JenREES 7-12-20

Wind-damaged Corn: The evening/early morning hours of July 8-9 caused quite a bit of IMG_20200709_105000damage to corn fields for some of you reading this. It’s always hard to see crop damage. For field corn, it came at a critical time prior to pollination. The severity and amount of recovery for every field situation will vary depending on the soil moisture at time of the wind, root mass structure, hybrid planted, severity of leaning/bent/snapped plants, and growth stage of the plants. It will also depend on where the bending and snapping of those plants occurred. ‘Recovery’ encompasses the plants righting themselves, re-establishing roots, and re-orienting leaves as they have the ability to bend and grow up towards the sunlight in areas of the plant where plant tissues were not yet lignified (hardened). We know hybrids have been bred to better withstand greensnap. We know that plants that are leaning due to root lodging may have better ability to upright themselves (and have seen this in some fields since the storm). We also know that it is harder for plants near tasseling to upright themselves compared to plants at earlier vegetative stages.

What to expect? It really depends on the conditions outlined above. We all will learn a lot and I encourage us to share what we are observing. For fields very close to tassel with severe bending near ears, we may see pollination, possibly even ear formation issues. There may be fields that were leaning and will have minimal impacts after uprighting themselves. The main research I can find regarding corn lodging yield impacts comes from the University of Wisconsin in 1988. In the study, they manually lodged corn at various growth stages over 2 years to determine yield impacts. Corn lodged at V10-V12 resulted in a yield reduction of 2-6%. Corn lodged at V13-15 resulted in a yield reduction of 5-15%. Corn lodged after V17 resulted in a 12-31% yield reduction.

What to do? Recommend waiting, observing, call your crop insurance adjuster. Don’t apply products right now. Economically, we need to see how each field recovers before putting more into the crop. Plants are already stressed so give them time to try to recover. A respected agronomist shared another point with me-that adding heavy amounts of water right now can add weight onto the plants and keep them sticking together when they’re trying to separate. For those who were planning on fertigation, I’ve seen soil sample results and heard from several people that we’re seeing increased mineralization this year in fields due to the heat. It may be worth a tissue and/or soil test to see if you really need additional nitrogen (final application at brown silk). Regarding fungicides, my recommendation prior to the storm was to wait till at least brown silk (or after) due to low disease pressure, uneven growth stages in fields, waiting for southern rust, and economics; I stand by that after this storm. Fungicides can’t help much with the plant stress being experienced.

Spidermites have been found in low levels in corn, but in some cases, fairly high levels in soybean. Higher levels have been observed in stressed fields (due to off-target herbicide damage and/or beans stressed due to drought). If you’re noticing pockets in fields that appear to be yellow/brown/dying and spreading, check the top side of the leaf for stippling (yellow needle-like pin-pricks) and undersides for webbing and mites. Seeing them in non-stressed beans at low levels as well. Check out this information from Illinois for guidelines on when and how to control: http://bulletin.ipm.illinois.edu/?p=5080.spidemite tweet

Gardening Resources: Nebraska Extension is hosting a series of 12 virtual learning sessions for home gardeners to discuss timely issues around vegetable gardening and trees. Each session will include a short (15-20 minute) presentation on the specified topic and opportunities for participants to chat about their issues and “ask the expert”. Sessions will be each Tuesday through September at 7 p.m. CST. Participants can register via go.unl.edu/grobigredvirtual – you can register for all the sessions you’re interested in at one time. You can also view the series via this Facebook post: https://www.facebook.com/events/1195072680839800.

grobigred series

Japanese Beetles

Japanese Beetles: Areas of the State have seen Japanese beetles for a few weeks. They’ve shown up strong in the York/Seward county area this past week with the number of calls I’ve received.

Unfortunately they cause two problems. The larvae are grubs that can impact our lawns. IMG_20200702_085759The adult beetle is ½” in length with a metallic green head and white ‘tufts’ that look like spots on its abdomen. Adults emerge from grassy areas like lawns, ditches, and even fields; however, they don’t emerge at the same time. They emerge over a 4-6 week period beginning in late June and last for around 4-6 weeks. There’s one generation per year. Adult beetles feed, mate, and lay eggs in lawns and grassy areas. The eggs hatch 10-14 days later into grub larvae and feed on turf and grassy areas in the August time-frame. They also over-winter in turf and grassy areas.

Adults feed on 300 plant species, but their favorites are ones that are in many of our

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Japanese beetles making quick work of my knockout roses. In this garden area, they are also impacting my cannas but not my lillies, beesbalm, salvia, milkweed, or sunflowers.

landscapes (roses, cannas, marigolds, grapes, Virginia creeper, and trees such as lindens, birch, Japanese and Norway maples, cherry, plum, peach, American elm). They also feed on soybean and corn crops. They love hot weather and full sun and feed on leaf tissue during the day (leaf tissue will look skeletonized or lacy and turn brown). Trees may be severely impacted with browning occurring from the top to bottom. Thankfully healthy trees will re-leaf next year since the underlying twigs and branches aren’t damaged-even if the entire canopy is impacted this year. It’s not recommended to remove branches or trees.

