Category Archives: Crop Updates
Crop Update May 5, 2017
Received numerous alfalfa questions about browning and wilting of leaves/stems. This photo shows those symptoms of frost/freeze damage.
Check the upper-most cluster of buds on alfalfa to determine any affects on regrowth. This is where the growing point is located. Most of the alfalfa plants I’ve observed have healthy buds. With the cool temperatures, regrowth has been delayed. You may need to wait 7-14 days after the frost/freeze event to determine if regrowth is occurring from upper buds or from crown buds-and also to determine if an early harvest is warranted if there’s no regrowth from upper buds. More information on alfalfa frost damage and management considerations.
I’m also observing alfalfa weevils in low numbers in alfalfa fields. It will be important to scout your fields and monitor regrowth for second cutting. More information on alfalfa weevil thresholds.
Soybean planted April 21 at 2″ depth with good growth (I should have removed the soil from the root for this picture-did so after taking it and the root is healthy). Corn planted April 24th, 48 hours prior to cold rains in Clay County, showing beginning germination and a healthy seed. More information on potential chilling injury to corn and soybean seeds.
Cooler temps last week slowed stripe rust of wheat which I found in low incidence April 26. Powdery mildew (gray/white spots in this photo) is still moderate-heavy in lower canopy. April 6th was a beautiful day when I was in the area looking at crops, but with so many wheat fields with herbicide apps in that time-frame, I didn’t walk into fields to know how close wheat was to jointing. Since then I’ve noticed a more sprawling growth to wheat instead of erect. This week I’m noticing thicker than normal nodes where wheat is trying to erect itself-and you can see that in this photo with the bent stems. I’m not observing noticeable damage from frost/freeze at this time thankfully. It will be important to watch as heads emerge for any difficulty emerging from the boot, damage to awns, or white colored florets/heads.
Germination of corn in York County Corn Grower plot planted April 22. Soil temperature in the field that morning was 46F with a weekend of warm air temperatures.
Crop Updates-May 2016
May 27: Sunshine has been welcomed for corn amidst the rains we’ve received. Corn ranges from 1-4 leaf depending on emergence dates. For those who put the majority of nitrogen application pre-plant, soil and/or foliar samples may be necessary to determine the extent of nitrogen available to the crop throughout the season.
May 27: Receiving numerous calls on marestail escapes in corn this year. At this point, there’s no options guaranteed for 100% control. Our Guide for Weed Management shows options for 80% control right now including: Buctril + atrazine, Buctril + dicamba, Hornet, Realm Q, Resolve SG/Solida or Resolve Q, and Status. Please read and follow all label instructions. For soybeans, options are even more limited and control mostly goes down to 70%. Page 116 of our Guide for Weed Management provides options for consideration.
May 27: Also was called to a field for unique situation to me. Field had been two years of soybeans before planted to corn this year and had received hail 2 days before and over 4″ of rain within a few day period. Night crawler trails and holes the diameter of pencils existed throughout the field. The hail-stripped leaves were being moved down into holes. Where the stripped leaves were still attached to plants, the entire plant was bent over into the holes. It’s a unique situation in which the corn will hopefully outgrow with warm weather and sun. This unique occurrence is also mentioned at the following Purdue University website: http://extension.entm.purdue.edu/pestcrop/2010/issue9/index.html
May 23: Corn is looking good for the most part with few major concerns yet. Some have commented on the yellow-looking corn. This is most likely due to cool, wet soils rather than any nutrient issues. There may be field-specific issues such as saturated soils, compaction, and some herbicides that can cause this yellowing too. Also had a call on cutworms in seed corn but not widespread calls on this yet. Extension Educators have set up light traps for tracking cutworm moths and you can find that information here: http://go.unl.edu/rhhe. Cutworms will cause the most damage the first 7 days after corn emergence so scouting is important. The York County Corn Grower Plot was planted on April 24th with the corn currently at 2 leaf stage. Special thanks to Ron, Ray, and Brad Makovicka for hosting and the work put into this plot each year!
May 23: Soybeans are emerging and the concern several have discussed is crusting. Soybeans have an amazing ability to push through crusted soil and we were hoping for rains this past weekend to soften the soil and help them along. I’ve watched soybeans lose both cotyledons when trying to push up through the soil. Surprisingly these can survive if the growing point is still intact, and a small plumule will begin to develop.
