The linden trees are in full bloom and their fragrance is incredible!!! Last week I was out of the office with family, so didn’t get to check fields but heard from some of you who provided me updates on what you’re seeing. Corn is rapidly growing and closing the canopy. A few have reported early planted soybeans are already flowering. The corn planted into cereal rye looks more yellow right now, which is to be expected with the nitrogen being tied up by the rye. It should start releasing the nitrogen shortly. I realize it doesn’t always look as good right now; my experience has been that it will turn around come July and hopefully that continues to be the case.
With the post- herbicide applications being made, have heard/seen comments about waterhemp/palmer in fields with corn or soybean planted into rye. There is no silver bullet for weed control and cover crops aren’t one either, but they do greatly help in weed suppression and are another tool in our toolbox for a system’s approach. In previous weeks of walking fields, waterhemp and palmer tended to appear in areas where rye was thin and in endrows, otherwise the fields were fairly clean. In many green-planted soybeans, the rye formed a really nice mat to suppress weeds. Also, each field situation can be different. Some growers did a second pass with their residual after killing the rye. It stinks to do this but some have had more success in waiting to apply residual to better allow it to get down to the soil. Some added their residual to the burndown on tall rye (greater than 12-18”) and, depending on the product and its water solubility, the product may not have gotten to the soil yet. With this second scenario, there’s also differences when some used more water-soluble products, or applied prior to a good rain/applied irrigation, as these seemed to have better results with their residual products.
It has been hot, but it’s also been very humid, so crops aren’t using as much water as one thinks. That’s where having an ET gage or viewing ET information can be helpful. The CropWatch website is one resource for this information at: https://cropwatch.unl.edu/et_resources.
There’s also been concern about weather conditions and potential for temperature inversions. Al Dutcher shared the following, “If skies are clear and there is no wind at sunrise, it is a guarantee that an inversion is in place. Dew formation is another tell-tale sign (although during droughts dew may not form). When the high pressure is directly overhead, the inversion can last up to 4 hours depending on time of the year. During the summer it is lessened due to intense solar radiation early in the morning as compared to April and early May. Operators should be taking a temperature measurement at canopy height and at least 8 feet in the air to see if the inversion is still in place at the surface. A smoke bomb serves as a secondary control as the inversion may have lifted at the surface, but still exists above 8 feet (happens a lot in river valleys). The smoke bomb will rise up and if an inversion layer still exists higher up, the smoke will flatten out and drift sideways. If no inversion exists, the smoke will rise up and dissipate with height.” A great resource on temperature inversions from North Dakota State can be downloaded as a PDF here: https://www.ag.ndsu.edu/publications/crops/air-temperature-inversions-causes-characteristics-and-potential-effects-on-pesticide-spray-drift.
Light Trap Data for four Nebraska locations can be viewed at: https://entomology.unl.edu/fldcrops/lightrap.
Interseeded Cover Crop Driving Tour: If you’re interested in what we’ve been doing with interseeding cover crops into corn and soybeans, please save June 29th for a driving tour of some on-farm research fields! We’ll begin in Clay County and move to Hamilton, York, then Seward counties. I will share details next week. Essentially, I will provide the start time we’ll be at each field and you’re welcome to meet us there for one location or as many as you’d like. We’ll only plan on being at each location for 30-45 min. before moving to the next one. Will provide time for people to grab some lunch wherever you prefer in York before hitting the Seward county fields.
End of news column.
For fun: for those who have followed me a long time and/or know me/my family better, I arrived at the farm last Sunday afternoon to a 16 person water fight; also had another precious niece arrive this past week 🙂 May we enjoy our families and take time for these moments in our lives as time goes so quickly!
Grateful for the nice weather last week for post-emergence spraying! As crops continue to rapidly grow, a reminder for proper growth staging using the leaf collar method. 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. You can also paint a certain leaf of the plant, such as V5 or V6, inside the field (not endrows), so you can continue to count leaf collars as the lower leaves start to slough off.
