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JenREES 8/29/21

Congratulations to all the 4-H youth who competed at the Nebraska State Fair this past weekend! The talent of our youth never ceases to amaze me. It’s also so encouraging to see life skills being developed such as public speaking, plant and insect identification, and the responsibility and care for animals.

Also so grateful to receive rain last night! And, that should finish up irrigation, or get it pretty close, for many that didn’t have late-planted crops. It’s really important to know your crop growth stage and to finish well. There’s some fields that are obviously over-irrigated with water standing after this last rain. On the flip side, it’s important to monitor soil moisture and crop growth stages to not stop too soon in spite of the long irrigation season and how tired farmers are. Several questions last week on ‘how’ to finish with irrigations and when physiological maturity occurs in soybeans.

Last irrigation: if you’ve been triggering irrigation during the growing season based on the recommended 35% depletion (average of 90 kpa on watermark sensors), you would have around 1.28” of moisture available in the top 4 feet for the plant in silt loam soils. A consideration for a step-wise approach I’ve used is this: Corn at ½ milk line needs around 13 days or 2.25” to finish the crop to maturity-so subtracting that from 1.28 would be 0.97”. As we consider allowing the soil moisture profile to deplete to 50-60% for recharge over the winter, a person could delay to 40-45% depletion (around 130 kpa average on watermarks) before triggering irrigation the first 7 days and then allow for 50% depletion (around 150 kpa average on watermarks) that last 7 days to finish irrigation for corn.

Soybean pods

Soybeans range from full seed (R6 end of seed enlargement) which needs 18 days or 3.5” of water; R6.5 (leaves yellowing/pod membranes still clinging to seed) which needs 10 days or 1.9” yet; or physiological maturity in which the pod membrane has separated from the seed and no more water is needed. The NebGuide, “Predicting the Last Irrigation of the Season”, speaks to yellowing leaves as the beginning of physiological maturity. But the question I kept getting last week was “how yellow is considered yellowing leaves?”. Perhaps a better indicator for today’s varieties would be to also look at the pods. Until the pods reach R7, physiological maturity, the plant is still utilizing water. At R7, at least 50% of the field plants will have one mature pod anywhere on the main stem. A mature pod is considered when the pod membrane no longer clings tightly to seeds in that pod (this is like black layer on corn where the nutrient/water supply is cut off from the kernel forming the black layer). So essentially, if you pull off a pod on the main stem, carefully open it up and look at the membrane surrounding the seed. If it’s still clinging tightly to it, it’s not quite mature. If you see separation of the membrane and seed, it’s considered mature and will no longer use water. There can be a range of pod stages on a plant, but between yellowing leaves and pod color changes, one can get a pretty good idea when R7 has occurred and no additional water is needed for the plants. The timing of the ending R stages in soybean is determined by planting date and varietal maturity group, though the date of R7 can be hastened if water stress and high temperatures prevail in August — something we are seeing this year.

Soybean stems typically turn brown shortly after R7 begins, though the stem can remain green longer due to a number of reasons, including fungicide use. The final soybean stage is R8, which occurs when 95% of pods have attained maturity and have a variety-dependent color of brown or tan. Seed moisture in a soybean pod dries down from 70% at R7 to about 13% at R8. This has shown to be around 12 days based on research, but can be faster or slower depending on solar radiation, humidity, temperature, wind speed and soil surface moisture.

So, for scheduling last irrigation in beans: if we use the same example of having 1.28” of available water at 35% depletion in silt loam soils in top four feet, soybeans would need 2.22” with 18 days to finish at R6 or 0.62” with 10 days to finish at R6.5. Using the stepwise approach, one could again allow the soil moisture to dry down to 40-45% the first week and 50-60% the second week. This also allows room to catch rain like we finally experienced last night.

Fall armyworms have been on the increase in alfalfa and pastures recently, so please be scouting as they can decimate a field quickly in the late larval stages. The threshold is 3 or more per square foot and they’re easier to control if the larvae are ¾ inch long or less. When they’re larger than this, they’re more difficult to control and choosing to harvest the alfalfa may be a better control method. Insecticide options include products with active ingredients including the pyrethroids, Alpha-cypermethrin (Fastac CS), Beta-cyfluthrin (Baythroid XL), cyfluthrin (Tombstone), Gamma-cyhalothrin (Proaxis, Declare), Lambda-cyhalothrin (numerous products), permethrin and Zeta-cypermethrin (Mustang Max), organophosphates, chloropyrifos (numerous products), and carbamates, carbaryl (Sevin) and methomyl (Lannate). 

