Author Archives: jenreesources
Fall Armyworms: Received numerous reports of fall armyworm damage this past week from Kansas-Nebraska state line north to York. Damage was occurring in new alfalfa seedings in addition to established alfalfa, a new triticale seeding, and several lawns. With moths still being observed, we may see fall armyworms around for a few weeks yet, so it would be wise to be watching any alfalfa, wheat, rye, triticale and lawns for them. There’s no good way of knowing where they’ll appear; it’s all based on where the moth chooses to lay her eggs. Several reports of one field affected while the field next to it is fine. Same with lawns. Egg masses are fuzzy white masses that can include up to 200 caterpillars and the eggs can hatch in 2-5 days. Newly hatched larvae will be thin and often black/gray in color. I have some pictures from my colleague Jody Green at jenreesources.com.
In town, if you find the egg masses on lawn furniture, siding, or garden features, simply wipe them up with paper towel and discard in the garbage. They’re far easier to control when the larvae are ¾ inch or less. When they get larger than this, insecticides aren’t as effective, and usually, by that time, so much damage has occurred that the area will need reseeded. Products with active ingredients such as bifenthrin or permethrin are effective and are options for both farmers for fields and also homeowners with lawns. Sevin is also an option for both. Kentucky bluegrass lawns may be able to recover from rhizomes regrowing in the spring. However, fescue and ryegrass will need intervention this fall for reseeding. An organic insecticide option is Dipel which will take a little longer to work, but is still effective on smaller larvae. For lawn situations, it’s important to water the insecticide product in the ground to get the granules off the leaf blades and into the soil.
(Photo caption: Fall armyworm moth, egg mass, and larvae. Photos via Jody Green and UNL Entomology).
Large grubs on concrete: Had several reports last week of large white grubs on concrete stairs, sidewalks, and driveways. They are really large, up to 1.5 inches. What’s interesting about them is they crawl on their backs! These are grub larvae of the green June beetle which is a large beetle that often sounds like it’s ‘buzzing’ during June and July. The adult beetle can cause damage to ripening fruits such as stone fruits and berries. However, the grub larvae are not a major turf pest, unlike other grub species. They feed on thatch layers and organic matter, but don’t really attack lawn roots. They make holes in the soil, so rain and irrigation will drive them out onto concrete.
Small Grains and Weed Control: Last week I mentioned considerations for wheat planting. Even if small grains aren’t taken for seed, they do a tremendous job for weed and erosion control, provide an option for grazing, and uptake excess moisture and nutrients (helpful in seed corn field situations). Small grains, particularly oats and rye, have been proven to help with reducing soybean pathogens such as fungi and nematodes causing SDS and SCN. I’ve been watching a couple side-by-side soybean fields in which one was planted green into rye and the other didn’t have rye. Even the farmer commented on it to me this week how the quarter without rye has senesced earlier and has problems with anthracnose and Diaporthe complex (including pod and stem blight) while the other is essentially disease free.
Wheat provides an option for both grazing and grain. Rye provides the best option for earliest green-up/growth in the spring and longest seeding time as it can be seeded into December. Triticale provides the most biomass, including for haying and small grain silage, but produces the latest into late May/early June. It’s too late to plant oats for the fall, but they are an option for the spring. All keep the ground covered from light interception penetrating the soil surface which allows weed seeds to germinate.
Researchers from K-State looked at marestail (horseweed) and palmer amaranth control from 2014-2015 in no-till soybeans at six locations in eastern Kansas. They also found the majority of marestail emerged in the fall (research from UNL showed up to 95% does). They compared five cover crop treatments including: no cover; fall-sown winter wheat; spring-sown oat; pea; and mixture of oat and pea. Cover crops were terminated in May with glyphosate and 2,4-D alone compared to a control of no herbicide use. Ten weeks post-termination, palmer amaranth biomass was 98% less in winter wheat and 91% less in spring oat compared to no cover crop and no herbicide control. The same cover crops were also compared to a no cover crop treatment where all received a May herbicide application of 2,4-D and glyphosate with residual herbicides of flumioxazin + pyroxasulfone (Fierce). With the addition of residual, there was no difference in palmer amaranth biomass in the no cover crop with residual herbicide and all the cover crop species where a residual herbicide was added. I share the Research Figure on my blog site which is incredibly visual and have shared it in pesticide trainings as well. To me, it so visually shares how well residual herbicides can work, which we’re aware of. However, what strikes me the most is how much work that residual had to do on its own to achieve the same control as a cover crop + residual herbicide. Adding the cover crop reduced the load of the herbicide alone and is another tool in the toolbox. It also shows how effective cover crops for weed control can be for organic systems if there’s a solid way for terminating them. I realize cover crops don’t fit every field or every situation. Just some considerations as we especially think of situations where planting a small grain this fall could be used for weed and erosion control and/or grazing.
