last update on July 11th, we continue to run ahead of average GDU accumulation by 4-5 days.  However, the 6-14 day temperature outlook is for much cooler temperatures (see maps below).  In fact, forecasted temps look to be 8-10 degrees below the average over the next 7-14 days.   If this plays out, we will lose whatever ground the crop has gained over the past month.  This will be (like most everything), a pro and con….pro meaning no stress on the crop….con meaning greatly increased potential for diseases on corn and soybeans.  More on this in the topics below.

The above maps show the current 6-10 day temp/ precip and 8-14 day temp/precip forecasts from the AgriTools app.  You can see that much of the cornbelt will is expected to experience below normal temperatures and overall drier conditions over the next two weeks.  Keep this in mind as you think about disease and overall crop water usage.

What’s going on in my field?

Most of the corn crop is in the R2 (Blister Kernel) stage to some early R3(Milk) stage.  This is 7+ days ahead of 2019.   Early indications are that overall pollination is good and very typical.  However, expect to see some uneveness in pollination/silking due to the uneven emergence we saw this past spring.

  • Blister Kernel occurs approx. 10-14 days after silking.  Starch has begun to accumulate in the watery endosperm and the kernels are beginning a period of rapid, steady, dry matter accumulation that will continue until physiological maturity in approx. 50-60 days after silking.
  • At Blister Kernel, maximum ear length is achieved.  Although not as severe as at Silking, stress over the next two weeks can still have a profound effect on yield through kernel abortion.
  • Kernel abortion from stress can occur through the Milk stage(18-22 days after silking), however when the plant reaches Dough, kernel abortion will no longer take place, and any yield reduction from then on out will be from lower test weight.
  • Cooler temps during grain fill means less stress on the crop, which is a positive for high yields, as was mentioned above.
  • As far as sunlight is concerned, we are currently running, believe it or not, 5% percent below normal over the last 14 days, or since silking started.  Sunlight, of course, is now a much bigger yield factor, since we are now in the crucial grain fill period.   As such, how much sunlight and when it occurs during the grain-fill period, will play a role in overall yield and late-season plant health.   Lack of sunlight early in the grain fill period (i.e. right now)  can lead to the ear tipping back as well.
  • Extra stress will occur if sunlight is reduced and temps (especially nighttime) are higher than average.  This stress occurs because, since temps are high (especially nighttime temps) the energy demand on the plant is higher than average; couple this with reduced photosynthesis, and this leads to greater energy in the plant just going to maintain itself and not to filling the ear.  It is an axiom in corn production that when you have to run your air conditioner at night, it is not good corn growing weather.  The past couple of weeks have seen somewhat higher than normal average lows, which has helped the crop to keep moving along.
  • Relative Humidity over the past two weeks has been 10% higher than normal.  This, coupled with average high temps in the upper 70’s to low 80’s, greatly increases the potential for leaf disease to develop, which is what is forecasted over the next two weeks.  So far, we are now seeing quite a bit of Gray Leaf Spot start to show up in area fields, on the lower leaves, especially the corn-on-corn acres.  There is a lot of bacterial leaf streak around now as well.
  • We have just observed our first Southern Rust lesions this week.  Photo is southern rust lesion west of Elgin… Keep an eye out for this disease, as it can be a fast mover and will impact yield if it takes off.   https://www.pioneer.com/us/agronomy/southern_rust_cropfocus.html
  • The forecasted temperatures will also increase the potential for Northern Corn Leaf Blight, a disease we normally do not see here but that can blow up in cool temps.  https://www.pioneer.com/us/agronomy/northern_corn_leaf_blight_cropfocus.html
  • The forecast for the next two weeks, will keep the likelihood of further development of these diseases on the increase.  If we experience warmer temps than forecasted and/or sunlight is plentiful, the potential for impact from diseases will be reduced.
  • Fungicide application should be on, or going on over this next week, for best yield response.  You want to protect the plant when it is working the hardest, which is silking through milk stage.  Fungicide will not help control bacterial leaf streak.

Average ET rates will continue to stay in the .25+ in/day through the Milk stage, so maintaining an adequate soil moisture profile will be key yet over the next two weeks or so.  However, the lower temps that are forecasted over the next 10-14 days will keep ET rates lower than normal.  As you think about irrigation needs over the next two weeks, keep temperatures in mind as we move forward to see what actually occurs to help reduce potential water stress or potential over watering.

