Planting Cover Crops into Storm-Damaged Fields
A common question lately has been “I’m considering planting cover crops into areas of corn and soybean fields with hail damage. What are my next steps?”
First, it’s important to consult your crop insurance provider to determine if you can do anything before the adjuster examines the field.
In some areas hail stripped corn and soybean plants to the ground, leaving just stems standing. Cover crops offer an opportunity to rescue nitrogen already in the field to achieve other goals.Next, look at your cover crop options, based on potential herbicide carryover from the previous crop and what your end goal is for the cover crop.
Herbicide Carryover
Herbicide carryover from the corn or soybean crop also can be a concern. Check out the herbicide carryover replant options in UNL Extension’s Guide for Weed Management with Insecticide and Fungicide Information on pages 160-171.
To determine if herbicide carryover is a concern for your fields, first check the herbicide label(s) for potential problems. If a rotation (waiting) interval is a concern, contact the chemical manufacturer and explain your conditions. Although the label is the law, companies have conducted extensive research on their products. Sometimes, they can give you a percentage survival chance for planting a crop within a cropping interval. Producers will assume the risk if the germination of the next crop is severely affected, but it may be worth a small calculated risk to potentially get a cover crop established.
Home germination tests also can be conducted. (Planting delays with cover crops, though, may be a concern). Simply take soil samples from the hailed fields and place into containers such as plastic cups with holes in the bottom. Plant about 20 seeds per cup of whichever cover crops you are interested in and wait 7-14 days to determine percent germination. If you don’t have seed, check a cover crop seed supplier to request some free seeds for testing.
Select Seed to Match Your Need
Know what your goal is for the cover crop in order to determine what to plant. Do you want to capture the nitrogen already in these fields? Both legume and non-legume cover crops can capture soil profile nitrogen in their plant tissues for release in subsequent seasons. Late summer or early fall seeded cover crops favor the brassicas (turnips; oilseed radishes including Tillage Radishes®; and canola) for nitrogen trapping for the next crop. Oats make a good complement to seed with the brassicas, since the oats provide quick, weed-suppressing biomass while taking up excess soil nutrients. These plants can survive a light frost and keep on growing.
If reducing compaction is your concern, turnips may help with surface compaction while radishes provide a longer taproot to work through deeper compaction.
If forage is needed for haying or grazing, good choices would be winter annual grasses such as cold-tolerant “winter” oats, cereal rye, winter triticale, and winter wheat. Winter legumes such as yellow sweetclover and winterpeas also may be included in a mix with winter triticale to increase protein content; however, these legumes will need to be planted before early September to provide grazing benefits.
Corn and soybean fields also can be used for forage instead of grain. Silage is probably the best option when the moisture drops to 60%. Currently, the immature hailed corn fields are still about 80% moisture, so producers will either have to wait for the crop to dry or mix dry forages such as straw with the wetter silage in the right proportion. Conversely, if the plants get too dry, it will be hard to pack the silage. To check the moisture, harvest several stalks and chop into smaller pieces with a corn knife, and then test for moisture content. Usually, the feeding value of immature, hailed silage is similar to prairie hay based on nutrient content.
Grazing the hailed fields is another option. However, acidosis may be a concern if cows graze primarily on the immature ears. Cows should be fed some grain for a few days prior to turn out on the hailed fields to help their rumens adjust to a higher carbohydrate diet.
Haying and earlage also may be options, but forage curing is difficult with the cooler days, especially if ears don’t dry well on damaged stalks. Bruce Anderson, UNL Forage specialist, says that it takes 10-14 days longer to dry the damaged corn stalks after crimping than drying cane hay. So, the risk for mold potential on the forage is higher than moving the forage into silage.
Thanks to Todd Whitney, UNL Extension Educator, for his contributions to this article!
Also check out:
Storm Damage Update #1-Soybeans
It’s been five days and soybean fields that were the greatest affected by the storm are now near-brown. Planting some type
of cover crop in these fields can allow for grazing opportunities as well as reduced soil erosion as there are many months before planting season next year. I’ll talk more about cover crop research in another post.
For fields that still have some leaves and some green to them, there are several criteria to look at when assessing hail damage to soybeans. These include determining plant stand, percent leaf defoliation, percent nodes cut off or broken over, and amount of stem damage. Determining percent leaf defoliation and subsequent yield reduction based on growth stage in indeterminate soybeans can be seen in the chart below. Most of our soybeans were between R4-R5 which is a critical time for yield loss in soybean. The remaining charts can be found here.
