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Corn Newsletter : 2018-17
Double Crop Soybean ConsiderationsAuthor(s): Laura Lindsey
Small grain harvest will soon be underway. For profitable double crop soybean production, there must be adequate time for the production of the soybean crop and soil moisture. Double crop soybean management differs from traditional, full-season soybean management.
Relative Maturity- Relative maturity has little effect on yield when soybeans are planted during the first three weeks of May. However, the effect of relative maturity can be larger for later planting dates. When planting double crop soybean, the latest maturing variety that will reach physiological maturity before the first killing frost is recommended. This is to allow the soybean plants to grow vegetatively as long as possible to produce nodes where pods can form before vegetative growth is slowed due to flowering and pod formation.
Table 1. Recommended relative maturity ranges for soybean varieties planted in June and July in northern, central, and southern Ohio.
Suitable Relative Maturity
Row Spacing- Double crop soybeans should be produced in narrow rows- 7.5 or 15-inch row spacing. The later in the growing season soybeans are planted, the greater the yield increase due to narrow rows. Soybeans grown in narrow rows produce more grain because they capture more sunlight energy, which drives photosynthesis.
Seeding Rate- Harvest population for mid- to late June plantings should be between 130,000-150,000 plants/acre. Harvest population for early July plantings should be greater than 180,000 plants/acre. Harvest plant population is a function of seeding rate, quality of the planter operation, and seed germination percentage and depends on such things as soil moisture conditions, seed-soil contact, and disease pressure. In our double crop soybean trials planted in June 2017, 250,000 seeds/acre was required to achieve a harvest population of 143,200 plants/acre due to excessive rainfall after planting. In July 2016, 213,000 seeds/acre was required to achieve a harvest population of 204,000 plants/acre.
For more information on double crop soybean production, see https://stepupsoy.osu.edu/soybean-production/double-crop-soybean-production-guidelines. Double crop soybean research was funded by United Soybean Board and Ohio Soybean Council.
Rest of June warmer than normal with high rainfall variabilityAuthor(s): Jim Noel
Not much has change since last week in terms of the outlook. The rest of June is likely to be warmer than normal with high variability of rainfall but tendency to above normal rainfall.
It appears a heat dome will be centered in the south central U.S. this summer with periods where it shifts over the corn and soybean belt and Ohio Valley. The next surge of heat will come this weekend into early next week. With these surges come a ring of fire of storms around the heat dome leading to locally heavy rainfall. However, that rain will be scattered in nature.
It also appears tropical moisture form the Gulf of Mexico later this week will combine with a tropical system from the eastern Pacific Ocean and come around the heat dome by next week into the Ohio Valley enhancing rainfall at that time.
The outlook for July is for the above normal temperatures to remain but with a drier rainfall picture at that time.
Rainfall for the next two weeks will average 1-4 inches with normal being near 2 inches. Isolated totals of greater than 4+ and less than an inch can be expected. See attached image from NOAA/NWS/Ohio River Forecast Center for more information on rainfall distribution across the entire corn and soybean belt.
Wheat and Barley: Cool, Wet Late-Season ConditionsAuthor(s): Pierce Paul
Cool weather and moisture after flowering often means extended grain-fill and high yields, especially when disease levels are as low as they were at the time of pollination and early grain development in some fields. However, excessive rainfall associated with the cool temperatures could increase the severity of diseases that thrive under cool conditions. But with the crop now well into grain-fill and even turning in some locations, there is very little you can do about late-season diseases. The pre-harvest interval for some of the best fungicides is 30-45 days, which mean that they are now off-label in most areas, given that harvest will likely begin in less than 30 days.
If you did apply a fungicide at heading or flowering, that should have helped to delay disease spread within the field and up the plant, minimizing grain yield and quality losses. There are still lots of fields out there with healthy flag leaves, and by the time those leaves eventually become diseased, the yield would have already been made. An application of Prosaro or Caramba at heading (for barley) or flowering (for wheat) would have also helped to reduce head scab and vomitoxin. But since these fungicides only suppress the disease, you may still see some scabby heads in your field. Now is the time to walk those fields to see if head scab is present and how much – this will help you to plan your grain harvest and handling strategies.
Consider harvesting fields with moderate levels of head scab (5-10% incidence; that is, 5 to 10 heads out of every 100 with some scab) at the very first dry-down (18-22% moisture). Harvesting early will reduce problems with sporting and further contamination with vomitoxin, once the grain is dried (13-15% moisture) and stored. You should also increase your combine fan speed to blow out scabby, light-weight kernels. We have found that increasing the air flow through the harvester can reduce scabby grain by an average of 40% and vomitoxin by an average of 17%.
Western Ohio Precision Ag Field Day Planned
Western Ohio Precision Ag Field Day is planned for July 16, 2018 beginning at 8 a.m. at 9060 Versailles, Southeastern Road, Versailles.
This event will feature field demonstrations on nutrient placement, management, and utilizing field data to make decisions. Credits will be available for fertilizer applicator re-certification, certified crop consultants, and certified livestock managers.
Several agribusinesses will be participating in the trade show. Those currently include Integrated Ag Services, Apple Farm Service, Green Field Ag, Precision Agri-Service, Fennig Equipment, Crop Production Services, Southwest Automation, Ohio Ag Equipment, Koenig Equipment, Bumper Crop Imagery, Otte Ag, Rogers Grain, Ohio Soybean Council, Graves-Fearon Agency, Ebberts Field Seed, and Heritage Cooperative.
