Planting

Maximum Corn & Weed Size For Delayed Herbicide Applications

Source: Penn State University

Table 2.2-10 (from The Penn State Agronomy Guide) Maximum corn size, weed sizes for delayed preemergence/early postemergence herbicide applications.

See specific herbicide label(s) for additional information on application. This type of application generally is used when weather conditions preclude the use of a standard pre­emergence program. For most products, do not apply in liquid fertilizer if com has emerged. Poor control from residual herbicides may result if annual grasses such as foxtail and panicum have emerged at the time of application; tank-mix with product that controls emerged grasses. Delayed preemergence/early postemergence programs can work well with herbicide-resistant corn hybrids now available (e.g., Roundup Ready and Libertylink). When tank-mixing with other pesticides, follow the most restrictive product label.

Maximum Corn and Weed Sizes

Trade Name Maximum Corn Size Maximum Weed Size
Acuron 12 inches 3-inch broadleaves; inconsistent on emerged grasses
Acuron Flexi 30 inches 3-inch broadleaves
Anthem Maxx, Anthem ATZ 4 collars (V4) 2-inch broadleaves, before grass emergence
Atrazine 12 inches 1.5 inches
Axiom before emergence before emergence
Balance Flexx 2-leaf (V2) 1 true leaf stage
Bicep II Magnum 4-leaf or 2 collars 1- to 2-leaf
Corvus 2-leaf (V2) <2 inches (in general)
Dual 5 inches 2-leaf
Dual II Magnum, Bicep II Magnum, Bicep Lite II Magnum, Cinch ATZ Lite 5 inches 2-leaf
Fierce before emergence 2-inch broadleaves; by tank-mix partner for grasses
Guardsman Max/G-Max Lite 12 inches 1.5 inches broadleaves; before grass emergence
Halex GT 30 inches 4 inches
Harness, Harness MAX, Harness Xtra1, or Degree Xtra 11 inches or by tank-mix partner before broadleaf emergence, 2-leaf grasses or by tank-mix partner
Instigate 2-leaf (V2) 3 inches
Lexar EZ 12 inches 3-inch broadleaves; before grass emergence
Lumax EZ 12 inches 3-inch broadleaves; inconsistent on emerged grasses
Outlook 12 inches before emergence or by tank-mix partner
Prequel before emergence before emergence
Princep before emergence before emergence
Prowl H2O 30 inches before weed emergence
Python WDG/Accolade 20 inches (V6) before weed emergence
Resicore 11 inches 3-inch broadleaves
Resolve 12 inches 2-inch grasses; 3-inch broadleaves (in general)
SureStart II/TripleFLEX II11 inches 11 inches limited activity on 1-inch broadleaves; before grass emergence
Surpass NXT, FulTime NXT, TopNotch, or Keystone NXT, Breakfree NXT ATZ2 11 inches or by tank-mix partner before emergence or by tank-mix partner
Verdict before emergence before emergence
Zemax 30 inches (8-leaf) 3-inch broadleaves; before grass emergence
Zidua early postemergence before emergence or by tank-mix partner

1May be tank-mixed with Accent, atrazine (Harness), Banvel or Clarity, Marksman, Permit, or Roundup (Roundup Ready corn).
2May be tank-mixed with a number of different products, including Accent Q, Banvel or Clarity, Prowl, etc. See an herbicide label for specific information.

Current Weed Issues II: Revised Herbicide Management Strategies for Late Planting

Source: Dr. Mark Loux, OSU Extension

We’re running about a month behind in many cases, and with respect to weeds we are a month later than normal in implementing herbicide programs.  The most important thing to know about this is that we are well into the period of summer annual weed emergence, most of which occurs between early May and the end of June, which overall shortens the period of weed control that we need and allows earlier application of POST herbicides.  There are some advantages to this – here’s what it means for those fields just planted or that will still be planted within the next couple weeks:

Because we are this late, the burndown has become a major part of what is usually our in-season herbicide program, and is taking care of a good portion of the summer annuals that residual and POST herbicides would usually control.  The big glaring issue at this time is nasty burndown situations, and we provided some suggestions for this in previous articles.  Lots of pretty yellow fields due to cressleaf groundsel.  Keep in mind that this and other winter annuals that have flowered are ending their life cycles, so they have died or started dieing on their own anyway.  Focus should be more on the large giant ragweed, lambsquarters, marestail, etc that are present.  We are also late enough that waterhemp is part of the burndown mix in come fields.  Don’t skimp.

