C.O.R.N. Newsletter 2009-39

Dates Covered: 
November 24, 2009 - December 8, 2009
Greg LaBarge

New Herbicide Update for Corn, Soybeans, and Wheat

A number of new products for corn, soybeans, and wheat have been made available to Ohio growers over the past year. Some of these were used on a limited basis in 2009, but 2010 will be the first year of widespread use for most. As in previous years, some new products are simply new premix formulations of existing products (Flexstar GT, for example), but two brand new active ingredients were also registered. These include saflufenacil, the basis for the Kixor family of products, and thiencarbazone-methyl, which is a component of Corvus and Capreno. The 2010 Weed Control Guide for Ohio and Indiana contains information on all of the products discussed here. The 2010 guide is available in pdf format on our website, https://agcrops.osu.edu/weeds, and the print version should be available in early December. This information can possibly make it easier to wade through and interpret the marketing blitz that is in progress for some new products.

Corn Products

Kixor Based Products
Kixor is the overall name for saflufenacil-based herbicide technology. BASF has introduced three new products based on the active ingredient, saflufenacil, a broad-spectrum broadleaf weed herbicide. The three new products include: Integrity, a premix of dimethenamid (Outlook) and saflufenacil for field corn and popcorn; Sharpen, which contains just saflufenacil and is labeled for corn, soybeans, and wheat; and Optill, a premix of saflufenacil and imazethapyr (Pursuit) for soybeans. Saflufenacil represents novel herbicide chemistry, but not a new herbicide site of action. It is a PPO inhibitor (group 14), the same site of action as Valor, Authority, Cobra, and Flexstar, among others.

Saflufenacil products are labeled for preplant or preemergence use only, and provide residual control of most annual broadleaf weeds at the rates that can be used in corn. The dimethenamid component of Integrity adds control of annual grasses. We have previously tested Integrity at rates as high as 20 oz/A, which provided residual broadleaf weed control comparable to or better than competitive standards – atrazine premixes, Lexar/Lumax, etc. However, similar to the approach that Dow has taken with SureStart, Integrity is labeled for use only in planned preemergence followed postemergence herbicide programs. Integrity is labeled at use rates of 10 to 16 oz/A for this type of program, and it should provide the initial control needed to make this type of program work. The rates of Sharpen that are labeled for corn, 2 to 3 oz/A, and provide similar rates of saflufenacil in comparison to the use rates of Integrity.

Sharpen is labeled at the rate of only 1 oz/A in soybeans, because soybeans have less tolerance to saflufenacil compared with corn. Use rates of Optill contain a similar amount of saflufenacil. The lower rates for soybeans result in reduced residual broadleaf weed control, to the point that Sharpen should not be expected to provide substantial residual broadleaf weed control unless mixed with another residual herbicide. The Sharpen label prohibits combinations with other PPO-inhibiting herbicides, due to the possible risk of injury from combining two PPO inhibitors. This prohibition includes includes any PRE product containing flumioxazin (Valor, Valor XLT, Envive, Enlite, Gangster), sulfentrazone (Spartan, Authority First, Sonic, Authority MTZ, and Authority Assist), or fomesafen (Prefix). As a result, the most effective herbicides to combine with Sharpen to improve residual control may be Canopy/Cloak DF or EX, metribuzin, or Scepter.

Sharpen has activity on emerged weeds in addition to preemergence activity, and is apparently being promoted as a replacement for 2,4-D ester in preplant burndown treatments. Our research shows that while Sharpen applied alone has some foliar activity, it will not adequately control emerged weeds in no-till fields unless mixed with another herbicide that has effective foliar activity (glyphosate, Ignite), and is likely to contribute more activity on annual weeds than on biennials or perennials. This is fairly typical for herbicides that are not translocated (saflufenacil is a PPO inhibitor with contact activity), such as atrazine, metribuzin, and paraquat. All of these contribute significantly to control of emerged weeds, but effective control of the spectrum of winter weeds commonly found in Ohio no-till fields usually requires the addition of translocated herbicides also (glyphosate, 2,4-D, chlorimuron). It is also possible that two or more herbicides with contact activity can provide adequate burndown – atrazine + Gramoxone, Ignite + metribuzin, or Sharpen + Ignite, for example. In our research, Sharpen and Ignite have actually worked better in mixtures than Sharpen and glyphosate. We have observed inadequate control of purple deadnettle with the latter.