DO NOT use Japanese beetle traps!!! Research shows they attract beetles to the landscape and many homeowners I’ve talked with will attest to this!

Beetle Control: Wait till dusk (7-9 p.m.) before trying to control beetles as they are less

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One control option: Wait till 7-9 p.m. then drown Japanese beetles in soapy water after removing them from plants. This method of control takes diligence over several nights.

active then and to reduce impact to pollinators. Organic means include hand-removing beetles by knocking them into soapy water. You can also spray trees with water to knock them down to the ground and then drown in soapy water. This takes diligence over many days. With heavy beetle infestations, it’s not uncommon to literally have scoop shovels full of the beetles when removing from trees. Neem and Pyola are two organic sprays that will protect for 3-7 days. Applying these products regularly (once per week) can also be effective as a repellent.

Japanese beetles often impact the same flowering plants that other pollinators visit. Use insecticide products correctly to avoid damage to pollinators. Avoid spraying insecticides on windy days or when pollinators are present (best to spray late in day near dusk) and be sure to read and follow all label instructions and harvest intervals (for cherries, plums, etc.). Conventional insecticides can provide 2 weeks of control: pyrethroid products like Tempo and Bayer Advanced Lawn & Garden Multi-Insect Killer (cyfluthrin) or Ortho Bug B Gone (bifenthrin). Sevin (carbaryl) is another option although more dangerous for bees.

Grub Control: Turf damage can be evident in Aug./Sept. Products that control common white grub can also provide control of Japanese beetle grubs and should be applied mid-to-late June. Dylox can be used as a rescue treatment if grub control is needed later on and no grub products were applied in the spring.

Next Year: Systemic products like imidacloprid can be used as a soil drench around plants (apply around Mother’s Day). These products can’t be used on Linden trees. You may also wish to swap out more susceptible plants for those less susceptible as you observe which plants they tend to impact most in your backyard.

Also seeing green June beetles and this shows the difference between them and Japanese beetles. Green June beetles don’t have the same impact on leaf damage. They do lay eggs in turf which become grubs as well.

green june beetle vs japanese beetle-purdue

Green June Beetle (left) and Japanese beetle (right). Photo via Purdue Entomology.

Click to access Japanese%20Beetle%20Tips%20and%20Tricks.pdf

JenREES 7-5-20

Corn: Corn plants are rapidly growing and at or nearing tasseling soon. One sign of rapid

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Wrinkled/wavy leaf edge symptoms of rapid growth of corn.

growth is to look at the new leaf edges. Sometimes there will be a white margin, more transparent look, wrinkles, or notches in them. All of those are signs of rapid growth which take place during cell division.

Fertigation and Irrigation: Some fertilizer is occurring now before tassel. I also recommend 30 lbs of N at brown silk if needed. This is based on research from Purdue University sharing today’s hybrids use 30-40% of their total Nitrogen from flowering through maturity. In the past, some have asked about applying fertilizer during pollination. The following information is from Dr. Tom Hoegemeyer, Plant Breeder and UNL Professor of Practice Emeritus, “Pollination mostly occurs between 8:30 a.m. and Noon. Thus, as a precaution, I would not run a pivot on pollinating corn from 6 a.m. to Noon. When the temperature is 90°F to 95°F, the pollen is killed by heat and is seldom viable past 2 p.m. That leaves lots of time to run pivots, apply N, etc. when it won’t harm pollination. Silks tend to be viable for three or four days at these temperatures, so if a plant isn’t pollinated one day, generally the next day will work just fine. (If nitrogen is needed), I’d recommend that nitrogen go on as soon as practical. Corn nitrogen use is very high during the pre-tassel growth phase and again at kernel growth, from one to three weeks post pollination. About seven to ten days post pollination (before brown silk) lower N will start causing kernel abortion and serious yield loss in corn.” The UNL recommendation for fertigation is to use 30 lb of N with 0.25″ of water or 50-60 lb of N with 0.50″ of water.

Insects and Diseases: Thus far, insects and diseases have been pretty minimal in corn. Seeing some spidermites in low numbers. Japanese beetles are showing up in areas where they’ve traditionally been more of a problem. In corn, the threshold is 3 or more beetles per plant, clipping silks to ½” or less, with pollination less than 50% complete. The hard thing about the beetles is they have a long emergence of 3-4 weeks where they don’t all emerge at the same time…and they live as an adult for 3-4 weeks. The threshold for corn rootworm beetles for silk clipping is similar. Light trap data for western bean cutworm is showing moths are beginning to appear in low numbers. They prefer laying eggs on upper leaf surfaces of corn in late whorl stage to early tassel (however, I’ve seen them lay eggs on the underside of leaves and on leaves closer to developing ears in high heat). The current UNL economic threshold for treatment is 5-8% corn plants with eggs or larvae.