Herbicide programs do not have to last as long in crops planted late.  When we plant in early May, we need an herbicide program that controls weeds from then until the end of June or so, which is in part why we use residual herbicides and frequently apply POST herbicides 5 to 6 weeks after planting.  Applying the POST too early in a crop planted in early May introduces the risk of poor control of weeds that emerge soon after that application, before the crop is developed enough to control them on its own.  This is much less of an issue with a late-planted crop.  Since summer annual weed emergence tapers off as we move through June, the POST herbicides can be applied much sooner after planting without sacrificing control.  Planting soybeans this late can therefore allow earlier POST applications when weeds are small – more like 3 weeks after planting.  This can help minimize carryover concerns with fomesafen, and also provide a wider window to look for the right conditions to apply dicamba (see below).

In studies of reduced-rate POST applications that we conducted a couple decades ago, planting soybeans in late May or early June allowed us to use earlier POST applications (e.g 21 days after planting) at lower rates and still maintain control.  There were just fewer weeds emerging after planting and the duration of weed emergence after planting was also shorter.  It was not possible to achieve this in early-planted soybeans – we needed either two applications at reduced rate or a later application at full rates for control.

One issue with later POST sprays is the potential for herbicide carryover from products such as mesotrione and fomesafen (Flexstar, etc), among others.  Fomesafen carryover has been rare in the state but risk increases with later applications, especially if rainfall subsequently becomes limiting.  Where glyphosate and fomesafen are being combined in a late POST application to control ragweeds, it may become necessary to replace the fomesafen with lactofen (Cobra/Phoenix) as applications move into July.  Our research indicates that the lactofen products are less effective than fomesafen in this mix by about 10 to 20%.

Another concern would be POST applications of dicamba on Xtend soybeans shifted later into the hotter weather that occurs as we move from June into July.  The consensus of the weed science community is that both of the approved dicamba formulations have potential to move via volatilization, and the risk of this would increase with increasing temperatures and increased frequency and duration of inversions.  The current long-range forecast also indicates a trend for hotter than normal temperatures as we move into mid-summer.  Current labels allow application through 45 days after planting or prior to the R1 stage, whichever occurs first.  For soybeans planted early, the 45-day limit is often the main determinant, but later planted soybeans progress through growth stages more rapidly so the R1 stage may be the more frequent limitation.  Movement of dicamba onto other types of soybeans later in summer also has increased potential to reduce yield, since long-term effects of exposure to dicamba are more severe when soybeans have flowered.  Bottom line here is that there is less weather and time suitable for dicamba application with late-season applications, and movement and injury that does occur can have more substantial impact.  Planting within the next couple weeks and looking for the right conditions to spray starting about June 21 would provide more flexibility with regard to weather and weed size than deciding to wait until about July 10 to spray when it’s hotter and weeds are already large.

Can residual herbicides be omitted in late-planted soybeans?  Maybe.  Reduced weed populations could make this more feasible, but we really hesitate to recommend it.  Omitting residuals is never the right thing to do in fields with a history of weed control problems or high weed populations, or those with waterhemp and Palmer amaranth.  One advantage of omitting residuals would less risk of antagonism with burndown herbicides in mixtures.  Applying certain soybean residuals in June can increase risk of carryover.  The effectiveness of current soybean herbicide-tolerance trait systems makes this more of a possibility, but lack of residuals generally increases risk of problems and selection for resistant weeds, and makes timing of POST herbicides more critical.  The latter point is important because with a compressed season, applicators can be required to cover a lot of acres within a short period of time.  Keeping residuals in the program allows for more flexibility overall.

