Monthly Archives: August 2022
Last Irrigation: This really is dependent upon everyone’s individual soil moisture situation by field, crop development stage and crop rooting depth for that field. I have a fairly proven method I’ve used for watermark sensors, but being there’s so many different irrigation scheduling tools used, it won’t be applicable to everyone. We’re most likely done irrigating most ‘normal season’ corn in the area at this point. Corn at ½ milk needs approximately 13 days and 2.25” to finish. Corn at ¾ milk needs about 7 days and 1” till black layer. At this point, we’d say you can draw soil moisture down to 60% of field capacity. If you have the top foot at field capacity for a silt loam soil, there would be at least an inch available in the top foot alone, not accounting for soil moisture in the next several feet. So, you could wait a week and see where soil moisture is and adjust from there.
What I said for corn above can also be applied for soybean. I think what’s trickier for soybean is determining the end reproductive stages, especially as we have been conditioned to look at ‘leaf yellowing’ as the beginning of physiological maturity, yet many factors can cause leaf changes. So I feel perhaps a better indicator of maturity is to look at the pods. For soybean development stages from R2 (full flower) to R6 (end of seed enlargement), we are looking at pods at the top 4 nodes of the plant. For R7 (full maturity), we are looking for at least 50% of the plants having one mature pod anywhere on the main stem.
So how do we know a pod is mature? Inside of each soybean pod, there is a whitish membrane around each seed that provides water and nutrients to the seed. A mature pod is considered when the pod membrane no longer clings tightly to seeds in that pod (this is like black layer on corn where the nutrient/water supply is cut off from the kernel forming the black layer). So essentially, if you pull off a pod on the main stem, carefully open it up and look at the white membrane surrounding the seed. If it’s still clinging tightly to it, it’s not quite mature. If you see separation of the membrane and seed, it’s considered mature and will no longer use water.
Soybeans at full seed (R6 end of seed enlargement) need approximately 18 days to maturity or 3.5” of water. At R6.5 (leaves yellowing/pod membranes still clinging to seed) the soybean needs 10 days or 1.9” yet until R7 (physiological maturity), in which the pod membrane has separated from the seed and requires no more water.
Soybean stems typically turn brown shortly after R7 begins, though the stem can remain green longer due to a number of reasons, including fungicide use. The final soybean stage is R8, which occurs when 95% of pods have attained maturity and have a variety-dependent color of brown or tan. Seed moisture in a soybean pod dries down from 70% at R7 to about 13% at R8. This has shown to be around 12 days based on research, but can be faster or slower depending on solar radiation, humidity, temperature, wind speed and soil surface moisture.
Eastern Nebraska Wheat and Alfalfa Expo will be held Sept. 1 at the Tuxedo Park Exhibition Building in Crete. The expo will begin at 8 a.m. with a light breakfast and exhibitor booths. The educational program starts at 9 a.m. and ends at 3 p.m. Wheat topics in the morning include: wheat variety recommendations, underseeding red clover, hail damage and wheat streak mosaic virus, cost-share programs for growing wheat, and feeding wheat grain to cattle. Topics on alfalfa in the afternoon include: benefits of diverse crop rotations for wildlife, managing potato leaf hoppers, irrigating alfalfa, and herbicide management. There’s no charge but please RSVP to 402-821-2151. More info. at: https://croptechcafe.org/alfalfawheatexpo/.
For Fun: Something that brings me great joy is the opportunity to teach youth who love to learn. I’m so blessed to have a wonderful group of families with youth interested in plants and science in my Crop Science Investigation (CSI) group! The youth pictured above were interested and old enough to compete at State Fair for the 4-H Weed and Grass ID (left) and 4-H Horticulture (right) judging contests. They invested a lot of time into studying and what makes my heart so happy is to see them so greatly enjoy learning and having fun while we identify plants! The York teams received 1st and 3rd place teams in Weed and Grass ID with 6 of the 7 youth placing in the top 10. We also had an individual place in the top 10 in Horticulture ID. So cool to see these youth learning these identification skills they will use for life!
Corn Silage Resources: For those making corn silage this year, hopefully the following resources can be of help. The multiplier for corn silage value from UNL is 7.65 times the market value of corn grain.
- Making corn silage considerations: https://go.unl.edu/qven
- Estimating a fair value for standing forage (including silage): https://go.unl.edu/sy6j
- Value of Standing Forage excel spreadsheet (scroll to mid-page): https://cap.unl.edu/forage
Spidermites: I’m hoping that the cooler weather and either rainfall/irrigation are helping a beneficial fungus help us in the battle against spidermites. Last week I was showing growers how to distinguish this via a hand lens. We mostly have two-spotted spidermites in fields, which are yellow with two black spots on them. Anytime they start looking different (darker, cloudy, white) where the spots are no longer visible, it can be an indication that they are infected and will die. Unfortunately I didn’t grab any pics from the field. The economic threshold from Colorado State says spraying is no longer beneficial past hard dough. I can appreciate that’s hard with the severity in some upper canopies, so here’s hoping the cooler weather helped with the battle.