And, often there’s discussion about fungicide applications at tassel time or throwing in a

Primordial tips

Corn ears with primordial tips looking like this are just one of several abnormalities (including ear abortion, barren plants, bouquet ears, pop-can ears) that can occur when NIS is applied to corn plants from V10-VT.

fungicide with an insecticide (or vice versa) to save an application cost. I shared a great deal about this a few weeks ago; please be very careful with growth stages and what is applied in the tassel time. With uneven emergence, not all plants in the field will be tasseling at the same time, which allows for corn ear abnormalities when NIS in particular is added to the tank (or is in the product formulations) and applied just prior to tasseling. That’s why I prefer to see fungicide applications delayed to at least full brown silk and preferably later if there’s no disease pressure to warrant the application.

Research at UNL South Central Ag Lab showed we can still apply fungicide to dough stage with no yield difference, particularly in low disease pressure years. The research also didn’t show an automatic yield increase with tassel applications. This allows us to account for southern rust which has occurred at some point all but two years of my Extension career. With tight economics, it just makes more sense to me to delay fungicide applications to when disease warrants it vs. applying too early as some have had to repeat applications (when southern rust occurred after applying too early). It’s also just good resistance management to not apply when disease and insect pressure doesn’t warrant it. Also be aware that we can see corn leaf aphids flare after fungicide applications as the fungicide kills a natural fungus that keeps their numbers in check. Aphids also can interfere with pollination by covering tassels.

Soybeans: As soybeans approach R3 (beginning pod), that’s the critical time to avoid

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Japanese beetle on soybean. Japanese beetles can be identified by their metallic green heads and white tufts of hair on the abdomen that look like white spots.

water stress in soybean (similar to tassel for corn). We recommend avoiding irrigating during flowering whenever possible to reduce disease pressure (such as white mold and SDS). Don’t pull insecticide triggers too early for soybean defoliators. UNL recommends 20% defoliation at reproductive stages from all defoliators.

JenREES 6-28-20

Independence Day: As we approach July 4th this year, I can’t help but think how

Large flag hanging from cranes displayed at the 9/11 10 year remembrance ceremony in Omaha.

different it may be on many levels, particularly from all that’s occurring in our Country. Our flag is one of the most beautiful things to me because it represents so much…many willingly put their lives on the line for my freedom and freedom for all of us…many dying to do so. The flag and patriotism, gratitude for this Country, those who serve(d), and families left behind means much to me (most likely to many of you as well). My hope and prayer is that this Independence Day also provides an opportunity for families to talk about our independence, freedoms, patriotism, respect, and that freedom isn’t free. I hope that in spite of all the challenges and division occurring that we would pause, remember, and be grateful that we live in the greatest Nation in the world! We are so blessed!

July 4th Food: To ensure you’re staying safe from food-borne illness and for fun family recipes, check out this information from our Food experts: https://food.unl.edu/july-food-calendar#4th!

Crop Update: Corn and soybean have been rapidly growing in spite of having difficulty in closing canopies this year. Dr. Roger Elmore shared a paper with me on high winds altering corn leaf architecture (will share more next week). So it may be part of what we’re seeing in addition to hybrid differences? Many continue to contact me about bacterial leaf streak and there’s nothing outside of hybrid tolerance to do for it. Seems like hail occurs weekly in some part of the State. Resource: https://cropwatch.unl.edu/hail-know/assess-my-damage.

Chiggers: For whatever reason, chiggers, ticks, mosquitoes all find me. There’s all kinds of information/hypotheses available as to why some people tend to get bites more than others. Never have chiggers gotten me as bad as this year! As bites tend to peak around the 4th of July with more families outdoors, here’s some things to consider. Chiggers (also known as redbugs or jiggers) are the immature stages of red harvest mites. They tend to hang out in moist, tall grassy/weedy areas such as along streams, road-side ditches, forested areas, lawns. But they can also hang out in moist and dry lawns with a lot of trees too. They bite humans and other animals including pets. Eggs are laid on clusters on plants and the larvae hatch and wait for their host to come along. They latch onto clothing, shoes, and fur and can hang on while working their way to the skin (often to an area where clothing is tighter like around socks, undergarments, back of knees and under armpits). They actually don’t burrow into human flesh. They only survive on a warm-blooded host for around 3 days before falling off to molt for the next stage in life cycle which doesn’t feed on humans.

They have needle-like mouthparts that allow them to pierce the skin then inject saliva that dissolves body cells in the area to aid them in feeding. Thus, they don’t feed on blood but liquefied cells. The feeding creates an allergic reaction in which many see swelling, intense itching, and small, clustered, red bumps (which can become larger welts in some). To prevent chigger bites, avoid sitting or lying on the ground when picnicking or working outdoors. Wear loose-fitting clothing and apply a repellent like DEET to shoes, socks, and pants before going into areas more favorable for chiggers. It’s also wise to take a hot shower with plenty of soap as soon as possible after being outdoors and launder clothing with hot water before re-wearing. Also launder any blankets/sheets being used outdoors. If you receive bites, rubbing alcohol can be used then apply an anti-itch cream to help reduce itching. Thankfully chiggers can’t live in the home but they can become dislodged in bedding and on floors, so laundering bedding and vacuuming is also wise.

Keep lawns and shrubs well-manicured, particularly where adjacent to dwellings. If you tend to have problems with chiggers in your lawn, they can be reduced from 75-95% for several weeks with a liquid treatment of bifenthrin. Be sure to read and follow all label instructions.