In late-planted corn, residual herbicides may be effective enough to reduce need for POST herbicides.  Or the residuals could be applied early POST, after the rush to plant is over (keeping rotation guidelines in mind).  Some corn fields are already in this situation, planted without any herbicide applied yet.  The table below shows restrictions on POST use of residual corn herbicides (source – U of Illinois).  This information can also be found in the herbicide descriptions in the Weed Control Guide , and is also summarized in this PSU newsletter article and this table from the MSU weed control guide.  Reminder that use of 28% UAN as a spray carrier is prohibited for POST application of herbicides with the exception of Degree Xtra.

 

 

Einstein’s Theory of Relativity as it Applies to Soil Moisture

Source: Dr. Bob Nielsen, Purdue University (Edited)

 

 

While Dr. Nielsen wrote this for Indiana, it unfortunately fits Ohio this year also.

 

Suitability of the soil moisture and whether a field is “fit” for field work and planting is partially “in the eyes of the beholder”, but is also subject to the “laws of relativity” and calendar date. Use your best judgement.

The bad news is that Monday’s USDA-NASS crop progress report estimated that only 6% of Indiana’s corn (4% of Ohio’s Corn) had been planted as of May 12, which puts our farmers in the unenviable position of suffering through the slowest planting progress EVER for this point in May. Nationally, only 30% of the corn crop was estimated to be planted as of May 12, compared with the most recent 5-year average progress of 66%. With more rain moving through the state late this week, let me offer a contrarian (if not “tongue in cheek”) view about soil moisture and planting.

The superintendent of our Purdue Agronomy Farm and I commiserate every planting season when it comes to deciding when the soil is “fit” to work or plant. We scuff the surface of the fields in mid-April, dig a few spadefuls of soil, squeeze the soil into a ball like the soil scientists tell us to do, and then agree that the soil is too wet to work or plant.

Around the first of May, we scuff the surface of the fields, dig a few spadefuls of soil, squeeze the soil into a ball like the soil scientists tell us to do, and then agree that the soil is too wet to work or plant.

Again in mid-May, we scuff the surface of the fields, dig a few spadefuls of soil, squeeze the soil into a ball like the soil scientists tell us to do, and then agree that the soil is maybe just about right to work or plant, but we’ll give it a few more days.

By late May, we scuff the surface of the fields, dig a few spadefuls of soil, squeeze the soil into a ball like the soil scientists tell us to do, and then agree that the soil is just as wet as it was back in mid-April, but maybe we ought to be working ground and planting anyway.

Einstein was right…………it’s all about relativity.

The point of my sharing this annual ritual with you is that we are rapidly approaching the point in the planting season where we need to “fish or cut bait”. Yes, there are risks of working ground too wet or planting “on the wet side” (see articles below), but there are also risks of waiting so long for the soil to become “fit” to begin planting that the majority of your corn ground gets planted way too late.

Heaven forbid that I should recommend anyone to work ground or plant corn in soils that are wet enough to cause severe compaction that will haunt you later this summer. But, you know, when you decide back in mid-April to wait, you’ve got quite a bit of good planting season left to go. When you decide in mid-May to wait AND you have a lot of acres to cover, what you save by avoiding some soil compaction now may be less than what you risk by planting the bulk of your corn acres very, very late.

If you concur with these thoughts and decide to “mud in” your corn and suffer serious yield losses; then you did not hear it from me. If you “pull the trigger” now and successfully avoid planting the bulk of your corn in mid-June and win the yield jackpot; then I’ll accept all the credit.

There are no black & white answers to this situation, there are no silver bullets, and there are no certainties in farming. Use your best judgement in deciding when to head back to the fields over the coming days and/or weeks. You know your fields and soils better than anyone else.

Delayed Planting Effects on Corn Yield: A “Historical” Perspective

According to the USDA/NASS, for the week ending May 5, only 2% of Ohio’s projected corn acreage was planted – compared to 20% last year and 27% for the five-year average. Persistent rains and saturated soil conditions have delayed corn planting. The weather forecast this week indicates the likelihood of more rain, so it is probable that many soggy fields may not dry out soon.

Long-term research by universities and seed companies across the Corn Belt gives us a pretty good idea of planting date effects on relative yield potential. The recommended time for planting corn in northern Ohio is April 15 to May 10 and in southern Ohio, April 10 to May 10. In the central Corn Belt, estimated yield loss per day with delayed planting varies from about 0.3% per day early in May to about 1% per day by the end of May (Nielsen, 2019). These yield losses can be attributed to a number of factors including a shorter growing season, greater disease and insect pressure and higher risk of hot, dry conditions during pollination.

