Category Archives: Trees
The Nebraska Department of Agriculture (NDA) confirmed Emerald Ash Borer (EAB) was found in a trap at the Blue Valley Campground in Seward, NE in early August 2020. This article will share information from Elizabeth Killinger, Extension Horticulture Educator, about what this means for your ash trees and what you should be doing now.
“Finding borer holes in ash trees doesn’t necessarily mean you have EAB. There are several different types of borers that attack ash trees, so correct identification is key. There are several different native borers that are normally found on ash trees. The ash/lilac borer, banded ash clearwing and carpenter worm can attack healthy ash trees. The redheaded ash borer, banded ash borer, flatheaded apple tree borer and eastern ash bark beetle attack stressed or dying ash trees. Knowing exactly which insect is in your tree will let you know if you should start looking for a replacement or if you need to treat.
EAB is an invasive beetle that attacks and kills all species of ash. It is a small, metallic-green beetle that is about 1/2 inch long. The larvae of this wood-boring insect tunnel under the bark of ash trees, disrupting the flow of water and nutrients, ultimately causing the tree to die. EAB infested ash trees will exhibit thinning or dying branches in the top of the tree, S-shaped larval galleries under bark, D-shaped exit holes and suckers or advantageous growth along the trunk and main branches.
Proper tree identification is key to knowing if you should be concerned about EAB or not. The bark of ash trees have diamond shapes or capital “A’s”. Ash trees have an opposite leaf pattern, or the buds are across from one another on the stem. They also have leaves of 5 to 7 leaflets. If you are lucky enough to get the seeded variety, the seeds look like paddle-shaped helicopters and are held in clusters on the tree. Ash trees, those in the Fraxinus genus, can include the green, white, Patmore, Marshall’s Seedless, and Autumn Purple Ash. Mountain Ash is not affected because it isn’t a true ash.
If your tree has EAB-like symptoms, like canopy thinning, branch dieback, sprouting growth from the base of the tree, or D-shaped exit holes, it should be examined by a professional. Leave your ash trees in as long as they are healthy, in good condition, and in a good location. If your tree is dying or diseased, it may be best to hire a certified arborist to look at your trees and determine the cause of the decline.
Because of the cost, treatments are only recommended for high value and/or already healthy trees. Once EAB has been confirmed within the 15 mile radius of your location, then you can begin the proper treatment applications on healthy trees. Depending on the size of the tree, a soil drench is one option for homeowners. The drench can be applied to trees with under a 20” diameter trunk yearly throughout the lifespan of that tree. Tree care professionals are able to use additional products like trunk injections on larger trees. Contact a certified arborist for these treatments. Some products are best applied in the spring, while others can be done throughout the summer. We don’t recommend treatments this fall.
Ash has been a popular landscape and conservation tree for a long time due to its fast growing nature and overall appearance. Diversity in the landscape is important to the overall health of the community forest. Aim to have diversity and try not to have any one species make up more than 10% of the landscape. A diverse landscape isn’t as affected by single outbreak. Now is an excellent time to start thinking about replacement trees for ash. For a list of replacement trees visit The Nebraska Forest Service list of replacement trees or Trees for Western Nebraska (PDF). More information about the emerald ash borer, finding an arborist, and recommendations can be found at https://nfs.unl.edu/nebraska-eab.”
Crop Update: Grateful to see how corn ears in wind damaged fields were able to expand and expose silks to pollen! Noticing on the primary ear node one normal ear and another 1-2 small ears on the same node in some hybrids-more common this year than I’ve noticed before. Unsure what to think of it; just an observation. Southern rust has been confirmed in 19 Nebraska counties at low incidence and severity; levels not necessary for fungicide applications yet (in my opinion). Last week I shared UNL data that showed no yield differences between a check treatment vs. various growth development timings (through 100% dent) and various fungicides in two low and moderate disease years. For those dealing with spidermites, it’s important to determine whether the plants have two-spotted or banks grass mites as they differ in control. For more information, check out this information: https://go.unl.edu/idsm.
