Monthly Archives: May 2020
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 
article 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.
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 maggot
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
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:
Same growth stage but showing the environmental variability associated with frost damage.
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.
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.
Emerged beans were essentially unaffected in anything I looked at for this part of the State and are looking great now!
JenREES 5-10-20
The anticipated cool temps and potential for frost damage were on the minds of several towards the end of last week. The warm spring planting conditions allowed for more soybean emerged in Nebraska and the mid-west than I’ve ever seen before at this time-frame. From UNL small plot and on-farm research, it’s warm springs such as this that have provided the larger yield increases when soybean was planted early. As I’m writing this, low temperatures varied throughout the State Saturday night with more anticipated lows tonight. What should one look for in regards to frost/freeze recovery? First, we’d say to wait 3-5 days post frost to look for signs of regrowth. It may take up to 7 days depending on weather conditions following a frost event. I’ve provided photos in my blog at jenreesources.com to aid in what to watch for and will continue to add photos. Have learned a lot by flagging plants at different growth stages and taking pictures of their recovery. Would encourage you to do the same. One thing we’re always provided is the opportunity to learn!
Survival partly depends on how low temperatures got. Air temperatures of 28°F or less for at least two hours may result in damaged tissue and even death if the growing point is affected in corn and soybean. Air temperatures around 32°F typically don’t result in freeze of plant tissues. Why is this? Plant cells have solutes in the cytoplasm and just outside the cell membrane that act like a modest anti-freeze. Thus, the actual tissue temperature has to reach 28-30°F for frost damage to occur.
It also depends on stage of growth. For emerged corn, the growing point is still in the ground. Frost damage can appear as leaves discoloring and wilting due to plant cells rupturing. Eventually they will turn brown and slough off if new growth pushes through. It will be important to look at the growing point and make sure it’s white/yellow and firm and not discolored and soft. Warmer temps after frost event will help in reducing disease impacts from bacterial pathogens.
Soybeans that are just emerging with the hypocotyl hook exposed at or just above ground level, can be the most at risk for damage. The hypotcotyl hook is the area of the stem below the soybean cotyledon. Anything that impacts it will result in seedling death. Watch for plants that have soft, mushy, or pinched hypocotyls. These are situations where soybean seedlings tend to die. I’ve seen survival in seedlings with light scarring on the hypocotyl and cotyledons where there’s no pinching of the hypocotyl. Cotyledons just at the soil surface or above often will survive due to their high water content. They may have some light scarring yet they tend to survive. Look for the plumule (first true leaves from the shoot) within 7 days post-frost to ensure the growing point wasn’t injured. If unifoliolates were exposed, I’ve seen mixed results (depending on air temperatures and location in the field). Sometimes the unifoliolates will wilt and die but if the axiliary buds by cotyledons survive, new growth will occur.
For wheat, look for any splitting of the stems near the base of plants. Make sure the growing point looks healthy. Damage to wheat in jointing stage occur at 24°F for 2 hours and 28°F for 2 hours at boot. Impacts to wheat later on can also be seen at heading in white awns and spikelets and heads sometimes having difficulty to emerge from the boot (or being twisted). This CropWatch article shares more.
Low areas of fields, fields with coarser soil texture, and lower soil moisture contents can result in more frost damage. Fields receiving rains and wind prior to these cold temperatures may have aided in some protection. There’s often things I can’t explain when assessing frost damage. Sometimes a couple plants in a row will succumb while others around them at the same growth stage are fine. There’s just microclimate things that can’t always be explained. Here’s hoping most fields in the area are ok!
It’s also time to scout for alfalfa weevils and you can see more information and table of thresholds depending on growth stage in this CropWatch article: https://go.unl.edu/a7jw.
Rhubarb and Frost: If rhubarb leaves are not damaged too much and the stalks remain firm, it is still safe to eat. If the leaves are severely damaged or the stalks become soft or mushy, do not eat these stalks. Remove and discard them. New stalks can be harvested and eaten.