| % Leaf Defoliation | |||||
| Growth Stage | 20% | 40% | 60% | 80% | 100% |
| % Yield Reduction | |||||
| V2 | 0 | 0 | 0 | 1 | 2 |
| V6 | 0 | 0 | 1 | 3 | 5 |
| R1 – R2 | 0 | 5 | 7 | 12 | 23 |
| R3 | 3 | 6 | 11 | 18 | 33 |
| R4 | 5 | 9 | 16 | 30 | 56 |
| R5 | 7 | 13 | 23 | 43 | 75 |
| R6 | 16 | 11 | 18 | 31 | 53 |
| R7 | 1 | 2 | 4 | 6 | 8 |
Dr. Jim Specht, UNL Soybean Physiologist, shared some recent research data that may be of interest. He said R5 is 
also critical in that stem node number accrual (including new petioles with leaves and nodes on branches) ceases at R5. This occurs because the developing “sink” of newly developing seeds in the pods is a significant draw on the plant’s photosynthate. This draw is so powerful that very little other vegetative activity dependent on photosynthate is permitted.
With our current situation, Jim wasn’t sure if because of hailed off pods and seeds, if that “sink” to source signal would cease to exist resulting in new petioles and leaves. He didn’t think this would occur for two reasons:
1) Indeterminate main stem apices are not responsive to photoperiod induction, and might re-initiate new nodes, but since most of the indeterminate apical stem tips were hailed off in many fields, that possibility is unlikely.
2) During stage V0 to V1, all original lateral meristems in nodes 0 on up to about stem node 6 were cell clusters committed to vegetative phase development such as branches. Photoperiod induction, which occurs as soon as soybean plants of the maturity groups grown in NE attain the V0-V1 period, transduces in all other single-cell meristems in the lateral apices to become flowers (not branches). Thus the reason why we typically see the first soybean flower on about the 6th node or so. No more branches will form at higher main stem nodes the rest of this season under this scenario.
Soybean lateral apices will continue to be programmed to become flowers, because the days are short at all times during the
season from planting to maturity, for soybean varieties adapted to and sold in NE. Research has shown it takes about 28 to 32 days after the transduction of a lateral apical single cell (to transduce it into a floral pathway) before the flower tracing to that single cell appears. Any flowers appearing soon after the hailstorm would have had to have been cell clusters in transit before the hailstorm date (from a zero-day single cell transduction to a 28-32-day later observable flower). Thus, truly “new” flowers emanating from single-cell apical transduction to a floral state the day of the hailstorm would be appearing at the end of August or beg of September, and would not have sufficient time to become pods (with seeds) before the usual date of a fall frost.
Overall, Jim says at soybean stage (R5), it is hard for a soybean plant to recover from a hailstorm, and what recovery is possible is going to have to hurry given the approach of fall. Special thanks to Dr. Jim Specht for his insights into this post!
Reflections: After the Storm
It’s been an interesting few weeks. Last week I was continuing to receive calls about considerations for drought damaged corn. Then southern rust arrived in the area earlier last week. Followed by the tremendous August 1 storm that affected so much of our County.
Numb…..
is how I’ve felt these past few days-and I can’t imagine how difficult it is for you whose crops were affected! It’s just a
sickening feeling walking into field after field and driving around the County seeing the storm damage every day. I’m so sorry for those of you who have lost your crops! As I look at the crops, though, I’m a little puzzled at the way things are laying, the twisted plants….things aren’t all adding up for “straight-line winds”.
In spite of how difficult things look right now, I can’t help but wonder if we were spared from something much greater?
The follow passage in the Bible has been my go-to during times of drought and difficult times in farming. I was going to share this in a drought post…but I feel it still applies with as many partial and total crop losses we’ve experienced in the area.
Though the fig tree should not blossom and there be no fruit on the vines,
Though the yield of the olive should fail and the fields produce no food,
Though the flock should be cut off from the fold and there be no cattle in the stalls,
Yet I will exult in the Lord, I will rejoice in the God of my salvation! Habukkuk 3:17-18
In the midst of trying to provide advice, it’s nice to know that God has everything already figured out and that He’s always in control. Even in the midst of this, He is always good!
Storm Damaged Crops
The rain was welcome on Thursday but the wind and hail damage that came were devastating to a good portion of the
County. I’m so sorry to all of you affected….for some of you, this is two years in a row of severely hail damaged or totaled out crops. We are thankful the damage wasn’t worse. You can see more pictures here.
So the big question is what do you do now? Ultimately, each field will need to be assessed on a case by case basis. The following are our NebGuides for hail damage to corn and soybeans. For the most part we were in brown-silk to blister for corn and late pod-beginning seed in soybean (R4-R5). The concerns I have right now are stalk quality, disease, grain filling, and the amount of diseased grain we may have due to mushy areas on hail-damaged cobs right now. Several years ago, we watched how severely hail-damaged corn a little later in the season turned brown and died. We also know that southern
rust is in the area and while much of the leaf tissue in the County is damaged, it is still in the County in other fields and south of us. The Puccinia polysora fungus that causes southern rust, when severe enough, will infect and cause pustules on the stalks. With the wounding and low leaf area for photosynthesis, stalk strength is a concern and fungicides may be a consideration depending on potential yield loss-again need to assess on a field by field basis.