Virtual Field Days: As someone who enjoys field days and meetings to see and catch up with people, it’s been hard to not have field days this year! Thankfully we can share information via technology. The following are resources for weed management and wheat production/variety info:
- South Central Ag Lab Weed Science Field Day: https://go.unl.edu/2020weedfieldday
- Glyphosate Resistant Palmer Amaranth Field Day: https://go.unl.edu/palmer-amaranth2020
- Wheat Field Days (Part 1 Production background): https://mediahub.unl.edu/media/13563
- Wheat Field Days (Part 2 Varieties): https://mediahub.unl.edu/media/13564
Tree Problems: Trees are important to any landscape, whether in town or on the farm!
Often, there’s stories behind their planting and it’s always hard to see them decline/die. The #1 killer I’ve found of cedar windbreaks is landscape fabric used as a weed barrier when trees are planted. No matter what the product says or who tells you it will tear as the tree grows, it rarely does. It does a great job with weed control! And, 5-15 years down the road, it’s understandably forgotten. Once the tree trunk expands to where the original edge of the hole is, the trunk often can’t tear the fabric right at the soil line while the trunk above and below it tries to expand. Sometimes a tree can survive for awhile with the choking. However, if you ever see a tree that dies quickly with no other apparent reason, it usually
is due to something with the root system or choking somehow on the tree. I realize it’s a pain, but with as much work and money that goes into windbreaks, it’s a really good idea to take some time and pull weed barrier away from the tree trunks. A long-handled tool with tines can help but just make sure to carefully get all the way to the trunk to release any potential choking (I often have to get under the tree and cut the fabric next to the trunk to accomplish this). This goes for weed barrier used for any trees and shrubs. Weed barrier with rock is one of the biggest killers of plants I see in landscapes.
Bagworms are also impacting cedars, spruce, and various shrubs. Right now I recommend using Bifenthrin as it irritates the bagworms and makes them leave bags to be better exposed to the product. It has a two week residual and is used as an insecticide for many plant situations. Get really good coverage of the trees/plants when applying.
A number of fungal diseases are impacting evergreen trees. Many started the past few springs due to wet, humid weather. They are showing up worse now with recent humidity. The good news is trees can be treated with various fungicide products next spring that can be obtained from local hardware, farm, and landscape stores. PLEASE read and follow the label (can pull the label back in the store) regarding if the tree/plant is labeled for the product. I’ve been called out to disasters this year when the wrong products were applied to trees for which they weren’t labeled.
Japanese beetles continue to be a problem. Hopefully they’ll be finished in the next few weeks. Apply products at dusk to reduce harm to pollinators. Natural products include Neem and Pyola oil that can be applied every week. 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).
York County Fair Open Class: Quick note for those exhibiting in York County Fair’s Open Class, we ask that you have entry tags completely filled out including mailing address PRIOR TO fair this year. Entry tags can be obtained from the York Co. Extension Office and Wagner Decorating. All rules same as last year except Needlework is limited to 3 entries per exhibitor. Exhibits can be dropped off on the WEST side of Ag Hall Tues. Aug. 4th from 6-8 p.m. and Wed. Aug. 5th from 8-11 a.m. Volunteers will take items into buildings as much as possible.
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. The 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
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
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.
Storm damage resources: Have had a number of calls throughout the State this week
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.
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
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.
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.
Happy Spring! With warmer weather forecasted the next few weeks, it’s a great time to get outdoors! Raking leaves from lawns is a great activity this time of year for the whole family. You can also overseed bare areas of lawns right now. Don’t remove leaves or mulch from landscape beds yet. Leaves and dead tops of plants protect the plants and keep them dormant as long as possible. Warm sunny weather causes plants to break dormancy early and they become more susceptible to cold temperatures. If you’ve already cleaned up landscape beds, be prepared to cover plants again in the event of cold weather. If you have frosted tulip/daffodil foliage like mine, just leave them be for now.
Even though grass is greening up, it’s too early to apply fertilizers (ideally not till sometime in May). Mowing isn’t needed until after the grass begins to grow and requires mowing. Then maintain a mowing height of 3 to 3.5″ season-long. Pre-emergence herbicides targeted at controlling crabgrass and other warm season annual weeds shouldn’t be applied until soil temperatures consistently reach 50°F. It’s still too early. Soil temps can be found at: https://cropwatch.unl.edu/tags/soil-temperature
Wild/Bur Cucumber: In wet seasons like last year, wild and bur cucumber were seen 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 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.