These are pics I took in 2019. The soybeans in the left photo had cotyledons just at the soil surface at time of frost. They survived. The upper right-hand photo shows a seedling with light scarring on the hypocotyl and cotyledons. However, the hypocotyl wasn’t pinched and you can see the plumule between the cotyledons is alive and healthy. The lower right-hand photo shows the hypocotyl was damaged on these seedlings causing pinching. Thus these seedlings didn’t survive.
This is what a healthy growing point looks like on a healthy plant not impacted by frost.
Corn impacted 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.
Plants impacted by frost (first and last) while middle two at same growth stage are not impacted. I see this often and have no explanation!
The beans next to this corn field look really good with light scarring of the cotyledons and healthy plumules.
JenREES 5-3-20
Planting season has rolled on this year with large planting progress made in short time! I’m grateful for the general warming trend with no cold snaps unlike so many recent years. Like many of you, am also praying for rain. For pre- herbicides, it is important to have 0.5-0.75” of moisture within a week of applying them for activation. That was a topic of concern I was hearing from both growers and ag industry last week, thus why it was recommended that some start pivots. I’m starting to see grass and broadleaf weeds coming through on ground that didn’t receive moisture to get the herbicide activated. Corn and soybean are also emerging fairly quickly with these warmer temps. The latest in pheromone trapping cutworm counts across the State can be found at: https://go.unl.edu/jdd3.
Some have asked about interseeding covers into early vegetative corn or soybean. Perhaps the three biggest things we’ve learned are to make sure the seed is in the ground vs. broadcast, plan to seed between V2-V5, and think about your herbicide program before trying this. An easy to understand site for herbicide impacts to covers is at: http://interseedingcovers.com/herbicide-options/. That whole website holds good information. There’s an Upper Big Blue NRD soil health project with partners of The Nature Conservancy, NRCS, and Extension where we will have 6 on-farm research studies and several other demos of interseeding this year. Growers are looking at impacts of different mixes, corn populations, row direction, and number of rows interseeded (1 vs. 3) between the corn rows. Looking forward to these additional studies to add to the research base which we talked about in this CropWatch article last year: https://go.unl.edu/4nh7.
My prayers go out to livestock and poultry producers; I just can’t imagine. There are a number of resources at https://animalscience.unl.edu/swine for emergency depopulation of livestock facilities. Such a hard time all around in ag. Free farm finance and legal clinics for May can be found at: https://go.unl.edu/joos. Nebraska Farm Hotline/Rural Response Hotline: 800-464-0258.
Evergreen Tree Diseases: The wet springs the past several years have led to an increase of needle blights. Spring is the time to be spraying trees with preventive fungicides with timing depending on the disease. None of the options I list are exhaustive and not meant as endorsement. For windbreak situations of cedars and pines, some ag retailers have carried Tenn-Cop 5E or Camelot. For home-owner use for trees in landscapes, I will share what I’ve seen sold in our local stores. It’s important to read the product label to ensure it’s safe to use on the specific plant/tree you wish to treat as some copper products can harm plants. In Austrian and Ponderosa pines, tip blight (where tips die) and dothistroma needle blight (where needles turn brown and die) can be prevented with fungicide applications. Tip blight is best prevented in late April-early May with active ingredients of Propiconazole (found in Fertiloam liquid systemic fungicide), Copper Salts of Fatty & Rosin Acids (sometimes listed as copper soap such as Bonide liquid copper fungicide and other liquid copper formulations), or Bordeaux mixture. Dothistroma needle blight can be prevented in mid-May and a second application in mid-June with Copper salts of fatty and rosin acids and Bordeaux mixture. In spruces, needle cast can cause the yellow to reddish brown color of needles in the fall that remain that way in the spring. Fungicide should be applied when the new growth is half grown with a second application 3-4 weeks later. If your tree is severely infected, it may take applications like this for 2-3 years in a row. Chlorothalonil (found in Daconil and Fung-onil) is commonly recommended. Fungicides containing azoxystrobin, mancozeb, propiconazole, copper salts of fatty acids, and copper hydroxide are also effective at controlling this disease if the product is labeled for use on spruce. You can learn more about evergreen diseases, how to identify them, and more products for management at: https://go.unl.edu/rbcc.
It’s too early for bagworm control. I’ll share more on what to look for next week.
JenREESources's Extension Blog 