Monthly Archives: June 2017
Hail Damage
On-Farm Research Protocols:
Hail and wind damage occurred throughout the area I serve last week. Overall, I’ve been encouraged by the regrowth observed on corn and soybean plants affected by the June 14th storm. We were blessed with warmer weather and sunshine that allowed for regrowth to occur in many situations other than some fields around the Deweese area.
You can look for regrowth on leaves within the whorl of corn plants and on the axillary buds of soybeans. Even what appeared to be soybean ‘sticks’ may show regrowth by now.
The concerns I have for plants affected by these storms is all the stem bruising on both corn and soybeans and the potential for bacterial diseases to affect corn.
For those of you affected by June 16th storms, we recommend to wait a week to assess damage and any decisions. I realize we’re also at a critical stage for replant decisions as we continue later in the season. Ultimately, decisions need to be made on a field by field basis.
Resources:
- CropWatch Hail Damage Resources
- Resources from storm damage in 2014
- Fungicide Use After Hail or Wind
Fungicide Application
There’s no good research to Dr. Tamra Jackson-Ziems or my knowledge to support this. Fungicides only control fungal diseases. Bacterial diseases are favored after hail events and we have already seen bacterial leaf streak in the area prior to the storm. From past-years’ experience of prior wind/rain events, we can expect to see more of it in about a week. Fungicides won’t help that disease nor Goss’s wilt which is another we often see come in after hail events.
However, if you’re considering this, I’d like to have several farmers prove it to yourselves with on-farm research this year so we do have data for the future. It’s this simple. All you do is spray fungicide in enough width to complete 2 combine passes. Then skip an area for 2 combine passes. Then treat again and repeat across the field. Fungicide Protocol for Hailed Corn and Soybean. Please let me know if you’re interested in this!
Timing of fungicide app: ISU did a study to simulate hail damaged corn at tassel stage within an average of 3 or 8 days post-hail. They didn’t find the timing to provide any yield effects. They also didn’t find a statistical yield increase (90% confidence level) in fungicide application to hail damaged plants vs those which weren’t hailed although they also reported a numerical increase in 12 of the 20 fields.
Herbicide application: I spoke with Dr. Amit Jhala, Extension Weed Specialist for his thoughts regarding this. He said ultimately herbicides shouldn’t be applied to stressed weeds in order to achieve greatest efficacy. The concern for many including me right now is how well the weeds survived the hail and how quickly they are regrowing compared to the damaged corn and soybeans. This again is a field by field assessment regarding how well your corn and soybean regrowth is occurring and how rapidly your weeds are. I watched one palmer plant in one field after June 14 storm: 1 day post hail and 2 days post hail put on two sets of leaves in that time period. I also took pictures of soybeans reduced to sticks while 
waterhemp in that field was virtually untouched. I think many are trying to wait 5-7 days post-hail to apply herbicides but there were some fields I was suggesting to apply over the weekend with the recovery already occurring and less damage.
Corn replant: The biggest concerns with corn would be stands, eventual stalk rot/downed corn due to stalk bruising, and bacterial diseases. I’ve essentially watched stands reduced over the course of the growing season after early-season hail storms mostly due to bacterial diseases like Goss’ wilt. It will be important to have your crop insurance adjuster look at the field again prior to harvest. Splitting the stems of damaged plants across the field can help you assess any damage to growing points; they should be white/yellow and firm not brown and soft. Tattered leaves that are wrapped around the whorl should eventually turn brown and break off with the wind. They can sometimes impede new growth from the whorl as well though.
Soybean replant: Soybeans can compensate so greatly for reduced stands. From hail at this stage in the past, we’ve said to leave stands of non-irrigated at 60,000 plants per acre and irrigated at 75,000 plants per acre. Some soybeans reduced to sticks are shooting axillary buds. My biggest concern on soybeans is the stem bruising which isn’t accounted for in hail adjustments. If you want to prove replanting or not to yourself, consider slicing in soybeans next to the old row in strips across your field. Be sure to inoculate the soybeans and be sure to take prior stand counts. Soybean Replant Protocol.
There’s nothing like doing these studies and seeing the results on your own ground or from your peers’ farms. In 2006, I worked with a grower in the Lawrence, NE area on a non-irrigated soybean plant population study where he tested seeding rates of 100K, 130K, and 160K seeds/acre. He received hail at the cotyledon stage and because he was non-irrigated, chose to leave the stand. His actual stand counts were 74.4K, 89.4K, and 97.9K plants/acre respectively for the previous mentioned seeding rates which resulted in yields of 38.6, 40.6, 42.7 bu/ac respectively. Another soybean replant study occurred near Columbus, NE where the grower had an average plant stand of 75,000 plants per acre on June 11th. He chose to replant five strips across the field at a diagonal to the existing rows. The replanted soybeans ended up yielding 1 bu/ac less than the original plant stand. I realize it’s hard to want to do these extra steps for on-farm research, but this is why it’s important; it’s the way to answer these questions for yourself! Please contact one of our team members if you’re interested in on-farm research this year!