Crop Update: The cooler weather and rains have been welcome here even though other parts of the State have had excess and flooding. I think grain fill has slowed down some in the corn, which will hopefully help. The rains will help the beans, milo, and pastures. If we can escape storms, early planted beans look pretty powerful this year! In a recent conversation with Dr. Jim Specht, he was sharing how he was anticipating really high bean yields. Upon asking him about that and also about the smoke/haze, he shared that he didn’t think it would have much impact on soybeans compared to corn. This is because soybeans are C3 crops where the photosystem saturates out at lower solar radiation levels; C4 crops like corn don’t, thus cloudy/hazy days have more impact on corn. The high humidity we’ve experienced has reduced transpiration of crops, allowing many non-irrigated soybeans to hang on till these August rains. As I’ve looked at crops in several counties, for the most part, it’s taken awhile for beans to start turning, even in the non-irrigated corners compared to what we typically see in dry years. Here’s hoping for some nice bean yields!
York Co. Corn Grower Plot Tour will be held this Thursday, September 9th from 5:30-7:00 p.m. at 1416 Road I, York, NE. Pizza and beverages will be provided. Attendees can guess the highest yield without going over for a chance to win a $50 gas card. We’re grateful to Ron and Brad Makovicka for hosting the plot and to all the companies represented in providing entries! We hope to see you there!
Wheat: I realize planting wheat is most likely not on many people’s radar in this part of the State. Yet, after attending the wheat and alfalfa expo today, just wanted to share a few thoughts and resources for those considering it. For those seeking resources, my colleague Nathan Mueller in Saline County has dedicated a section of his web page (http://croptechcafe.org/winterwheat/) to growing wheat in Eastern NE including an email listserv that shares new information. The website has a virtual variety tour where you can view varieties and their characteristics. A new tool on the website I learned about is a seeding rate calculator that helps in ensuring correct seeding rate based on the seed weight of the lot you receive. CropWatch also has its yearly ‘wheat edition’ in September, so be on the lookout for that this month at https://cropwatch.unl.edu and you can also check out https://cropwatch.unl.edu/wheat. Key points I emphasize for wheat include: killing out volunteer wheat in a mile radius at least 2 weeks prior to planting new wheat, treating wheat with fungicide seed treatment, and ensuring proper seeding depth by ensuring enough weight on the seeder particularly when no-till planting into residue.
I realize the economics for one year don’t look great for wheat. However, looking at the bigger picture, what is the value of that wheat crop in allowing additional time for a forage or cover crop, breaking pest cycles, and giving you an additional 2-3 months-time before needing to apply herbicides for weeds like palmer amaranth? What value does the residue provide for the following year to help reduce the number of weeds and/or in conserving soil moisture for the successive corn crop?
There’s also different ways of adding wheat into an operation. There’s some who have tried double cropping with both short season corn or soybeans after harvesting wheat. There’s also been interest regarding relay-cropping wheat and soybeans on Twitter. This past year, I had the opportunity to watch a few growers in the Archer/Chapman area try relay cropping wheat with soybeans on acres that were in seed corn the previous year. Their goals included using the small grain in wheat to aid in reducing palmer amaranth pressure and to obtain greater economic benefit from harvesting both a wheat and soybean crop. The Panhandle Research and Extension Center in Scottsbluff was doing the same with wheat and dry beans. There’s a lot we’re all learning in this arena and it’s just another way, with a lot more management challenges, to consider adding wheat in a crop rotation. Perhaps the biggest thing we learned was to have a high wheat seeding rate and proper fertility to allow the heads to be more uniform with less tillers that are short (similar to if one is raising a small grain for seed).
