by: Horacio Lopez-Nicora, Stephanie Karhoff, OSU Extension
In early August we recommended to start scouting fields for soybean diseases. At that time (two weeks ago), disease incidence across Ohio was very low to moderate. Conducive environmental conditions, however, are turning things around and more fields are developing disease symptoms.
Sudden Death Syndrome (SDS)
We are finding fields in Ohio severely affected by sudden death syndrome (SDS) [Fig.1 and Fig. 2]. SDS is caused by the fungal pathogen Fusarium virguliforme. This species is the most prevalent in the region, however, other Fusarium species can cause SDS. SDS above-ground symptoms can be confused with those produced by a different fungus (Cadophora gregata) that causes brown stem rot (BSR). To distinguish SDS from BSR, symptomatic plants should be dug out and stem cut open longitudinally. SDS-infected plants have white, healthy-looking pith, while BSR-infected plants present brown discoloration of the pith. Moreover, fields with severe SDS symptoms can also have high levels of soybean cyst nematode (SCN). Visit here for more information on SDS.
Figure 1. Soybean field in south Ohio severely affected by sudden death syndrome (SDS) with premature defoliation in the R5/R6 growth stage (A); symptoms begin with interveinal yellowing (chlorosis) of leaf (B); eventually leaf tissue dies and becomes brown but veins remain green (C). The fungus infects the root and produces toxins that are responsible for the above-ground symptoms.
If you have SDS, we encourage you to submit a sample to the Soybean Pathology and Nematology Laboratory in the Department of Plant Pathology at The Ohio State University in Columbus (see address below). We will confirm if it is SDS or BSR; additionally, if it is SDS, we want to determine what Fusarium species is the causal agent. To submit samples, dig out three to five symptomatic plants (including roots), placed them in a plastic bag, and submit them to our lab. Do not hesitate to contact your extension educator or us if you have any questions.
Bacterial Blight, White Mold, and Phytophthora Root and Stem Rot
Wheat harvest is just around the corner, and it’s time to consider double-crop soybean production management. For double-crop soybean to be successful, you need adequate time and moisture for the production of the soybean crop. In southern Ohio, double-crop soybean after wheat harvest is common. In central and northern Ohio, double-crop soybean after winter wheat depends on the wheat harvest date and soybean prices. With high soybean prices, we anticipate interest in double-crop soybean production in central and northern Ohio this year.
Double-crop soybean management considerations.
- Soybean relative maturity. Relative maturity (RM) has little effect on yield when soybeans are planted during the first three weeks of May. However, the effect of RM can be larger for late plantings. When planting soybean late, 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 (RM) ranges for soybean varieties planted in June and July in northern, central, and southern Ohio.
- Row spacing. Double-crop soybeans should be produced in narrow rows- 7.5 or 15-inch row spacing. The later 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. The soybean plant population at harvest for mid-to-late June plantings should be between 130,000-150,000 plants/acre. The harvest population for early July plantings should be greater than 180,000 plants/acre. Harvest population is a function of seeding rate, quality of the planter operation, and seed germination percentage and depends on such things as soil moisture condition, seed-soil contact, and disease pressure.
by: Dr. Mark Loux, OSU Extension
It’s been a tough summer in parts of Ohio to do anything on a timely schedule and there are some weedy fields. The best advice we have for big weeds in full-season soybeans is to increase rates and the complexity of POST herbicide applications, while still adhering to cutoffs for the application of certain herbicides as much as possible. Dicamba products, XtendiMax, Engenia, and Tavium, cannot legally be applied to Xtend and XtendiFlex soybeans after June 30. This cutoff date pertains to use in double-crop soybeans also. If you are planning on planting Xtend or XtendiFlex soybeans in double-crop fields and using dicamba as a burndown, apply before Friday. There isn’t a cutoff date for most other POST soybean herbicides – it’s based on either crop stage (eg R1) or days before harvest.
Double crop soybeans usually need some type of weed control program, although how weedy they get depends upon weeds surviving down in the wheat that can take off once they receive light; how much rain we get in July, which drives additional weed emergence and rate of soybean growth; and how fast the soybeans grow and develop a canopy. Control can occur via the use of pre-plant/preemergence burndown herbicides, followed by POST as needed. It’s also possible to accomplish this with one early POST application in Enlist soybeans, using Enlist Duo or a combination of Enlist One with glyphosate or glufosinate. And also in LLGT27 soybeans with a combination of glyphosate and glufosinate. Herbicides need to address marestail in many fields, which is often lurking in the wheat ready to regrow. Marestail that are taller and get cut off by the combine will be more difficult to control than the smaller intact ones below the cutter bar. Herbicide options vary depending upon the weeds and what type of soybeans are planted. More effective options include:
- Glyphosate or glufosinate + Sharpen (1 oz) + MSO – any soybean, prior to emergence
- Glyphosate or glufosinate + 2,4-D – any soybean, at least a week before planting
- Enlist Duo; glyphosate or glufosinate + Enlist One (Enlist soybeans) – PRE or POST, no wait to plant
- Glyphosate + XtendiMax or Engenia (Xtend or XtendiFlex soybeans) – PRE, apply by June 30
- Glyphosate + glufosinate – PRE in any soybean, PRE or POST in LLGT27 soybean
It is possible to include residual herbicides with a PRE burndown treatment, but their value in this situation is questionable. Residual herbicides with long recrop intervals to corn should be avoided. POST options in double-crop include glufosinate, glyphosate, Enlist One/Duo, and conventional herbicides, depending upon the type of soybean planted. One caution here is to avoid excessive injury to soybeans that slows growth and development since this is likely to reduce yield due to the short season. Weed emergence is reduced and variable in July compared with May and June. Where burndown herbicides are used, but there is still a need for POST herbicides to control a flush of late-emerging weeds, consider reduced rates. Research we conducted back in the 1990s demonstrated that weeds up to 2 inches tall can usually be controlled with half of a typical labeled rate. When we planted soybeans in early June, the single application of a half-rate provided adequate control, versus early May when a second application was needed. So this should be a suitable approach for double-crop soybeans. Just be sure to start with an effective burndown at planting, and apply when weeds are well within the 2-inch size.
