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.
Great to see many farm families at Husker Harvest Days last week and also great to see harvest getting started! Just a reminder for all of us to watch for equipment on the roads and allow for extra time to slow down, particularly with the speed limit changes. Dawn, dusk, and the evening can be the hardest times to see equipment and it can be difficult to see how wide or long the equipment extends. Harvest is hard work and a lot of hours yet is also a blessing to finish the growing season. Here’s wishing everyone a safe harvest season!
Harvest: As storm and drought-damaged corn is being harvested, just a reminder that grain should be tested for presence of ear molds and any potential mycotoxins now in addition to moisture/test weight. I’m hearing some differences in what’s all being tested when the harvest sample is taken, so be sure to talk to your insurance agent about this. It’s important to also test for mold and potential mycotoxins as that gives you an indication of what’s in the grain, particularly if any grain is going into the bin. We’d recommend not binning the worst damaged fields/areas of fields, particularly if you have a lot of diplodia in the field. Drying grain to 14% moisture as quickly as possible will stop most fungal growth and we recommend drying to 13% if diplodia is an issue in your corn ears. I’m also consistently hearing about light test weights in the storm damaged grain.
Rapid crop dry down has been a topic of conversation; I’ll share more next week. Briefly, grain moisture loss occurs when husks lose their color, when portions of the ear are exposed above the husk, with looser husks around the ears, when ears turn down, and when there’s fewer and thinner husk leaves. For those asking about dying patches in soybean fields (in which pods are not filling seeds), I’m consistently finding anthracnose in samples but am unsure it’s always been the cause. The concern with rapid dry down in corn is just how quickly these plants are cannibalizing stalks to keep filling ears, the amount of stalk rot in fields, and large ears (watch for potential weakened ear shanks due to various stresses). I test for stalk rot using a pinch test where I pinch the internode between the lower plant nodes for 20 plants and determine a percentage throughout portions of fields. Consider harvesting fields with higher amounts of stalk rot/weakened ear shanks first and also consider harvesting at higher moisture. I’m finding stalk quality quickly deteriorating, even in non-storm damaged fields.
For those with palmer amaranth on field edges, just a reminder that 99% of the seed is still viable going through that combine. Thus, the combine is one of the best ways of spreading palmer throughout your field and from field to field. My recommendation from observing palmer spread the past five years is to avoid combining field edges, strips, or patches where palmer is an issue. Instead, disk down the field edges to bury the seed and then plant an inexpensive small grain like bin-run wheat to reduce early germination next spring. Some have also planted rye. I don’t know if shredding vs. one-time disking is as effective this time of year (since palmer shoots seed heads at the soil line too but unsure if if produces viable seed past mid-September here). As I’ve spoken during pesticide trainings and other meetings, farmers have also shared their experiences. Some farmers shared they took this advice and reduced the problem the successive year and didn’t spread it through their fields (even if they were no-till farmers and had to till the field edges one time). I’ve had other farmers share they combined that field edge or patch and could tell the following year exactly where the combine went for the first few passes within the field as the palmer was a problem there. So, just another consideration as it takes a system’s approach for everything we do including weed management; palmer management begins right now with harvest.
Another management consideration is to harvest soybeans as close to 13% (the elevator standard) as possible. And, I realize this is easier for me to write about than to actually do depending on many factors! Soybeans delivered below or above 13% moisture lose potential profit. At greater than 13% moisture, there is a moisture dock on the scale ticket for delivering wet beans, resulting in a lower price per bushel. And with less than 13% moisture, profit is lost because there are fewer “bushels” to sell rather than a dockage on the ticket. There are fewer bushels because the load weight is divided by 60 pounds per bushel (assuming 13% moisture) rather than by the actual pounds per bushel for the moisture content of the beans at the time of delivery. If you sell soybeans at 8% moisture, you’re losing about 5.43% of your yield; at 9% moisture, it’s 4.4%; at 10% moisture, 3.3%; at 11% moisture, 2.25%; and at 12% moisture, it’s 1.14% yield loss. That doesn’t take into account additional risk for shatter losses during harvest. For a field that’s yielding 75 bu/ac, harvesting it at 9% results in selling 3.3 fewer bushels per acre based on weight because you’re not selling the water that you’re entitled to sell if the beans were at 13% moisture. With soybeans priced at $7/bushel, that’s a loss of about $23 per acre (with greater loss when soybean price increases).
