Driving through Nebraska towns around Memorial Day, I find the streets lined with flags such a beautiful site. Grateful to live in our Country with our freedoms. I’m also grateful for those who paid the ultimate price for our freedom and for their families left behind.
Flooding/Ponding and Crop Effects: With the rain, some may be experiencing ponding/flooding of crops. Emerged corn prior to 6 leaves can survive from two to four days depending on temperatures and if entire plants are submerged or not. Cooler air temperatures (60’s and cooler) allows for longer survival than temperatures in the mid-70’s and warmer. Little data exists for germinated seeds and seedlings prior to emergence, but they most likely would experience soil oxygen depletion within 48 hours. Once emerged, soybean may handle a fair amount of flooding due to the growing point being above ground (depending on if they’re submerged or not). Four or more days of flooding may result in shorter plants due to shorter internodes and/or perhaps fewer nodes. Stand reductions may be observed after seven days of flooding (depending on size and if completely submerged or not).
Prevent plant may be another topic on some growers’ minds in addition to considerations after the May 25 corn planting date for crop insurance. These are addressed in this week’s CropWatch at http://cropwatch.unl.edu.
Interseeding Cover Crops: In a previous news column, I touched on the topic of interseeding cover crops into corn or soybean. For this week’s CropWatch at http://cropwatch.unl.edu, we provide more information based on the research available. For those considering this as an on-farm research study, please contact me or your local Extension Educator soon to work out details.
Wheat: Michael Sindelar and I looked at wheat in Clay and Nuckolls counties last week. For diseases we’re mostly seeing powdery mildew and septoria leaf blotch. Backlighting revealing yellow specks on upper leaves in some fields will most likely develop into leaf rust. Wheat ranges from nearing flag leaf to beginning flowering. My concern for wheat in the heading to flowering stage is risk of fusarium head blight (scab) with the rain we’ve been receiving at heading/flowering. The scab risk tool (http://www.wheatscab.psu.edu/) is showing a low to medium risk for our part of the State right now. If you do consider a fungicide, your best options include Prosaro, Caramba, or Miravis Ace as these products will help protect against scab in addition to kill any fungal diseases on your wheat leaves. Other products are off-label once flowering begins or are not as effective preventing scab based on research. Best application timing to prevent scab is when 30% of the plants in the field are at 15% flowering (early flowering stages).
Lawn Care: I know some are getting tired of mowing already! Just a reminder to keep mowing heights at 3″. Spring is an important time for deeper root establishment before the summer heat sets in and maintaining a higher lawn height allows the grass to develop that root system. I’m seeing several lawns being scalped in an effort to reduce amount of mowing. Mowing too short stresses the grass impacting its ability to set deeper roots for later. It will also allow for more weeds to germinate in the lawn.
Crop Update: So grateful for rain and truly hope those who wanted and needed rain received it! An update to soil moisture profile as of 5/17/18 can be found at http://jenreesources.com.
A number of crop issues surfaced this week. One being root burn and wilted-looking corn seedlings from anhydrous ammonia applications with the dry winter/spring we’ve had thus far. Anhydrous ammonia can expand in soils 2.5-3” in all directions and potentially more in dry soils. Pivots were running to help with that and hopefully rain events will help non-irrigated fields that were suffering in this way. Another problem observed in some non-irrigated corn fields has been fomesafen carryover injury from products such as Flexstar, Reflex, Prefix, etc. These products have a 10 month planting window back to corn which is fine in most years, but dry conditions didn’t allow for the herbicide to break down in all situations from applications last June. This active ingredient is in Group 14 (PPO inhibitors) and the injury from this particular active ingredient is unique in that it causes yellow/brown striping of the veins themselves instead of interveinal chlorosis/necrosis. Seedlings most affected right now are found on field edges or wherever there was overlap of application. Hopefully corn should grow out of this injury in time. Herbicide carryover may be a something to watch for in soybean as well from other active ingredients. We also saw regrowth occurring on plants affected by wind/dust/debris damage but there are situations where replanting will be needed on endrows, etc. Roger Elmore has a photo gallery explaining regrowth in this week’s CropWatch at http://cropwatch.unl.edu.
