Category Archives: dicamba
Crop Update: I’m so sorry to all affected by Monday night’s hail/wind storms! For those reading this before Monday, a reminder of hail damage meetings we’re having Monday Morning, 10 a.m. at the Utica Auditorium and Monday Afternoon, 1:30 p.m. at the Fairgrounds in Central City. I will post key points of what’s discussed at http://jenreesources.com after the meetings. Please also check out our Hail Know Website at https://cropwatch.unl.edu/hailknow and take the survey on the page to help us better know how to serve you with that resource.
This week’s CropWatch at http://cropwatch.unl.edu shares two different dicamba-related articles. One is a case study to walk through the forensic analysis for off-target dicamba movement showing how it originated from a corn field. The other goes into more detail regarding soybean still producing a new node every 3.7 days upon off-target dicamba movement (as long as the apical meristem has not been killed). It’s truly a significant piece of information, because without it, the assumptions within the forensic analysis don’t work!
Also, you have an opportunity to share your voice and input. This past week we’ve heard that EPA is planning to make their decision by mid-August on whether or not to extend registrations of XtendiMax®, Engenia®, and FeXapan® in order to help inform the seed and chemical industry for next year’s purchases. Some of you have called or talked with me about this. A few have understandably been pretty upset that these products are getting so much blame when, in this part of the State, much off-target dicamba movement starts from corn applications. That doesn’t get as much press nationally. While I’ve tried hard to share the story here and am grateful to our media partners who have helped me, I’m one very small voice. I have no idea what will happen; my concern is the bigger picture-potentially losing dicamba period as a tool in our toolbox.
So you have an opportunity to share your voice in Nebraska Extension’s survey that will be shared with the EPA: https://www.surveymonkey.com/r/JWDCY3C. Share your opinion on Xtend technology. Share your opinion on where you’ve discovered off-target movement from in 2017 and 2018. Share your opinion on dicamba. The results will also be compiled and shared on CropWatch and winter meetings. Thank you for considering this!
Aphids and Frogeye: I’ve also received a handful of questions regarding corn leaf aphids in corn and frogeye leaf spot in soybean. Both have rapidly increased in some corn and soybean fields. At beginning dent and various stages of starch-fill corn, I just have a hard time putting anything else into this crop. So I haven’t been recommending insecticides and there’s no thresholds this late to support it. In fields I checked from last week to this week with corn leaf and bird cherry oat aphids, I’ve also seen an explosion of beneficial insects and mummification occurring of aphids, which is helpful. Regarding frogeye, it’s one where we recommend a product containing a high amount of strobilurin at R3 or R5. Many beans are at R6 or almost there, so again, I’m having a hard time putting any more money into this. High humidity and leaf wetness for 12 hours or more will rapidly increase frogeye, so the worst situations I’ve seen through the years are in gravity-irrigated fields. Also, seeing a number of soybean defoliators in fields. Please check out this CropWatch article at: https://cropwatch.unl.edu/2018/soybean-defoliators to better help understand how much defoliation can occur in soybean.
Lawn Renovation: For those seeking to improve your lawn or get one established, August is a great time to do so! I really like this resource for this purpose: https://go.unl.edu/rz9z. If you’d prefer to watch videos, Backyard Farmer has a series of Lawn Renovation videos, but this link gets you to the most recent one regarding fall renovation: https://youtu.be/Fxd1NUQ8ScQ.
Thank you to all who made the York County Fair go so smoothly! It’s always a joy to see the 4-H and FFA youth and families rewarded for the hard work they put into their projects!
Crop Update: I didn’t get out to the field much this week with fair but did spend a few
hours one afternoon. There are portions of the area I serve that have been blessed with rains and look really good. The main thing that I’m seeing a lot more of this week is aphids in corn fields. This can be common in fields where fungicide is applied as the fungicide kills a beneficial fungus that attacks aphids. Some aphid species are also attracted to moisture stressed crops. The heat has also pushed the crop along quickly. We have another yield forecasting article in this week’s CropWatch at http://cropwatch.unl.edu where we talk about the impact of the heat on yields. As of right now, based on comparing this year to 30 years of weather data, it’s appearing corn may reach maturity 1-3 weeks early. Irrigated yields are estimated to be near average and above to near average for non-irrigated corn (where drought is not a factor). These yield forecasts are based on simulations under ‘perfect conditions’ (with no nutrient loss, disease etc.) but they can give us an indication of what may happen if we continue with higher heat conditions.