The plumule, which is the seedling stem tip and its undeveloped leaves above the cotyledonary node, may remain, but without the cotyledons to serve as a carbon and nitrogen source, development of new seedlings with small leaflets will be slow. These plants may not become competitive with surrounding plants. Therefore, when counting seedlings to determine plant stand after a soil crusting event, count only the seedlings that have at least one cotyledon. You can count seedlings missing cotyledons if they have large unifoliolate leaves that will soon unroll. Information from Purdue University shows that losing both cotyledons can lead to 2-5% yield loss.
May 15: After last week’s storms, some have wondered how long their germinated seed and emerged plants could survive under water. There isn’t a great deal of research regarding germinated corn hybrid seed. From some corn inbred research, it is not expected that germinated seed can survive in flooded conditions for more than four days. Within 48 hours, soil oxygen becomes depleted and crusted soils from heavy rains can lead to reduced emergence. A two day flooding event after soybean seed germination and imbibition (water uptake) reduced soybean stands from 20-43% in research conducted in the early 2000s. Corn less than 6 leaf growth stage at temperatures less than 77F can survive around four days. Temperatures higher than 77F may only allow those emerged plants to survive around 24 hours. As waters recede and for those who received hail on young corn, it will be important to monitor your plant stand. The high rains received early May 2015 in Nuckolls and Thayer counties resulted in a number of early corn diseases including bacterial soft rot and systemic goss’ wilt which reduced plant stands. We also saw an onset of anthracnose and a Xanthomonas bacterial disease that we couldn’t do anything about. Correct diagnosis will also be important. We would recommend monitoring your plant stand in ten areas of your field, counting plants from two adjacent rows in each area and assessing the distance of gaps between plants. Digging in the areas where gaps occur can help determine if seedlings still have an opportunity to survive. Seedlings that have leafed out underground or are corkscrewed will most likely not develop normally and may never make it out of the ground; it’s a judgement call on your part. An article is also provided in CropWatch this week to help with stand assessment for corn replant decisions at: http://go.unl.edu/iic6. One thing to keep in mind with the final decision table from Iowa State is that it all rests on an assumption of optimum planting of 35,000 seeds/acre planted in a window between April 20-May 5. That may or may not be a realistic assumption for your field conditions. Another thing to keep in mind is that while on average, as planting dates move into May, corn yields tend to drop, 2016 may not be an average year and the best planting date for 2016 with the weather conditions we’ve had may not have been the earliest ones. Regarding gaps, ISU shares gaps from 1.3-2.8 feet result in an additional 2% yield reduction while 4-6 foot caps result in an additional 5% yield reduction.
May 1: It never ceases to amaze me how quickly planting occurs each year! Corn planted the week of April 10th has emerged and for those fields that received hail from last week’s storms, I’m hoping we don’t see disease issues later on. Also of note, some have asked me about the CropWatch soil temperatures as they are higher than what some of you have been measuring in your fields before planting. The CropWatch soil temps at http://cropwatch.unl.edu/cropwatchsoiltemperature are averages of 24 hours under bare soil which may be different than the residue conditions in your fields and is an average of the entire day vs. one point in time. This may help explain some of the differences.
Many stands of alfalfa are lush green with over a foot of growth at this point. I looked at some alfalfa in Clay County that got dinged by cold temperatures in areas of the field and stopped growing. At this time I’m also finding quite a few aphids and a few alfalfa weevils. A disease common this time of year called spring black stem can be observed in nearly all alfalfa fields right now in the lower canopies. This disease consists of small black lesions on the leaves which eventually cause the leaves to turn yellow and drop. Normally this disappears with later cuttings as humidity and rainfall are typically high during the first cutting and can be managed with cutting the alfalfa. One option to consider according to Dr. Bruce Anderson, our Extension Forage Specialist, is to consider cutting alfalfa before bloom. He shares that weather can cause long delays and alfalfa doesn’t bloom very aggressively during spring. Bruce felt there were advantages to cutting alfalfa when it is 15-20” tall before bloom during first cutting including: weather compared to later spring, spread out alfalfa harvest if you consider cutting one field earlier, reduction in insect and disease problems by early harvest, and high feed value. It also potentially allows the second cutting to be ready before the summer heat which can lower forage quality. Disadvantages include lower yield from cutting early which could be made up in later harvest, regrowth may be slower if cut early, and the need to allow for longer recovery after first or second cutting to maintain long-term stands. So, harvesting before bloom may be something you wish to test in one of your fields this year and consider how this works for you, especially if you did have some frost damage or are having insect/disease issues in your alfalfa right now.