For those not desirous of planting wheat for grain, it can be used as a small grain cover crop for weed control as well. At two field days near Clay Center this summer, some individuals from Kansas and southern portions of Nebraska talked about how they recommend wheat or barley before a corn crop and rye before a soybean crop when considering a small grain cover crop for weed control. Their reasoning made a lot of sense. Wheat and barley don’t take off growing/greening up as fast as rye does. They also don’t obtain as much biomass (which also allows for faster nutrient cycling). They found farmers felt more comfortable planting corn green into wheat compared to rye for those reasons. I have no research or experience on that, but it makes sense and wanted to share if it’s something any of you would be interested in trying next year. In a soybean situation, I still recommend rye before the soybeans for weed control because of the increased biomass, and we’ll have data from Dr. Amit Jhala and his team this winter on that.
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.
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).
Crop Update: The heat has really pushed crops along. Grateful for the reports of some rain! It’s really important to know your soil moisture levels and work for the balance of not stopping too soon vs. leaving the field too wet going into the fall/winter. The following information comes from the NebGuide: Predicting the Last Irrigation of the Season found at: https://go.unl.edu/k74n:
- Corn at Dough needs 7.5” (approximately 34 days to maturity)
- 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)
- 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)
Alfalfa and Wheat Expo: Southeast Nebraska farmers can sharpen their management strategies at the inaugural 2021 Southeast Nebraska Alfalfa and Wheat Expo. The inaugural Alfalfa and Wheat Expo is scheduled for Thursday, September 2, 2021, in Crete at the Tuxedo Park Exhibition Building. The Expo will begin at 8:00 a.m. with refreshments and exhibitor booths. The educational program starts at 9:00 a.m. and ends at 3:30 p.m. Hosts and local Water & Integrating Cropping Systems Extension Educators, Nathan Mueller, Gary Lesoing, and Melissa Bartels said more diverse crop rotations are both underutilized and undervalued. Integrating alfalfa and winter wheat into the crop rotation can provide a critical tool to mitigate extreme weather, improve soil health, increase corn and soybean yields, combat troublesome pests, increase flexibility in manure management plans, and more. This new expo will help farmers prepare to grow these crops for the first time or fine-tune the skills of experienced alfalfa and winter wheat growers. Speakers and panelists will address important issues for southeast Nebraska farmers and allow for great one-on-one discussion with local private industry exhibitors and sponsors. The Expo is free to attend including lunch, but pre-registration is requested by August 31. For more info. and to pre-register, please visit https://croptechcafe.org/alfalfawheatexpo or call the Saline County Extension office at 402-821-2151.
Renovating Lawns in the Fall: August 15-September 15 are the best times to seed cool season grasses. 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.
Sarah Browning, Extension Horticultural Educator shares, “Late summer or fall fertilization of Kentucky bluegrass and tall fescue lawns is the most important time to fertilize these cool season grasses. Fertilizer applied now promotes recovery from summer stress, increases density of thinned turf, encourages root and rhizome growth, and allows the plant to store food for next spring’s growth flush. On older lawns, those that are 10 to 15 or more years old, that typically need only two fertilizer applications a year, make the fall application in late August or early September using fertilizer with all or some slow-release nitrogen. On younger lawns, two fertilizer applications during fall are recommended. Make the first one in late August or early September, and the second in mid to late October. For the first one, select a fertilizer with all or some slow-release nitrogen. For the later application, use a fast release nitrogen source so plants will take it up before going dormant.”
Other lawns can be improved via overseeding or total renovation. If overseeding is needed to fill in thinned areas but more than 50% of good turf remains, mow the existing grass 2.5” tall to make the soil preparation easier. For lawns needing total renovation, start with a glyphosate (Roundup application) followed by waiting at least 7-10 days to kill the lawn. Mow dead vegetation as short as mower goes to then prepare the soil for planting.
