Monthly Archives: May 2012
Crop Water Use Comparison Study
Water use efficiency (or crop water productivity) is important in crop production. The seed Industry has invested scientific efforts and financial resources into developing hybrids and varieties that can better tolerate environmental stresses such as water stress.
Rainfed corn has increased in acres, replacing sorghum year after year. This trend may be partly due to the basis price, herbicide options, and newer corn hybrids bred with root systems to better withstand water stress. In 2009 the question was posed, “Is sorghum still the most crop-water-use-efficient crop, given newer corn hybrids in rainfed fields are providing decent yields and more herbicide options?” To answer the question the Nebraska Grain Sorghum Board funded a project in south-central Nebraska.
On-farm research was conducted for three years in rainfed production fields near Lawrence with the most adapted and high-yielding corn, sorghum, and soybean hybrids and varieties for that area. The research was conducted in no-till fields where the previous crop had been sorghum. A randomized complete block design with three replications was used.
Corn and soybean were planted between May 5 and May 7; sorghum planting ranged from May 19 to May 28. Corn was planted at 20,000 seeds/acre, soybean at 135,000, and sorghum at 65,000. Rainfall in this area varied greatly from 2009 to 2011: 2009 was dry with only 10 inches of rain during the growing season; 2010 had 16 inches, and 2011 had 20.5 inches from May 1 to October 15.
To monitor soil moisture, Watermark sensors were placed at 1-, 2-, 3-, and 4-foot depths in each plot and the readings were recorded hourly throughout the growing season via Watermark dataloggers. Data were compiled and analyzed to determine crop water use efficiency (CWUE) values. The CWUE values were determined from the Watermark soil moisture data, actual crop water use (evapotranspiration), and grain yield for each crop.
Results: Table 1 shows actual crop evapotranspiration (ET) in inches, grain yield, and crop water use efficiency for each crop in each year. Corn was the most water use efficient of the three in 2009. Sorghum results in 2009 might have been different if rainfall had occurred to activate the sorghum herbicide as grass pressure was heavy in the sorghum plots that dry year. In 2010-2011, sorghum yielded the most, had good weed control, and had the best crop water use efficiency value.
|Table 1. Crop water use efficiencies in on-farm field trials conducted near Lawrence, Nebraska, 2009-2011.|
Overall in this study, sorghum had a crop water use efficiency of at least 5.5 bu/inch; corn, at least 4.3 bu/inch, and soybean, at least 2.0 bu/inch. These results show sorghum’s continued value as a crop that efficiently uses water. Sorghum produced more grain per unit of water used than corn or soybean, an important benefit in water-limited environments. On a three-year average, sorghum resulted in 1.2 bu/inch and 3.5 bu/inch more grain production per inch of water used than corn and soybean, respectively. This study did not compare sorghum or soybean with new “drought-tolerant” corn hybrids. Graphs, charts, and production information can be found here.
Acknowledgements: Special thanks to John Dolnicek of Lawrence, Nebraska for allowing this research to be conducted on his farm and for all his help and efforts to make it a successful study and to the Nebraska Grain Sorghum Board for funding this study.
Soil Crusting in #Soybeans Causing Concerns
On May 6, quite a storm was unleashed in south central Nebraska. Soybeans that had been planted two to three days before the storm seem to have emerged fine, while those planted May 5-6 tend to have uneven emergence and crusting. This is occurring regardless of tillage type, residue cover, etc. Many farmers have been running pivots to help the soybeans break through the ½- to 2-inch crust, often applying an inch of water before they see stand improvements.
The primary question for growers has been “Should I replant?”
UNL on-farm research has shown less than 1.4-2.0 bu/ac yield difference between planting 90,000 and 180,000 seeds/acre. (See report.) In our research, 90% of the planted stand was achieved at both seeding rates in irrigated 30-inch rows in no-till and ridge-till fields.