JenREES 6-21-20

Crop Update: The National Weather Service in Omaha shared that it’s been the 2nd hottest June on record (150 years) and the 2nd windiest June (72 years). It’s truly taken its toll on people, plants, and animals. It’s also resulted in increased stress levels with much to be done (spraying, hilling/cultivating, fertigating, changing herbicide plans, etc.) as crops rapidly grow.

June records

Tweet from NWS Omaha on June 17, 2020.

Since the Memorial Day rains, I’ve observed bacterial leaf streak (BLS) on corn in fields.

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Bacterial leaf streak on susceptible hybrid this past week.

BLS has long, narrow, red/brown colored lesions that follow leaf veins. The lesions also have a yellow halo when backlit. Upon close examination, the lesion edges are wavy, which differentiate it from gray leaf spot. It started fairly minor, but some more susceptible hybrids are showing higher levels of lesions right now. There’s also been a number of whitish colored lesions on leaves from wind damage/sand blasting (if they

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Been receiving a number of questions on white-colored lesions on leaves. Some are just due to wind damage. Some situations are herbicide related. A number of people are starting to notice BLS developing from these damaged areas on the leaves, particularly on more BLS susceptible hybrids.

weren’t due to herbicide situations). It’s from some of these wind damaged areas that BLS is also occurring. The bacterium causing BLS can infect directly through stomata; however, it can also infect through wounding. So the wind-driven rains and also high winds with sand blasting have also increased the incidence and severity of BLS in fields. Fungicides aren’t effective on it and it’s not known to result in yield loss.

Received a number of field calls/questions regarding herbicide application problems. Also recognize the challenge in figuring out a plan B, C, or D with some fields. Some practical things for those still needing to spray: know what traits are in what fields and double/triple check with whoever is spraying that the right product is going to the correct field. Double check the crop growth stage and the label as to what can be in the tank mix to avoid crop damage. Don’t go by plant height as there’s short beans that are flowering now and shorter corn in no-till and/or cover crop situations that is further along than one may realize. Proper tank/boom/nozzle cleanout is also always important to avoid crop damage to the next field being sprayed. And, spraying in high winds doesn’t help any of us.

For irrigation, UNL research shows we can wait till 35% depletion in the top 2 feet prior to tassel or top 3 feet once tasseling occurs. There’s a number of reasons why farmers have been irrigating: applying fertilizer, activating herbicide, small/replant crops with shallow roots, softening the topsoil for brace root establishment, and some may not be needing to water. There’s an article in this week’s CropWatch by Steve Melvin regarding irrigating considerations during the vegetative stages. We have a CropWatch poll to learn where people obtain their evapotranspiration (ET info.). Please help us by filling it out at: https://go.unl.edu/wxqv. There’s also ET and GDD info. available from CropWatch at: https://cropwatch.unl.edu/gdd-etdata and the NAWMN ETgage site (ET info. only) at: https://nawmn.unl.edu/ETdata/DataMap. The recent weather has helped with moving roots down. From digging plants and watching moisture sensors, many area fields from V7-10 have roots at least at 12” and below now.

Light Trap Reports: Light trap data can aid in scouting for various moth/butterfly pests. The closest light trap reports for the area are at UNL’s South Central Ag Lab near Clay Center and the Eastern NE Research and Extension Center near Mead. You can find all the reports online for the State at: https://entomology.unl.edu/fldcrops/lightrap.

Field Days: Weed Science (Clay Center) and Palmer Amaranth (Carleton) Field Days are cancelled for this year. Dr. Amit Jhala and his team are working on ways to present the data and information virtually. Nathan Mueller shared a self-guided tour is setup at the 2020 Jefferson County Winter Wheat Variety Trials in cooperation with Brian Maust (Variety Trial Technician) and Mark Knobel (hosting farmer). It’s located north of Fairbury on Hwy 15, then east 1 mile on 716th Rd, then 3/4 of a mile north on 569th Ave, east side of the road marked with a UNL sign. You can take a self-guided tour by grabbing a handout in the realtor box at the plots. It’s asked that you not walk/damage the wheat (i.e. pulling heads) and stay in the wide walking alleys. Please bring your own hand sanitizer so you can use it after touching the realtor box. Will keep you updated on additional information regarding these and other field days as details are released.


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Also seeing low levels of woolly bear caterpillars in soybeans. This guy was moving with the wind/heat trying to get in lower canopy. Thresholds for soybean defoliation: 30% defoliation for anything defoliating soybean in vegetative stages and 20% with insects present in the soybean reproductive stages.

JenREES 6-14-20

Storm damage resources: Have had a number of calls throughout the State this week

Hail damage to soybean at the V2 stage

Soybean recovering from hail damage.

from those who have experienced hail, flooding, and/or wind damage. The warmer temperatures were helpful for regenerating plant growth after hail; however, they’re not helpful for those who had heavy rains and flooding that didn’t recede. I shared this last week too but here’s a Hail Damage Assessment resource with many videos: https://cropwatch.unl.edu/hail-know/assess-my-damage. For flooding, corn plants prior to V6 can survive under water for 2-4 days if temperatures do not exceed 77°F. From V7-V10, plants can survive 7-10 days if temperatures do not exceed 86°F. For soybeans, yield losses are minimal if flooding lasts less than 48 hours. If flooded for 4-5 days, fewer nodes develop and plants will be shorter. If flooded for 6+ days, possible stand and yield loss. The longer it takes a field to dry out, the more yield loss that may occur. For soybeans at flowering, there’s potential for yield loss, especially on poorly drained soils.