This event is open to the public and was organized by OSU Extension Darke and Miami County. Credits will be available for fertilizer applicator re-certification, certified crop consultants, and certified livestock managers. Thank you to Koverman Dickerson Insurance and Nationwide - Matthew Jordan Agency for sponsoring breakfast and snacks for the day. For full details and a flyer, please visit http://go.osu.edu/westohioagevents . While the event is free, RSVPs are required by July 2 for a lunch count. Register online at go.osu.edu/westernohiofieldday or call 937.548.5215.
Diagnosing Soybean Seedling Issues in 2018
It seemed to take forever this spring, but hopefully all of your soybeans are planted – for the first and only time. Ohio’s biggest challenge is replanting; it is costly (new seed, cost of planting, lower yields due to delay in planting). The first step is assessing overall stand health – do you have enough plants to obtain the best yields? Based on a substantial amount of data, for soybeans planted in May, a harvest population of at least 100,000 plants/acre is generally adequate to maximize yield. Data from the Ag Crops Team on-farm trials indicate that a stand of 50,000 plants/acre only reduced yield by 15% compared to a stand of 116,000 plants/acre (when planting in May). Soybeans have the ability to compensate for low populations by increasing the number of branches, nodes, and pods per plant.
After evaluating the stand, the next step is to diagnose what happened, was it disease, insects or slugs, herbicide injury or flooding injury? Each of these will require a different approach when it comes time to replant the field. The more accurate the diagnosis, and the shorter the time frame to replant limits the yield losses that may occur due to any delay in planting. Yield loss resulting from delayed planting ranges from 0.25 to 1.0 bu/acre/day.
- Diseases – there are numerous soil borne pathogens that can attack seeds and seedling and they can be broken into two groups: true fungi and watermolds. The watermolds require free water in the soil – these are most common when 2 or more inches of rain fall between the day of planting and when seedlings emerge (~ 14 days). More than 30 different species of Pythium as well as Phytophthora sojae have contributed to seedling blights in Ohio. In fields where the disease was caused by watermolds, the seed should be treated with a combination of fungicides that are specific for watermolds. If the seed or seedling has deep brick-red lesions, this is often caused by Rhizoctonia solani. There are several fungicides that have very good efficacy towards this pathogen as well as Fusarium graminearum. Figures 1-4
- Early-season pests of soybean can be above or below ground. Below-ground pests include seed corn maggot, wireworms, and white grubs. These can reduce stand by feeding on seeds and roots, and there are no rescue treatments. Aboveground early season pests of soybean include bean leaf beetle, cutworms, and slugs, which feed on stems or foliage. If the main stem is cut or nibbled to nothing above the cotyledons, the plants will usually regrow. If plants are cut off below the growing point below the cotyledons, they will not recover. So a certain amount of feeding on foliage, and stem above the cotyledon is tolerable. In vegetative soybeans the plant can later compensate for as much as 30 to 40% defoliation. In cases where feeding is more extreme, a number of foliar insecticides are labeled for soybean pests. There are fewer, but some, options for controlling slugs (https://ohioline.osu.edu/factsheet/ENT-20)
- Flooding injury occurs when plants are submerged for more than 48 hours. Places in the field where ponding occurs can cause the CO2 to build-up in the soil and killing many of the organisms, including soybeans. When you are walking through these fields, there is often a strong smell associated to the area where the flooding occurred. Focusing on drainage is warranted for these fields.
- A number of residual soybean herbicides can cause minor stunting of new stands, which is usually readily outgrown and not of much concern. Historically, chlorimuron has been an active ingredient that has caused stunting most frequently, especially under high soil moisture conditions. Stunting can be more extreme from chlorimuron compared with other herbicides, requiring more time to be outgrown, but still should not reduce yield. Products containing flumioxazin (Valor etc.) and sulfentrazone (Authority etc.) have generally caused the most frequent and severe early symptoms in our research plots, and around the state. Part of the reason for the frequency is the extremely widespread use of these products under a broad range of tillage and weather conditions. Injury symptoms can consist of stunting, leaf malformation, and leaf necrosis, but not usually stand reduction. We observe injury from these products most often in our conventional tillage plots when they are applied immediately following planting. Injury has been much less frequent under no-till conditions, where we have most often applied them a week or more ahead of planting. Based on the previous comments, combining either of these actives with chlorimuron can result in higher risk of injury compared with other combinations. We have observed soybeans to eventually outgrow injury of even 25% or greater, but row closure can be delayed compared with uninjured soybeans. Our primary recommendation to minimize injury from these products is to apply a week or more ahead of planting.
Herbicide injury – during the past 2 seasons we have been able to replicate the herbicide injury that can occur when PPO herbicides are applied to soybeans after planting. This is not recommended, but we can all appreciate in Ohio how tough it is to get that herbicide down 2 weeks early. Especially in years when the soil temperatures never got above 40F, winds did not die down until it was 2 weeks after the best calendar date to plant! This study is one of those we do in Extension to remind us why we have these recommendations in place to begin with. The study was planted at two locations, Northwest Branch and Wooster, for the evaluation of herbicides applied 2 to 3 days after planting. The damage from each herbicide is in the next series of Figures. Special Thank you to Pioneer Seeds for supplying the seed for this study so we could take it to yield.
About the C.O.R.N. Newsletter
C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.
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