Perhaps it was the hard winter, but I’m finding the flowering trees to be exceptionally pretty this year! Corn and even some soybean went into the ground this past week too. In last week’s column I shared regarding planting considerations yet would still encourage growers to keep considering your local field conditions before planting. You’re hearing some of these same things from both Extension and Industry partners and we realize field situations differ. We keep repeating these things to provide reassurance when you’re questioning decisions. We’ve already seen problems with anhydrous application in too wet of conditions in some fields. We’ve already seen some situations that were too wet when corn was planted leading to problems with compaction, depth issues, and not closing seed vee’s. With the cold snap, it’s important to consider soil temperatures (preferably around 50F or warmer for next 48 hours), soil moisture conditions, air temperatures for the next 48 hours, potential for cold rain, and cold tolerance of seed. Soil temperatures are listed at http://go.unl.edu/soiltemp and I would also encourage you to check your own particular field conditions. Last week, I was finding soil temperatures in local field conditions to be cooler than what was being reported from high plains regional climate center. If you don’t have a soil temperature thermometer, you can do this with a meat thermometer (and just dedicate it for field use).
I can appreciate the added concern and stress with this week’s forecast. There’s several planting-related articles in this week’s CropWatch at http://cropwatch.unl.edu. Two really helpful articles from Roger Elmore share on corn planting windows where he used USDA NASS data to show Nebraska data and also shared how other states throughout the Corn Belt have found similar results regarding planting windows. The key point is there’s a planting window between mid-April to mid-May within which optimum yields are usually obtained. After this period, yields decrease rapidly. So there’s still time and the planting conditions play a role in determining final yield by getting that seed off to a good start. You also keep hearing me talk about planting soybean early. Even as early as you can in May is better than mid to late May for higher yields if that works for your situation.
Browning Evergreen Trees and Shrubs: This past winter was hard on many things. When it comes to evergreen trees, the deep frost line and extreme cold led to the inability for transpiring trees to uptake moisture. This resulted in needles appearing brown and looking dead, particularly on the north and sometimes west sides of trees. I’m seeing this particularly on junipers, cedars, arborvitae, white pines, and some spruce. We’d recommend waiting till June before pruning any dead portions out or removing any trees/shrubs to see what happens with new growth.
Rhizosphaera Needle Cast in Spruce has been really bad the past few years. If you’re seeing spruce needles on lower parts of the tree turning yellow/reddish-purple/brown, then this disease may be the problem. The fungus continues moving upward on the tree. Affected needles are prematurely cast from the tree. Above average moisture during the growing season in parts of the State led to an increasing number of spruces affected by the Rhizosphaera fungus. What’s interesting is that the fungus infects the needles in spring but the symptoms often don’t appear till the following spring. One way to double check is to look for tiny black specks on the needles and on the twigs. The good news is that fungicide applications of chlorothalonil (Fungonil, Daconil, Bravo) or Bordeaux mixture in May can help when shoots are ½ to 2” in length! If we get frequent rains this growing season, applications can be repeated every 3-4 weeks.
Vegetable Planting Guide: Gary Zoubek had put together an excellent vegetable planting guide for the area which can be obtained at the Extension Office or at: https://go.unl.edu/d7qk.
Spring Lawn Seedings: With the difficulty of this past year, many didn’t get dormant seedings on because of all the snow and typically lawn renovation in the spring is difficult because of the inability for applying crabgrass preventer to newly seeded areas. However, a new product has changed this! 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. We’d still recommending seeding as soon as possible or else wait till August. 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).
Rhubarb and Frost: For those impacted by frost/freeze this past weekend, if rhubarb leaves are not damaged too much and the stalks remain firm, it is still safe to eat. If the leaves are severely damaged or the stalks become soft or mushy, do not eat these stalks. Remove and discard them. New stalks can be harvested and eaten. Rhubarb often develops seedheads following cold temperatures, but this also does not affect eating quality of the stalks. Remove rhubarb seedheads and discard.
Planting Considerations: Everything we do at planting sets the stage for the rest of the year. We’re blessed to have equipment that can allow for many acres to be planted in a short amount of time. And, we have the ability to mess up a lot of acres in a short amount of time.