It may also be helpful to get irrigation scheduling equipment installed soon. For those with watermark sensors, we’d recommend to soak the sensors in water for 24 hours and then read them to make sure they’re under 10 kilopascals. Then allow them to dry out to 199. Before installing, soak again (but only needs to be like 5 min.), and they should still read less than 10 kpa before installing. Last year I made a video regarding installation if it can help (https://youtu.be/4r5gn2pvvB4). For those looking for telemetry options, there are options available for watermark sensors too. One option from Servi-Tech is called the Profiler through their STEPS program. Another option is from Irrometer who makes watermark sensors. For those who use ET gages, remember to use distilled water when filling the main column, prime the small tube with the stopper and ensure there’s no air bubbles, and remember to fill the ceramic top with water before adding the stopper. With Dr. Suat Irmak’s departure from UNL to Penn State, the ET gage site has been decommissioned. ET information can also be found at UNL’s CropWatch website at: https://cropwatch.unl.edu/et_resources.
Weed Management Field Day: Growers, crop consultants and educators are encouraged to attend Nebraska Extension’s Weed Management Field Day from 9 a.m. to 1 p.m. June 23, 2021 at the South Central Agricultural Laboratory near Clay Center. The field day will include on-site demonstrations of new technology and new herbicides for corn, soybean, sorghum, and sweet corn. An early morning tour will focus on weed management in soybean and sorghum followed by a tour of weed management in field corn and sweet corn. Field experiments will provide information for weed control options with various herbicide programs. Three Certified Crop Advisor (CCA) Continuing Education Units are available in the integrated pest management category. There is no cost to attend the field day, but participants are asked to preregister at http://agronomy.unl.edu/fieldday. The South Central Agricultural Laboratory is five miles west of the intersection of Highways 14 and 6, or 13 miles east of Hastings on Highway 6. GPS coordinates for the field day site are 40.57539, -98.13776.
Bagworms: Have received a few questions regarding if bagworms have emerged yet. The very cold winter hopefully may have impacted bagworm survival since they weren’t as insulated on trees. I haven’t checked trees yet, but here’s a trick to help know. 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/if you see larvae emerge, it’s a good indication to start checking your trees in the next weeks. 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/. For more info., please see: https://go.unl.edu/rgju.
Crop Update: Grateful for when the rains were light to break crust and grateful for sunshine this weekend! Hoping weather works out for those who need to finish up planting! For those whose beans were further along, have received comments about crusted soils and lower soybean populations. A general guideline is to leave a field alone if plant populations are greater than 50,000 plants per acre, the stand is fairly uniform, and the field can be kept fairly weed free. I don’t have research going down to 50K, just observation. As you assess plant stands, keep in mind that a gap in one plant row will be compensated by plants in the adjacent flanking rows. They will form extra branches to take advantage of the sunlight. Thus single-row gaps may not be as yield-reducing as you might think, especially in narrower row spacings.
Soybeans greatly compensate for reduced populations by increasing branching. Nebraska On-Farm Research from eastern Nebraska and western Nebraska from 2006-2018 showed only a 1.3 bu/ac yield increase when seeding 180,000 soybean seeds/acre compared to 90,000 seeds/acre in 15-inch or 30-inch rows. (No studies were in sandy soils). Average final plant stands became 154,924 vs. 83,067 plants per acre respectively. Specific examples with lower final plant stands follow:
- A non-irrigated field in Nuckolls County in 2006 was hailed at the cotyledon stage, so planted populations of 100K, 130K, and 160K became average actual stands of 74,417; 89,417; and 97,917 plants per acre with a 4 bu/ac yield difference between highest and lowest plant populations. The average yield in the field was 40 bu/ac.
- A York County irrigated field in 2018 comparing 90K, 120K, and 150K became final plant stands of 60,875, 88,125, and 121,750 plants/acre with yields of 93, 94, and 97 bu/ac respectively.
Every challenge also provides opportunities for learning. So, if you consider replanting, consider leaving some check strips and/or consider an on-farm research study. To do this, consider:
replanting 2 combine widths, skipping 2 combine widths, replanting 2 combine widths, skipping 2 combine widths, replanting 2 combine widths.
It’d be great if you could do that even more often across the field, but just that pattern mentioned above will give you 4 reps that would give you more confidence in the yield results obtained. A Platte County grower did this in 2014. He originally planted 145,000 seeds/acre on May 10 no-till into heavy corn residue. With a plant stand of 75,000 plants per acre, he chose to replant soybeans in strips across the field. He left the original stand and planted an additional 145,000 seeds/acre. Final yields were 58 and 57 bu/ac for the original and replanted stand, respectively. Please let me know if this is something you’re interested in and I’d be happy to help you.