To prepare the soil for seeding, it’s helpful to aerate the lawn making three passes. Watering a day or two beforehand can make the aerification easier. The full seeding rate for turf-type tall fescue is 6-8 lbs./1,000 sq.ft., and 2-3 lbs. for Kentucky bluegrass. When overseeding into an existing lawn, the seeding rate can be cut in half. Drilling the seed is perhaps easiest for a total lawn renovation. Otherwise, use a drop seeder to apply the seed (not rotary ones as the seed is too light to spread evenly). Make sure to seed half the seed north/south and the other half east/west to ensure even distribution. Then lightly rake in the seed to ensure seed to soil contact. Starter fertilizer is helpful for new seedings where the total phosphorus is 1 to 1.5 lbs/1000 sq. feet. It’s also important to keep the top ½ to 1” of soil moist as seedlings germinate. Thus, it may requiring watering several times a day the first two weeks, depending on temperature and moisture. As seedlings develop, reduce the watering schedule to allow root development. When the grass is tall enough to mow, reduce watering to only 2-3 times/week with deeper watering. Mowing as soon as the grass allows encourages tiller development and thicker new stands.
God, I’m so grateful that we can come before Your throne to receive mercy and find grace to help in time of need. My heart is so broken for the situation in Afghanistan…I’ve struggled for words. The news…the photos and video footage…all just glimpses into the horrible truth that lies there. I’m just so grateful when there’s nothing else I can do that I can come to You in prayer for this situation.
Please God, be extra close to the women, children, all those individuals who helped our military, all those who converted to Christianity, all those who may in the future, all the Americans trapped there. I can’t imagine what they’re all going through…can’t imagine what they’re facing and fearing…Please help them to know You can be their refuge and strength, helper and deliverer in the midst of all the turmoil. Help them to experience Your love, peace, comfort in this midst of this storm. Please be with all those helping with evacuations, all the pilots in the rescue efforts and the trauma they must be facing and living with, all their families who are supporting them…I just don’t have words…as I cry out with tears, I just can’t imagine this entire situation. Please God, raise up leaders in Afghanistan willing to fight for their country to take it back. Thank You God for being a God who knows, sees, hears!
And God, my heart goes out to all our military members and their families…the sacrifices made, the prices paid, all those still serving there aiding in evacuations. So many different experiences and perspectives. Please God, be with them all. Help each one, especially now, not to isolate, but to reach out and talk to someone. Help them to find peace in their purpose even now. And please God, protect our military members who will be the last out whenever that occurs.
God, I don’t understand Your sovereignty yet I’m so grateful You’re in control and I’m not. I’m so grateful Jesus already defeated death and the grave and will one day reign victorious! Please let me…let all who put our hope and trust in You rest in that hope…for that’s the true hope we have in the midst of so much brokenness on this earth. I’m so grateful You allowed me to live in the U.S…so blessed to live in this Country…broken, but still the greatest nation in the world. Please God, heal our land and divided nation. Please be with all our Government leaders, help them seek Your face and give them wisdom and discernment. Please continue to be with our military and their families.
Thank You God for how You’re working…in the ways we can and cannot see. Thank You for the comfort You provide when I come to You in pouring my heart out to You! I thank You for all this and pray this in Jesus’ name, Amen.8/16/21. Updated as I continue to pray. Shared in the event it could help anyone else and for those who’ve asked for thoughts. Ultimately, we can pray and we can reach out to veterans and their families to see if they would like to talk.
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.
Thank You to all the volunteers; ag society and 4-H council members; Extension staff; and all the youth and families who made the 2021 York and Seward County Fairs successful! It was a joy for me to see ‘normal’ fairs, youth and adults excited to find their projects and show their ribbons, the number of people out attending activities, walking through buildings, and just talking with each other!
Crop Update: Thanks also to the crop consultants and ag industry agronomists who dropped off samples during fair and kept me in the loop with what you were seeing in the fields! Southern rust was also confirmed in Hamilton and York counties this week. Frogeye leaf spot is also showing up on some soybeans with the high humidity and dew on soybean leaves.