As we deal with corn leaf loss due to natural sloughing off, early frost, and recent hail

and wind damage, it can make corn development staging tricky for post- pesticide applications. The reason I keep emphasizing development stages is because I’ve been called out to many ear formation concerns the past several years. No one intends for these things to happen! These are opportunities for all of us to learn. In all cases, mis-diagnosis of development stage occurred prior to the pesticide application (whether herbicide, insecticide and/or fungicide). The use of non-ionic surfactant (NIS) in the tank from V10-VT resulted in the ear formation issues in addition to increased surfactant load from multiple products in the tank mix. My hope in emphasizing corn development staging this year is to hopefully reduce the incidence of ear abnormalities that occur from post- pesticide applications. I put together the following video to hopefully help: https://twitter.com/jenreesources/status/1272370173853470720?s=20.

Gardening 101 resources: A team within Extension pulled together all the vegetable gardening resources to create a one-stop place for vegetable gardening. This resource, housed on the backyard farmer website, is a place for beginning gardeners and experienced ones. Check it out at https://go.unl.edu/veggies101!  

Sunscald/scorch on green beans: This past week I received a few pictures of green beans that had large brown ‘burnt looking’ areas. This is caused by sunscald. The sun and wind has been intense. Seek to evenly water and avoid watering the foliage.

Trees: Lots of tree questions past few weeks. If leaves are pre-maturely turning yellow and dropping, it’s most likely due to fungal disease. This is mostly happening since the 3” rain over Memorial Day. All the trees I’ve looked at are already starting to develop new leaves. Weed whackers cause more injury to trees that one realizes, so be very careful using them around trees, or put mulch around them to reduce weeds. Remove ‘mulch volcanoes’ around trees as the mulch against the trunk can cause rot. Mulch should not be piled against the trunk. Seek to make clean and proper pruning cuts for all the storm damage that has occurred to trees. For those who’ve experienced bark removal from lightning strikes or winter cracking, don’t paint anything over the wound and don’t fertilize or do anything to the tree. Allow the tree to seek to heal on its own. It’s amazing what trees can overcome! Winter and spring dessication injury may be causing evergreens (cedars, junipers, yews, and arborvitae) to suddenly turning brown. Kelly Feehan, Extension Educator shares, “During warmer than average temperatures in February and March, moisture was lost from green needles and could not be replaced from frozen or cold soils. This was followed by a dry spring; and then above average temperatures and extreme winds. These conditions increase the rate of transpiration and increased moisture loss from needles. If the moisture is not replaced quickly, tissues dessicate and eventually die. Evergreens growing in open exposed sites, near pavement or light colored houses, and those planted in the last three to five years are most susceptible. Other than using organic mulch and keeping soil moist, there is not much to do. Once an evergreen or a branch turns completely brown, it will not recover.” You can prune out dead branches/areas and see how the plants overall recover.

JenREES 6-7-20

*The York and Seward County Extension offices are now open to the public. We ask that visitors please wear a mask when entering the buildings.*

This past week was interesting to say the least! For those who experienced hail and/or wind damage, the following site provides guidance via information and videos for early-season hail damage: https://go.unl.edu/u5ns. We do say to be patient and wait 4-7 days to determine recovery and warm temps can help. For home owners, there was also a great deal of tree and plant damage. Make clean pruning cuts and don’t treat/paint over cuts, don’t add fertilizer, and leave as much leaf area as possible.

Most of this week’s questions centered around soybeans. The past two weeks, the

Sensitive Soy Variety to PPO

Sensitive soybean variety to PPO-inhibitor herbicide. Notice stunting, chlorotic appearance, leaf abnormalities.

majority of my soybean questions have been around emergence problems. Two common things I’m finding: many were planted around May 18-19 and they have a great deal of PPO-inhibitor injury to hypocotyls. In touching base regarding what we were seeing, John Mick with Pioneer shared that some soybean varieties are more sensitive to PPO-inhibitor injury. ‘Sensitive varieties’ means later on plants appear stunted and chlorotic in appearance. These plants also tend to have wavy leaves with some leaf cupping, which may have been mis-diagnosed as off-target growth regulator injury in the past. I’ve seen those symptoms for several years but just told people the plant was working to metabolize the pre-emergence herbicide and it was most likely taking longer due to the environmental conditions at the time. So, in a way, it was correct, but now we can all be more aware there are sensitive varieties to PPO-inhibitors. Thus, it’s important to talk with your seed dealer/agronomist about their variety ratings (if they exist). If planting a sensitive variety, it’s better to apply your pre-emergence application a week or so before planting to reduce the herbicide load on that germinating seedling. I’ve put a lot more explanation and pictures in this CropWatch article and the pics also on my blog.