Weed Guide Survey: The Weed Guide has been published since 1960 with over 15,000 copies printed each of the past 5 years. Please consider completing a survey to help us understand the latest trends on how our customers use the weed guide and its value to you: https://ssp.qualtrics.com/jfe/form/SV_1ImdUrOCRmUq9Uy. We really do need and value your input!
Progressive Ag Safety Day June 3: This is a fun-filled day of learning for school-aged children and will be held at the York County Fairgrounds from 8:30 a.m.-1:00 p.m. on June 3. Topics for demonstrations and discussions include: Electrical Safety, Pipeline-Gas Safety, Grain Safety, ATV/UTV Safety, Look-a-Likes, Power Tool Safety, Equipment Safety, and Internet Safety. The registration fee is $5.00. This safety day includes lunch, snacks, a T-shirt, and a take-home “goody” bag. Register with the York County Extension office (402-362-5508). Registration is due by May 25th to ensure a t-shirt and take-home bag; however, please do sign up even after May 25th if you read this after the date! We’d rather have the youth get signed up as this is a great learning opportunity! Contact the York County Extension Office (402-362-5508) or Jason Perdue (402-366-2821) for additional information. We hope to see lots of youth there!
Corn Emergence and Growing Degree Days: For this week’s column, I’m going to share information my colleague, Nathan Mueller, Extension Educator in Saline, Gage, and Jefferson counties wrote in his recent blog post. “Many factors affect corn growth and development, especially early in the growing season. A common question this time of year after corn is planted and some fields have emerged whiles other have not is “How many Growing Degree Days (GDD) does it take for my corn to emerge?” Since corn emergence is directly related to soil temperature (and of course soil moisture), the days to emergence vary especially when one compares early planting dates to later planting dates. The general assumption is 120 Growing Degree Days abbreviated GDD for corn to emerge under favorable conditions. However, we know that some planting practices and environmental conditions can decrease or increase the amount of GDD needed for corn to emerge. We use the GDD calculation for air temperature to estimate how long it will take corn to emerge even though soil temperature is the driving factor.
Growing Degree Days (GDD) or Growing Degree Units (GDU) calculation is determined from air temperature. The corn equation for GDD or GDU = (Daily Maximum Air Temperature + Daily Minimum Temperature)/2 – 50. When the maximum air temperature is greater than 86 degrees, we set the value at 86 in the equation, as the growth rate of corn does not increase much beyond 86. Likewise, when minimum air temperature is less than 50 degrees, we set the value equal to 50 in the equation. The sum of daily GDD or cumulative GDD for corn emergence is approximately 90 to 120 under favorable conditions. As a base line for GDD required for corn emergence, colleagues at the University of Wisconsin report that 125 GDD are required for emergence. Based on research in Iowa, corn typically required 90 to 120 GDD from planting to emergence. This range assumes adequate soil moisture and will vary with planting depth, tillage system, and residue cover.
Research shows some adjustments are needed to help fine tune expected emergence dates based on GDD determined from air temperature. Planting practices that change the amount of GDD for corn to emerge include planting date, depth, and residue cover (view full table of variables at https://cropwatch.unl.edu/growing-degree-units-and-corn-emergence). It takes about 10-25 more accumulated GDD for emergence with early planting dates. Planting deeper than 2 inches will increase the number of GDD to emergence by about 15. More than 75% residue cover increases the accumulated GDD needed for emergence, ranging from 30 to 60 GDD more. Additionally, the soil moisture, soil condition, and soil texture change the needed GDD for corn to emerge. Dry seedbed conditions will require more GDD. Crusted or cloddy soils can increase GDD by 30 more. Heavy textured soils require more GDD than do coarse textured soils. Corn genetics also can affect GDD needed for emergence. Therefore, the amount of accumulated GDD from planting to corn emergence can range easily range from 90 to 200 GDD.