Many have asked why the crops aren’t using much water. ET is evaporation from soil and leaf surface + transpiration (process of water lost through leaf stomata) from the crop. The high humidity has kept plants wet, especially soybeans, longer during the day (which is why I think the soil moisture use has been showing up less on soybeans than corn). I know many, including myself, have been trained that crops automatically remove 0.30”+ a day upon tassel and flowering, but that’s just not true. That thinking doesn’t account for the environmental factors at play which change every day of every year. Higher ET occurs on sunshiny days with high heat, higher wind, low humidity. Cloud cover, humidity, and low wind all reduce ET (and we’ve had a lot of these lately). As I’ve worked with farmers through the years, I’ve heard many say how helpful their ET gage was, because it’s such a visual representation of what’s going on with the environment and crop water use. If you don’t have an ET gage, the UBBNRD is sharing daily crop water use from the High Plains Regional Climate Center via email, so you can contact Marie there if you would like this info. each day. Thankfully, the humidity has allowed non-irrigated crops to hang on longer, due to lower crop water demand, in spite of the humidity being harder on us and animals.
Pollination: I realize there’s pockets of really good looking corn out there. And, I also realize that a lot of corn may look good from the road, but there’s concerns and questions about pollination and tip back in fields. As I think about when pollination occurred, the smell of pollen was thick in the air some mornings, and even early evenings when pollen shed was delayed from high humidity. Many fields I walked into had ample pollen shed. There’s a range of pollination dates in the area, so heat/humidity could have played a role for your specific fields. Dr. Tom Hoegemeyer shared the following about high heat and humidity during corn pollination in a CropWatch article, “Just a day or two difference in flowering, or planting, or other factors can make a substantial difference in (kernel) set. Stress during pollination and silking could result in shorter ears, increased tip back and fewer kernels per ear. All of these contribute to less yield potential.”
- When soil moisture is sufficient, one day of heat over 95-98F during pollination has little to no yield impact. After four consecutive days, there can be a 1% loss in yield for each day above that temperature. Greater yield loss potential occurs after the fifth or sixth day.
- Heat over 95°F depresses pollen production. Prolonged periods of heat can reduce pollen production and viability (ability of pollen to fertilize silks).
- High humidity helps reduce crop water demand. High humidity, without a drop in humidity during the day, can delay pollination or prevent pollen from leaving anther sacs. “The process of releasing the pollen from the anthers is called “dehiscence.” Dehiscence is triggered by the drop in humidity, as the temperature rises. However, when it is extremely humid and the humidity falls very little, dehiscence may not occur at all, or it may be delayed until late in the day. If one has breezes, while the humidity is still very high, the anthers may fall to the ground before pollen is released.”
I also think about what I’ve seen the past few weeks with all the silk balling, pollination misses, tip back, and what’s being shared with me by others in the field. The July 9 wind event that hit a portion of this area seems to have impacted plants more greatly that were within 1 week of tasseling. With the resources it took to right plants in developing additional brace roots, thickened nodes, etc., I wonder how much of the resources that would’ve been put into “normal” pollination were used for these other purposes instead and how that may have impacted pollination timing, silks pushed out of husks, etc.? A number of agronomists are reporting abnormal ear development they’re seeing in addition to pollination misses and tip back of various levels. This is what’s known from the research regarding wind impacts to yield on lodged plants (however the specific causes of the yield losses are not mentioned):
- Research found lodged plants after a wind event had yield reductions of 2-6% (V10-12 stage), 5-15% (V13-15 stage), and 12-31% (V17 and after stages).
- We’ve also personally observed yield losses greater than this due to abnormal ear development on lodged plants in the area after wind events.
Regarding tip back, it’s important to count kernels long as there may be more kernels than one realizes in spite of tip back occurring. Tip back on corn occurs most often from some sort of stress. One can tell the approximate timing of stress events by the appearance of the kernels. If kernel formation isn’t evident, the stress occurred before or during pollination. If kernels are very small or appeared to have died, the stress was after pollination as the kernels were filling. Japanese and rootworm beetle silk clipping can impact tip pollination. We’ve also had high heat with humidity since pollination in addition to cloudy/hazy days and I haven’t dug into the weather data yet. Hopefully this helps a little for the questions received thus far.
Reminder of the Seward and York County Fairs this week! August also brings the season of field days! Soybean Management Field Days will be held next week at various locations in the State from Aug. 10 to Aug. 13. The closest to this part of the State is Aug. 12th near Rising City at the Bart & Geoff Ruth Farm. More info. at: enrec.unl.edu/soydays.