Pollination: I sure appreciated seeing and smelling all the pollen shed in these replant fields last week! It was perfect weather for it, hopefully a bright spot in the midst of a difficult situation. Been hearing and seeing complaints about poor pollination in non to less severely hailed areas. I don’t remember smelling pollen this year like I normally do in July, but I also admit most of my time has been spent in this large replant area this year. The following is about poor pollination, not kernel abortion.
What I’ve learned from Dr. Tom Hoegemeyer and Dr. Roger Elmore about corn pollination through the years: Heat over 95F depresses pollen production with prolonged heat reducing pollen production and viability. When soil moisture is sufficient, one day of 95-98F heat has little or no yield impacts. After four consecutive days, a 1% yield loss can occur for each day above that temperature with greater yield loss by day 5 or 6. High humidity, without a drop in humidity during the day, can delay pollination or prevent pollen from leaving the anther sacs. Pollination mostly occurs between 8:30 a.m. and noon. When the temperature is 90°F to 95°F, the pollen is eventually killed by heat and is seldom viable past 2 p.m. Pollination typically occurs over a span of six to ten days depending on variability of growth stages in the field.
So, I did some digging into weather data. I don’t have all the tools that you may have, so do something similar for your operations based on the timing of when your specific fields were pollinating and where you’re located. First, I did a general map of Nebraska showing the number of days over 95F from July 9-19, 2022. The eastern 1/3 of the State only had 0-1 days that fit this criteria.
Perhaps bigger factors may have been humidity and timing of silk emergence compared to pollen shed? We’ve had high humidity. For pollen shed to occur, relative humidity needs to drop between 50-65% and the pollen is no longer viable at 30%. As I look at weather data for different locations in the area, many places had over 65% relative humidity as an average for the day for at least 5 days in the time period listed above. It really comes down to at what time the relative humidity dropped enough during the day to release viable pollen. It’s possible that for several days, the anther sacs dropped without releasing pollen if the humidity didn’t drop in the morning. I also remember mentioning in July about how extra long the silks seemed this year prior to pollen shed. That can be a problem, particularly for pollination on the lower end of the ear. The first silks that emerge from the husk are attached to kernels at the base of the ear and they begin to form 8-10 days prior to R1. Silks then continue to emerge sequentially up the ear with the ear tip silks emerging last. Silks are receptive to pollen anywhere along the silk, but after 10 days, the silk senesces (and they’re most receptive to pollen in the first 4-5 days of emergence). Some drought tolerant hybrids may have genetic X environmental responses which trigger silks to emerge 4-5 days prior to any pollen shed (which can result in poor pollination). Older silks can also get covered up by newer silks and miss exposure to pollen. Drought stress adds an entire other complexity to this discussion. Japanese beetles clipped silks in some areas, but it sounded like most were sprayed timely or the silk clipping occurred after the silks had pollinated (turned brown). I don’t know the specifics of every individual situation. These are some thoughts to consider if you’re dealing with pollination issues this year.
With every development stage this replant corn crop achieves, I’m grateful! Many fields will hopefully begin pollination soon. Late-planted crops can have quite a bit of disease and insect pressure develop late. Would encourage you to wait and treat fields when needed instead of automatically at beginning tassel.
Last irrigation: (days listed are based on GDUs, so consider this for your crop growth stage and field soil moisture levels so you can start tapering off). This tool helps you calculate potential black layer date based on your planting date and relative maturity: https://mygeohub.org/groups/u2u/purdue_gdd. What I’m currently seeing is that 2022 is around 70 GDD higher for York than the 30 year average and is tracking pretty similarly to 2012.
- Corn at Dough needs 7.5” (approximately 34 days to maturity)
- Corn at Beginning Dent needs 5” of water (approximately 24 days to maturity)
- Corn at ¼ milk needs 3.75” (approximately 19 days to maturity)
- Corn at ½ milk (Full Dent) needs 2.25” (approximately 13 days to maturity)
- Soybean at beginning seed (R5) needs around 6.5” (approx. 29 days to maturity)
- Soybean at full seed (R6) needs 3.5” (approx. 18 days to maturity)
- Soybean with leaves beginning to yellow (R6.5) needs 1.9” (approx. 10 days to maturity)
I share that yet acknowledge what I’ve heard in the weariness of irrigating and the temptation to quit early. My guess is there’s many feeling this way…and it seems especially long to those who have replant crops. Ultimately would just encourage you to finish strong!
Verbal Land Lease Agreements: Have received a few questions on timing to notify of terminating a verbal land lease; that date is Sept. 1 for Nebraska. I have searched and am unaware of a good template for this notification. The verbal lease date doesn’t apply to written leases as dates should be specified within them. Templates for written leases can be found at: https://aglease101.org/doclib/.
Renovating Lawns in the Fall: August 15-September 15 are the best times to seed cool season grasses. Improving Turf in the Fall at https://go.unl.edu/rz9z is a great resource to walk you through renovation depending on your situation. Some lawns can be easily improved by adding fall fertilizer.