In Nebraska, the U2U tool (https://hprcc.unl.edu/gdd.php) can be used to determine local accumulated GDD based on your planting date. For example, at the tri-county corner of Saline, Jefferson, and Gage counties from May 1 to May 13, we accumulated 114 GDD and the 30-year average is 139. In summary, remember that numerous factors drive corn emergence and assuming a standard 120 Growing Degree Days (GDD) for corn to emerge will not always hold true.”
Tree seeds and leafing out: I’ve been watching silver/red maples and ash trees noticing that some, including one of mine, is very heavy in seed production like what we experienced in 2019. There’s also quite a range in oaks with some leafing out normally and others leafing out rather slowly. I think the seed production possibly is due to the warm March. Information from Ohio State shared that, “Every spring, maple trees produce small flowers that turn into seeds. Normally, a cold frost kills some blossoms, but this year the usual chill didn’t arrive at the right time. More blossoms than usual turned to seed.” Oaks leafing out at different rates could be due to the fact we’ve had a cool April/May and it’s also a survival mechanism to not all leaf out at once. We’ve also been experiencing some oak decline (which is also observed in August when leaves prematurely turn brown), and this can also result in slower leafing out. These are just some thoughts; I really don’t know the answers, just sharing that for those who are asking, I’m also observing this.
Hopefully the rains were a blessing in helping the crops where crusting was a concern, adding moisture to the seedbed, and in activating herbicide. This article reaches people throughout the State, so with some experiencing frost potential as I write this, if rhubarb leaves are not damaged too much by frost 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. Rhubarb often develops seedheads following cold temperatures, but this also does not affect eating quality of the stalks. Remove rhubarb seedheads and discard.
This week will share on the results we obtained from on-farm research studies where cover crops were interseeded into corn. In 2019, there were two locations in York and Seward counties (interseeded at V5-V6). In 2020, 6 of 11 locations were conducted via on-farm research in York, Seward, Clay, and Hamilton counties (interseeded at V4). Four of the six locations compared an interseeded cover crop to a check treatment of no cover crop. One location compared two corn populations (27,000 vs. 31,000 seeds/ac) to determine corn yield and cover crop biomass impacts. One location compared using only the middle drill unit to interseed the cover crop vs. using all three drill units between the rows to determine any differences in cover crop biomass.
2019 Results: In 2019, the cover crop at the Seward county location emerged and then died, we hypothesize, due to reactivation of Group 27 herbicide. Thus, no biomass samples were taken. At the York county location, cover crop biomass sampled prior to the first hard freeze ranged from 97-220 lbs/ac. It was good to see successful establishment at both locations and that cover crop growth occurred at one of them. In 2019, there were no yield differences between the corn in the check treatments (241 and 258 bu/ac) vs. cover crop interseeded treatments (241 (N mix), 243 (diversity mix), and 256 bu/ac) at the York and Seward locations respectively, which was also encouraging. Net return was less for the interseeded cover crop treatments vs. the check.
2020 Results: In 2020, cover crops emerged at all locations and grew throughout the season. Cover crop biomass varied by location with the most occurring in fields that were damaged by the July 9, 2020 windstorm (the location with the greatest biomass had 45% green snap). Thus, the open canopy resulted in greater weed and cover crop biomass. Biomass samples were collected in late September by taking three 30” X 30” or 36 X 36” squares for each treatment (dependent upon row spacing). The samples were sorted in the field into weeds, interseeded forbs/legumes, and interseeded grasses and placed in separate paper bags. Samples were weighed and dried. We wanted to compare any differences in weed biomass between the check and interseeded treatments, especially since no residual herbicides were used in 2020. There were no differences in weed biomass between the check and interseeded cover crop treatments. Total cover crop biomass accumulated varied by site and ranged from 277 lb/ac to 3818 lb/ac. It should be noted that the cover crops continued to grow after we sampled until the first hard freeze occurred. The cowpeas provided the greatest biomass and grew to the tops of the tassels. They also formed a ‘bridge’ between corn rows where the canopy broke open. Cowpeas, hairy vetch, sweetclover, and forage soybean were all fixing nitrogen during the 2020 growing season. The red clover and hairy vetch that survived the winter were fixing nitrogen in the spring of 2021.