Continue reading Delayed Planting Effects on Corn Yield: A “Historical” Perspective →

Corn Management Practices for Later Planting Dates – Changes to Consider

Source: Peter Thomison, Steve Culman

As prospects for a timely start to spring planting diminish, growers need to reassess their planting strategies and consider adjustments. Since delayed planting reduces the yield potential of corn, the foremost attention should be given to management practices that will expedite crop establishment. The following are some suggestions and guidelines to consider in dealing with a late planting season.

Although the penalty for late planting is important, care should be taken to avoid tillage and planting operations when soil is wet. Yield reductions resulting from “mudding the seed in” are usually much greater than those resulting from a slight planting delay. Yields may be reduced somewhat this year due to delayed planting,  but effects of soil compaction can reduce yield for several years to come. Keep in mind that we typically do not see significant yield reductions due to late planting until mid-May or even later in some years. In 2017, favorable growing conditions allowed many growers to achieve exceptionally grain high yields in corn planted as late as early June.

If you originally planned to apply nitrogen pre-plant, consider alternatives so that planting is not further delayed when favorable planting conditions occur. Although application of anhydrous N is usually recommended prior to April 15 in order to minimize potential injury to emerging corn, anhydrous N may be applied as close as a week before planting (unless hot, dry weather is predicted). In late planting seasons associated with wet cool soil conditions, growers should consider side-dressing anhydrous N (or UAN liquid solutions) and applying a minimum of 30 lb/N broadcast or banded to stimulate early seedling growth. These approaches will allow greater time for planting. Continue reading Corn Management Practices for Later Planting Dates – Changes to Consider →

Yield Response of Corn to Plant Population in Indiana

Source: RL (Bob) Nielsen, Jim Camberato, & Jason Lee Purdue University (Edited)

Summary:

Results from 97 field scale trials around Indiana since 2008 suggest that maximum yield response to plant populations for 30-inch row corn grown under minimal to moderate stress conditions occurs at about 32,150 plants per acre (ppa), equal to seeding rates of about 33,840 SEEDS per acre (spa). Economic optimum populations are several thousand lower than the agronomic optimum. Corn grown under extremely challenging conditions (e.g., severe drought stress) may perform best at plant populations no higher than 22,800 ppa and perhaps as low as 21,000 ppa under truly severe growing conditions (e.g., actual drought, non-irrigated center pivot corners, non-irrigated sandy fields with minimal rainfall).

The cost of seed corn is the largest single variable input cost for most Indiana corn growers(Dobbins et al., 2019). Minimizing that cost involves a combination of shrewd purchasing skills and wise selection of seeding rates. This summary focuses on our recent research evaluating the yield responses of corn to plant populations in field scale trials conducted around the state of Indiana since 2008.

Reported corn plant populations have increased steadily in Indiana (and Ohio) for the past several decades, at an annual increase of approximately 315 plants per acre (ppa) per year, based on historical data summarized by the USDA National Agricultural Statistics Service. In 2018, the average reported plant population for Indiana (and Ohio) was approximately 30,400 PLANTS per acre (USDA-NASS, 2019). Considering stand establishment success typically ranges from 90% to 95%, the average reported population suggests that the average seeding rate statewide is 32,000 to 33,800 seeds per acre (spa). Among the agronomic factors that support the steady annual increase in plant populations has been the genetic improvement in overall stress tolerance that has resulted in a) ear size and kernel weight becoming less sensitive to the stress of thicker stands of corn and b) improved late-season stalk health.

Click here to read the entire study

 

SPRING ROLLER COASTER RIDE COMING

Source:  Jim Noel (Edited)

It is spring and with it often comes wild swings. This is what we expect for the rest of April 2019.

A parade of storms will begin later this Thursday (4/11) into Friday (4/12) and follow every 3-5 days. This will cause 2-3 inches of rain on average for Ohio the next two weeks as shown in the attached graphic. Normal rainfall is now almost 1 inch per week. Hence, slightly above normal rainfall is expected. The one exception could be northern and northwest Ohio where it is possible to see less rainfall depending on the exact storm tracks.