Renovating Windbreaks: Do you have a windbreak that has several dead or dying trees in it? Steve Karloff and Jay Seaton, District Foresters, shared to think 15-20 years down the road. What would be your goals for the windbreak (wind/snow protection; bloom time; fruit, nut, wood; wildlife/pollinator habitat, etc.)? Each situation will be unique, so these tips won’t apply to each one. Determine whether you’d like to remove the entire existing windbreak or do a partial clearing over time. For those choosing a partial clearing, they suggest to consider leaving the north and west rows and removing the south and east side for sunlight, establishment, and protection purposes. Stumps can be left (unless Scotch or Austrian pine), or can be removed. A stump treatment listed in the UNL Weed Guide is 2 qts of low vol 2,4-D per 10 gallons of diesel. Apply to point of runoff. Don’t use Tordon especially if you’re cutting out and stump treating elm or hackberry trees that get intermingled in trees you wish to save as the Tordon can affect the roots of those trees too. If existing trees, such as pines, have been trimmed up due to dead branches but the remainder of the trees are ok, one could simply consider adding a row of shrubs to cut down on wind.
Also, think about diversifying species based on one’s goals to ensure the windbreak isn’t eliminated due to pest problems. That’s something we’ve unfortunately had to deal with regarding Scotch and Austrian pines due to pine wilt. Conifer specie options include: cedar (most hardy), Ponderosa pine, and Norway and blue spruce. Shrubs include viburnums and hazelnuts; however, there are numerous species to consider depending on goals. Consider 3-5 rows as optimal with 1-2 rows as conifers, 1 row of hardwoods or tall conifers, and 1-2 rows of dense shrubs. However, there’s not always that kind of room available and that may not fit one’s goals. It’s helpful to stagger plant the trees in each row and the gaps can be filled with shrubs or the shrubs can be planted in one row. Next week I’ll share more on site preparation considerations.
Trees Hanging onto Leaves: Driving in the country or in towns I tend to observe what’s going on in the fields, but also observe what’s occurring with the trees. Right now I’m noticing many maples trees looking like mine: hanging onto a portion of greenish/gray/brown leaves. Typically my silver maples are the first to lose their leaves each fall along with a neighboring ash. But the season didn’t start off typical for them either! Some of you, like me, have dealt all year with the huge seed load produced by these and other trees this spring. So why are some trees hanging onto leaves this fall? Most likely a cold snap in early fall interrupted the normal process deciduous trees follow to prepare for winter survival. As days shorten, a layer of cells (abscission zone) form between the tree branch and the individual petioles (stems of leaves), allowing the leaves to fall from the tree. This helps protect the tree from water loss in the winter. Some tree species, such as oaks, have an adaptation to maintain their leaves during the winter called leaf marcescence. It’s unknown exactly why. The hypotheses for why oaks maintain their leaves include: better protection of winter buds, allow for trapping of snow around the tree base, and allow for a flush of nutrients when leaves drop and are decomposed in the spring. So while it’s not normal for maples, lindens, ash, and other species to maintain leaves over the winter, there’s nothing we can do about the delay in leaf drop. If the leaves don’t drop this fall/winter, they will be pushed off by new growth from buds next spring. Leaves may continue to drop this fall/winter with wind and snow events. One thing to be aware of is the potential for increased limb breakage from wind/snow events in trees maintaining heavy leaf loads.
Are you interested in helping understand the noise of farming? Researchers at the University of Iowa developed (and are currently testing) a ‘HearSafe’ system to measure noise exposure of farmers. The goal is to provide information about exposure to loud sounds on the farm and how to protect one’s hearing. This system will consist of a small noise monitor, smart phone, and a laptop. They are looking for farm workers to try these new devices. The research activities are short term (between 1 day and 2 weeks), equipment and training are provided, and there’s compensation for participation. Those ages 18-65, active in farm production (20+ hours per week on average), who have access to a device with high-speed internet are eligible to participate. For more information please contact Jackie Curnick at firstname.lastname@example.org or (319) 335-4425.
Nov. 25 Heuermann Lecture Focuses on Protecting Ecosystems while Advancing Agriculture: Strategies for achieving agricultural advances while preserving Nebraska’s healthy agricultural ecosystems will be discussed at the Heuermann Lecture Nov. 25. It will be held at 3:30 p.m. at the Nebraska Innovation Campus Conference Center in Lincoln and via livestream at: https://heuermannlectures.unl.edu. Following the discussion will be a showing of the documentary film “Follow the Water.” Dinner is included to those staying for the showing. The event is free and open to the public.