Another situation that surprised me this year was finding seed corn maggot damage in
soybean. At first I was puzzled as the beans were clearly treated but then learned the beans didn’t have an insecticide added to the seed treatment. In scouting a number of fields, I’ve actually seen quite a bit of seed corn maggot damage, particularly in tilled fields and those with manure applied or those with cover crops that were green or where termination included tillage. I’ve also been surprised how many have told me they don’t use an insecticide seed treatment on early planted beans. We didn’t have any research in our early soybean planting studies without insecticide + fungicide seed treatment so we just automatically recommend both. Unfortunately this year we’re seeing what can happen without it with higher insect pressure in some fields. For seedlings with the insecticide seed treatment, I’m seeing light scarring on the cotyledons and hypocotyls but no maggot penetration. In fields without the seed treatment, I’m actually seeing penetration of the cotyledons and hypocotyls. The good news is that most of the maggots were also pupated, pupating or will be soon. But it is something to watch for, particularly in fields that have been tilled and especially if manure was applied or they were tilled and had a cover crop on them. They are not as attracted to no-till fields. Regarding stands, from my experience with soybean pops and stand loss due to crusting, hail, herbicide injury, etc., I keep stands of 60,000 plants/acre or more. It really stinks to talk about replanting anything right now with guys still trying to finish planting. If you choose to replant soybeans, consider proving it to yourself by planting strips and leaving strips. If you’re interested in that, I’d be happy to work with you. You can learn more about seed corn maggots here: https://crops.extension.iastate.edu/cropnews/2016/04/look-seedcorn-maggot-corn-and-soybean.
Wheat in the area ranges from boot to flowering. A couple of wheat fields I know of
were taken for hay. For those still considering silage, check out the CropWatch article this week where Todd Whitney shares data on wheatlage (wheat silage): https://go.unl.edu/qkbr. The rainfall will greatly help our wheat right now. And, rainfall at heading to flowering makes me think about the potential for Fusarium Head Blight (scab). The wheat scab prediction monitor http://www.wheatscab.psu.edu/ is predicting medium to high risk for scab in Nebraska for the next 48-72 hours. Some years I feel the model is delayed in prediction, but I still feel it’s a good tool and resource. Scab is caused by Fusarium graminearum and is favored by warm (70-80°F temps), humidity, and rain events before and during flowering. Once wheat begins flowering (Feekes 10.5.1), many foliar wheat fungicides are off-label. In fact, recent research presented at the 2017 Fusarium Head Blight meetings shows that in general, strobilurin products can actually increase the presence of deoxynivalenol (DON) in wheat if applied at full heading (Feekes 10 or 10.5). Thus, your better fungicide options for preventing scab are Caramba and Prosaro and these products can also kill any fungal diseases present on leaves (such as powdery mildew, tan spot, and rust). These products aren’t 100% for scab prevention due to the variation of heading and flowering that occurs in so many fields. Better efficacy is obtained with more uniform plants which begins at seeding time. So I would recommend watching the growth stage in your fields, the weather, and the prediction tool regarding if you feel you need to treat any fields this year to prevent scab. Research has shown best efficacy to be obtained when at least 50% of the plants are at 1/3 flowering. Flowering begins with yellow anther sacs in the middle of the head with flowering continuing throughout the head from there. Once the pollen is released, the anther sacs turn white.
LBNRD Open House Public Hearing: The Little Blue Natural Resources District (LBNRD) is hosting a public hearing on May 29th from 6:30-9:00 p.m. at the Davenport Community Center in Davenport, NE. The purpose of the hearing is to provide information and receive testimony on proposed amendments to Groundwater Management Rules and Regulations. The hearing will be an open house format allowing individuals to ask questions of the NRD staff, look at exhibits, and offer testimony. The proposed rule changes and additional information can be found on the LBNRD website at: http://www.littlebluenrd.org/. Please contact the NRD with any questions at (402) 364-2145.
Not part of my news column: on a more positive note after mentioning all the crop problems, the lilacs in general were beautiful and smelled amazing!!!