I talked with a number of people on Friday regarding thoughts on silage, green chop, haying/baling, planting cover crops, etc. Dr. Bruce Anderson, UNL Extension Forage Specialist, said the most common salvage operation for corn damaged by hail, wind, drought, or other calamities is to chop it for silage. Don’t be in a hurry, though. Standing corn currently could be over 80 percent moisture. The easiest way, and maybe the best way, to lower moisture content is simply wait until some stalks start to turn brown. Waiting also allows surviving corn to continue to add tonnage.
But in some of our damaged fields, I don’t think we can wait to make silage. Bruce also shared you can reduce moisture by windowing the crop and allow it to wilt one-half to one full day before chopping. You also could mix grain or chopped hay to freshly chopped corn to lower the moisture content. It takes quite a bit of material for mixing though – about 7 bushels of grain or 350 pounds of hay to lower each ton of silage down to 70 percent moisture from an original 80 percent moisture. That’s 7 bushels grain or 350 pounds of hay for each ton of silage.
Or, you can allow that windrowed corn to dry completely and bale it as hay. Be sure to test it for nitrates before feeding. Grazing might be the easiest way to use damaged corn, and this is a good way to extend your grazing season. You might even plant some corn grain or sorghum-sudangrass or oats and turnips between rows to grow more forage for grazing if you can wait until late fall before grazing. Be sure to introduce livestock slowly to this new forage by feeding them before turning in to reduce the chances of digestive problems. Also, strip graze the field to reduce trampling losses and get more grazing from the corn.
Southern Rust
Several of us had been watching the USDA IPM Pipe Map for weeks. It wasn’t showing southern rust moving and only Georgia
was really lit up. Yet, I had heard reports in Texas and Oklahoma at one point. Spots were evident on corn leaves when backlit-so they were bound to develop into something.
That something has showed itself to be southern rust last week as it was confirmed in 11 Nebraska Counties: Kearney, Adams, Clay, Nuckolls, Thayer, Fillmore, Gage, Platte, Polk, York, and Boone. I’d like to thank all the crop consultants and ag industry professionals for sharing information on what we all were seeing and for submitting samples. 
So the common question was, why didn’t the map show anything south of us? Federal funding was no longer available for this site and scouting efforts associated with it. Many Extension Plant Pathologists weren’t aware that the site was even still online and were sharing information via other means instead. The map for Nebraska will continue to be updated, but for surrounding states, it is advised to consult with your local Extension Plant Pathologist.
Differentiating Rusts:
When differentiating between southern rust vs. common rust, there are several criteria to consider and this NebGuide is a great resource. Typically common rust will have brick-red pustules randomly scattered on the upper and lower leaf surfaces that are larger in size.
For southern rust, we’re seeing very small, raised, tan-orange pustules on the upper leaf surface of leaves in localized areas on mid-upper leaves. These pustules are tightly clustered on the leaves. 
However, color and size are relative as sometimes the two diseases can look alike.
Microscopic observation is the best way to differentiate the two diseases. Fungal spores from Puccinia sorghi causing common rust will be near perfect round circles whereas fungal spores from Puccinia polysora will be oblong in shape.
Disease Progression:
With the cooler weather last week, we were unsure how the disease would progress. Southern rust likes sustained temperatures in the 80’s-90’sF with humidity and leaf wetness. So we encourage scouting for it.
We saw how southern rust can be devastating to fields in the past regarding removing photosynthetic tissue leading to cannabalization of the stalk. In determining a fungicide application, consider 
disease pressure in your field, stage of growth, pre-harvest intervals, and length of time for fungicide residual in addition to economics.
Look-A-likes:
Other plant samples brought in contained diseases such as physoderma brown spot (which isn’t a significant yield limiting disease of corn). Because the spores of this fungus move via water (it’s closely related to oomycetes), numerous lesions can appear on leaves in bands or areas where water collects. While the lesions may look like early southern rust, there will be no pustules present and often the purple colored lesions will also be observed in the midrib, leaf sheath, stalk, and outer husks.
- More information can be found in this article from UNL Extension’s CropWatch.
County Fair Time!
This year marked my 10th Clay County Fair. It was bitter-sweet in a way as I have watched this group of youth from their pre-4-H 
years through graduation this year. It’s neat seeing the young men and women they’ve become, ready to take that next step in life towards college and careers! Rachel and Kristen, our interns, helped us greatly in different ways which was a blessing; it was another smooth fair overall!
Also bittersweet is the fact that this was Cindy Strasheim’s last Clay County Fair as a UNL Extension Educator as she plans to retire in December. We will miss her and if you see her around, please thank her for her 29 years of dedication to the Clay County Fair and serving our constituents here!