Alfalfa defoliation by fall armyworms
Heavy defoliation of alfalfa by fall armyworms in a Nebraska field. Photo by Nathan Mueller

JenREES 8/15/21

Crop Update: It was great to see people at soybean management field days last week and to hear their experiences around cover crops and weed management! White mold in soybean was the primary question received last week. It was already heavy in some Butler and Polk county fields and has since increased in York county with calls over the weekend. I don’t get too concerned about managing different insects/pathogens/weeds as we have various management strategies for them. White mold, though, is a very difficult one to manage.

It’s a soil-borne disease in which the fungus survives in a black structure (sclerotia) that resembles mouse droppings. Rain events and irrigation during flowering can favor it along with extended dew periods and fog like we’ve experienced this year. If you see random plants in an area that are turning brown but remaining upright, look into the canopy and see if there’s white cottony fungal growth on the stem. You may also see the black sclerotia on either the outside or inside of the stems. It can continue to spread from plant to plant. Management right now includes managing soil moisture and irrigation. It’s important to keep the top portion of the soil as dry as possible (which I realize is practically impossible with heavy dews). When it comes to irrigation management, infrequent, heavy watering is better than light, frequent watering in heavy-textured soils. It’s a good idea to keep notes on areas of the field you’re seeing it this year so you’re aware of it the next time soybeans are planted.

Some cultural and crop rotation things going forward that may or may not fit for your operation, yet good to be aware of: No-till allows the sclerotia to die more quickly on the soil surface (within 2-3 years), whereas tillage allows sclerotia that are buried to survive longer. Also, as we think of cover crops and crop rotations, fields with a history of white mold should avoid rotations for 2-3 years with edible beans, field peas or other pulses, canola, turnips, radishes, sunflowers, or potatoes. Grass crops (corn and sorghum) and using small grains like wheat, rye, oats, etc. in rotation can help reduce the amount of sclerotia that survive. For more detailed information, check out: https://soybeanresearchinfo.com/soybean-disease/white-mold/.

Watch insects in soybeans regarding clipping pods; not seeing too much of that yet. Am seeing bean leaf beetles and grasshoppers in several counties. Saw woolly bear and green cloverworms in Nuckolls co. last week. I have no idea why Japanese beetles are still around for all who keep asking!

Have been seeing sudden death syndrome (SDS) for several weeks now. For those seeing it in fields where beans were treated with ILeVO or Saltro, the symptoms can still appear on beans treated with those products. In spite of this, from our on-farm research fields that had a history of SDS, the symptoms were less in the treated beans than the check treatment.

Mid-August brings a sigh of relief to many agronomists in getting closer to the end. I’m sure our farmers will be grateful to get to the end of irrigation season this year too. Many soybeans are at R5-R5.5 (can see seed development in pods on upper 4 nodes). At this point, flowering stops. Soybeans at R5 still need around 6.5” of moisture to finish. At R6 (full seed), that amount drops to 3.5”. We don’t talk about last irrigation yet for corn at milk stage. For fields at dough (R4), corn needs around 7.5” of moisture yet to finish and 5” at beginning dent.

Seward County Ag Banquet to be Held August 23: The Kiwanis Club of Seward partnered with SCCDP and Seward Co. Ag. Society will honor Seward County Ag Leaders on Monday, August 23, 2021 with our 53rd Annual Agriculture Recognition Banquet. The banquet begins with wine, cheese, and sausage at 5:30 p.m. and a prime rib meal at 6:30 p.m. Ag Promoter, Educator, and YouTube Sensation, Greg Peterson will be the evening’s entertainment. This event provides an excellent opportunity to recognize the importance of agriculture in Seward County. The evening will honor the Seward County farmers, producers, ag businesses and ag students for their continued economic contributions to our strong local agricultural economy. Due to COVID not allowing us to have a banquet in 2020, we will be honoring individuals and families selected in 2020 and 2021. Please contact Pam Moravec, Banquet Chair, 402-643-7748, or Shelly Hansen, 402- 643-3636 information about becoming a banquet sponsor. The cost to attend the banquet is $30.00 per person.  You can contact Pam or Shelly to reserve you seat. The Kiwanis Club of Seward will use the proceeds from the event to support the youth of Seward County through a variety of programs and events, including the Agronomy Academy.