Panelists will include Craig Allen, professor in the School of Natural Resources and director of the Center for Resilience in Working Agricultural Landscapes; Andrea Basche, assistant professor in the Department of Agronomy and Horticulture; and Michael Forsberg, co-founder of the Platte Basin Timelapse Project and assistant professor of practice in the Department of Agricultural Leadership, Education and Communication. The film tells the story of connections between the environment and people, and a river that shaped the land. Forsberg, a conservation photographer, and Pete Stegen, a filmmaker, journeyed for 55 days through the watershed by bike, foot and canoe, gathering footage with their smartphones. A panel discussion will follow the viewing so the audience can explore the themes of the film with Forsberg and his team.
Heuermann Lectures are funded by a gift from B. Keith and Norma Heuermann of Phillips. The Heuermanns are longtime university supporters with a strong commitment to Nebraska’s production agriculture, natural resources, rural areas and people.
Crop Update and Hail Damage: While I don’t remember numbers as well, calendar dates are something I tend to remember. And, in agriculture, there’s numerous dates that accumulate over one’s life from hail, tornado, blizzard, flood, and wind events. I was reflecting on the Aug. 6th hail storm that occurred in Merrick, York, and Seward counties in 2018. This past week on August 7th, some woke up to hail/wind damage in Adams, Clay, and Nuckolls counties. The tree damage was incredible. Michael Sindelar, Clay Co. Educator, and I surveyed damage a day later. My estimation of the worst hit crops: corn around 80% defoliation with varying percentages of greensnap above/below ear and soybeans around 50% defoliated/broken off/with at least 50% pods on the ground. Where hail stones hit the ears, the kernels are mushy and mold is already setting in on corn at milk stage. There’s also mold setting in on soybean pods hit with hail stones. It’s hard to receive crop damage any time. The good news is that nothing appears to be a total loss; the majority of what we looked at was less than 40% defoliated and in general, the hail did not seem to penetrate the stalks, thus early stalk rot doesn’t appear to be setting in. Pictures at https://jenreesources.com.
Tree Problems: The majority of my questions the past 10 days were regarding tree leaves turning yellow and dropping from trees. They look stark against green grass. In general, what’s happening is the fact that we’ve had high humidity for a period of time now and we’ve had rain throughout spring and summer. Fungal pathogens thrive in these conditions. So, ornamental/flowering pears have pear rust; crabapples and apples have scab and also cedar-apple rust (depending on varieties); maples, ash, sycamores are showing anthracnose; and a number of other fungal leaf spots are observable on shade trees in general. Evergreen trees show various fungal needle spots. Ultimately, we don’t recommend doing anything for these diseases this time of year. We typically don’t recommend to spray shade trees in general, but fruit and evergreen trees should be sprayed in the spring if fungal diseases have occurred in the past. So, fungal diseased leaves may drop early and you may or may not observe a new flush of leaves yet this year. These fungal diseases won’t kill deciduous trees. They can kill evergreen trees over a period of years.
Oak leaves turning brown in clusters was also observed this past week. Sometimes
browning of leaves can be due to a fungal disease called anthracnose. Most of what I’m seeing, I believe, is environmental. It could be due to changes in hot/cool and periods of heavy moisture followed by lack of moisture on trees that had a huge flush of leaves due to moisture this spring. I really don’t know the cause for sure, but it doesn’t appear to be disease related from what I can tell. We wouldn’t recommend doing anything for the trees at this time.
UBBNRD Public Hearing: The Upper Big Blue NRD will hold a public hearing and informational open house on Aug. 19 at 7:00 p.m. at the Holthus Convention Center. The purpose is to receive comments on proposed changes to District Rule 5 – Ground Water Management Area Rules and Regulations. A complete copy of Rule 5 and the proposed changes are available at the district office and at www.upperbigblue.org/publichearing. The public will have the opportunity to learn more about these proposed changes and their effects, and address NRD board members about their concerns or support.