Unfortunately, pockets in the area continue to miss rains. The drought monitor still is not
reflecting the drought in this part of the State; at this point, I’m unsure what else either Al Dutcher or I can do about this. One farmer reminded me drought occurred in the same area in 2006, 2012, and now 2018-six years apart each time. Driving the area, hardest drought-stressed crops really took a turn this past week with corn in hard dough to early dent with some kernel abortion and soybeans are beginning to abort pods and quit filling seeds. One question has been on weighing taking corn for silage or not. If you have at least an estimated 50 bu/ac grain in most of the field other than highly compacted areas, it may be more profitable to keep for grain (unless you’re looking for cattle feed). The following are some resources to consider further:
- July 2018 BeefWatch article on considerations for green chop/silage for cattle feed, include best management practices, etc.: https://go.unl.edu/e3y5
- July 2018 K-State article for considerations on taking corn for silage or grain: https://enewsletters.k-state.edu/beeftips/2018/07/02/considerations-for-use-of-drought-stressed-corn-for-cattle/
- All UNL Drought Resources: http://droughtresources.unl.edu
Dicamba: We’ve often mentioned the research showing a soybean plant producing a new node every 3.7 days upon reaching V1 stage. And, I’ve used that in the forensics assessment for determining a timing for off-target dicamba movement. One question I’ve had was “Do soybean plants continue to produce a new node every 3.7 days upon being affected by off-target dicamba?” My assumption in the forensic analysis I have used is that a new node continued to be produced every 3.7 days in spite of off-target dicamba. However, the only way to really test this would be to have the same soybean variety in both an Xtend and non-Xtend version. We will release a CropWatch article next week in which a situation like this occurred at the Eastern NE Research and Extension Center. Dr. Jim Specht counted nodes in both the non-Xtend variety with off-target dicamba and the Xtend variety that wasn’t affected. He found the same number of nodes in spite of the dicamba affected non-Xtend variety being shorter in height and having less canopy. So that in itself is good information for use in forensic assessments. However, he also found plants in which a higher off-target dicamba dose affected the top-most growing point. When that occurred, the number of nodes was affected.
Last year, a group of us released a dicamba survey during Soybean Management Field Days. Reminder those are upcoming this week (https://enre.unl.edu/soydays)! The survey helps us understand your perspectives about dicamba and this year we’ve added questions regarding using Xtend technology. Hopefully it will provide helpful information for all of us and the results will be shared via CropWatch and winter meetings. We’d encourage and be grateful for any soybean growers to participate at: https://www.surveymonkey.com/r/JWDCY3C.
South Central Ag Lab Field Day: Please hold August 29, 2018 for UNL’s South Central Ag Lab (SCAL) Field Day near Clay Center! Attendees can choose which sessions you would like to attend. Options include the latest SCAL research in the areas of Irrigation/Water Use; Nutrient Management; Weed, Disease, and Insect Management; Cover Crops; and Cropping Systems. CCA credits will be available and there’s no charge to attend. Will have more specifics for you next week but please hold the date for now!
Vine Crop Problems: The following resource explains options for diagnosing various problems with cucumbers, squash, and melons: https://hortnews.extension.iastate.edu/2011/8-24/cucurbitwilt.html.
Crop Update: This past week was fairly interesting with southern rust being confirmed in a few Fillmore, Thayer, and Saunders County fields. We would recommend to continue scouting fields as the disease was low incidence at all these sites. There also were a number of questions regarding fungicide applications.
For those asking about chemigating fungicides, it’s important to ensure the fungicide
product label allows for chemigation and to follow the recommended irrigation amount if specified on the label. If an irrigation amount isn’t specified, Tamra Jackson-Ziems and I were talking about trying to apply with as small amount as possible (perhaps like 0.25″). She has chemigation data at 0.25″ vs. 0.50″ vs. ground application from 2005-2007, but not vs. aerial application. The data had a high degree of variability numerically in the yield data in spite of non-statistical differences. The only other info I could find was the University of Georgia recommends only 0.10″ on chemigation using fungicides, but they didn’t show any data. I encourage those who can to please consider doing this as an on-farm research study where chemigation occurs in pies throughout the field with other pies left untreated. I realize it’s not popular to leave areas untreated, but it may be of interest to you. For those asking about comparing aerial vs. chemigation for corn, that would be very difficult with one pivot with true research involving replication. Perhaps it could be done if a producer had a couple of quarters side by side, planted the same day with same hybrid and crop rotation where we could truly compare via research. If you do and that’s of interest to you, please contact either Tamra or myself. A couple have also discussed maybe applying half a pivot aerially and the other half via chemigation and just taking observations, which may also be beneficial to you.
