Monthly Archives: September 2019
Crop Update: Thinking about harvest as we continue to watch corn and soybeans progress toward maturity. And as I write this, my desire is to be honest about what I’m seeing and the concerns growers and other agronomists are seeing too. Perhaps part of my perspective is the fact that I’m typically called out to problem situations! But hopefully that perspective helps you in some way know what to watch for in your own fields. So before harvest occurs, would encourage growers to get out in your fields and see for yourself how your crops look. It’s just a great way to estimate what your true harvest potential is prior to harvest. And, it’s always easier to diagnose yield potential problems now vs. post-harvest. There are some tremendous looking fields out there, especially non-irrigated ones! Yet sometimes (once we hit canopy closure) we forget about the early season challenges and the variability that can occur. Variability such as plant stands and plant emergence based on variable seed depth that can be seen now with variable ear sizes. There’s misshapen ears due to various stresses based on specific field practices/situations as well.
The warm, drier weather this week allowed for some noticeable changes. Perhaps the biggest one is the concern regarding tops of corn plants rapidly senescing. This could be due to either anthracnose top dieback or another disorder called ‘top leaf death or dieback in corn‘. Anthracnose can cause leaf lesions, top dieback, or stalk rot. To diagnose if anthracnose is the culprit, you can look for black fungal anthracnose lesions which may be blotchy in appearance on the stalk underneath the leaf sheaths. You can also split the upper or lower stalk looking for any discoloration in the pith or nodes. If you don’t see the lesions or pith/node discoloration, the discoloration in the top of the plant may be due to top leaf death or dieback. A Canadian researcher documented greater top leaf senescence during a period of warm, dry weather during grain fill. Another researcher documented this tends to be more common during good grain fill years. We have experienced that type of weather with a good grain fill period, so top leaf death/dieback may be the bigger culprit.
Yet, be sure to check for stalk rot in these fields. I’m finding stalk rot increasing with each week especially where there’s nitrogen deficiency, areas where water ponded, high plant populations, higher disease pressure, and areas with hail damage. There’s also something interesting happening where in specific hybrids, it appears the refuge in a bag plants are dying early (and have stalk rot) in comparison to the primary hybrid planted (I’m unsure exactly why).
The other thing noticeable this week was husk tissue turning color and ears turning down as hybrids mature. We’ve had a long grain fill period creating large ears with deep kernels. There are specific hybrids where I’m concerned about large ears and small shank diameters. Shanks appear firmly attached for now, but it’s still something to watch. Been recommending growers get those fields out earlier if possible.
To evaluate percent stalk rot, at least 100 plants throughout the field should be assessed. I prefer the ‘pinch test’ and do this by taking my thumb and first finger and pinching the stalk internode that occurs between the lower nodes above the soil line. Do this for 20 plants in an area and get a percentage for those that crush. Then do this for several areas of the field. This YouTube video helps show how to do this: https://www.youtube.com/watch?v=7z75VN1c51Q. Fields that have the greatest percentages of stalk rot prior to harvest may be prioritized over others. Where it worked in their operations, some growers in 2018 chose to harvest at a higher moisture content in order to get at fields in a more timely manner.
Some soybean harvest has started. Taking my final on-farm research notes in fields, I’m noticing dead plants next to green ones. The dead plants often have anthracnose and/or pod and stem blight. In some fields early death is due to sudden death syndrome. Also noticing red/purple leaves on some varieties indicative of cercospora leaf blight. Thus, we have potential for discolored, chalky seed and also purple seed stain again; hopefully nothing to the extent of 2018.
I’m writing this column from our National Agriculture Agents meeting. Tonight was our inspirational service. Our speaker was Marine Corporal Joshua Bleill. He was conducting combat patrols in Fallujah in October of 2006 when his vehicle was struck by an improvised explosive device. He suffered multiple injuries, including the loss of both legs. He shared about his background in ag, learning how to walk again, and the importance of family. He also shared how grateful he was for everything that happened to him for how it grew his faith and made him who he is today. I could relate to gratitude for difficult things in life for how they can shape us. I think many of us have been through difficult things. This year has been especially difficult for many in agriculture. Sharing two things that helped my perspective right now. These things aren’t new, but I needed a reminder. One: Remember the ‘why’ behind what we do every day and keep that fire within us to do our best. Two: Live life so at the end of each day we hopefully made a difference to another person. Again, not new, but good for me to have these reminders when I’m a bit weary right now. Sharing in the event these reminders help you too!
Crop Updates: Grateful for sunshine and some heat last week to help with seed fill and moving along maturity! Seeing some early death and/or compromised stalks in corn plants that are nitrogen deficient, in compacted/formerly ponded areas of fields, or plants with sidewall compaction. I’m not always finding a stalk rot pathogen present right now, but the stalks are compromised and crush easily. So it will be important to continue monitoring fields to assess which should be harvested first. In soybean, sudden death syndrome is causing early maturing and death in some situations. If you’re also seeing pods on plants shriveling up and dying, look for symptoms of pod and stem blight (rows of black dots on the soybean stem). Anthracnose is also present in fields and is indicated by black ‘blotches’ on soybean stems. I have photos on my blog at https://jenreesources.com. There’s nothing to do for either of these right now. Pod and stem blight is part of the Phomopsis/Diaporthe complex that caused dark and chalky looking seed at harvest in 2018. Also note what varieties appear more impacted.