Consider what was found in 2006 in one dryland field in Nuckolls County where populations of 100,000, 130,000, and 160,000 seeds/acre were planted. This field was at the cotyledon stage when it was hailed. Some plant stands dropped to 67,000. Yield was 4 bu/ac less than in the 160,000 seed/acre planting that had a final stand of nearly 98,000. The average yield in the field was 40 bu/ac. While this is only one field and one year of research, it is an example of how soybean plants can compensate for reduced populations by branching and how August rains in dryland can still allow reasonable yields to be produced.
UNL research conducted by Dr. Jim Specht, UNL Soybean Physiologist, also has shown that for every day planting is delayed after May 1, there is the potential to lose 1/4 to 5/8 bushel per day. As we near the end of May and early June and consider that late planting yield penalty and the dry soil conditions (particularly in dryland fields), along with the seeding rate results from this UNL on-farm research, we are recommending that growers leave stands in many fields. Based on our on-farm research, leaving dryland stands of at least 65,000 plants/acre and irrigated stands of 90,000 plants/acre is likely a better choice than replanting.
We realize that there are some larger gaps in various rows in the field, and while we don’t like to see that, the gaps are disappearing as plants continue to grow and branch out. Keep in mind that a gap in one plant row will be compensated by plants in the adjacent flanking rows. They will form extra branches to take advantage of the sunlight, thus single-row gaps may not be as yield-reducing as you might think — especially in 15-inch row spacings.
We’re also seeing how resilient soybeans are. Some soybeans have been in the ground for two weeks and in many cases, are fairly healthy below the crust. Soybean seedlings emerge by pulling (not pushing) their cotyledons upward. The seedlings rely on the cotyledons as a reserve source of carbohydrate, protein, and lipid to support early seedling development until leaflets open for photosynthesis. When a seedling tries to pull its cotyledons through a crack in the crust, the crack may be too small and the cotyledons may be stripped off.
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 in terms of pod and seed production. 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 such as the picture on this page.
Recommendation: When deciding whether to replant your field, consider UNL research findings that showed a minimal yield difference between stands of 90,000 and 180,000 seeds/acre. We recommend leaving irrigated soybean plant stands of 90,000 or more and dryland plant stands of 65,000 or more. Uniformity of plant stands is also important, but “patch” planting may be used to deal with local areas of low plant stands.
For more information on reduced soybean planting rates, see the April 20, 2012 CropWatch story, Drop Soybean Seeding Rate and Save $10-$18 per Acre.
Future of Rural America
Sunsets over rolling hills of green pastures and straight corn rows. Barely seeing above soybeans I was walking to remove weeds. Attending a small school that provided an excellent education with opportunities to participate in a variety of activities to become more well-rounded. These are a few of numerous memories of growing up on the farm and in a rural community that I hold dear. While I enjoy hearing my grandparent’s stories of what life was like for them farming 60 years ago and even enjoy watching the Nebraska State Cornhusking Contests held each year, I also realize times have changed and don’t have a false sense of nostalgia about what rural means today. While technological advances allow our farmers to produce more food for more people with less inputs and less water than ever before, what hasn’t changed about rural communities is the hard work ethic, dedication, risk, determination, and reliance on Faith and family to get through each year.
Last week I had the opportunity to participate in the Rural Futures Conference held in Lincoln. For me, it was the best conference I’ve attended; the energy and enthusiasm from 450 people gathering from a variety of backgrounds all to discuss the future of rural America was refreshing to say the least. My favorite part of the conference was the first evening. The key note speaker Joel Sartore, a Nebraska native who is also a National Geographic photographer, challenged us to maintain a positive attitude and to look for the opportunities that were available in our small towns. For example, one town in Kansas was all about a certain sparrow where they would take people out on field trips to “listen”-they didn’t even get to “see” the sparrow-and people paid money for that! There was also a town in Oklahoma where all they had was rattlesnakes…so they made the most of that too and created a huge attraction around snake handling, pics with snakes, snake skinning, etc.