Soybean Update

  • Much of the crop is in the mid-R3(pod set) to R4(full pod) stage of growth.   This is about one week ahead of average.
  • Peak water use, nutrient demand, and overall energy demand in the plant occurs at R3 and into R4 stage….i.e. right now!
  • ET rates in soybeans are at peak (R3 stage) and will continue to stay high through R6(full seed).  However, with the current temperature forecast, overall ET rates in soybeans will be lower, and one will need to be careful not to water constantly to help reduce disease potential (see below on white mold) due to a constantly ‘wet canopy’.  In heavy soils, if irrigation is needed, we recommend running a heavy irrigation amount (.80 to inch) and then leaving it sit for a while.
  • Any fungicide/insecticide application should be on, or go on ASAP, for best yield response as most soybean fields will are in the prime growth stage for treatment.  Same goes for any nutrient application such as N, as well.
  • Any 2nd treatments for White Mold should be on or going on.   So far we are not seeing any plant symptoms, however, we are seeing a lot of the fruiting bodies on the ground inside the canopy.  See the attached link for more info and pictures of the fruiting bodies.  Current weather forecast will greatly increase the potential for an outbreak of this disease.    http://www.pioneer.com/us/agronomy/managing_white_mold_soybeans.html         We recommend Aproach or Delaro fungicide for any white mold control.

Insect Update

  • Keep scouting for Western Bean Cutworm larvae.  Moth flight has dropped over the past week.  However, I do think light numbers will continue to fly over the next few weeks, leading to a potential slow buildup of infestation levels.  However, any potential treatments should be on, or going on ASAP, as we are now finding small larvae on the ear tips, at top of the silks.  Any delay in treating, and they will be too far into the ear tip for control.  Overall infestation levels are not as high as first thought considering the high moth capture, but many sandy fields could still have fair numbers of larvae in the tips if not treated.
  • Corn Rootworm pressure has been higher this year versus the past few years.  Adult rootworm beetle control should already be on, or going on now if planned.
  • 2nd generation Thistle Caterpillar larvae are out now.  Overall numbers compared to last year have been extremely low.  Keep scouting for this pest over the next week, but I do not expect any major problems from this insect.   Also, begin scouting for Bean Leaf Beetles as they will begin feeding on developing pods over the next few weeks.  So far we are not seeing much for Soybean Aphids.   If you have made an insecticide application already, this should give you season long control unless a severe outbreak of one of these insects occurs….keep in mind that 2020 is not over…ANYTHING is possible….
  • Dectes Stem Borer – be on the lookout for this insect starting now and into harvest.  This is a new insect that borers into the stem and we saw our first case of this insect in August last year.  Watch field edges first and let us know if you are seeing wilted and dying plants as they move in from the grassy edges.   https://www.pioneer.com/us/agronomy/stem-borer-dectes.html
  • With the cooler temps, expect to see high numbers of Corn Leaf Aphids(dark green aphid) in area corn fields starting this month and into September.  Their numbers really increase with cooler temps.  They are not an economic concern, but be aware that you may see high numbers of them, much like we have the past couple of years.
  • We are also finding our first Spider Mite colonies in some of the sandy fields.  The current forecast should keep this pest under control, however, keep an eye out for an isolated outbreak of this insect.

Granular Insights

There is still time to get signed up for the Granular Insights imagery….there is still much to see over the next two months.  If you are not signed up and would like to, please contact us.

Please contact us with any questions, concerns observations you are seeing.  Thank you for your support!!

 

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Agronomic Update – July 11, 2020….

Fun fact: A single tassel produces approximately 5+ million pollen grains….

Topics:

– Growing Degree Day Update

– What’s going on in my fields?…..Corn Development, Disease, Roots

– Insect Update

– Soybean Development

As of July 10th, we have accumulated approximately the following for Growing Degree Days in 2020:

Planting Date     GDD’s2020          Average GDD     Departure from average

April 21               1327                        1220                      +107 (+4 days)

April 26               1274                       1190                       +84 (+3 days)

May 1                  1223                        1145                        +78 (+2.5 days)

 The heat of the past two weeks has really allowed the corn crop to gain ground since last update.  Last update we were trending right at the normal…currently, we are trending above normal.  2020 is now ahead of 2019 for growth stage and GDU accumulation.  However, this rapid growth has widened the window for exposure to green snap and we have seen some of this in the area from the recent spate of storms.  As usual, it is related to many factors such as hybrid, recent N applications, field conditions, etc.

The above maps show the 6-14 day temperature  and precipitation forecasts.   As you can see, temperatures for much of the rest of July are forecasted to be above much above normal.  This will speed  up crop development.  However, precipitation over this same time period is forecasted to me normal to slightly below normal.  The recent rains will be a blessing during the next few weeks if the heat forecast is true.