Table from “Predicting Last Irrigation of the Season” NebGuide: https://extensionpublications.unl.edu/assets/pdf/g1871.pdf

JenREES 8-30-20

Grateful Nebraska held our State Fair this year! Seeing the youth competing, showcasing 4-H projects, and the excitement, smiles, and friends reconnecting from across the State this past weekend was heartwarming!

Received many calls about end of season irrigation this past week. Would encourage our farmers to finish the season well! You’ve been through much in another trying year and the past few weeks have been extra hard keeping up with irrigation, cleaning out bins, and getting combines ready in the heat. It can be tempting to just stop but would encourage you not to quit irrigating too soon, particularly on soybeans. Soybean maturity (R7) is defined when 50% (or all) of the field plants possess one mature pod (when the interior white membrane no longer clings to the seed). In most years, most leaves and pods will have changed color (from green to yellow-green or yellow) by this plant-based R7 date.

The heat has pushed crops along, but we’ve also had a great deal of humidity. Corn is moving the starch line slower in irrigated fields. That’s a good thing for fill and a harder thing regarding labor, time, and money. A lot of corn in this area is 1/3 milk and I just saw a few fields at ½ milk over the weekend. 

  • Corn at ¼ milk needs 3.75” (approximately 19 days to maturity)
  • Corn at ½ milk needs 2.25” (approximately 13 days to maturity)
  • Corn at ¾ milk needs 1” (approximately 7 days to maturity)
  • Soybean at full seed (R6) needs 3.5” (approx. 18 days to maturity)
  • Soybean with leaves beginning to yellow and pod membrane still attached to seeds (R6.5) needs 1.9” (approx. 10 days to maturity)

So, we’re potentially looking at one to two more irrigations yet for some of this corn and soybeans depending on the current status of your soil moisture profile, development of the crops in your particular fields, and any rain. It is recommended to allow that soil moisture profile to dry out to 50-60% depletion towards the end of the season to capture moisture in the off-season. So one way to consider this is a step-wise approach. If you typically irrigate at 35% soil moisture depletion and have around 2” left, the next week you could wait till a trigger of 40% depletion with the following week’s trigger around 50%. Again, this depends on your individual field’s soil moisture status and crop development after a taxing August.

Upon physiological maturity, corn ears begin drooping down. However throughout the area, corn ears are doing this that aren’t at ½ starch yet. These ears will black layer prematurely at the cost of yield. Dr. Bob Nielsen from Purdue shares that yield penalty can be as much as 40% at denting when there’s essentially no milk line visible and around 12% at half milk. So what causes this? The ear shank can collapse when there’s a lack of turgor pressure due to stress from the inability to keep up with crop water demand. August has been abnormally dry with warmer than average temperatures the past few weeks. Sometimes the ear shank also cannibalizes itself, similar to what can happen in stalks. Perhaps part of this can be from poor root development or lack of root development into deeper layers? In areas that have received less rain, perhaps deeper soil layers are drier in spite of having moisture in the top soil layer from irrigation? For those with conventional hybrids, European corn borer tunneling can also cause this type of collapse. There’s also some hybrids that I notice this happening more than others; perhaps genetics also plays a roll? That shank is the source for feeding the ear, so when it collapses, it weakens it. Keep an eye on ears in these fields as we approach harvest and consider getting at them sooner if possible.

Drooping corn ears in this irrigated field with green plant tissue above ears. This corn was getting close to 1/2 milk.
Photo by Dr. Jim Specht showing end of season soybean development stages. Notice the white membrane still attached to the seed in R6 stage and how it disconnects at R7 (maturity). Not all pods on the plant may be at R7 at the same time. R7 for all the plants in the field is considered when 50% (or all) of the field plants possess one mature pod (when the interior white membrane no longer clings to the seed). In most years, most leaves and pods will have changed color (from green to yellow-green or yellow) by this plant-based R7 date.
Sudden Death Syndrome (SDS) has been observed for the past several weeks in fields. Thankfully it’s been minor this year compared to last year. It’s wise to take a soil sample for soybean cyst nematode (SCN) in these areas of the field to determine if you also have a nematode problem. The combination of the diseases has a synergistic impact on yield.

JenREES 8-16-20

Crop Updates: For the past week, crops used around 0.22” per day in the York area, around 0.20” as one goes east towards Ithaca and closer to 0.25” per day going south towards Harvard and Guide Rock (based on High Plains Regional Climate Center data posted on CropWatch).