The windstorm greatly impacted yields as well. Across all the sites, corn yield for the check averaged 214 bu/ac while corn yield for the interseeded treatment yielded 209 bu/ac. At four of the six sites, yield was significantly lower where the cover crop was interseeded. At the remaining two sites yield was not different between treatments. Net return for the corn where the cover crop was interseeded was less at five of the six locations. Net return includes the yield and price of the corn crop and cost of cover crop seed and application. Other than the York county location (two years), all the location data is based on one year of research. These studies will continue in the same fields and strips for at least three years, so it will be interesting to watch for any changes in soil biological and physical properties over time as well. Visually, in the field where the center drill unit vs. 3 was used, it appeared that the 1 drill unit had more biomass. Statistically, it ended up the same as the three drill units for total cover crop biomass. At the York location where cover crops were interseeded into two corn populations, there were no yield differences between the corn populations; however, both yielded less than the check treatment. A special thanks to all the growers working with us on these interseeding cover crop studies and to The Nature Conservancy, Upper Big Blue NRD, NRCS, and Kellogg’s for their partnership with Nebraska Extension on this effort. If you’d like more information, I’ve provided tables of data and links to videos we produced at my blog site jenreesources.com.
Cover crop biomass as a result of interseeding using three drill units (left) vs. only the center drill unit (middle). Close up of Penn State Interseeder drill units (right).
Nebraska On-Farm Research Virtual Field Day Interseeding Videos:
- Interseeding drills: https://cropwatch.unl.edu/interseeding-cover-crops-steve-melvin-june-12-2020
- Interseeding into Soybean: https://cropwatch.unl.edu/interseeding-cover-crops-soybeans-steve-melvin-june-10-2020
- Interseeding studies: https://youtu.be/gQKAGzkweG4
- Interseeding Mixes: https://youtu.be/b64PCMV1pwc
- Interseeding and Herbicide programs: https://youtu.be/5P8tE3oQ7hA
With the challenge of growing cover crops, particularly after corn harvest, interest in interseeding cover crops into living corn and soybean has increased in recent years. Goals for doing so include using the cover to: grow nitrogen for the crop, remove excess nitrogen (in the case of seed corn), aid in weed and erosion control, increase biodiversity, determine any soil health benefits, and desire for fall biomass for grazing. Some are also concerned about increasing regulation and wanting to figure things out ahead of the curve. Planning is key when it comes to interseeding cover crop into corn or soybean. Planning needs to include the goal of why interseed, the cover crop species interseeded, how the cover will be interseeded, the corn/soybean crop development stage for interseeding, and the herbicide program used.
A few years ago, we wrote an article sharing what was known about interseeding cover crops. The following is information we’ve learned as an interseeding project between The Nature Conservancy, Upper Big Blue NRD, Nebraska Extension, 11 farmers, NRCS, and Kellogg’s.
Timing: In corn, we’d recommend aiming for V4 (four leaf collars). V5-V6 is almost too late in years where canopy closure occurs quickly. The literature says there’s no yield loss after V2. For soybean, aerial interseeding around senescence (leaves turning yellow) is one option. From plots interseeded at V4 in 2020, we felt that was almost too late for aiding establishment. This year we will be trying at planting through V2.
Species: Penn State has a mix that’s considered the interseeding standard; it includes annual ryegrass, red clover, and hairy vetch. From the 12 species mixes we tried, the annual ryegrass, vetch, red clover all survived and were growing this spring. Thus, most likely why it’s considered the standard.
In corn, we’ve tried multispecies mixes because of the growers’ and partners’ goals and testing what came through different herbicide programs. We found the first species to emerge were the buckwheat and cowpeas. The farmers liked the species that provided more of an understory like the annual and Italian ryegrass, collards and other brassicas, and buckwheat. Cowpeas grew up to the corn tassels and provided the greatest biomass. Most of the species went to seed. Cowpeas, forage soybeans, and sweet clover were fixing nitrogen in season.
For diversity, the flax and buckwheat upon flowering drew many beneficial insects to the field. Pests like grasshoppers ate the covers in the interseeded strips and left the corn alone from what I observed.
In soybean, wheat was planted in the soybean management field day trials last year with some success. This year we’re considering wheat + red clover for the fields that will be interseeded from planting through V2.