Corn Update: I realize this week’s column shares lots of problems seen in the field last week. My goal is always to increase awareness, but sometimes it feels ‘heavy’ hearing about the problems. Grateful we’ve had few problems overall this season till now! The high humidity has allowed non-irrigated crops to hang on and crops in general to not use as much water as anticipated for crops at this stage. In general, fungal disease is still low in fields. I’m starting to see baby lesions that will most likely become gray leaf spot around mid-canopy, so that will be something to watch in coming weeks. Spidermites have also been flaring above the ear in some fields, particularly non-irrigated.
For our area of the State, southern rust has been confirmed in Adams, Nuckolls, Thayer, Gage, Saline, Clay, and Fillmore counties. There are probable samples at time of writing this for Seward and Jefferson counties (https://corn.ipmpipe.org/southerncornrust/). In all the samples, incidence and severity were very low. Many are being found around waist-high in the canopy. Three samples I confirmed last week were from fields that had already been sprayed and the pustules were found mid-canopy. This happens every year, regardless of the residual applied in the first application. I know a couple farmers who have paid a little extra to have the aerial applicator increase gallonage from 2 gal/ac to 3 gal/ac. They felt that aided in coverage a little further into the canopy. For those with chemigation certification, I also know several growers who chemigate their insecticide and/or fungicide effectively, which allows for better plant coverage into the canopy (as long as pivot doesn’t have drop nozzles below canopy).
I really enjoy observing what occurs with plants, yet I honestly don’t know anyone who wishes to see abnormal corn ears, especially after wind events such as July 9. I feel it’s important to observe and document what occurs on these plants that bent and didn’t break. The goal is awareness to know what type of ear development exists so there’s not such a surprise at harvest if yields are off, and to be aware when working with your crop insurance agent. There’s unfortunately some ugly looking ears out there. Some similar stress events occurred this year comparable to 2016, minus the drop in temperature prior to the wind event. I’m not seeing anything yet to the level like what we saw in 2016, which is encouraging. What I’m seeing ranges from row abortion above where the ear stress occurred to torpedo and banana shaped ears to pinched areas on ears including various forms of ‘barbells’. Finding greater damage in fields where the plants were within a week of tasseling when the wind event occurred. It also appears like those fields that were 2 weeks or more from tasseling at the time of the wind event aren’t as impacted. For growers that had plants that blew down or leaned and then righted themselves but didn’t break, it’s wise that you and/or your agronomist are checking ear development on them. Each field can be unique depending on stage of development the particular hybrid was in at the time of the wind event. Pictures of what is being observed are at jenreesources.com.
Soybean Update: Received a number of calls regarding poor-looking patches in soybean fields this week. Drought stress is showing up in non-irrigated fields. Be checking those areas for spidermites as well. If they’re present, I tend to find them towards the edge of the patch between the impacted area and what appears to be healthier beans. White mold in soybeans is something that’s becoming more common in counties such as Butler. It can have patterns such as several plants in a row impacted and/or a patchy area in the field. The plants will have a white cottony fungal growth on them and eventually the stem (upon splitting) has black fungal structures that look like mouse droppings in them.
Sudden death syndrome (SDS) and/or brown stem rot are also showing up in small patches of fields where the leaves have a chlorotic/necrotic look between the veins. The humidity has allowed the blue/gray fungal growth characteristic of SDS on the rotted taproots to be observed even mid-day. If you split the stem and the pith is brown, the culprit is most likely brown stem rot; if it’s not but the taproot is rotted and you can easily pull it from the soil, it’s probably SDS. Plants can sometimes have both diseases. All of these are soil-borne fungal diseases and there’s no control measures for this time of year. It would be wise to pull 0-8” soil samples to check for soybean cyst nematode in areas of fields you’re finding SDS and brown stem rot in. Dectes (soybean) stem borer tunneling can be confusing when determining dectes vs. brown stem rot. At this time of year, I don’t typically see dectes moving far (more than 1-2″ either direction) from the initial point of hatching near the petiole. This is in comparison to brown stem rot which would have browning of pith from soil line. Dectes also will not kill plants (just create conditions for lodging and breaking off near harvest). This is because the vascular bundles of soybeans are found on the outside edge and not in the center of the stem. Thus, death of plants this time of year are due to another cause.