As we think about water use the finish the year, the following come from the NebGuide Predicting the Last Irrigation of the Season found at: https://go.unl.edu/k74n:

  • Corn at Beginning Dent needs 5” of water (approximately 24 days to maturity)
  • Corn at ¼ milk needs 3.75” (approximately 19 days to maturity)
  • Corn at ½ milk (Full Dent) needs 2.25” (approximately 13 days to maturity)
  • Corn at ¾ milk needs 1” (approximately 7 days to maturity)
  • Soybean at beginning seed (R5) needs around 6.5” (approx. 29 days to maturity)
  • Soybean at full seed (R6) needs 3.5” (approx. 18 days to maturity)
  • Soybean with leaves beginning to yellow (R6.5) needs 1.9” (approx. 10 days to maturity)

Spent a lot of time last week looking at ear development in fields, particularly those impacted by the July 8th windstorm. Also appreciated a long conversation with John Mick with Pioneer on what he was seeing. For the most part, I’m seeing a lot of ‘normal’ ears that vary in the amount of tip back from lack of pollination and/or kernel abortion. Less commonly seen are ears with 3/4 husks. On plants that were pinched, continue to see messed up secondary and/or tertiary ears after the loss of the primary ear. On plants that bent and righted themselves, seeing a variety of things. Some are more ‘normal’ while other ears are much smaller that either didn’t pollinate well and/or had kernel abortion.

Last month, had mentioned a curious thing regarding how many hybrids are putting on multiple ears on the same ear shank, on the primary ear node. It’s far more than I’ve ever seen before. In sharing some observations with Dr.’s Tom Hoegemeyer and Bob Nielsen, they share it’s most likely a genetic X environmental response under excellent growing conditions or some other phenomena. As I continued to see these ears in fields and husk them back, for the most part, they don’t appear to be detrimental to the main ear, which is good. So it’s more of a curiosity than anything.

Many of us probably don’t examine ear shanks much in comparison to the ears. However, when one does look at ear shanks, one will observe they are similar to the corn stalks in that there are nodes and internodes. Each node also produces a leaf (in this case a husk leaf) instead of a collared leaf such as what happens on the main stalk. And each node (on stalk and on ear shank) has an axillary meristem which allows for ear development. Normally, there must be genetic or hormonal suppression so that only one main ear is formed on a shank at a stalk node. It’s not uncommon for us to observe an ear on different nodes of the stalk (ex. Nodes 12 and 13). What is more uncommon is to observe multiple ears on different nodes of the same ear shank, such as what is being observed this year.

Renovating Lawns: If your lawn is in need of repair, now through mid-September is a great time-perhaps the best time-to do so! This resource, Improving Turf in the Fall at https://go.unl.edu/rz9z is a great one to walk you through renovation depending on your situation. Some lawns can be easily improved by adding fertilizer this fall and/or overseeding. Some may need total renovation, which starts with a glyphosate (Roundup application) followed by waiting at least a week to then prepare the soil for planting.


Multiple ears on the same ear shank (with husk tissue on left and husked on right). Doesn’t appear to be impacting main ear in most fields I’ve seen these in. And, this is occurring on primary ear nodes and within fields (not just in endrows or in lower population areas).

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Pretty impressive brace root development on leeward side of plants that tried righting themselves.

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Ears from the plants with the brace roots from above photo. These are pretty decent with some tip back, but otherwise more ‘normal’. Other plants like this have ears that have poor kernel set.

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Seeing some ears with 3/4 husk.

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Bent plant that tried righting itself with a ‘zippered’ appearance to ear and poor pollination in addition to kernel abortion.

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Plant with loss of the primary ear showing multiple ears on the secondary and tertiary ear nodes.

More on Last #Irrigation

It’s been a long irrigation season thus far, but we are so thankful for irrigation in this part of the Country during this drought of 2012!  Questions continue to roll in regarding last irrigation for corn and soybeans.  Corn at 1/2 starch only needs 2.25″ to finish up so it’s important to know what your soil moisture status is.  For most irrigated producers, at 1/2 starch, you should be finished irrigating.  

For soybeans at R5 or beginning seed fill, you still need about 6.5″ to finish out the crop.  At R6 when the seeds are filling, that drops to 3.5″.  At R7 when you begin to see leaves yellowing, that is beginning maturity and you are finished irrigating.  They key is we don’t want to fill the profile going into the fall as we’d like to replenish the profile with fall and spring rains and winter snow.  However, with soybeans, it’s also critical not to stop irrigating too soon during seed fill.

Gary Zoubek, Extension Educator in York County sheds more light in the following video produced by UNL’s Market Journal.

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