For the past ten years I’ve come across farmers who really believed in applications of sugar to reduce their pest populations. Being no research to my knowledge to prove it, I tucked the observation in the back of my head for future reference. With farmers looking to increase yields and looking to other farmers such as Kip Cullers for information, some of our on-farm research producers were curious about sugar applications in their operations with the hopes of increasing yield.
Nebraska On-Farm Research Corn Results
Using the application rates that Kip Cullers uses, one Clay County producer applied 3 lbs of sugar (purchased pallet of cane or beet sugar from the local grocery store) per 10 gallons of water at V7-V8 on corn in 2010-2011. Cullers also tanked mixed the sugar solution with a post-herbicide application like glyphosate but this producer didn’t do that. To simulate any affect of the water or driving through the field, he also drove through the untreated check spraying water only. Two years of research results showed no significant increase in yield. However, there was a noticeable difference in standability at harvest. This producer did not apply a foliar fungicide either year. When it came to harvest, this producer needed the reel in 2010 for the untreated check. Stalk rot ratings were taken using the pinch test two weeks prior to harvest. To him, the $1.25/acre of sugar was worth it to improve standability even if yield was not significantly improved. You can view the full research report here.
Several York County producers have also tried this with one producer finding a non-statistical 2 bu/ac yield difference with the check yielding better while the other producers found a statisically significant 2 bu/ac increase to the sugar treatment. Another producer in Hamilton County is testing this using the corn product he grows-using 1 qt of corn sugar (high fructose corn syrup) per 10 gal of water applied still at V7-v8.
In 2012, a small plot study was conducted at UNL’s South Central Ag Lab near Clay Center to determine any differences between sugar application, fungicide application, and untreated check in corn. All treatments were applied at R2. Because of the drought in 2012, there was minimal disease pressure, thus there were no significant differences between the three treatments regarding area under the disease progress curve. The untreated check did show the most stalk rot (via the push lodging test). The sugar application reduced the lodging rating by half and the fungicide application showed the lowest lodging rating. For yield, there were no significant yield differences with the untreated check yielding the highest followed by the fungicide and sugar applications. The entire study report can be found here.
In Soybeans we have had producers apply 3 lbs sugar in 10 gallons of water at R3 (beginning pod). In all years, there have been no significant differences in yield. Lodging ratings were not taken as that is more variety and water dependent.
has shown that application of sugar to crops increases the numbers of beneficial insects in those fields. South Dakota research entomologists showed that lady beetles benefited from a combination of prey and non-prey foods. In a follow-up study, these entomologists applied sugar sprays to soybeans and quantified the frequency of sugar feeding by analyzing the gut contents of common lady beetles in three states. They found all the tested lady beetles regularly consumed sugar-like nectar in soybean fields, even when it wasn’t applied as a supplement. They also found more lady beetles in the sugar treated plots compared to the untreated plots.
At this time we can’t explain the standability effect we’re seeing from our sugar applications to corn. Our hypothesis is that early application of sugar to corn is increasing beneficial microbes that may be keeping the exposed brace roots and stalks healthier. We hope to conduct more research in the future to answer this question.
the application of sugar to corn and soybeans has not always shown increased yield. However, in nearly all of the corn studies, sugar treated plots have shown increased stalk strength at harvest. Research has also shown an increase in the number of beneficial insects in fields where sugar was applied. Further research is needed to understand the interactions aiding stalk strength in corn.
If you are interested in conducting on-farm research studies in your field, please contact any of our UNL Extension Educators or Specialists! You can also follow the conversations this year via our Facebook page and Twitter feed!