We are also fast approaching our end of the freeze season typically in mid April up to around the 20th for much of the state. Some places in the north it can be late April. Right now, everything looks like a normal end to the freeze season. We do see the possibility of another freeze this weekend on Sunday AM especially north of I-70. A few more could happen into the next week or two before coming to an end.

Temperatures are expected to overall be slightly above normal for the rest the rest of April but with wild swings. This should help bring 2-4 inch soil temperatures into the normal range, possibly a degree or so above normal. The exception would be northern Ohio where above normal ice levels this past winter on the Great Lakes will keep water temperatures on the Lakes lagging and may keep air temperatures closer to normal there.

With all the storms lined up, we do expect a windy April as well. Winds of 30-40 mph with gust to 50 mph can not be ruled out Thursday (4/11) or Friday (4/12) this week with storm number one. 30-40 mph winds will also be possible with the storm later Sunday into next Monday and can not be ruled out with the third storm later next week.

After a wetter April indications are for a warmer and not as wet May with the possibility of normal or even a bit below normal rainfall.

Early indications for the summer growing season are normal or slightly above normal temperatures and possibly a bit wetter than normal though June could be a bit drier.

Soybean Planting – Does maturity group affect planting date?

Source: University of Illinois

Should later-maturing varieties be planted first in order to take maximum advantage of the longer time in the field? There’s no problem with doing that, although early planting moves up harvest date some, so works counter to the goal of spreading harvest time by using different maturities. In 2018 we ran a trial at Urbana, supported by a seed company, to see how varietal maturity affected response to planting date. The first planting date was April 26, the last was June 6, and varieties ranged in maturity from MG 2.3 (very early for this location) to MG 3.6, which is a little later than average for this location.

 

For all but the earliest-maturing variety in this trial, the planting date response was almost perfectly linear, with the loss of nearly 7/10ths of a bushel per day of planting delay—a total of more than 27 bushels—over the 41 days from the first to the last date (Figure 2). This loss rate accelerated a little for the latest-maturing variety between May 24 and June 6. The earliest-maturing variety lost only 17 bushels from first to last planting, but only because its yield at the earliest date was so much lower than yields of the later-maturing varieties.

The month of May 2018 was much warmer than normal, and this got the soybean plants off to a very fast start. Warm nights are conducive to early flowering, and this was especially notable in 2018. In the early-planted crop, first flowers appeared in early June, well before the longest day of the year, and unlike the interruption of flowering that often takes place under normal night temperatures for about a week before and after the longest day, flowering was early and continuous in 2018. As a result, nearly half of the Illinois soybean crop was flowering by July 1. The warm May probably affected the yield response to planting date as well; with warm temperatures, early-planted soybeans as fast as late-planted ones, and this widened the developmental gap between the different plantings.

Planted on April 26, the earliest variety reached first flower on June 9 and matured on August 28, compared to June 15 and September 17 for the latest-maturing variety. When planted on May 24, the earlier and later varieties flowered on June 15 and July 2, and matured on September 12 and September 25, respectively. So when planted late, both varieties flowered very early in their life cycles, both spent less time in reproductive stages than when they were planted early, and they ended up yielding about the same. While in this case it’s accurate to say that the later-maturing variety benefitted more from early planting, that’s only because the early-maturing one was physiologically less able to use the longer growing period allowed by early planting to produce high yield.

Knox County Soybean Seeding Rate – Trial #1

A BIG thank you to Jim & Susan Braddock for allowing me to put two of my Soybean Seeding Rate trials on their farm this year!

 

 

The results are listed in the tables below.

The 2018 report is now available in both a print and e-version. To receive a printed copy, stop by the Knox County Extension office.  The e-version can be viewed and downloaded here at go.osu.edu/eFields.

Knox County Soybean Seeding Rate – Trial #2

A BIG thank you to Jim & Susan Braddock for allowing me to put two of my Soybean Seeding Rate trials on their farm this year!

 

The results are shown in the tables below.

The 2018 report is now available in both a print and e-version. To receive a printed copy, stop by the Knox County Extension office.  The e-version can be viewed and downloaded here at go.osu.edu/eFields.