The pre-emergence products did a great job for the most part. Thus, a common

soybean growth stages

Source: UNL Guide for Weed, Insect, and Disease Management.

question/discussion this week was around spraying essentially ‘contact’ herbicides in the absence of weeds. Could appreciate those thoughts. Regardless if the farmer wanted to apply glyphosate, liberty, or dicamba, we did talk about the importance of spraying earlier than one thinks is necessary and the need for residual products. I was going to share more about that here, but Amit Jhala wrote a very good article in this week’s CropWatch at: https://go.unl.edu/y3r8. He explains which products are options to consider at this point depending on if you have emerged weeds or not, what growth stage they can be applied, and some label restrictions. There’s a picture on my blog for soybean development stages. The cotyledons are not counted. The unifoliolates are counted as V1 only when the trifoliolate leaf edges above them are no longer touching. This continues up the plant. New nodes with leaves will be produced every 3.75 days. Note that early planted soybean may flower soon; they don’t have to wait till June 21 (longest day of year) to do so.

Because of that, for those near the 45 day window for post-dicamba application to soybean, be sure to check fields as the label states 45 days after planting or R1 (at least 1 flower on any node), whichever occurs first. Follow label instructions and I’m also recommending documenting development stage via picture/video on all post- applications to crops this year. Regarding use of soybean dicamba, Nebraska Dept. of Ag Director Steve Wellman stated, “The Nebraska Department of Agriculture has not issued a stop sale order and will enforce the sales and applications of these products as they are currently registered in Nebraska.”

Thistle caterpillars are being observed in some early planted soybean fields. Threshold for pre-flowering is 30% defoliation.

Corn post-herbicide applications: Said I’d share on this, but ran out of room; I

1-6 corn nodes-Lori Abendroth

Leaf collar correlating to split stalk method. Courtesy L. Abendroth, Iowa State University.

wrote a CropWatch article here: https://go.unl.edu/jz9v. Recommendations for any applications this year: Go into the field (beyond the endrows) and document growth stage of the plant via picture/video using the leaf collar method and/or split stalks (once reach V6 due to leaves sloughing off). Do this before any applications are made to the field. If the growth stage isn’t correct for the application, don’t spray. How I explain the split-stalk method of development staging: The growing point emerges above ground around V6. Dig a plant without breaking the stalk. Carefully split the stalk down the middle through the root ball. At the base of the stalk is an inverted triangle that contains Nodes 1-4 (but they can’t be differentiated). Next look for the white area above that (about ½-3/4”) followed by the next visible band. The white area is the internode with the band being the 5th node (V5). There’s about an inch of internode between V5 and V6. After that, internode length is more dependent upon air temperature instead of soil temperature. Every leaf is attached to a node. Pull off the fully collared leaves and follow them back to where they break off at a specific node. Count the nodes on the stalk to the highest collared leaf that breaks off at a node to determine the growth stage.


Soy pic3

Soy pic1

My concern with some of these plants is them becoming brittle and potentially breaking off at some point in the season.

Soy pic2

Soy pic4

There’s been mis-diagnosis/confusion about PPO-inhibitor injury vs. ILeVo ‘halo’ effect which shows the seed treatment is working. ILeVo causes no burning to the hypocotyls and the effect isn’t seen on leaves other than cotyledons.

Soy pic 6

Also been confusion between PPO-inhibitor injury and Phytophthora. Phytophthora will have discolored root and lesion from soil line upward. PPO-inhibitor won’t cause discoloration/rotting of the root. We have seen burning of stem near soil line due to rain/irrigation splash from PPO-inhibitor, so dig up seedling to check the roots for root rot.

JenREES 5-31-20

Corn: I really enjoy this stage when corn is just tall enough to give the fields a green cast when looking at them from an angle. There continues to be discussion and questions about uneven corn emergence. Like many, I wasn’t anticipating seeing uneven emergence after having great soil conditions (right moisture and a warming trend of temps) for planting. Variations in soil temp, depth, and moisture can delay germination from a few days or longer. Residue blowing back over the row explained much difference in emergence this year. I wish I would’ve noted the days on my calendar, but there’s a couple warm days in late April during planting where it just seemed like the moisture rapidly left the soil surface. And, in conversations it seems as if others noticed that too. So I think moisture around seed was another factor as was fertilizer burn in some situations. Purdue University has some research which showed yield reductions of 6-9% for plants emerging 1.5 weeks later than a uniformly emerging stand. They also found yields of uneven stands to be similar to planting the stand 1.5 weeks later.

If you’re side-dressing nitrogen and interested in testing different rates, we have some on-farm research protocols available at:  https://go.unl.edu/tv63.

With warmer temperatures anticipated, corn will grow rapidly. This week we wrote an Corn growth stage-Reesarticle in CropWatch regarding proper growth staging of plants; this will be extra critical once we hit V6+. Remember to use the leaf collar method and this is how I explain it. A collar develops at the leaf base near the stalk after each leaf fully expands. Think about collars like the collar on a button-down shirt. The collar flares slightly at one’s neck, just as a true exposed leaf collar flares at the base of the leaf at the stem. Start counting leaves at the base of the plant with the smallest rounded-tip leaf with a collar as #1. From there count every leaf with a true collar. Leaves that are still wrapped in the whorl around the main stem without exposed leaf collars are not counted. I recommend taking a picture inside the end rows to document the growth stage of your field prior to the post-application of herbicide. Next week I will share my experiences with proper growth staging to avoid ear abnormalities. Also be aware of potential off-target movement with dicamba products and higher temperatures.