  • Based on the above numbers, when can we expect to silk?  If we look at P1197 genetics we see that it takes approx. 1400 GDU’s to silk, this means that we would be looking at a potential silk date around July 13-17.  Hybrids such as P0688 (1280 GDU’s to silk) are close to tasseling and should be pollinating next week.   In other words, due to the fact that most of the corn was planted in a 7-9 day window, we can expect to see most all fields begin tasseling next week, with pollination occurring at the end of next week into the following week.   This is slightly ahead of the average.

What’s going on in my field?

  • Overall much of the corn crop looks very good!  Very good color and uniformity for the most part.  Much of the corn crop is in the V14-V16 leaf stage, depending upon hybrid and planting date.  This is slightly ahead of last year.   From V10-VT, corn gains a new color every 50 GDU’s, or about every other day.   
  • Kernels per row begin around V12 and continue through and up to tassel stage
  • Nitrogen needs will continue to grow through tasseling and into early reproductive stages.  Nitrogen uptake in corn – very rapid now through tassel (up to 4-8 lbs per day).  Today’s hybrids use nitrogen later in the growing season and into the reproductive phases.  You will want to keep that last shot of N available for after tasseling.    This year so far, we haven’t experienced conditions that usually lead to N loss from leaching or denitrification.   Expectations are that more N is potentially available in the soil profile.  Also, the higher temps over the past few weeks and those that are forecasted should lead to higher N-mineralization rates versus other years, meaning a potential increase of available N to the plants.
  • We are now into the rapid growth and accumulation of dry matter by the plant.  The window for brittle snap is still open over the next 7-10 days.
  • Under field conditions, pollen shed usually occurs in the late morning and early evenings.
  • Pollen shed will extend for one to two weeks, but if field is uniform in plant emergence and height, pollen shed is 80% complete in 5-7 days from full tassel emergence.
  • At tassel, vegetative development is now complete; maximum plant height and root depth is achieved.  The storms of the past week have led to some root lodging in spots, mainly on those hybrids with a weaker root strength score.
  • VT overlaps with R1 (silking stage) when visible silks appear before the tassel is fully emerged.  By definition, growth stage R1 (Abendroth et al., 2011) for an individual ear is defined when a single silk strand is visible from the tip of the husk. An entire field is defined as being at growth stage R1 when silks are visible on at least 50 % of the plants. This whole field definition for growth stage R1 is synonymous with the term “mid-silk”.
  • A captured pollen grain takes about 24 hours to grow down the silk to the ovule for fertilization.
  •  Peak pollen shed usually occurs in mid-morning.   Some research indicates that pollen shed decreases after temperatures surpass 86F.   A second “flush” of pollen often occurs in late afternoon or evening as temperatures cool.   Pollen shed may occur throughout most of the day under relatively cool, cloudy conditions….. https://www.pioneer.com/us/agronomy/corn_pollination_success_cropfocus.html
  • Weather conditions influence pollen shed.  If the anthers are wet, the pores will not open and pollen will not be released.   Thus, on an average summer morning following a heavy evening dew, pollen shed will not begin until the dew dries and the anther pores open.  Similarly, pollen is not shed during rainy conditions.   Cool, humid temperatures delay pollen shed, while hot, dry conditions hasten pollen shed.
  • Generally 2-3 days are required for all silks on a single ear to be exposed and pollinated, with the silks on the butt of the ear emerging first.  The silks will grow from 1-1.5 inches each day and will continue to elongate until fertilized.  If not pollinated, silk elongation stops about 10 days after silk emergence due to senescence of the silk tissue. Unusually long silks can be a diagnostic symptom that the ear was not successfully pollinated.
  • Silk emergence and growth is dependent upon turgid pressure within the plant, in other words how much water is available in the plant to cover all of its needs.   If this is limited, (ie. dryland, low-gallon wells, etc.) silk emergence will be slowed and delayed with potential to miss the pollen shed.   Under severe water stress conditions pollen shed will still take place like normal, however, silks can be delayed, which means potential for poor pollination.
  • It takes approximately 55-60 days from silking to physiological maturity.  So if a field is silking on July 14th, it will need until September 14th to reach maturity, given average weather.  Current forecast for the next two weeks is slightly above normal GDD accumulation of 26-27 GDU’s per day.
  •  High nighttime temperatures (ie. any stress) begin to play a role in final yield during grain-fill as this causes the plant to work harder to maintain both yield and overall plant health.