Weed Management/Cover Crops Field Day — Views from VanDeWalle
During the summer, our crops extension team has some great field days to share research and management strategies to farmers. One of those opportunities to learn more about weed management and cover crops will be on June 28 at the South Central Agricultural Laboratory near Clay Center. There is no charge for the field day […]
via Weed Management/Cover Crops Field Day — Views from VanDeWalle
Corn Concern in Wheat/Rye Cover
What we see is larger plants next to stunted or shorter plants. The smaller plants often show some type of ‘flagging’ of the leaves where one or several leaves or sometimes the whorl is brown and wilted. Upon digging these plants, the roots were healthy and there were no symptoms of damping off or other obvious disease issues. While there have been reports of some wireworms, this also hasn’t been the main issue with these plants I’ve been seeing.
John Mick with Pioneer alerted me to what he was seeing and several of us have since found the same. Carefully unrolling leaves from the stems of these plants revealed feeding on the stems and crown area. You can see from this photo the small larva of what we believe to be wheat stem maggots (top leaf). I’m finding from 1-3 per plant (on this plant there were more in the disfigured area of the stem). I’m also noticing some plants that are tillering such as is shown in this photo after they’ve been damaged.
The larva in another plant.
The growing point area of the same plant.
Carefully unroll the leaves to reveal any potential larvae.
Also found wheat stem maggot in some rye stems from rye that didn’t completely die. White heads in wheat and rye can be an indication of their feeding. You can then pull on the head and easy removal reveals where the maggot was feeding.
So two questions:
- Why are we seeing this this year?
- Is there anything we need to do?
The short answer to both is that we really don’t know. Perhaps one hypothesis is our warm winter allowed for an earlier generation of wheat stem maggots to pupate and emerge as flies during corn planting when they would typically do so later in May. Perhaps in fields where wheat or rye wasn’t yet terminated, the flies could lay eggs and the larvae that hatched moved from the wheat or rye to the corn upon emergence and once the cover was terminated.
The larvae we’re finding now are in different stages and some are getting close to pupating. After pupating, they will emerge into flies that will lay eggs in grass crops. We don’t know for certain if the flies will lay eggs in these corn fields again or if they will move to other grassy species. We’re not recommending insecticide applications.
South Dakota State and Kansas State have previously reported rare incidences of this occurring in corn. This is my first time observing this in Nebraska. To date, I’ve seen stand loss range in fields from 5-50%.
This doesn’t mean that all potential stunted plants or stand concerns are due to this particular insect as a number of other factors could be involved. This post is intended to increase awareness of another option to look for with the number of questions I’m receiving right now regarding corn concerns in terminated rye or wheat cover.
Dr.s Justin McMechan and Bob Wright are surveying fields and conducting studies to better understand any potential concerns in future years. We will keep you informed as we continue to learn more.
Crop Update May 25
Yellow banding can be seen on corn plants from the cold temperatures at various times of the plant’s growth. Some have been packed with mud from rains or have wind-whipped leaves. I’m also seeing some evidence of seedling diseases caused most likely by Pythium sp. in portions of fields with excess moisture.
I’ve been asked to look at fields where soybeans appeared to be dying and/or had discoloration of the cotyledons and hypocotyls. Most of what I’m seeing thus far with the discoloration of cotyledons and hypocotyls have been in fields where a pre-emergent herbicide program containing a PPO inhibitor was used. These are helpful products in reducing weeds. We’ve just seen this in the past as well after rain events that the chemical can be rain-splashed onto the cotyledons and/or the plant is unable to outgrow the effects of the chemical quickly enough in comparison to the damage observed. Hopefully most of these fields will still be ok with plant stands if enough plants can grow out of it; we’d say to leave plant stands of at least 75,000 plants per acre because of the way soybeans compensate for reduced populations without a significant yield effect. There may also be situations of damping off diseases occurring in soybeans. They keys are to look at where the damage is occurring. Discoloration of the roots/below-ground stem would most likely be due to seedling diseases whereas, PPO injury will occur on the cotyledon and hypocotyl-so essentially above the soil. There could be instances where the stress of herbicide damage is also complimentary to Rhizoctonia root rot, but I haven’t sent any samples in to confirm this. The following article is from a few years ago, but summarizes the situations in which damage could more likely be anticipated: http://go.unl.edu/2jbf.
The symptoms on this soybean plant with the ‘halo’ effect on cotyledons is typical of what we see with ILeVO seed treatments. The effects will be on the cotyledon but not on the unifoliate leaves or above.
Soybeans planted April 21st at 2″ depth have been battered by recent rain and wind events. Currently close to V1 stage with first trifoliate unfurling.
Wheat is in various stages of pollination to beginning filling. Stripe rust and leaf rust continue to spread on leaves but wheat is past the point of fungicide application if it is over 50% pollinated.
Really pretty wheat field I’ve been watching this year. Very even growth and low incidence and severity of rust in this more resistant wheat variety.
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