For soil conditions, it’s important that we’re not mudding in fertilizer and seed to avoid compaction and uneven emergence issues. Soil temperature information can be found at: https://go.unl.edu/soiltemp. It’s best to plant when soil temps are as close to 50°F as possible, check weather conditions for next 48 hours to hopefully maintain temps 50°F or higher, and avoid saturated soil conditions. If planting a few degrees less than 50°F, make sure to check with seed dealers on more cold-tolerant seed and only do so if the forecast is calling for warm temperatures the next few days that would also help increase soil temperatures. Once planted, corn seeds need a 48-hour window and soybeans need a 24-hour window when the soil temperature at planting depth does not drop much below 50°F. Otherwise chilling injury is possible.
With the variability of weather each spring, we perhaps need to shift our focus from “calendar dates” to “planting windows”. The optimum planting date for corn may not be in April every year. Research from Iowa State found optimum planting date windows to obtain at least 98% yield potential range from April 15-May 9 for northwest and central Iowa; from April 17 to May 8 for southwest Iowa; and from April 12-30 for north central and northeast Iowa. To achieve at least 95% yield potential, those ranges extend from April 15 to May 18 for northwest and central Iowa; from April 12 to May 13 for southwest and southeast Iowa; and from April 12 to May 5 for north central and northeast Iowa. It’s not Nebraska data, but could be considerations for us for similar areas of Nebraska. And, while we don’t have a lot of data in Nebraska, one can use USDA ag statistic yields and I’ve also used the Hybrid Maize Model to show how yearly weather can impact optimum planting windows for best potential yield.
Planting soybean early is critical to maximizing yield. Beyond genetics, this is the primary way to increase soybean yield through numerous University studies in addition to grower-reported data. Because of this, an increasing number of growers are planting soybean earlier than corn or at least at the same time as planting corn. ‘Early’ is within reason, though. While we’ve had on-farm research fields and many growers’ fields planted from April 22 and after (in good field conditions), be aware that crop insurance date is April 25. We also recommend adding an insecticide + fungicide seed treatment when planting in April as we have no data without seed treatment in our planting date studies.
Planting depth is also key. Aim to get corn and soybean in the ground 1.5-2” deep. This is critical for correct root establishment in corn to avoid rootless corn syndrome. While not as critical regarding root establishment for soybean, our UNL research showed lowest yields when soybean was planted 1.25” or less or 2.25” or greater with the highest yield at 1.75” deep. This is most likely because moisture and temperature were buffered, particularly when soybean was planted early. It’s important to get out and check seeding depth for all planter units within every field. Even with monitors showing down force and seeding depth, it’s still important to check. I’ve seen how adjusting down force can lift up planter ends resulting in shallow planting in the outside rows, particularly with center-fill planters. Results of improper/uneven planting depth can be seen all season long and may affect yields. While this takes time, you’ll be glad you caught any issues before too many acres are planted incorrectly!
For corn seeding rates, it’s best to check with your local seed dealer as all our research shows that optimal corn population varies by hybrid. However for soybean, our recommendation after 12 years of combined on-farm research studies continues to be: plant 120,000 seeds/acre, aim for a final plant stand of 100,000 plants/acre and you’ll save a little over $10/acre without reducing yields. If that’s too scary, try reducing your populations to 140,000 seeds/acre or try testing it for yourself via on-farm research! Please contact me if you’re interested in that. We have an article on our soybean seeding rate data in this week’s CropWatch at http://cropwatch.unl.edu.
Lawn Crabgrass Preventer and Fertilizer Application: Crabgrass is a warm season grass and needs soil temperatures to reach 55 degrees F for a few consecutive days to germinate. It doesn’t all germinate at once, thus the potential for a second flush in the summer. The targeted window to apply pre-emergence herbicides for crabgrass in eastern Nebraska is April 20 to May 5. Keep in mind that the product needs to move into the soil within 3 days or it will start breaking down due to sunlight exposure. You may also consider applying your crabgrass preventer with first lawn fertilizer application around the beginning of May.