Wheat Updates-May 2016
May 27: Wheat is in the milk to soft dough stages of filling with later heads still pollinating in Clay/Nuckolls county fields. Stripe rust greatly increased in severity, particularly on susceptible varieties. This photo is showing progression on Overland. I haven’t seen stripe rust yet in fields planted to Wolf. Barley yellow dwarf is appearing in small amounts in more fields, but is limited to field corners/borders thus far.
May 23: (Photo: barley yellow dwarf in wheat-characterized by yellow-purple flag leaves. It is vectored by aphids). Wheat is in the late flowering to beginning milk stage in many Clay/Nuckolls county fields. Stripe rust increased in severity this past week in more susceptible varieties and barley yellow dwarf is also appearing more often in patchy areas of fields.
May 15: Rain is falling this morning in parts of our area and wheat is in a variety of heading and flowering stages. While the risk management tool at: http://www.wheatscab.psu.edu/ still says “low risk” I’ve been concerned it had the potential to be higher with our growth stage and weather conditions. Last week I received numerous wheat fungicide questions. Caramba and Prosaro are the two products you can apply legally once your wheat is flowering. Twinline is off-label once flowering begins. Yes, it has metconazole in it (also active ingredient in Caramba) in addition to a strobilurin, but it only legally can be applied to Feekes 10.5 which is full heading and is off-label once flowering occurs. Caramba and Prosaro will help prevent scab in addition to kill the rust already occurring in your plants. Unfortunately, I was also starting to see barley yellow dwarf appearing in Nuckolls County fields. This virus is vectored by a number of aphid species. We’d been seeing aphids and stripe rust for a month at this point but both remained below threshold levels/low incidence. Barley yellow dwarf can be identified by the flag leaf turning a bright yellow-purple color. With 80% of wheat yield coming from the flag leaf and there being nothing you can do about barley yellow dwarf, this also needs to be part of your decision making process if you were planning on applying a fungicide for preventing scab/controlling stripe rust.
May 9: We’ve been seeing stripe rust in wheat for over a month now, but the amount of rust has remained low. Some have chosen to spray wheat at this point; however I’m also concerned about the potential for Fusarium Head Blight (scab) in wheat. Fusarium head blight is caused primarily by Fusarium graminearum, the same fungus causing Fusarium stalk, root, and ear rot in corn. The fungus survives the winter in corn and other small grain residue and then releases spores in the spring. However, wheat planted into soybean ground can still be affected by scab because the fungal spores can be wind-blown in addition to being water-splashed to wheat that is in the flowering stage.
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.
May 1: Wheat progressed quickly in one week! Wheat in Clay and Nuckolls counties have flag leaves emerged even though wheat is really short. The color is getting better thanks to moisture, root establishment, and nitrogen uptake. I also didn’t see an increase in rust incidence this past week and aphid numbers were holding steady. For those asking about fungicides, I’m still hoping we can hold off a little longer with current wheat economics, especially since in those counties rust wasn’t increasing due to the colder temps. With warmer temperatures this coming week, please be checking your wheat. If possible, one option that could be more economical in non-irrigated situations would be to consider treating your wheat once during flowering with either Caramba or Prosaro (as these products both prevent scab at the proper application timing and also kill fungal diseases including rust already present on the leaves). We’ll have to see what happens with rust development and with how long it takes for heads to emerge. There’s also been consistency with some varieties rated high for rust resistance where I have yet to find rust in them-so that’s a good thing!
Wind-Hail Crop Damage Meeting
Recent wind and hail storms have created damage across our area counties in Nebraska and Kansas. This brief meeting to be held on Monday near Gladstone, NE is designed to answer farmers’ questions regarding harvest, crop insurance expectations, and what to expect regarding crop maturity and future damage. Please click on the image to enlarge.