We also released a few CropWatch articles this week on differentiating growth regulator herbicide injury in soybean and using a forensic method to diagnose off-target dicamba
injury in soybean. Please check them out at http://cropwatch.unl.edu. I hadn’t heard anyone really explain the difference between 2,4-D and dicamba in how they work in plants so felt that information was important in addition to the fact dicamba is highly translocateable and 2,4-D isn’t. That also has been important in home-owner discussions regarding off-target movement to garden produce. And, a reminder to all home-owners that weed control products used in lawns and empty lots often contain dicamba and/or 2,4-D…so it’s important to read those labels regarding environmental conditions in applying them and also when you can/can’t use grass clippings as mulch.
Buzzing Beetles: This past week, several people came to the office or called
regarding large green beetles flying around that sounded like bumble bees. These are called Green June beetles. They only fly during the day. There are also smaller green beetles with white spots (tufts of hair) around the abdomen; those are Japanese beetles. Japanese beetles feed on crops in addition to favorites such as Linden trees and knockout roses. Both have larval forms that are white grubs and both have a one year life cycle. In the beetle form, both adult beetles are fond of ripe fruit such as grapes, berries, plums, and peaches. As larvae, the grubs feed on decaying organic matter and grass roots in the soil. However, the June beetle larvae can reach 2″ long creating larger tunnels in lawns and pastures as they move in the soil.
Some have said, “I thought June beetles were golden/tan!” And you would be correct! There’s several types of “June” beetles. The most common and perhaps most damaging is known as the June beetle or masked chafer which is golden/tan in color and has a one year life cycle. There’s also a May/June beetle (also known as the 3 year grub) which tends to do more damage in range/pasture ground. Those beetles are tan to brown/near black in color.
When it comes to damage, start looking for browning areas of turf occurring late July, throughout August, and early September. The turf may look like drought stress or fungal disease; however, if you can gently roll the turf back like a carpet, it’s most likely grubs (and you should also find the presence of grubs). Other signs of grubs can include birds, skunks, etc. tearing up your lawn. White grubs in general feed on decaying organic matter, lawn and ornamental roots in the soil. Grubs don’t tend to be an issue in fescue lawns or lawns that are low maintenance or newly established. They tend to prefer Kentucky bluegrass lawns that are highly maintained with fertilizer and irrigation. They also may be spotty in their feeding such as under yard lights or on irrigated slopes. The threshold level for turfgrass damage by masked chafer larvae is 8-10 white grubs per square foot of lawn…so I would assume that to be the case for all grub species. One or two grubs per square foot is normal and does not require control. If grub control is needed, products like Sevin or Dylox provide the best control for mature grubs and should be watered in after application.
This past week contained many off-target herbicide concern calls. Prior to Memorial Day I had made a note that post-herbicide applications to corn began in much of the area and anticipated phone calls to begin in about two weeks. Most of the conversations this week were more FYI to let me know they had soybean leaf cupping.
Here’s a few things to consider if you are having soybean leaf cupping.
- First, was a post-herbicide application made to your soybeans? If so, check for any potential tank contamination (Check out this CropWatch article: https://go.unl.edu/fnig). If not, check out this publication (http://ipcm.wisc.edu/download/pubsPM/dicamba2004.pdf) to determine if any of the criteria mentioned could possibly be contributing to the problem.
- Determine how old the plant is by asking when the soybean was planted and even better when it emerged. A soybean plant will produce a new node every 3.75 days.
- To determine the timing of damage, I count the total number of nodes on the plant to the last trifoliolate where leaf edges are not touching. The total number of nodes may differ in different parts of the field such as irrigated and non-irrigated especially after herbicide damage and drought-stress (Example 8 nodes irrigated and 6 non-irrigated). Take the number of nodes X 3.75 to get total approximation of plant age. Then count back on the calendar to determine approximate emergence date. If I use 8 nodes in this example X 3.75 = around 30 days ago the plant emerged.