Soybean: In most cases, soybeans are looking really good. There have been situations this week with herbicide damage to beans that may have been cracking when irrigation or rainfall event occurred allowing some pre-emergent herbicide to enter the row. Pre- herbicides can also rain splash onto cotyledons and first leaves making them look bad, but usually doesn’t kill them unless the weather stays cold and wet. If the plants end up severely pinched below the cotyledons, they won’t survive. Otherwise, keep watching them as they may continue to grow (warm weather will allow them to grow and metabolize the chemical better). I think we’re also possibly seeing some environmental effects from the cold conditions that occurred after planting/emergence when we can’t always explain the appearance of injury on the plant by herbicide. The ‘halo’ effect of ILeVo is another thing that is being mistaken as herbicide and/or environmental injury but it doesn’t last past the cotyledon stage.

Coronavirus Food Assistance Program for Crop Producers Webinar: There will be a webinar on June 4th at Noon (CST) to learn more. Registration is required at the following site: https://go.unl.edu/wj0e. In the meantime, Dr. Brad Lubben has put together an article with more information at: https://go.unl.edu/h3aq. All webinars are also archived at that same web link.

Irrigation Scheduling Equipment: It’s also a great time to get irrigation scheduling equipment installed! I decided to make a quick video instead of writing; it can be found at: https://youtu.be/4r5gn2pvvB4.

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Sensors prepped and ready for 2020 on-farm research projects!

Gardeners: For all of you gardening for the first time, congrats! Some tips: keep soil moisture even by ensuring plants have around 1” of water/week (Best to water at base of plant; if use sprinkler, do so in early morning). Mulching gardens with leaves, grass clippings, straw, newspapers aids in conserving moisture, reducing weeds, and maintaining stable soil temperature. If herbicides were added to grass clippings, make sure to read the label for if/when they can be applied to a garden. In general, many labels will say grass clippings are safe after 4 mowings.

JenREES 5-21-20

This Memorial Day will be different not gathering to honor those who have gone before us. Grateful for those who paid the ultimate sacrifice for our freedom! May we still take time to honor them.

Crop Update: Several weeks ago we were seeing large numbers of seed corn maggotIMAG4806-20180520-202958269 flies. This past week have seen and heard reports of seed corn maggots attacking soybean seed/seedlings. Typically insecticide seed treatments provide protection; the exception is with high densities such as what we’re experiencing this year. They’re attracted to cover crop fields, fields with manure application, and tillage. There’s several generations but we shouldn’t have to worry about it again unless we experience replant situations. Fly emergence for the first three generations occurs when 354, 1080, and 1800 growing degree days have accumulated, respectively since January 1. There’s an updated article in CropWatch this week sharing more. They can reduce stands, but soybeans can withstand a great deal of stand loss. We recommend to leave a stand of at least 50,000 plants per acre with fair uniformity. That goes for anything that can reduce a soybean stand such as crusting, hail, herbicide damage, insects, disease, etc. We have research showing that the early planting will out-yield a replant. I realize there’s other considerations such as weed control and Dr. Shawn Conley at Wisconsin suggested putting the dollars into weed control instead of replant. They only found 2 bu/ac yield difference in stands of 50,000 plants/ac vs. optimal stands of 100,000-135,000 plants/ac. If you do consider replanting for any reason, we’d recommend going in next to the old stand with a similar maturity and proving it to yourself. Here’s a protocol if you’d like to test it yourself: https://go.unl.edu/wq24.

Post-Herbicide Applications: At pesticide training, I talk about the importance of overlapping residual. Ag industry partners talk about this too. It means aiming to apply the post-herbicide before the residual from the pre wears out. Many of us have seen fields that are clean one week with a flush of weeds the next. Sometimes it then rains, delaying post-applications. Dry conditions created difficulty getting pre-herbicides activated, allowing some weed escapes. Depending on the product, soil conditions, weather conditions, Dr. Stevan Knezevic shared that pre-products can last anywhere from 4-8 weeks. Page 24 of the 2020 Weed Guide also provides guidance on potential residual (also known as persistence in the soil) of herbicides if you’d like to check that out.