The proposed changes would stipulate that an approved nitrification inhibitor must be applied at the manufacturer’s recommended rate with pre-plant nitrogen fertilizer in the following situations: The application of anhydrous ammonia prior to March 1; The application of all nitrogen fertilizers other than anhydrous ammonia after February 29. In addition to these requirements, in Phase II and Phase III areas pre-plant application of nitrogen fertilizer shall not exceed 120 lbs. per acre. The remaining nitrogen fertilizer may be applied post plant. Prior to applying nitrogen fertilizer, but no later than April 1 of each year, each operator in the management area will be required to report information regarding the use of best management practices. For more information, visit www.upperbigblue.org or call (402)362-6601.
York County Corn Grower Plot Tour will be held Aug. 20th from 5-7 p.m. at 1611 Rd. 14 east of York. Pizza and refreshments will be provided and check out the latest hybrids. Guess the winning yield without going over and win a $50 gas card. All are welcome!
*End of News Column. Hail damage photos below.
Heat and Pollination: With last week’s heat and anticipated heat later this week, we were receiving questions regarding the impacts of heat and humidity on pollination. You can view the entire article in this week’s CropWatch at https://cropwatch.unl.edu. Key points include: Heat over 95°F depresses pollen production and prolonged periods of heat can reduce pollen production and viability. When soil moisture is sufficient, one day of 95-98°F has little or no impact on yields. After four consecutive days, there can be a 1% loss in yield for each day above that temperature. Greater yield loss potential occurs after the fifth or sixth day. High humidity, without a drop in humidity during the day, can delay pollination or prevent pollen from leaving anther sacs. We’ve been blessed we only had days of extended high heat around pollination, received a break in the heat in addition to weekend moisture.
Insect Pests: From light trap reports, peak western bean cutworm (WBC) flight appears
to have occurred last week, so scout for egg masses and live larvae with a 5-8% treatment threshold. Thistle caterpillars grew rapidly last week. Others are with me in considering spraying closer to 15% (instead of 20% threshold) with stressed fields from flash drought and/or off-target dicamba injury that don’t have canopy cover yet. In CropWatch, check out the articles regarding scouting for grasshoppers in field borders and what to expect for insects depending on crop growth stages yet this year.
Cattle Losses from High Heat: If the recent heat/humidity conditions are determined to be an extreme weather disaster event, then livestock losses would be covered by the Livestock Indemnity Program (LIP). Livestock producers who lost livestock should document losses in the expectation that they may be covered by LIP and contact your local Farm Service Agency (FSA) to report those losses.
South Central Ag Lab Field Day Aug. 1: View current field trials on improving crop production and profitability at UNL’s South Central Ag Lab (SCAL) on August 1 near Harvard. Guests can customize their day to select the tours they’re most interested in. Presentation topics include: Cover crops, pollinators and weed management; European corn borer, corn rootworm, and cover crop insect control; Herbicide-resistant weed management; Assessing injury and management decisions in corn and soybeans; Corn and soybean disease updates; Sensor-based nitrogen management in irrigated corn; Corn stover harvest management and impacts; mobile beef lab and hail machine demonstrations. Registration is at 8:30 a.m. followed by tours through 4 p.m. Lunch and refreshments are included. CCA credits have been applied for. For more info. see the program brochure and register at: https://go.unl.edu/2019scalfieldday.
Silage Webinar Aug. 2: With this year’s challenging weather and the need for forage, there may be more opportunities for harvesting corn for silage. Aimed at feedlot, cow-calf, and dairy producers, a silage webinar on August 2 at Noon CST will focus on moisture at chopping, chop length, inoculants, proper packing, silage covers and more. Pre-registration for the webinar is necessary and can be done at: https://go.unl.edu/vau7.
Trees Losing Leaves: The wet spring and humidity allowed for fungal diseases on leaves of shade trees with flowering pears and crabapples in particular dropping leaves early. I’ve also had a number of questions regarding red maple leaves (Autumn Blaze and Sunset) suddenly turning brown on trees. These symptoms may also be experienced on ash, tuliptree, and other maples. We think it’s environmental stress from having so much cool and wet early to almost a ‘flash drought’ situation in eastern Nebraska prior to this weekend’s rains. Sarah Browning has been recommending watering and mulch as the best ways to reduce stress and to prevent additional root death and tree decline. I’ve been seeing new growth starting to occur on trees so my hope is if your tree is experiencing this, that 10-14 days from now you will also see new growth occurring on your trees.