My favorite part of the conference occurred after that during the youth panel. A panel discussion with Caleb Pollard, Executive Director of Valley Co. Economic Development in Ord, NE; Amanda Crook, Graduate Student; Anne Trumble, Executive Director of Emerging Terrain in Omaha; Jim McClurg, University of Nebraska Board of Regents; and University of Nebraska Med Center’s Bob Bartee answered questions moderated by Dr. Ronnie Green, IANR Vice Chancellor. The young people struck a chord with me-most likely cause we were of similar age. Some key take-away quotes:
- Vibrant organizations identify strong leadership.
- Failure can be a good thing as it can lead to the next innovation.
- To go some place and change the trajectory of history is exciting!
- We need to change the way we place young people into jobs….we don’t offer young people jobs; we offer them opportunities.
These young people were so excited about living in Nebraska! Some of them had spent time elsewhere before choosing to move back to Nebraska and eventually choosing to find a small town to raise their families or have the rural way of life. Another theme that emerged throughout the conference was the need to get young people involved in the local community such as youth representatives on city council, etc. even as early as when they’re in high school. Some people think small town communities in Nebraska are dead…but that’s not necessarily the case. It mostly depends on leadership-a strong leader will rally the town around an idea to grow it or create opportunities. That’s what’s happening in Ord, NE with Caleb Pollard. Another example comes from Fairfield Iowa. Sometimes it just takes the right person to ignite a spark and help the rest of the town see the possibilities. Nebraska has so much to offer!
Frans Johansson, author of The Medici Effect, was also a phenomenal speaker! He spoke about creating breakthrough innovations by thinking outside the box and working at intersections of different disciplines/cultures, etc. Key points I obtained from him include:
- New ideas are combinations of existing ideas.
- People who change the world try FAR more ideas.
- Diverse teams can unleash an explosion of new ideas.
- Find inspiration from fields/cultures other than our own.
- Look for the smallest executable step-essentially don’t eat the elephant in one bite.
- Stepping into intersections isn’t risky-it’s risky to do the same thing over and over again.
Maybe these aren’t earth-shattering new concepts, but good reminders for a task as large as creating a Rural Futures Institute…and frankly for anything in life.
There was much discussion about the role of a University/State/Community Colleges in trying to save rural communities…how is this done…how build partnerships and trust…how to provide incentives to faculty working in creative/innovative ways in a structured academic setting when it comes to promotion and tenure…and even if the University changed its incentives, how does that bode if a faculty member moved on to another University? How are incentives provided to teams and excellent team work? We are standing at the crossroads…maybe an intersection right now in academia which can shape the future of creatively rewarding innovative work while still maintaining needed structure in the promotion/tenure process. I remain positive that we’ll find a way to work through this!
There were discussions in small groups regarding the meaning of rural. What does it entail? Often we think of agriculture-and I would argue that’s a strong part of rural-but it’s also much more…health care, infrastructure, industry, schools, broadband, etc. Some were saying we need to use the term non-metro instead of rural in order to get away from the ag connotation. Yet others felt the discussion was too focused away from agriculture on other components of rural and missing ag as a key component. Needless to say, the entire conference provided interesting discussion, dialogue, and a chance to meet people from a variety of backgrounds. It truly provided an opportunity to look for intersections with which to create innovative ideas for the future.
There was also the reality that hit during focused group conversations that there are also problems that need to be addressed in rural communities that weren’t touched on at this point: poverty; crime; infrastructure; food deserts; building trust and interfacing with university, college, and other partners, etc. Overall it was a thought-provoking conference and has the feel that several small steps can be achieved in the coming year. I would encourage you to check out the Web page and follow the Facebook page. You can also check out the Twitter Conversation at #RFC2012. This conference was also not just focused on Nebraska as the focus was the Great Plains and people from numerous states attended. I’m looking forward to seeing the small executable steps that will occur in the future and am also looking forward to doing my part to maintain strong rural communities as I’d like to see the next generation enjoy the rural life and learn the values I did growing up!
The Season for #ag & #horticulture Questions!
This past week was a blur of calls, questions, and visits to homes and fields but it was a great week and flew by staying very busy! I’ll touch on a few of the common questions I’ve received this week.