Herbicide Programs: This is the difficult part. I think ideally (and I’m unsure if this is even realistic yet), a cover between rows aiding in weed control, adding nitrogen, providing fall biomass, and regrowing the following spring to aid in weed control again with only needing to add herbicide in a band, would be pretty cool.
In the wet year of 2019, Callisto-type (Group 27) products did their job and kept re-activating. This led to covers dying in one field. So in 2020, I suggested no residuals in post- apps. The guys went with me on this with most doing a pre- with residual followed by a post- of only glyphosate or Liberty prior to interseeding. The July 9th, 2020 windstorm causing plants to greensnap and/or bend caused problems with the canopy opening up and weed control in addition to biomass growth became a problem in these fields in competing with the corn crop. I was just sick about this and the guys extended much grace to me.
This year, for corn, some guys are sticking with last year’s program because it worked well for them, particularly in no-till with heavy residue. Another thing some may try is to apply a pre- with residual, interseed at V4 and then upon 1-2” growth of the covers, apply Dual II Magnum or Outlook (no grazing restriction with Outlook) to provide residual to aid in weed suppression. One farmer who applied generic Lexar pre-plant in some fields and did split app in others in 2020, still saw cover crop growth and emergence from the split applied. The cover crop growth in the split-applied was just stunted and thin compared to the fields where he applied the full rate pre-. He’s testing herbicide programs this year.
For soybean, there’s even more risk. For those who wish to plant and interseed at the same time, we’re trying a burndown immediately prior to interseeding (if they hadn’t applied an early pre- already), allowing the cover to get 1-2” tall and then go with a Group 15 chemistry. The other option we’re trying is going with their pre- with residual followed by interseeding at V2 and application of Group 15 herbicide after cover reaches 1-2” of growth. We also have guys who are planting soybean green into rye and will try interseeding after rye termination. We have no idea how all this will work and if others have ideas, please feel free to share! Next week I’ll share the yield and biomass results from the past few years.
The above pics were post-harvest. The covers showed good at that time still but they seemed to disappear pretty fast upon more hard frosts.
The above pictures were taken in March 2021 of spring growth. Annual ryegrass, hairy vetch, red clover, and collards survived the winter. As time went on, one could easily ‘row’ where the covers were interseeded in June 2020. The taproots on the red clover were extra impressive to me! Also, pretty much always saw earthworms when I dug up one of these plants.
Warmer conditions have arrived for planting season this week! Quick reminder to check planting depths across your planter for the different fields as conditions may vary from field to field. Also a reminder to everyone to be extra aware on the roads with farm equipment moving much slower than regular traffic. Here’s wishing you a safe planting season!
Lawn Care: If your lawn is in need of fertilizer, the first round of fertilizer can go on sometime between now and May 10. Many crabgrass preventer products also contain fertilizer, so that can be used as your first application instead. A reminder to read and follow the instructions on the fertilizer package regarding rate, need to water in, and use the settings provided for lawn spreaders. Also be sure to remove granules from sidewalks and driveways as these get moved into stormwater systems and streams if one doesn’t. If you hired a lawn care company, make sure they’re removing granules from sidewalks and driveways as well.
If you have new seedings, weed control products such as crabgrass preventer, can damage new grass seedlings, depending on how much growth is present. If this is your situation, there actually is a product you can use that will prevent crabgrass without damaging your new seedlings. Scott’s Turf Builder Starter Food for New Grass contains mesotrione which provides PRE and POST control of weeds without affecting the new bluegrass or fescue seeding. Tenacity is also a product containing mesotrione that works as a POST for emerged crabgrass, foxtail, and for those dealing with nimblewill (best to apply on troublesome grassy weeds up to 1” tall).
Preventing 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. Another professional product called 3336-F is labeled for various turf, horticultural, and tree diseases (such as tip blight and dothistroma needle blight of pines). 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.
Prevent Wild/Bur Cucumber in Shelterbelts: The past few years we’ve seen wild and bur cucumber overtaking windbreaks. These are fast growing, warm season annual vines. They die each fall and come back from seed which germinate and begin growth typically in May. Vines can be cut at the base or pulled if there’s only a few of them this spring. Many asked about chemical treatments last year. A pre-emergent control option for large shelterbelts is Simazine (Princep 4L) to kill weed seeds as they germinate. Don’t apply more than 4 qt. Princep 4L per acre (4 lb. a.i./A) per calendar year. Don’t apply more than twice per calendar year.