By: Eric Richer & Chris Bruynis, OSU Extension Educators
Planting progress goes differently every year and in each part of the state. This year is no different in Ohio. Some places got in early and are finished. Others had their ‘normal’ planting progress with ‘normal’ Mother Nature breaks, perhaps with some re-plant needed. And still others have not had ideal conditions all spring to plant. As such, we have received some recent calls regarding the mechanics and economics of utilizing the Prevent Plant through crop insurance this year in certain parts of the state. First and foremost, we are not crop insurance agents, so speaking with your agent is of utmost importance. In this article, we will walk through an example on the economics of electing Prevent Plant.
In Ohio, once you arrive at the final plant date of June 5 for corn (already passed) and June 20 for soybeans, you basically have 3 options in a corn scenario: Continue reading
Mother nature is finally cooperating, allowing us to get some corn and beans in the ground. Later this summer it will be time for postemergence herbicide applications. The table below from the “2022 Weed Control Guide” lists important information on rainfast intervals, spray additives and crop size for soybean postemergence applications.Click on the table to print a camera ready copy
by: Dr Mark Loux, OSU
There is a lot of speculation about herbicide shortages for the 2022 growing season, and some products are apparently getting more expensive and/or scarce now. This will affect herbicide buying and weed management decisions for the 2022 season. The two main active ingredients that we’re hearing about right now are glyphosate (Roundup, others) and glufosinate (Liberty, others), for which prices have increased substantially. There will likely be limited supplies of other pesticide active ingredients as well, but in the short term, a shortage of these two active ingredients poses some major challenges for corn and soybean production. The purpose of this article is to discuss ways to minimize the impact of herbicide shortages, primarily glyphosate, on corn and soybean production. As you search for alternatives to these two herbicides and others, the weed control guides and technical guides produced by University Extension and industry are an important tool for planning weed management programs and herbicide purchases.
Some guiding principles based on our experience that may help with decisions, especially where glyphosate will not be in all applications:
- Spring tillage is an option to replace herbicide burndown. Can cause long-term compaction problems if tilled when too wet. Waiting until weeds are large makes tillage less effective. Weeds that survive tillage will be difficult to control with POST herbicides. In other words, till when soil conditions are fit and before weeds are huge.
- Where it’s only possible to use glyphosate once, it may be needed most in the burndown. Saflufenacil can be added for enhanced control of rye and ryegrass, and marestail. ACCase herbicides (e.g. clethodim, quizalifop) can then be used for POST grass control in soybeans. Glufosinate, Enlist Duo, or XtendiMax/Engenia can be used for many broadleaf weeds, especially the glyphosate-resistant ones. Where residual herbicides are omitted, or do not provide enough control, we would expect POST treatments to struggle more in the absence of glyphosate with weeds such as lambsquarters. So use residuals. Glyphosate is still more than just a grass herbicide.
By: Laura Lindsey
The AgCrops Team will host the 2nd annual virtual Corn College and Soybean School on February 15, 2022 from 9:00 AM – 4:00 PM featuring your OSU Extension state specialists, including the new corn agronomist, Dr. Osler Ortez, and new soybean pathologist, Dr. Horacio Lopez-Nicora. CCA CEUs will be available during the live presentations (2.0 CM, 5.0 IPM, and 1.0 NM).
To register, please go to: http://go.osu.edu/cornsoy There is a $10 registration fee for this event, which goes directly to support OSU AgCrops Team activities. Presentations will be recorded and uploaded to the AgCrops Team YouTube channel after the event (https://www.youtube.com/c/OSUAgronomicCrops).
MORNING SESSION 9:00-noon
9:00-9:40 Laura Lindsey
Soybean Management for 2022
9:50-10:30 Osler Ortez
Corn Management for 2022
10:40-11:20 Horacio Lopez-Nicora
Soybean Disease Management
11:20-noon Pierce Paul
Corn Disease Management
AFTERNOON SESSION 1:00-4:00
1:00-1:40 Kelley Tilmon
Soybean Insect Management
1:50-2:30 Andy Michel
Corn Insect Management
2:40-3:20 Mark Loux
Weed Management for Corn and Soybean
3:20-4:00 Steve Culman
Meeting Nutrient Needs for Corn and Soybean