Sarah Browning, Extension Horticultural Educator shares, “Late summer or fall fertilization of Kentucky bluegrass and tall fescue lawns is the most important time to fertilize these cool season grasses. Fertilizer promotes recovery from summer stress, increases density of thinned turf, encourages root and rhizome growth, and allows the plant to store food for next spring’s growth flush. Lawns that are 10-15 or more years old typically need only two fertilizer applications a year. Make the fall application in late August or early September. On younger lawns, two fertilizer applications during fall are recommended. Make the first one in late August/early September, and the second in mid-late October.”
If overseeding is needed to fill in thinned areas but more than 50% of good turf remains, mow the existing grass 2.5” tall to make the soil prep easier. For lawns needing total renovation, start with a glyphosate (Roundup application) followed by waiting at least 7-10 days to kill the lawn. Mow dead vegetation as short as mower goes to then aerate the lawn three times. Full seeding rate for tall fescue is 6-8 lbs./1,000 sq.ft., and 2-3 lbs. for Kentucky bluegrass. When overseeding into an existing lawn, the seeding rate can be cut in half. Drilling the seed is perhaps best, otherwise, use a drop seeder. Seed half the seed north/south and the other half east/west for even distribution. Then lightly rake to ensure seed to soil contact.
The buildings and barns are now emptied, exhibits taken home and people are weary. But what remains
are the friendships, the connections re-established, the smiles, the gratitude, the pulling together, the awards given to the youth, the lessons learned. When I was in 4-H, I had no idea the amount of time that Ag Society, Extension staff, volunteers, my 4-H leaders or even my parents put into the fair. I could’ve said ‘thank you’ so much more! This was my 19th county fair on ‘the other side’ and it never ceases to amaze me the list of items to accomplish in order to ensure a successful fair. It takes many dedicated people to achieve all of this. I’m so grateful to the ag society, 4-H Council, Extension staff and board, FFA advisers, 4-H leaders, numerous volunteers, and parents that pull together each year to pull off county fairs! As I reflect, things that make my heart happy and make me smile are thinking about the number of wonderful people who help me in Ag Hall each year, the youth proudly wearing their medals around the fairgrounds on Thursday evening after the award’s ceremony in York Co., the crop plot for ag literacy in Seward Co., seeing the fairgrounds so busy in spite of the heat, watching people from across the counties reconnect, people pulling together in the midst of adversity, and the hard work that especially ag society puts into the fair behind the scenes to ensure that attendees enjoy the fairs. Thank you also to all of the sponsors! Grateful to all for making the York and Seward Co. fairs a success!
Produce not Ripening: Many have green tomatoes. My colleague, Scott Evans shared it’s due to the heat as temps over 90F prevent the plant from producing lycopene and carotene. You can bring mature green tomatoes indoors to ripen (sunlight isn’t needed) or you can wait for cooler weather for them to turn. How do you know if they are mature enough to bring indoors for ripening? Look for an off-green to a tinge of white on the shoulders of the fruit on the stem side on fruit that is the right size of for that variety. He said the same can be done for peppers that aren’t turning orange, red, or yellow. For cucumbers, fruit production declines with the heat but doesn’t impact maturity.
Spidermites: Just a reminder of this helpful article as the heat has really brought on spidermites in crops: https://go.unl.edu/9v6u. For those with gardens, spidermites are also impacting vegetable and flower plants. Symptoms include webbing and yellowish ‘stippling’ or tiny spotting on the leaves which eventually turn brown. You can take a white piece of paper and knock the leaves on it. If you see tiny insects the size of pinpoints moving, it’s most likely spidermites. Spraying plants with heavy streams of water ensuring each side of the leaf is hit helps knock them down. Proper watering (reducing drought stress) can help reduce spidermites. Those two things can drastically and naturally help with spidermites in garden settings. Insecticidal oils and some plant extract products can help. Just be sure to read the labels to ensure the product is safe for the plant you’re applying it to and never apply these products when temperatures are above 90F to avoid damage to the plant.
Irrigation: The heat is progressing plant and seed development in crops not replanted. Corn at dough needs 7.5” till maturity, 5” at beginning dent, 3.75” at ¼ milk, 2.25” at ½ milk, and 1” at ¾ milk. Soybean at beginning seed (R5) needs 6.5”, end of seed (R6) needs 3.5”, and 1.9” at leaves beginning to yellow.
Soybean Management Field Days are this week (Aug. 9-12)! Last year a team of us tried an approach of more discussion with attendees and this year we’re seeking to format more parts of the field days this way. Each location will be unique to the situations that area of the state is experiencing. Join us for discussions on insects, diseases, weed management, cover crop implementation, precision ag, economics, irrigation, and biodiesel. Closest locations are Blue Hill on Aug. 9 and Central City on Aug. 10. Hope to see many at one of the locations this week! More info. here: https://go.unl.edu/xukf.