Pollinator Garden Webinar Series will be held May 4, 11 and 18th from 6:30-7:30 p.m. If interested, you can learn more and register here: https://go.unl.edu/bmnw.
Evergreen Problems Webinar will be on April 22 from 7-8:30 p.m. Please call Platte County Extension at 402-563-4901 to RSVP. They will send you the Zoom link and password. There is no fee.
Considering Carbon: opportunities and challenges webinar will be held April 21 at 11 a.m. CST. Info & registration here: https://nationalaglawcenter.org/webinars/climate21/. There is no fee.
Reminder: Household Hazardous Waste Collection April 24th for Seward (8 a.m.-Noon) and Butler (1:30-4:30 p.m.) counties.
Soybean germination and planting: When I first began Extension, research on early soybean planting was just beginning. At the time, I hadn’t thought about planting soybean at the same time as corn, or even before corn. Soybean genetics and seed treatment improvements have allowed for this. Our recommendation for increased yield is to aim for planting the last few weeks of April if conditions are right, use a seed treatment, and plant 1.75-2″ deep. It seems like each year during planting season, we experience 1) soil temps in the mid-40’s with solid soil conditions and on a warming trend and 2) the potential for cold snaps with cold rains/snow after planting. What should one do and what’s the time-frame for risk of chilling injury?
For soybean, and corn for that matter, I’m not as concerned about #1 if the soil is fit and proper seeding depth (2”) is maintained. For #2, if the soil conditions are right and there’s at least 24 hours before a cold snap, consider planting beans instead of corn. That’s because soybean imbibes (takes up) water more quickly than corn. Once that imbibitional period is completed, the risk of chilling injury also ends. The seed can then remain (in osmotic phase) at cooler soil temperatures for a period of time in a sort of ‘dormant state’, until warmer temperatures return for continued seedling development.
In March 2021, Dr. Jim Specht and I began indoor and outdoor demonstrations. To be clear, we’re not recommending planting soybean in March in Nebraska. And, the point of these studies wasn’t to encourage increasing risk of pushing planting prior to cold snaps. I’m grateful for conditions like this year that make the decision to not plant easy when we know it’s staying cold with precipitation in the forecast. Our demonstrations just provided time looking at windows of 40-50F soil temps and increasing/decreasing trends. Soybeans are just beginning emergence from the March 10 planting in York. Soil temps in soybean and corn residue and living rye cover crop have been monitored since then and can be seen in an article at cropwatch.unl.edu. The soil under rye cover was 1-5 degrees cooler than under corn residue which was 1-2 degrees cooler than under soy residue.
We used coolers at 60F and 36F at the York Co. Fairgrounds to conduct an indoor experiment, explained in more detail at cropwatch.unl.edu. Enough trays were planted with soybean and corn seed so they could be switched between the coolers every 2 and then 12 hours for a total of two days. We didn’t have space for replications. All trays were removed to my house after 72 hours. They were kept at 50F for 9 days (which in many cases, early planted soybean do set in the soil for a period of time before emergence). Then they were kept at 60F soil temp with emergence counted each day until termination April 8. In the soybean, similar percent emergence was found in the 60F control; and where soybeans were at 60F for 8, 10, 12 and 48 hours before switching to 36F. This showed that we no longer saw reduced emergence upon 8 hours prior to a cold snap (in this non-replicated experiment). This potential 8 hour critical period has been within the time-frame of published research studies and non-published field observations.
The 36F to 60F switch showed that a warming trend in the first 2-6 hours led to greater emergence. We don’t recommend planting into soils at 36F, but it served as a nice low extreme. We would anticipate the emergence would improve if the soil temp was 40F or mid-40’s with a warming trend.