Trees: Some trees such as willows, hackberries, tops of maple trees, ash, and black walnut are just taking time leafing out. Some trees leafed out once already and dropped leaves. Things that may have caused this were the sudden flux of temperatures from very warm to cool and the strong winds we received. Some trees have also unfortunately had herbicide drift damage that caused leaves to drop. On those trees, watch for new buds as nearly every situation I’ve looked at thus far have new buds forming after about a week-10 days. With all these situations, give the trees a few weeks to leaf out again and if they’re still not doing it, feel free to give me a call. Trees are interesting plants as sometimes environmental impacts that happened 3-5 years ago will show up that much later-and sometimes environmental impacts show up right away!
Disease/Insect issues: This year has been a strange year all around but with our warm winter, I was concerned about an increase in diseases and insects. Thus far, we’re experiencing increases in both-so hang on-it may be a long growing season! Our high humidity, warm temps, and heavy dews have created perfect conditions for fungal diseases on our trees, ornamental plants, lawns (I’m currently fighting a bad case of powdery mildew-as a plant pathologist it is kind of pretty but I don’t like what it’s doing to my lawn!), and in our wheat and alfalfa crops and some pasture grasses. Fungicides may help in some of these situations, increasing airflow can also help as can more resistant varieties or hoping the weather will change. In the case of most ornamentals, we don’t usually recommend doing anything. The same goes for insects as insecticides can help in some situations. I’ve received several calls this past week of people afraid they had herbicide drift damage. While there were a few cases of that, many of the cases were actually fungal leaf spots on leaves. There are various fungicides and insecticide products available from home/garden centers, etc. Be sure to read and follow all label directions and only apply the product on places the label specifies it can be applied.
Crops Update: Later this week we may have a better idea on the extent of storm damage and if some fields will need to be replanted after the storms from last week. Dr. Bob Nielsen from Purdue University reported that most agronomists believe young corn can survive up to about four days of ponding if temperatures are relatively cool (mid-60’s F or cooler); fewer days if temperatures are warm (mid-70’s F or warmer). Soil oxygen is depleted within about 48 hours of saturation and we know soil oxygen is important for the root system and all the plant’s life functions. So we’ll have to wait and see what happens.
Have also had a few calls regarding rye cover crops. When rye is killed out and decomposing, it releases toxins that can affect the germination of other cereal crops such as corn if it’s going to be planted into that rye cover crop. Thus we recommend at UNL that the producer kill the rye and then wait at least two weeks to prevent any major damage to the crop. I realize at this point with the rains to get in and kill that crop on top of waiting an additional two weeks, we’re getting close to the end of the month and will most likely be looking at reduced yields…and depending on maturity, you may need to consider different seed if you end up having to plant in June. If you have specific questions about this, please let me know and we can talk through some situations.
Stripe rust and powdery mildew have been obliterating mid-lower canopies of many wheat fields. I’ve received several calls on why wheat canopies are yellow-that’s the main reason but other factors such as the dry spell prior to these rains and/or deficiencies in nitrogen/sulfur or some viruses may also have been factors. Wheat in Nuckolls County last week was beginning to flower. Fungicides such as Prosaro, Folicur, or Proline are labeled for up to 50% flowering and cannot be applied after that. Remember the wheat head begins pollination in the middle-so if you’re seeing little yellow anthers at the top or bottom of that head, you’re towards the end of flowering. All those products have a 30 day pre-harvest interval-which has been the other main question-are we going to be harvesting in a month? I do believe we’ll be harvesting a month earlier than normal just because pretty much everything in wheat development is about a month ahead of schedule. I still feel the 30 day window for the fungicide application is worth it with the large amount of disease pressure we’ve seen. Wheat in Clay Co. and north still may have time for a fungicide application; those products mentioned above will help prevent Fusarium Head Blight (scab) as well as kill the fungi causing disease already present on your leaves. A list of all fungicide products, pre-harvest restrictions, and rates can be found here. Also check out my previous blog post with video on scouting for wheat diseases.