According to research, wheat is susceptible from flowering through soft dough development stage. “Typical” fungicides used for control of fungal leaf diseases are off-label thus illegal to apply once the wheat has flowered and they do not have activity on the Fusarium fungus causing scab of wheat. Management for scab includes the use of the preventive fungicides Caramba or Prosaro. Both are labeled for headed and flowering wheat. There’s a 30 day pre-harvest restriction for both. Rainfast varies from ¼ hour to 2 hours or when dry depending on environmental conditions. Both fungicides can help prevent scab and control rust on the plant.
Research from the US Wheat and Barley Scab Initiative (which is a combined effort of several Universities in the U.S. and Canada) has found that the best prevention using these products occurs when wheat is headed and 30% of the plants are in the beginning flower stage. Application within five days of these criteria still showed positive results. This research also showed that application before or after this time period greatly reduced effectiveness of preventing scab. Understandably, the economics of fungicide application are difficult in wheat, yet, if you are aiming to make one application, this could be your best option for both scab prevention and controlling rust in your plants. The risk map for scab can be found at: http://www.wheatscab.psu.edu/. With wheat at heading to beginning flower and rain/humidity this risk in reality could be higher for us.
With the recent rains in Nebraska, the potential for wheat scab has increased. This video shares more information including a fungicide table of products to consider with product efficacy ratings for scab. For more information, please check out http://cropwatch.unl.edu. Thanks to Rachel Stevens, UNL Extension Intern, for producing this video!
Last week was a blur of phone calls but it’s great to receive them and know so many of you are doing your best to wait for your soil to be depleted before scheduling your first irrigation! There are some of you in the Little Blue NRD who haven’t received the rains the past few weeks and have hit the 90-100 trigger on your watermark sensors to schedule your first irrigation. Most of you reading this won’t have to irrigate till after tassel (and then you can take into account the 3rd foot in your average)! The 90-100 trigger relates to 35-40% soil moisture depletion and is proven by research via Dr. Suat Irmak at South Central Ag Lab for our silty clay soils. Waiting for the trigger, regardless if you’re on load control or not, will still allow you at least a week to 10 days before you have to worry about getting behind. Please continue to call with questions. There’s also a discussion topic on my blog for your comments/questions.
Corn and beans are looking good overall, are closing canopies, and corn is rapidly growing. Wheat is being combined in the southern tier of counties and there has been quite a range of yields due to the dry weather producing small heads and disease issues such as scab, smut, and ergot. Scab (Fusarium Head Blight) is a concern when we receive rain and high humidity during and around flowering. We were recommending fungicides at that time. Some people escaped it, some put the fungicide on, and others didn’t-so there’s a range of yields out there from that. Common bunt (stinking smut) is the smut that creates clouds of black spores when you’re combining and the grain smells like fish. Loose smut is loose in the head and doesn’t form a kernel shape like common bunt does. Both can be prevented by not saving contaminated seed and using fungicide seed treatments at planting.
Ergot is one I hadn’t seen in wheat since I’ve been here but have in roadside grasses. Ergot is caused by a fungus that infects the wheat head during cool, wet conditions during flowering. Like the fungus that causes scab, it simply replaces the normal pollination process and instead, a black/purple hard fruiting body (sclerotia) is eventually formed. Before this is formed, a sugary drop called honeydew is formed which then turns into the sclerotia. It’s a problem for our producers because I don’t know that you can set your fans to blow it out like you can for light, scabby kernels since ergot sclerotia are denser. The problem with ergot is that it contains toxic alkaloids (one is like LSD)…in fact, it’s blamed that ergot-contaminated grain is what caused the Salem Witch Trials. These alkaloids are also toxic to livestock so contaminated grain should not be fed or even blended off for livestock. Federal grain standards classify wheat as ergot infested when it contains more than 0.3% sclerotia. If you are finding ergot-contaminated grain in your fields, do not save seed back next year; start over with disease free certified seed. The sclerotia will live on top of the soil for a year (they will produce spores next growing season so don’t plant contaminated wheat fields back into wheat, barley, oats, or triticale). Mowing roadside ditches and keeping wheat fields free of other grasses can help prevent ergot infested grasses from spreading the ergot fungus to wheat via blowing spores and rain splash. More information can be found by checking out the UNL Extension publications Head, Grain, and Seed quality on the http://cropwatch.unl.edu/web/wheat/disease Web site.