Corn Disease July 2015
Radio advertisements, email blasts, and other media are warning of corn diseases and the need for fungicides. Two months of humid, wet weather has allowed for disease development. It’s important to know what diseases truly are in your field before spraying a fungicide, particularly with today’s economics. Here’s what we’re seeing in fields right now in the Clay, Nuckolls, Thayer, Adams county area. Based on the diseases we’re seeing, we would recommend you scout your fields to know whether you have mostly bacterial or fungal diseases present. Consider disease pressure, where on the plant the disease is occurring, growth stage, and economics. We have had southern rust show up in 10 of the last 11 years I’ve been serving in this area. If you spray a fungicide at tassel, you may not have enough residual to ward off southern rust when it appears later, potentially resulting in the need for a second application. In our area thus far, I’m not seeing enough disease pressure in many fields to warrant a fungicide at tassel; consider delaying an application till later for economic and resistance-management reasons. Ultimately this decision needs to be done on a field by field basis. Please also see this UNL CropWatch article regarding fungicide application and corn growth stage. Although I don’t have a photo of it, I’ve also seen common rust in the mid and lower portions of corn canopies thus far.
Anthracnose has been observed in fields for a good month now. It is mostly seen on lower leaves of plants, particularly in fields where we’ve had high amounts of rainfall, standing water, and/or hail. Lesions are tan in the center and have a wavy yellow colored margin. I haven’t seen it moving up the plant very far yet. There are fungicides labeled for this, but we don’t often recommend fungicide treatment for anthracnose.
We saw this disease in the Saronville/Sutton area last year. This year, we are seeing it throughout Nuckolls, Thayer, Clay, and Adams counties…and most likely others too. Some hybrids (and have seen this across companies) are highly affected by this bacterial disease. Neither last year, nor this year, has the pathogen causing this disease been confirmed. Plants will have vein-limited lesions in streaks on the leaves. It is often confused with gray leaf spot early on. Take a hand-lens and looking closely, you will see wavy margins on the lesions which doesn’t usually occur with gray leaf spot. Over time, these lesions become elongated and can coalesce with other lesions. Also looking closely with a handlens or microscope, one finds the leaf tissue eventually becomes transparent. While other diseases can look similar to it, under the microscope, no fungal spores are found other than secondary ones. Putting an infected leaf in water reveals cytoplasmic streaming in which the bacteria is escaping the leaf tissue. (The pathogen causing Goss’ wilt also does this, but this disease is not the same as Goss’ wilt). Fungicides will not cure bacterial diseases and the products advertised for targeting bacterial diseases haven’t been researched for this disease. This is the primary disease we are seeing in our area right now-and it looks nasty in some fields! Unfortunately there’s nothing we can do about it. If you are considering testing one of the products for bacterial diseases, please let me know as I’d appreciate testing it with you via on-farm research.
Goss’ wilt (bacterial disease) has been observed in fields as well. I typically notice it along field edges, pivot tracks, pivot/well roads or hail-damaged fields as plant wounds in general allow an entry for bacterial pathogens. However, research has shown that the bacterial pathogen causing Goss’ wilt can enter through the leaf stomates as well. Leaf miner damage can be observed at the top of this photo, and often, but not always, I notice this occurring together in fields. There is nothing we can do for Goss’s wilt if you have this disease in your fields right now. There are products targeting bacterial diseases on the market. If you’re interested in trying these, please consider an on-farm research experiment to prove the efficacy to yourself and help us obtain data.
Physoderma brown spot typically doesn’t occur in our area until tasseling (which is where we are at now in some fields). However, I was seeing this as early as two weeks ago on some hybrids. The pathogen causing this disease is a fungal-like pathogen that moves with water. You will notice a purple/brown color on midribs of leaves, leaf sheaths, stalks, and tiny yellow/brown/purple spots on leaves. This disease isn’t considered yield-limiting or of significance to us in Nebraska. Some confuse this disease with southern rust, but there are no pustules produced with Physoderma brown spot.
The larger, rectangular lesion is typical of gray leaf spot found in some lower leaf canopies right now. It is easy to confuse with anthracnose as both diseases appear a little different on various hybrids. Gray leaf spot will be vein-limited while anthracnose is more blotchy in appearance. Comparing gray leaf spot with the unknown bacterial disease, the lesion edge will be straight for gray leaf spot and wavy for the bacterial disease.