- I then count the number of nodes to the very first damage I see on leaves (Example 3). Multiply this number of nodes times 3.75 and count forward on the calendar from emergence to that date. For instance, in this case, damage occurred around 11 days after emergence.
- I also like to count how many completely unfurled trifoliolates are affected (Example 6 trifoliolates). Take that number and multiply by 3.75 (Example 6 X 3.75= approximately 23 days ago the damage occurred).
- In this example, it worked to count either direction (from emergence and from current date) to determine approximate timing of off-target movement occurring. In all the situations I’ve looked at thus far, the timing goes back to around Memorial Day with post-dicamba herbicide applications applied to corn.
- Auxin-like herbicides affect only cell division. Thus, fully developed leaves (no longer expanding via cell division) are not affected even though they may be expanding by leaf cell enlargement. Only the tips of the newest exposed soybean leaves may experience damage to dicamba as they are still undergoing cell division. Otherwise, it can take 7-14 days for leaf damage from dicamba injury to appear on susceptible plants and damage will occur typically 4-6 nodes. This is because dicamba is also translocated once inside leaf cells. Thus it impacts cell division of the leaf primordia at the stem apex. We may not even see those leaves yet because they are still enclosed in the stem apex tissue.
- In a matter of weeks, affected fields can go from appearing to have minor damage, to looking really bad, to growing out of damage. It looks worst when those affected nodes push upward giving the field a grayish/white cast to it as the leaves become much reduced in size and are tightly cupped. Eventually the leaves will begin to look more normal again in time (as long as a second off-target movement doesn’t occur).
What can you do? Water via irrigation and/or rainfall is the best recovery tool for dicamba damage. Waiting is another. We’re blessed to grow indeterminate soybean in Nebraska which continues to produce nodes and leaves upon flowering which allows our soybean to grow out of damage.
- Wait till harvest to determine any yield impacts if there are areas impacted vs. those which aren’t. Otherwise, field-scale damage is difficult to discern yield impacts.
- You can talk with your neighbors/ag retailers regarding what they sprayed. In our area of the State, it’s often difficult to pinpoint the source of off-target movement with so many applying dicamba products to corn for palmer control often around the same time-frame. Now that post-apps to soybean are also occurring, that may also become a challenge. Of all the fields I visited last year, less than a handful of farmers sought any sort of compensation and those were more often due to tank contamination issues. If you wish to pursue that route, you need to file a complaint with the Nebraska Department of Ag.
- For future dicamba applications, check out these best management tips: https://go.unl.edu/97ok.
- For those of you reading this in a source outside of my blog, I created a video to hopefully be more visual and clear on understanding this method of diagnosing timing. You can check it out at my YouTube site: https://www.youtube.com/user/jenreesources.
Bagworms: It’s June and one of my top questions has been “Have I found bagworms yet?” Well, they’re now feeding and forming new bags on junipers and spruces. What you’re looking for are not the old bags at this point, but very small (fingernail size) new bags that move as the caterpillar is feeding and making the larger bag. This video from Backyard Farmer (https://youtu.be/05A2quj9nO4) does a great job of showing various stages of bagworms and sharing on control methods. Check it out!
Irrigation Scheduling Workshops: Steve Melvin, Extension Educator in Hamilton/Merrick Counties asked I share about upcoming irrigation workshops hosted by UNL and Upper Big Blue NRD. The program will focus on installing the equipment and making irrigation scheduling decisions using the data generated by Watermark sensors. The workshops will be held from Noon-1:30 p.m. on June 25th at the Corner Café, 221 Main St in Stromsburg and also at the same time June 28th at the Hordville Community Building, 110 Main St. The Upper Big Blue NRD will provide the lunch. The first presentation will be Installation of Watermark Sensors and Data Logger presented by Dan Leininger, Water Conservationist with the Upper Big Blue NRD. The second will be Deciding When and How Much Water to Apply Using Watermark Sensor Readings presented by Steve Melvin. The irrigation scheduling strategies presented in Steve’s presentation can be used with any soil water monitoring equipment data. More information is available by calling Steve Melvin at (308) 946-3843 or visiting https://extension.unl.edu/statewide/merrick/.