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JenREES 4/4/21

Hope you had a blessed Easter! For me, it was an extra blessing to worship in person and be with family this year! This week sharing on a variety of questions I’ve received.

Private Pesticide Certification/Recertification: for those still needing pesticide certification:

  • Easiest option: attend a Zoom training being held this week on April 9th at 9:00 a.m. You can register at the following site: https://go.unl.edu/patapril9. You will receive a zoom link to attend that training. The materials and payment will occur at the local county Extension office of your choice. Cost is $50.
  • Online pesticide training: This is self-paced with quizzes. You can register and pay online here: https://web.cvent.com/event/4efa4d41-c770-4a78-99d7-4c4ea75d45ae/summary. Cost is $50. If you have bad bandwidth or have difficulty with computers, please call your local Extension educator.

2021 Nebraska farm real estate survey can be found here: https://go.unl.edu/9exp.

Emerald Ash Borer Map: We don’t recommend treatment for ash trees until your tree is within a 15 mile radius of where emerald ash borer has been confirmed. Right now, most of Seward county is in the treatment zone but York county is not. We also only recommend considering treating high value trees that don’t have obvious health issues. You can view a map of the suggested treatment areas at:  https://nfs.unl.edu/documents/EAB/EABmap1-22-21.png. More information can be found at: https://nfs.unl.edu/eab-faq.

Small Grains and Jointing: The jointing stage of wheat, rye, and triticale is when the growing point comes above ground. This is a critical stage when taking these crops for grain, as growth regulator herbicides, particularly dicamba, can cause injury to the stem base (causing wheat to grow prostrate) and heads of the plants (emerge deformed) if they’re applied. The best way to check for jointing is to pull up a plant by the roots, slit open the main (thickest) stem from the base up, and see if you can see the developing head or not. I was seeing jointing occurring in earliest planted rye in York Co. last Thursday. 2,4-D and MCPA are labeled from full tillering till prior to boot stage but I’ve still seen 2,4-D at jointing to cause wheat to grow prostrate at times. K-State shares in spite of this, they don’t typically see yield loss in these situations when 2,4-D was applied.

In this picture, splitting the stem with a box cutter or razor blade, reveals the rye is jointing as the growing point (shown above) is visible above ground.

Cover crop termination: University of Missouri recently released results of a multi-state study funded by the United Soybean Board looking at herbicide options for cover crop termination. Control of cereal rye and wheat used for cover crops was best with glyphosate alone or in combination with 2,4-D, dicamba, Sharpen, or Select. For legume cover crops, glyphosate, gramoxone, and liberty were all similarly effective, particularly in combination with 2,4-D, dicamba, or Sharpen. Brassica species weren’t reviewed in this study, but there are ratings available in the front section of the 2021 weed guide which show highest control ratings with glyphosate + 2,4-D or dicamba. The full study results can be found here: https://ipm.missouri.edu/IPCM/2020/3/coverCropTermination-KB/.

Seed corn maggots: Something on my mind is the potential for seed corn maggot pressure this year. They tend to be a problem when fields recently had manure applied or have green plant material, like cover crops, that have been incorporated into the soil within two weeks of planting the cash crop. But we’ve also seen them when the covers or manure haven’t been incorporated. The past few years we’ve seen increased seed corn maggot damage to soybeans, particularly when planted into a field that had a brassica cover crop such as turnips, radishes, and forage collards. I’ve rarely seen damage warrant replanting soybean. There’s no rescue treatments. Insecticidal seed treatments often provide protection and in-furrow insecticides can provide additional preventive protection for fields with a history of seed corn maggot damage. Extension entomologists also recommend to avoid planting during peak fly emergence which occurs when 354, 1080, and 1800 GDD have accumulated since Jan. 1 (using a base temp of 39F for the calculation), but this may not always be feasible.

Seed corn maggot feeding on germinating soybean.

JenREES 5-21-20

This Memorial Day will be different not gathering to honor those who have gone before us. Grateful for those who paid the ultimate sacrifice for our freedom! May we still take time to honor them.

Crop Update: Several weeks ago we were seeing large numbers of seed corn maggotIMAG4806-20180520-202958269 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

IMAG5463

Bush with a severe bagworm infestation in 2018. Hard to see the bags in the brown part, but you can see them to the right in the green foliage.

have emerged yet or not. If you have last year’s bags on your trees that are sealed (don’t have an open hole at the top), you can pick off some bags, place them in a ziplock bag, and place it outdoors on the south side of your house. When you see larvae emerge, it’s a good indication to start checking your trees in the next weeks. Each bag can hold 500-1000 eggs. The larvae are really small and hard to see. Stand still and watch the tree. If bagworm larvae are present, you will see very tiny movements as they begin the process of building new bags. I have pictures and a video at: https://jenreesources.com/2015/06/27/bagworms-in-evergreens/. Egg hatch is from mid-May to early June, depending on the year. Some caterpillar larvae remain on the same trees containing the bags from which they hatched. Others are blown by the wind to area trees allowing for new infestations to occur. For homeowners with small trees or only a few trees, bags can be picked from trees now and drown in soapy water or burned. In the summer, they can be squished, drowned, or burned. I have a great memory of visiting Grandma in the care center with my family. Grandma was concerned about the spruce in the courtyard. Seeing bagworms, I turned it into a science lesson for my nieces/nephews. They had a blast making quick work of picking off bags and squishing them to the delight/disgust of the residents watching (and their parents) 🙂 That’s not feasible for most situations though. We recommend waiting to treat trees until bags reach around 1/2” in size to ensure egg hatch is complete. Good coverage is needed when treating trees. With ground sprayers, we say to spray to the point of runoff. Bt products are effective early on. Most often I recommend a permethrin or bifenthrin product. Aerial application may also be an option for windbreaks. For more info., please see: https://go.unl.edu/rgju.

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