Soybean Quality Research Project: Speaking of seed quality, a study funded by the Nebraska Soybean Board is focusing on influence of water regime (irrigated vs. non-irrigated) on soybean seed quality parameters (seed protein, oil concentration, and test weight). We’re looking for farmers who have BOTH irrigated and non-irrigated fields (dryland field corners don’t count as non-irrigated fields) and asking for help collecting seed samples at harvest time. Plastic jars will be provided to collect samples in each field (at around 25%, 50%, and 75% of the field being harvested). This seems like a lot of sampling, but it’s to help understand any variability of seed quality across fields. If you are interested in helping, please contact myself or your local Extension educator.
Wheat Information: I’ve had a few calls regarding wheat planting. Some have asked about using seed that has scab. Using that seed can greatly reduce the germination and seedling vigor. It’s best to clean the seed and have a fungicide seed treatment applied. I recommend a fungicide seed treatment for all wheat seed regardless if it is bin-run or certified seed. The August 30th UNL CropWatch edition at https://cropwatch.unl.edu has wheat information including seeding rates, disease and insect management, and variety information so be sure to check it out!
Fall Invaders: It’s that time of year for fall invaders such as millipedes, centipedes, crickets, spiders, roly polys, earwigs, and lady beetles. Control fall invaders once they enter the home by vacuuming them. There are home-owner sprays that can be used on the outside perimeters of homes to help reduce the number that enter your home. Sealing any cracks and crevices is another way to help exclude them.
*I’m grateful to Dr. Richard Ferguson, former Extension Soil Fertility Specialist, for reviewing this article; Dr. Charlie Wortmann, Extension Soil Fertility Specialist, for sharing research-based studies with me; and Glen Slater, SCAL Research Technician, for sharing details of the SCAL study mentioned below.
Nitrification Inhibitors: Two weeks ago, my column included a general overview regarding nitrogen losses in addition to general summary statements based on research. Nitrification inhibitors are best thought of as an insurance policy against loss of applied ammonium-based fertilizer due to excess rain in the first month or so after fertilization. Dr. Richard Ferguson, former Extension Soil Fertility Specialist, and his team have conducted much research regarding the use of nitrification inhibitors over time. Much effort has occurred in sandier soils within the Central Platte NRD. However, an ongoing study at UNL’s South Central Ag Lab (SCAL) near Clay Center is conducted on silt loam soils which are more common in the UBBNRD. Twenty-eight years of this study are summarized here. The majority of the study at SCAL compared Spring pre-plant anhydrous vs. side-dress application with and without the use of nitrification inhibitor N-Serve (nitrapyrin). This product was the product available back in the 90’s. The study actually began by comparing 2 different in-season side-dress applications before switching to pre-plant vs. side-dress in the early 2000’s. Soil samples for nitrate and ammonium content were taken when funding was available. In talking with Dr. Charlie Wortmann, UNL Extension Soil Fertility Specialist, he mentioned that they found yield to be correlated to amount of nitrogen in the soil. A yield increase due to nitrapyrin applied pre-plant was observed in 6 of 28 years with a mean yield change of 2 bu/ac/year. Only 1 of 28 years was a yield increase observed when nitrapyrin was applied in season during side-dress application with a mean yield change of 0 bu/ac/year. In this study, they found that delayed side-dress N with nitrapyrin could reduce plant N uptake. A detailed analysis of nitrapyrin effects on N uptake and soil accumulation from early years of this study can be found in Ferguson et. al (1991). The duration of inhibitor efficacy was measured in other studies where it was found a nitrification inhibitor such as nitrapyrin to last around two weeks with Spring applications. They’ve seen it last as little as 1 week to as long as 6 weeks depending on soil temperatures and moisture. The use of inhibitors is not advised in season as research showed they can release N too slowly for the crop demand resulting in yield loss and/or resulting in increased leaching of nitrogen when it was released too late in the growing season for crop uptake. In general, the research is more supportive for nitrification inhibitor use in sandy soils vs. heavier textured soils; yield benefit to a nitrification inhibitor may be none to a few bushels/acre for silt loam or silty clay loam soils.
In-Season Applications of Nitrogen: In-season application means the nitrogen is applied when the crop is actively growing and utilizing it, greatly reducing potential for loss. Recent on-farm research studies compared side-dress applications using either the UNL equation/Maize N model or industry models such as Climate Field View. In all these studies, the recommended rate was compared to rates that were at least 30 pounds over and under the recommended rate. Some of the studies went as high as +/- 50 lbs/acre compared to recommended rate. I’ve compiled these results in a table at https://jenreesources.com/2019/04/14/jenrees-4-14-19/. Take homes: In none of the studies did the addition of 30-50 lbs N/ac above the recommended rate increase the yield statistically. A few of these studies also compared side-dress applications vs. pre-plant alone. One situation resulted in a statistically lower yield with pre-plant alone while the other two resulted in no yield differences. Many of you have most likely heard of Project Sense in which a grower’s nitrogen application was compared to 75 lbs pre-plant + variable rate in-season application using sensing technology. This project was an on-farm research partnership with Nebraska Extension, Nebraska Corn Board and Corn Growers, and numerous NRDs including UBBNRD. From 2015-2017, 48 site-comparisons were conducted. The results showed 28.7 lbs less nitrogen was applied using the Project Sense method with a loss of 1.4 bu/ac in yield, and greater profitability of $7.24/ac. All of these results were statistically significant at the 95% level.
To reduce the risk of leaching or denitrification, consider applying the majority of nitrogen close to when crop demand is high with more nitrogen applied during the growing season vs. pre-plant. Also for consideration is the fact that farm operations differ in equipment and labor and growing seasons like 2019 present additional challenges, including for nutrient management.