Sharpen does have considerable activity on marestail, and while we need additional data in this area, mixtures of Sharpen with glyphosate or Ignite have effectively controlled marestail. This provides an option for burndown of marestail (and other weeds) in fields where a grower is unable or unwilling to wait 7 days between application and planting. BASF is apparently positioning the combination of Sharpen, glyphosate, and Scepter as a replacement for combinations of glyphosate, 2,4-D ester, and other broadleaf PRE herbicides such as Valor XLT, Sonic, etc. in fields with marestail. The prevalence of ALS-resistant marestail populations will result in inadequate residual control of marestail in some fields where Scepter is used, unless an effective rate of metribuzin is added (0.38 to 0.5 lbs ai/A), and since Scepter is not the most effective residual herbicide on marestail anyway. An alternative and possibly more effective approach would be a combination of glyphosate, Sharpen, Canopy DF, and metribuzin. Keep in mind that early in the spring when it is still possible to use 2,4-D ester, combinations of glyphosate, 2,4-D, and a broad-spectrum PRE herbicide, which contains an effective rate of Valor, sulfentrazone, or metribuzin, are likely to be as or more effective than Sharpen treatments. Any PRE herbicide can be mixed with the glyphosate/2,4-D mixtures, whereas certain products cannot be mixed with Sharpen. Sharpen treatments are also not likely to be as effective on dandelion as mixtures of glyphosate, 2,4-D, and a chlorimuron-containing herbicide.

Thiencarbazone-methyl Based Products
Thiencarbazone-methyl is an ALS-inhibiting herbicide developed by Bayer that has residual and foliar activity on annual grasses primarily, and it has been effective for preemergence and postemergence control of grasses in OSU research. Corvus is a premix of isoxaflutole and thiencarbazone-methyl, along with cyprosulfamide, the same safener that is in Balance Flexx. Corvus rates range from 3.33 to 5.6 oz/A, and it can be applied preplant, preemergence, or postemergence up to the V2 stage of field corn and certain corn inbreds. Preplant applications of Corvus in burndown can control weeds up to 6 inches tall, although other herbicides with foliar activity should generally be added to control the spectrum of winter weeds commonly found in Ohio no-till fields. Corvus provides broad-spectrum residual control of grass and broadleaf weeds when applied preemergence, but the addition of atrazine will improve control of large-seeded broadleaf weeds (giant ragweed, cocklebur, morningglory). The addition of atrazine will also improve control of emerged weeds in burndown or postemergence applications. Adjuvants or herbicides other than atrazine should not be included in postemergence Corvus treatments.

Capreno is a premix of tembotrione (Laudis) and thiencarbazone-methyl, a new ALS-inhibiting herbicide that has foliar and residual activity on annual grass weeds. This product can be used on field corn and certain corn inbreds. Capreno can be applied postemergence from the V1 through the V7 stage of corn growth, although it should be applied with drop nozzles after the V6 stage. Capreno is most effective when broadleaf weeds are less than 6 inches tall, and grasses are less than 3 inches tall and not tillering. The addition of atrazine can improve the speed of control, and effectiveness on certain weeds. The label specifies application with crop oil concentrate and either UAN or AMS.

Other Corn Herbicides

Balance Flexx (Bayer) is a new formulation of isoxalutole that contains the safener, cyprosulfamide, which reduces the risk of corn injury. This product can be used in field corn and certain corn inbreds, and replaces Balance Pro. Balance Flexx can be applied preplant, preemergence, or postemergence up to the V2 stage of corn. Postemergence application of Balance Flexx alone will generally not control weeds larger than the 1-leaf stage, but it can be mixed with atrazine to improve control.

Prequel. (DuPont) is a premix of rimsulfuron (Resolve) and isoxaflutole (Balance Pro) for preplant and preemergence use on field corn hybrids. This product is intended for use in a planned preemergence followed by postemergence program. Prequel provides residual control of grass and broadleaf weeds, which can be improved with the addition of atrazine. Prequel can control small, emerged weeds in no-till, but the addition of atrazine or a burndown herbicide is required for weeds more than 3 inches tall.

SteadFast Q and Accent Q(DuPont) are new formulations of these products that contain isoxadifen, a safener to reduce the risk of corn injury. Labels are overall similar to those for Accent and Steadfast.

Soybean Herbicides

Flexstar GT (Syngenta) is a premix of glyphosate and fomesafen (Flexstar) for postemergence use in Roundup Ready soybeans. The product is formulated with adjuvants, but it should generally be applied with ammonium sulfate. The label recommends the addition of crop oil concentrate, methylated seed oil, or nonionic surfactant for “difficult to control” weeds, or under adverse conditions. OSU research results have shown that the addition of crop oil concentrate or methylated seed oil is necessary when using this product to control glyphosate-resistant ragweeds. The adjuvants in most glyphosate formulations are not adequate to maximize fomesafen effectiveness on these weeds. This product will not control glyphosate-resistant marestail, regardless of rate or adjuvant used.