I realize I say this every year, but we wouldn’t have fair if it wasn’t for all of our 4-H and FFA leaders, families, and youth-so thank you all for your hard work and efforts with your projects and the many ways you volunteer at fair! Thank you to our awesome fair board who we greatly enjoy working with and who kee
p our fairgrounds looking great! Thank you to Deanna, Holli, and Cindy for the long 
hours of preparation and also during fair in ensuring everything ran smoothly! Thank you to our 4-H Council and all our Superintendents for working so hard in various capacities during fair and throughout the year! Thank you to Tory, Kris, Teri, Karla, and Megan with the Clay County News for sticking out all the shows in the heat to cover the fair for us; we truly appreciate your support! Thank you to Lonnie Stripe for auctioneering, all our auction buyers, plaque and award sponsors, and donors for supporting our 4-H and FFA youth! Thank you to everyone who made the 2013 Clay County Fair a success!
Goss’ Wilt in Corn
Goss’ wilt was found this week in corn damaged from Memorial Day storms in Clay County. I’ve also received pictures that appeared to
be Goss’ from crop consultants in other areas of the State. Goss’ wilt lesions have a wavy edge, have a varnished look to them when wet, and have characteristic black “freckles” within and particularly along the lesion edges. We are seeing some plant death due to the systemic version of Goss’ wilt. This can be seen by taking a cross-section of the stem and looking for orange discoloration in the vascular bundles. Because this is a bacterial disease, fungicides are not effective in controlling Goss’ wilt. If you are interested in trying a product that is labeled for treating bacterial diseases in corn, we would recommend you test its effectiveness via on-farm research. Spraying in a paired comparison treatment design will give you a true answer if the product made a difference for you or not.
To do this simply:
1-Spray a pass or round with the product (depending on sprayer size) to ensure you can harvest two passes from the center of the treated area.
2-Skip the same amount of distance as you previously sprayed.
Repeat steps 1-2 at least three more times
Mark a few plants in each plot and take photos throughout the growing season to determine if disease progresses or not. You may also wish to keep track of percent of plants affected in each untreated and treated area throughout the season, and check for percent stalk rot and harvest population in each area before harvest as well.
Make sure to harvest two passes from the center of each treated and untreated 
area. Then compare the weights as shown in the harvest figure. Please let Jenny Rees jrees2@unl.edu (402) 762-3644 know if you decide to conduct this study and if you have any questions!
More information:
Goss’s Wilt from UNL
Sample Submission to UNL Plant and Pest Diagnostic Clinic
Nebraska On-Farm Research Network
Crop Update 6-20-13
The sun has been welcomed and crops are rapidly growing in South Central Nebraska! Corn right now is between V6-V8 (6-8 leaf) for the most part. Quite a few farmers were side-dressing and 
hilling corn the past two weeks. It never fails that corn looks a little stressed after this as moisture is released from the soil and roots aren’t quite down to deeper moisture.
Installing watermark sensors for irrigation scheduling, we’re finding good moisture to 3 feet in all fields in the area. The driest fields are those which were converted from pasture last year and we want to be watching the third foot especially in those fields. Pivots are running in some fields because corn looks stressed, but there’s plenty of moisture in the soil based on the watermark sensor readings I’m receiving for the entire area. So we would recommend to allow your crops to continue to root down to uptake deeper moisture and nitrogen.
The last few weeks we observed many patterns from fertilizer applications in fields but as corn and root systems are developing, they are growing out of it. We’ve also observed some rapid growth syndrome in plants. This can result from the quick transition we had from cooler temperatures to warmer temperatures, which leads to rapid leaf growth faster than they can emerge from the whorl. Plants may have some twisted whorls and/or lighter discoloration of these
leaves, but they will green up upon unfurling and receiving sunlight. This shouldn’t affect yield.
Damping off has been a problem in areas where we had water ponded or saturated conditions for periods of time. We’ve also observed some uneven emergence in various fields from potentially a combination of factors including some cold shock to germinating seedlings.
We began applying sugar to our on-farm research sugar vs. check studies in corn. We will continue to monitor disease and insect pressure in these plots and determine percent stalk rot and yield at the end of the season.
Leaf and stripe rust can be observed in wheat fields in the area and wheat is beginning to turn. We had some problems with wheat streak mosaic virus in the area again affecting producers’ neighboring fields when volunteer wheat wasn’t killed last fall. Alfalfa is beginning to regrow after first cutting and we’re encouraging producers to look for alfalfa weevils. All our crops could really use a nice slow rain right now!
Weed Science Field Day
Hope to see you at this weed science field day at UNL’s South Central Ag Lab near Clay Center on July 2nd! No charge. Please RSVP to (402) 762-4403. More information at: http://scal.unl.edu.
JenResources 