The other major disease appearing in wheat is barley yellow dwarf virus. This is a virus vectored by bird cherry oat aphids which we were seeing earlier this year. Unfortunately, this disease causes the flag leaves to turn bright yellow-purple causing yield loss (at least 80% of the yield comes from the flag leaf) as there’s nothing you can do once the virus manifests itself in those leaves. If you have a large incidence of barley yellow dwarf in your fields, you may wish to reconsider spraying a fungicide as the fungicide won’t kill the virus; however, it will help kill the fungi on the remainder of your leaves and potentially help protect some yield from the two leaves below the flag leaf.
#Wheat Disease Update
Questions have been rolling in regarding dead leaves in the mid to lower wheat canopy. Wheat is heading in much of South Central Nebraska and in some cases has begun to flower. When considering a fungicide application, once your wheat has begun to flower, there are only certain products that are labeled for use. These include but are not limited to fungicides such as Proline, Folicur, and Prosaro. All of these have a 30 day pre-harvest restriction and can only be applied up to 50% flowering. For more information on all fungicides, rates, and pre-harvest restrictions for wheat, please check out this resource from Dr. Stephen Wegulo, UNL Extension Wheat Pathologist. Below is a short video of me scouting a wheat field so you know what to look for in your fields. Fungicides will not help leaves affected with barley yellow dwarf as that’s caused by a virus; however, with the amount of stripe rust in our canopies and seeing it on the flag leaves already in addition to the rain and humidity allowing for increased risk of Fusarium Head Blight (scab), I still feel a fungicide is a good option.
Evergreen Tree Diseases
Somehow April flew by without me reminding you to apply fungicide sprays to Austrian and Ponderosa pines that have had problems with Sphaeropsis tip blight in the past. I’ve also received several scotch pine samples in the office to diagnose for pine wilt nematode. While there is no cure for pine wilt, I recommend to take a 6” long, 1-2” diameter sample of a dead branch to your local Extension office for diagnosis before cutting down the tree. Pine wilt affects Austrian (long needles groups of 2) and Scotch pines (short needles in groups of 2) as they are non-native trees while the nematode is native. Since ponderosa pines (long needles in groups of 2 and 3) are native to Nebraska, they don’t seem to be affected by pine wilt nematode.
Pine wilt is caused by beetles carrying pine wood nematodes vomiting them into the water-carrying vessels of the tree (xylem). The tree senses the nematodes and essentially blocks water to those branches. Often you will observe a branch then perhaps a side of the tree and eventually complete death of the tree within 6-9 months. While I have diagnosed many samples of pine wilt, more often when I visit homeowners the tree problems are due to fungal diseases which occur on the needles. If you look closely at your needles and observe dark bands or rings on them followed by death of the needle either direction from the band, the tree problem is most likely due to a fungal needle blight like dothistroma in Austrian and Ponderosa pines or brown spot in Scotch pines. They can all be prevented by spraying a fungicide containing copper sulfate in the spring.
With everything about 3 weeks early this year, now is the time to spray Ponderosa and Austrian pines for needle blight and spruce trees that have had problems with needle cast or shoot blight where the new growth has died in the past. In early June spray for needle blight problems in Scotch pine and cercospora blight on cedars. If you have a windbreak of combinations of these trees and don’t want to spray twice, I recommend at least spraying in early June to catch all of them. Increasing air flow by cutting out some trees is another way to reduce fungal diseases on your trees.
Also watch trees for bagworms as you may be able to tank mix a fungicide/insecticide application in early June if needed. We would recommend picking the bags off trees and burning them, but that’s just not feasible in windbreak situations. To know when to spray, take a few of the bags off the tree, place them into a plastic ziplock bag, and place outside on the south side of your house. When the larvae emerge from the bags, check your trees to see if larvae can also be observed on them. Pyrethroid insecticides are recommended for managing bagworms because they cause an irritation that makes the larvae leave the bags and allow them to be exposed to the pesticide.
Great brochure! Evergreen Diseases