Northern corn leaf blight is a disease we’re hearing a lot about but I have yet to see it in our area. Most have been mistakingly calling the unknown bacterial disease shown above and even Goss’ wilt, northern corn leaf blight, but there’s truly a difference as you see these photos. Compared to gray leaf spot, northern corn leaf blight will be more cigar-shaped instead of forming a rectangle. As this photo taken from the Mead, NE area shows, lesions are often forming in close proximity to each other on the leaves in Nebraska right now. This disease is one to watch as it has been expanding on certain hybrids in some fields, particularly in eastern, Nebraska. However, I still haven’t seen it in our area and haven’t received any confirmations of it being found in our area at this time. (Photo courtesy of Aaron Nelson, Nelson Precision Agronomics).
Sugar Application in Crops
Corn is approaching or at V7-V8 growth stage. A few weeks ago, we published research results in our UNL CropWatch website. That information can be found in the links below the video. If you are interested in trying this in your field this year, please see the Nebraska On-Farm Research protocals also shown below.
Crop Update June 9
Corn that was hail-damaged on June 3rd is starting to regrow. Leaves wrapped up in the whorl are beginning to slough off as wind and warm temperatures cause the damaged tissue to die and break off. For more information on how stand loss impacts yield, please check http://cropwatch.unl.edu.
Some corn plants more severely affected were reduced to stems. Sometimes no new growth is appearing while in other plants new growth can be seen. I split open the stem on this plant since no new growth was apparent and the center looked discolored.
In this corn plant, a bacterial rot has set in as can be seen from the discoloration at the upper portion of this plant and the discoloration at crown area. This plant may not survive. This is typical of what we were seeing in Nuckolls/Thayer counties with the 8-10″ of rain they received there. My concerns for corn at this point are bacterial diseases such as this or Goss’ wilt that may continue to reduce stands through the season. Some growers are considering a fungicide application but fungicides don’t target bacterial diseases. We’d recommend anyone considering this to consider an on-farm research experiment and I’d be happy to help set this up for you.
These soybeans were reduced to stems yet are showing new growth 5 days later. UNL research has shown that soybean stands can be greatly reduced without a significant yield effect. Several growers are considering replanting; we’d recommend taking into account the research or conduct an on-farm research experiment to see any differences for yourself like this farmer did. The other thing we have looked for is bruising on stems and some flooded areas truly did not have plants survive. For more information, please check out http://cropwatch.unl.edu.
Crop Update June 5
This year I was counting my blessings as we made it through May with no tornadoes in Clay County and no Memorial Day storms! Yet history seems to repeat itself on days. Last year, hail went through the counties north of us on June 3. This year, hail hit us on June 3rd….an estimated 30% of Clay County. Please also see the resources listed at the end of this post for more specific information regarding decision-making.
Earlier that day, I had looked at wheat in a number of counties where white heads were appearing in wheat. Most often they easily pulled from the head and weren’t more than 2% of fields. Those were attributed to wheat stem maggot. The white heads that were hard to pull from the stem were most likely due to some late frosts that we had in the area.
The evening of June 3rd resulted in various rainfall totals throughout the county and hail damage to an estimated 30% of the County. This photo is of the west fork of the Upper Big Blue River that was flooding many fields along Hwy 6 between Hwy 14 and Sutton.
This was June 4: Water along both sides of Hwy 6 from Hwy 14 to Sutton and over the road in a few areas. The road was closed on June 5th after another 3-4 inches fell in the area Thursday night. Portions of fields were flooded throughout the County and we’ll have to see how long it takes for water to recede and what temperatures do to determine any replant situations.
Corn in the V5-V6 stage ranges in hail damage. The worst damage of plants were reduced to sticks. Time will tell how well the plants recover. I’m concerned about bacterial diseases in corn-particularly Goss’ wilt showing up later…but also a bacterial rot that we were seeing in Nuckolls and Thayer Co. after the heavy rains they received last month.
Soybeans ranged from planted to V3 in the County. Many of the hail-damaged beans still had a cotyledon attached. In the past, I’ve seen new plumules shoot from the top of the stem when the growing point wasn’t too damaged. We again will need to wait and see what happens.
First cutting alfalfa is down in much of the County waiting to be baled.
Severely hailed wheat field. You can also see the amount of stripe rust present in this field. We estimated 75-80% of wheat heads in this field were broken over and wouldn’t fill the heads.
Another hail-damaged wheat photo. We have a great deal of stripe rust of wheat in the County and some farmers with livestock have chosen to hay wheat that is severely affected by stripe rust. Some did spray fungicide which has held the rust back. Others are going to just see what happens yield-wise.
For more information on hail and replant decisions, please see:
JenResources 