What does this mean? If soil conditions are right for planting and seed is planted around 2” deep with a seed treatment, I’m not as concerned about planting soybean or corn at 45F soil into a warming trend. For planting prior to cold snaps, if one chooses to do this, we say aim for at least 24 hours for soybeans and 48 hours for corn. We know not every soybean field is completely planted at 24 hours prior to a cold snap, so to me, this gives some insight why we’ve seen fields, including two on-farm research ones in Seward county last year, still have 86% emergence prior to snow falling eight hours later. Also key is when the beans will emerge compared to frost potential. If the beans are in the ground or have cotyledons exposed, we haven’t observed a need to replant due to frost damage thus far. It’s when the hypocotyl hook is at the soil line that can result in replant potential. Thanks to York Co. Ag Society for use of their coolers, Jerry Stahr for use of his field, Jed Erickson for providing the corn and soybean seed, and Dr. Jim Specht for his help in spite of being retired!
Household Hazardous Waste Clean-Up will be held at four times and locations for residents of Polk, York, Butler, and Seward counties. These clean-ups are funded by Environmental Trust grants with Four Corners Health Dept. and various sponsoring organizations overseeing the collection at the locations.
The collections will occur:
- Polk Co.: Saturday, April 17 from 8:00 a.m. – 11:00 a.m., Polk County Fairgrounds, Osceola
- York Co.: Saturday, April 17 from 1:00pm – 4:00pm at the York Landfill, 1214 Road 15
- Seward Co.: Saturday, April 24 from 8:00am – 12:00 p.m. at City of Seward Wastewater Plant Parking Lot – 1040 S Columbia
- Butler Co.: Saturday, April 24 from 1:30pm – 4:30pm at Butler County Fairgrounds, 62 L Street, David City – North Entrance
On the specific date and time, residents of that county are welcome to bring their residential household hazardous waste in boxes. Paint in one box and other materials in a separate box. If you are not sure what something is, keep it away from other materials.
Acceptable Materials (quantities of more than 5 gallons cannot be accepted): Acids, Antifreeze, Banned Materials (chlordane, DDT, etc), Cyanide, Fertilizers (yard chemicals), Flammables, Gasoline and Oil (in small quantities), Lead Acid Batteries, Mercury and Mercury-Related Materials, All Paint and Paint-Related Materials (stains, varnish, etc), Poisons, Pesticides, Florescent Bulbs (please do not tape together)
Non-Acceptable Materials: Empty/Dried Out Paint Cans (these can go directly into your regular trash), Tires, Farm Chemicals, Electronics, Medical Sharps, Recyclables.
IN SEWARD COUNTY ONLY: They’re also additional collections at the same date/time: Scrap Metal & Appliances $5 per appliance or load of metal. Electronics Recycling: $10 – all LCD monitors; $20 – CRT (glass tube) monitors or tv’s up to 25″; $30 – TV’s 27″ and up; $40 – Large wooden projection TV’s.
Soil Temperature information for planting and applying pre-emergence herbicides can be found at: https://cropwatch.unl.edu/soiltemperature.
Crabgrass Preventer timing: Crabgrass germinates when soil temperatures are maintained at 55F for 5-7 consecutive days. We’re getting closer to this. You can watch the CropWatch soil temperature maps at the link listed above. You can also use a meat thermometer (that you dedicate to only taking soil temperature!) for your own lawn situation at a 2-4” depth. Typically, towards the end of April/beginning of May is a good time for the first application, but it will vary by year. When they’re applied too early, they can move out of the zone where the crabgrass seed is germinating. Would also recommend that you consider splitting your crabgrass herbicide application. Apply half of the highest labeled rate when soil temps warm and the other half 6-8 weeks later. Often there’s a flush of crabgrass later in the season and splitting the application can help with that. It’s helpful for the products to be watered in within 24 hours for best results.
Pastures and annual grass control: Have looked at several smaller pastures (often grazed by horses & hayed) that have issues with foxtail. Foxtail tends to emerge when soil temps are sustained around 60F, so using a pre-emergent herbicide such as Prowl H20® can help in addition to grazing management. There’s a good article in this week’s CropWatch regarding annual grass weed control for alfalfa and pastures at: https://go.unl.edu/nzmy.
Planting Considerations: In an article last year at this link https://jenreesources.com/2020/04/12/jenrees-4-12-20/, I shared about planting considerations. I don’t have anything new to add to this, so you can check that out if you’re interested. Next week will share results of a soybean and corn germination/emergence experiment I’ve been working on since Mar. 10.