Two examples of shortened husks on developing ears. Husking back these ears often shows a pinch point that occurred during the windstorm resulting in jumbled kernels.
Last week I heard several mention close calls on gravel roads. Please, slow down/stop before crossing unmarked intersections, fully stop at marked ones, and please remind young people of this too.
Crop Update: Keep watching silk clipping on corn that’s pollinating; rootworm and Japanese beetles clipping silks to ½” long triggers treatment thresholds. Southern rust was found in Nemaha and Greeley Counties last week from two samples at low incidence and severity. You can view updates at: https://corn.ipmpipe.org/southerncornrust/. Consultants and farmers with suspect samples are welcome to get them to me as in the past, or send to the Plant and Pest Diagnostic clinic in Lincoln. I’ve only seen gray leaf spot on the lowest leaves of fields last week so far, so disease is currently very low.
South Central Ag Lab Field Day: Reminder of this field day near Clay Center this week on July 28th which will cover nutrient, insect, disease, and weed management topics in addition to irrigation, cover crops, and biomass ones. There was a press release from UNL that had the wrong date, so just want to make sure those in the area interested in attending are clear that this will be held on July 28th from 8:45 a.m.-4 p.m. (Registration at 8:30). More details and registration at: https://enrec.unl.edu/2021scalfieldday. Walk-ins are also welcome; we just ask for pre-registration to aid in meal planning purposes.
Workshops on ag land management, leasing, carbon credits: Nebraska Extension and the University of Nebraska-Lincoln’s Center for Agricultural Profitability will host a land management workshop. It will offer updated leasing information relevant to landlords and tenants, including the latest financial trends in Nebraska agriculture, updated land values and cash rental rates for the state, strategies for equitable leasing and farm succession considerations. The latest information on carbon credit contracts for ag producers and landlords will also be discussed. The presentations will be led by Jim Jansen, an extension educator and agricultural economist, and Allan Vyhnalek, an extension educator specializing in farm and ranch transition and succession. The meeting is free to attend with meal sponsored by People’s Company, but registration is required. Locations include:
- July 28, 10:30-1:30 p.m., Extension Office, Columbus, Reg. 402-563-4901.
- Aug. 2, 10:30-1:30 p.m., Fairgrounds, Auburn. Reg. 402-274-4755.
- Aug. 3, 10:30-1:30 p.m., College Park, Grand Island. Reg. 308-385-5088.
- Aug. 17, 10:30-1:30 p.m., Extension Office, Lincoln. Reg. 402-441-7180
- Aug. 18, 9-Noon, Extension Office, Wilbur, Reg. 402-821-2151
Leaf Drop in Trees: Still receiving questions on this. For leaves such as Linden and Birch trees that have a lacy appearance of feeding on them, this is due to Japanese beetles. We hopefully are on our last week of them. For crabapple, flowering pear, ash, maples whose leaves are turning yellow/brown and dropping, this is due to fungal diseases and we wouldn’t recommend you do anything for this either. Next week I’ll talk about iron chlorosis and treatments for trees.
Brown Leaves on Oak Trees: Browning on leaf margins of individual leaves is anthracnose, which is a common fungus of shade trees. We don’t recommend that you do anything for this.
The past few years around fair time, we’ve seen oak trees (but sometimes others such as hackberry, honeylocust, elm, linden) that get a cluster of brown leaves towards the ends of branches. This damage is caused by twig girdlers or twig pruners, different types of beetles. Basically, the adult beetles chew a circle in the bark between where the old and new wood occurs on a twig. This girdles the twig, cutting off the water and nutrient supply causing its death. Eggs are then deposited and larvae hatch, tunnel, and survive in the dead twigs. Twigs girdled by any of these insects may stay attached to the main branch for several weeks or be broken out of the tree by wind. Tunneling in the twigs may not be evident in the fall if twigs fall out of the trees before the insect eggs have hatched. Mature trees with heavy infestations can look bad, but the damage isn’t a serious health problem to the tree and no chemical control is recommended. You can burn or discard infected twigs in the fall and spring that contain developing larvae to minimize the impacts for the future.