Bagworms: I haven’t spent time looking at evergreen trees to see if bagworm larvae

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Bush with a severe bagworm infestation in 2018. Hard to see the bags in the brown part, but you can see them to the right in the green foliage.

have emerged yet or not. If you have last year’s bags on your trees that are sealed (don’t have an open hole at the top), you can pick off some bags, place them in a ziplock bag, and place it outdoors on the south side of your house. When you see larvae emerge, it’s a good indication to start checking your trees in the next weeks. Each bag can hold 500-1000 eggs. The larvae are really small and hard to see. Stand still and watch the tree. If bagworm larvae are present, you will see very tiny movements as they begin the process of building new bags. I have pictures and a video at: https://jenreesources.com/2015/06/27/bagworms-in-evergreens/. Egg hatch is from mid-May to early June, depending on the year. Some caterpillar larvae remain on the same trees containing the bags from which they hatched. Others are blown by the wind to area trees allowing for new infestations to occur. For homeowners with small trees or only a few trees, bags can be picked from trees now and drown in soapy water or burned. In the summer, they can be squished, drowned, or burned. I have a great memory of visiting Grandma in the care center with my family. Grandma was concerned about the spruce in the courtyard. Seeing bagworms, I turned it into a science lesson for my nieces/nephews. They had a blast making quick work of picking off bags and squishing them to the delight/disgust of the residents watching (and their parents) 🙂 That’s not feasible for most situations though. We recommend waiting to treat trees until bags reach around 1/2” in size to ensure egg hatch is complete. Good coverage is needed when treating trees. With ground sprayers, we say to spray to the point of runoff. Bt products are effective early on. Most often I recommend a permethrin or bifenthrin product. Aerial application may also be an option for windbreaks. For more info., please see: https://go.unl.edu/rgju.

JenREES 5-17-20

Congratulations to all who graduated from college or high school the past few weeks! You’ve experienced much challenge, change, and loss. Good can come from difficulty! May this experience better equip you for the future! Also wish to congratulate and welcome three new team members to the York and Seward county offices! Tanya Crawford will begin as the 4-H Educator in York County May 18. Emily Hemphill began as the 4-H Assistant in Seward County May 1. Kara Kohel will begin as the new Learning Child Educator in Seward County June 1.

Crop Update: Grateful for the recovery experienced on many frost/freeze damaged crops throughout the State! The worst damage I saw on corn in this part of the State resulted in exposed leaf tissue dying with new growth coming out of the ground within 5 days. Soybeans fared well in the area to which I’m extra grateful with the large number of early planted soybean acres this year!

There’s been some talk about uneven emergence in some fields. Most really aren’t too bad, just worse in fields that were worked or extra cloddy. And most often, seedlings are still coming when digging in the gaps. They’re just behind most likely due to depth or soil moisture variation. You may also want to check out an article on Early Season Insects in this week’s CropWatch at cropwatch.unl.edu. Also seeing and hearing of ammonia burn to roots of corn seedlings, mostly in strip till situations, due to the dry conditions. An inch or two of rainfall or irrigation can help dilute the salt concentration in the root zone and allow for growth of roots to resume. I realize this doesn’t help those without irrigation and we keep praying for rain. In a 2009 trial at UNL South Central Ag Lab near Clay Center, Dr. Richard Ferguson documented those plants being shorter in stature and appearing to have a purple color early in the growing season before later recovering.

For those asking about replanting, we have two articles to aid in decision making in this week’s CropWatch at cropwatch.unl.edu. I haven’t seen situations warranting this around here yet. It takes quite a stand loss. For example in corn, if there are 25,000 plants per acre and the field was initially planted on April 27 and you cannot replant until May 20, it would be better to leave your present stand, which has 95% yield potential, than to replant on May 20 when the yield potential for a stand of 30,000 would be 86%. Make sure you consider replant costs in your decision. Next week I’ll address thoughts on post applications to crops.

Lawn Update: As lawns grow, it’s important to not remove more than 1/3 of the height. During the spring and fall, cool season grasses such as bluegrass and fescue are also building their root reserves. Removing too much growth at once or continually mowing shorter than 3” puts more stress on the plant and doesn’t allow for as deep of roots for when the summer heat comes. UNL turf research found that lawns actually grow faster when they are scalped than when they are mowed at a taller height. So, if your lawn gets away from you like mine did last week, do your lawn a favor and raise your mowing height that one time and then go back to mowing at 3”.

Youth Learning Opportunities: There are a number of virtual and self-paced fun, learning opportunities for youth and families upcoming in the month of June! Many of the activities that were provided during the school year will be continuing with new sessions. You can check them all out at: https://4h.unl.edu/virtual-home-learning.

Building Better Babysitters Virtual Training: Additional childcare may be needed this summer. Babysitting is a big responsibility and it’s not for everyone. Youth ages 11 and up who are interested in building skills as a babysitter may be interested Nebraska Extension’s state-wide virtual babysitting training. Register by going to https://cvent.me/d4gWeD.


Adding some pics on frost recovery:

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Same growth stage but showing the environmental variability associated with frost damage.

frost on corn-growing pt

Seedling affected by frost on 3/9/20. Leaves watersoaked and wilted two days later. Splitting open stem reveals a healthy growing point (not brown or mushy) and green, healthy tissue below the wilted tissue. Thus, plants like these will likely recover, but it’s best to continue watching them for regrowth.

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Same field 5 days later. A little sunshine and plants are recovering nicely! The frost-damaged tissue is now brown, dead and will typically slough off with the wind. Sometimes, it wraps around the seedling making it more difficult for new growth to push through at first, but it will.

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Emerged beans were essentially unaffected in anything I looked at for this part of the State and are looking great now!

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