Corn Leaf Disease/Fungicide

  • The next four to six weeks will be critical for disease infestations and fungicide applications.
  • Begin scouting now and through the next few weeks for disease infestations.  So far not seeing much for leaf disease, mainly bacterial leaf streak (see attachment).    However, overall temps and humidity levels the past week or so, have been conducive for an increased development of leaf diseases.
  • If you are planning on only one fungicide application, the best timing for this application is after pollination as the crop is working the hardest and has the highest demand for energy at this time.  We want to protect as much of the leaf surface as possible in this time frame, which is two weeks after pollination.  (See attachment on disease and fungicide management)
  • While any hybrid can have a response to foliar fungicides, hybrids such as P0589, P0950, P1138, P1244, P1185, & P1366, are hybrids to focus on first for higher probability of response from foliar fungicides, especially if gray leaf spot infestations are high…..https://www.pioneer.com/us/agronomy/maximizing_foliar_fungicides_corn.html   Also, corn on corn acres…. https://www.pioneer.com/us/agronomy/bacterial-leaf-streak.html

Water Management

Below are some key water management tips to keep in mind:

  • The greatest yield loss from moisture stress occurs in the period two weeks prior to two weeks after pollination.  For the next two weeks, the corn crop will be at its peak water usage, with ET rates of .30+ inches per day – higher when temps are in the mid-90’s and higher yet when combined low humidity.
  • ET rates over the past couple of weeks have been high.  Thankfully we have received some timely rainfall in this period.  However, we are now fast approaching peak water use in corn, and with the higher temps forecasted for the next couple of weeks, it will be important to stay on top of overall water needs by the crop.
  • At present, we are seeing fairly good root depth according to the soil moisture probes….sandier soils are 12-24” and heavy soils are 20-36+” depending upon plant date, conditions and soil type.  Remember that maximum plant height and root depth are achieved once the plant tassels.

Insect Update

Western Bean Cutworm should begin to show up over the few weeks.  Keep these tips in mind over the next few weeks:

  • To scout for this insect, check the sandier fields first and look on the upper side of the leaf for a white, or purple, egg mass.  These will be found on the upper 1/3 of the plant.
  • We will again have the pheromone moth traps located west of Elgin.   We caught our first moth’s just the end of this week.   See this website under Grower resources for continued updated counts.
  • Treat when the fields are 95% tasseled.  Use high rates of a Capture-like produce to give you 3-4 weeks of residual control.
  • WBC are attracted to those fields that are closest to tasseling.
  • Once a field has been tasseled, any egg masses that hatch will see the larvae head straight to the ear tip, so treatment soon after tasseling is critical.

Corn Rootworm pressure appears to be higher this year versus the past few years.   Monitor corn rootworm beetle emergence over the next two weeks for any potential silk-clipping issues.

Gall Midge in Soybeans – There is a continued increase of reports of Gall Midge in the counties to the east of us.  I would assume that we have this insect somewhere in our area in very light numbers.  Keep an eye out for plants dying on the edges of your field, or in the end rows, as this insect is most common on field borders.   See attachment for more info.   https://www.pioneer.com/us/agronomy/Gall-Midge-New-Pest-In-Soybeans.html

Soybean Development

  • Most of the soybeans in our area are at late R1 (Beg flower) to mostly R2 (Full flower).  Soybeans are somewhat ahead of normal for development.   I would not be surprised to see early R3 (pod set) on some fields next week.   Most fields are finally coming around and growing….not seeing as much leaf-cupping going on now.
  • Soybeans should be nodulating heavily at this stage.   At the beginning of the reproductive stage, soybeans will still put on 50% of their vegetative growth.
  • Crop water use in soybeans starts to increase rapidly at full flower, peaks at R3 and will stay high through R6, or full seed.
  • Flower stage is usually the time when the soybean plant begins to pull from the deeper root zones.  We are beginning to see this according to the soil moisture probes.
  • We continue to see a yield response from a fungicide application in soybeans, either at R1 for white mold or a later R3 stage of growth.  Environmental conditions over the next two months will determine disease incidence and overall level of disease infestation.  In 2019 we saw a lot of Frogeye Leaf Spot occur in soybeans, keep an eye out on this disease as well.  See attachment for more info on this disease….https://www.pioneer.com/us/agronomy/frogeye_leaf_spot_on_soybeans.html     Not all fungicides control this disease so make sure you check the label to see if this disease is controlled.  It remains to be seen what the drier conditions we have experienced so far this year will mean as far as disease outbreak is concerned.
  • White mold attachment:  https://www.pioneer.com/us/agronomy/managing_white_mold_soybeans.html

Thank you for your business!!   Please let us know any questions or concerns you may have!!

Starman Seed Service, Inc.

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