Crop Update: Grateful that in general (beyond seed corn), greensnap levels were lower for the widespread area compared to what we saw in 2020. It appears many fields with leaned plants have been working to right themselves with brace roots growing like crazy to help stabilize plants. Ear development on bent plants will be something to watch going forward. With plants bending in the wind instead of breaking, sometimes extra stress occurs where the ear is developing. Sometimes we see ear abnormalities and sometimes the ears are fine. With fields with severe bending, once the plant reaches tassel, it will no longer try to right itself and will switch to putting resources into the ear. For those with storm damaged fields who were originally planning on more nitrogen through the pivot, last year we took tissue samples to assess that need.
For fields with uneven development with plants ranging from vegetative stages to tassel, particularly storm damaged and uneven emerging fields, one needs to be aware that various adjuvants added to an insecticide and/or fungicide application pre-tassel can cause ear abnormalities.
So, the conversation with those at western bean cutworm thresholds with only portions of fields tasseling was to consider not adding the adjuvant (the same applies for those applying fungicide). I wasn’t sure how efficacy would be for different products without them (that would be a conversation for the chemical reps), but we know that adjuvants such as non-ionic surfactants can cause ear abnormalities when applied pre-tassel.
Also had several conversations regarding foliar fungicide applications. Fields have very low disease pressure right now with bacterial leaf streak being the most prevalent, and a fungicide won’t help with it. Gray leaf spot is very low in fields. Southern rust has been found in a few counties in mid- to southern- Kansas. It has not been found in Nebraska. You can view the tracking map at: https://corn.ipmpipe.org/southerncornrust/. Yield increases with automatic VT applications aren’t consistently proven in Nebraska. The following are fungicide timing studies conducted in Nebraska.
In 2008-2009, a UNL fungicide timing trial was conducted near Clay Center on 2 hybrids (GLS ratings ‘fair’ and ‘(very) good’) with a high clearance applicator. Timing over the two years included: Tassel, Milk, Dough, 25%, 33%, 50%, and 100% Dent comparing the fungicides Headline, Headline AMP, Quilt and Stratego YLD.
- 2008: No yield difference on GLS hybrids rated ‘good’ at any of the timings (Tassel, Milk, 33% and 100% Dent) nor the check when Headline or Stratego YLD were applied. For the ‘fair’ hybrid, no yield difference for any application timing nor the check for the April 30th planting except for Headline applied at milk stage (increased yield). Low gray leaf spot pressure.
- 2009: No yield difference on GLS hybrids rated ‘very good’ or ‘fair’ nor the check on any timings (Tassel, Milk, and Dough) using Headline, Headline AMP, or Quilt. Moderate gray leaf spot disease pressure.
In 2020, Dr. Tamra Jackson-Ziems and her team did another fungicide timing trial at UNL’s South Central Ag Lab near Clay Center. Fungicides were applied at planting, R1, or R3. There were no clear yield differences between applying foliar fungicide at R1 vs. R3 for any of the products except Miravis® Neo. Sometimes a product didn’t show a difference between other products or even the untreated check. There’s a picture of the data at jenreesources.com. Hybrids vary in disease susceptibility (thus response to fungicide application). With last year being a heavy southern rust year, being able to wait till at least R3 (milk) to apply a fungicide provided some additional time for the residual to work when southern really came on. I know some had to apply a second fungicide application when they automatically applied at R1. That’s just tough from an economic and resistance management perspective, in spite of higher corn prices. Thus, why I recommend waiting until disease pressure warrants the application. The main ‘plant health’ benefit observed in Nebraska when disease pressure was low (ex. 2012) was stalk strength.
July 28 South Central Ag Lab Field Day will be held from 8:45 a.m.-4 p.m. (Reg. 8:30 a.m.), near Clay Center. For all those who’ve talked with me about planting green into rye, there’s an excellent study by Dr. Amit Jhala and grad student Trey Stephens. They compare the same herbicide program with rye termination 2 weeks prior to planting or 2 weeks after planting in both corn and soybean. It was really interesting to visualize the differences in May and I’d encourage anyone interested to take a look at this now in July. Additional topics include disease, insect, and nutrient management, cover crops, and irrigation. You can RSVP at https://enrec.unl.edu/2021scalfieldday