Cheminova is marketing “generic equivalents” of several soybean herbicides, including Rhythm (Flexstar), Dawn (Reflex), and Tackle (Extreme). Rhythm and Dawn formulations and labels are essentially identical to Flexstar and Reflex. Tackle contains a different ratio of imazethapyr (Pursuit) to glyphosate, compared with Extreme. The Tackle use rate provides 2 oz Pursuit 2L + 0.75 lb glyphosate acid, and the Extreme use rate provides 4 oz Pursuit 2L + 0.56 lb glyphosate acid. Note: the combination of imazethapyr and glyphosate has been one of the more injurious postemergence mixtures applied to Roundup Ready soybeans.

Nufarm is marketing Cloak EX and DF, which are generic equivalents of Canopy EX and DF. Product labels and rates are similar between Canopy and Cloak products.

Wheat herbicides

Axial TBC (Syngenta) is a premix of pinoxaden (Axial) and florasulam for control of ryegrass, foxtails, and barnyardgrass in wheat and barley. Axial TBC also controls some broadleaf weeds, but should generally be mixed with a broadleaf herbicide if these are present. Apply with Adigor Adjuvant when wheat is in the 3-leaf to boot stage. Axial TBC can be applied in a spray solution containing up to 50% nitrogen fertilizer solution (e.g. 28%). Allow 9 months between application and planting soybeans.

Olympus Flex (Bayer) is a premix of propoxycarbazone-sodium (Olympus) and mesosufuron-methyl (Osprey) for control of winter annual grasses in wheat, including annual ryegrass, annual bluegrass, cheat, and downy brome. Apply from when the first fully expanded leaf of wheat is visible, up through jointing. Apply with nonionic surfactant plus either nitrogen fertilizer solution or ammonium sulfate, or with methylated seed oil (nitrogen fertilizer not required). The spray solution can contain up to 15% nitrogen fertilizer solution. Application in fall will generally provide the most effective winter annual grass control. This product also controls many winter annual broadleaf weeds, including chickweed, henbit, deadnettle, and most mustard species, but may need to be combined with a broadleaf herbicide for other weeds. Soybeans can be planted when both these conditions have been met: 5 months has elapsed and 18 inches of precipitation has occurred since application.

Evaluating Soybean Cyst Nematode Resistance – Big Impact in 2009

The weather was a big variable across the state this year, with some areas getting heavy weekly rains to severe drought in other portions of the state. One soybean pathogen seems to do well under both conditions but we see greater impact when the dry spells are longer is soybean cyst nematode. This is a worm that survives in the soil as a cyst. A cyst consists of a leathery shell that surrounds a multitude (100 to 250) of eggs that can then get moved with soil, wind and equipment. The eggs hatch throughout the year and move towards soybean or other host roots, feed, move around, have a good time and then the female sets up shop. She has the unique ability to make the plant work for her and sets up a feeding site. Once she gets settled in and her body begins to swell with eggs, the well trained eye can spot her on the roots of the plants. She is white to tan and the smaller than the size of the pin head on those dress shirts that you buy in the stores but not by much.

Over the past two years we have participated in the North Central Soybean Research Program funded regional SCN project. In this study we have planted 5 soybean varieties in two locations during 2008 and three locations during 2009 to both better understand the SCN population in Ohio but also to get some local data on how these varieties were responding to SCN. In these studies, the varieties are replicated 4 times and planted in 200 to 250 foot strips and a soil sample is taken every 25’ of each strip – so 10 samples total. The fields are sampled at planting and before the soybeans emerge as well as right after harvest so we can monitor the changes in the SCN populations during the season. First thing – no you do not have to do this on your own field. This is helping us to assess if our guidelines are doing what we thing they should be doing.

This year the fields that were selected had very low to negligible SCN populations, but we still saw the effects. In particular for SCN counts from the spring soil collection, the Sandusky field average (mean of 200 soil samples was 187) ranged from 0 to 767 eggs per cup of soil while the Putnam location (mean of 3) had 0 to 20 eggs per cup of soil. The Shelby soil is still being processed.

Key findings:

1) At the Sandusky location, the key symptom was uneven maturity. As you looked across the susceptible strips – there were areas where plants were already mature and leaves defoliated (no sudden death) and other areas where plants and pods were still green. Stunting and uneven maturity are two key symptoms of soybean cyst nematode. https://agcrops.osu.edu/images/soybean/DSC00114.JPG

2) The distribution of SCN in these plots was VERY uneven. There were large pockets where there were no eggs detected and the next plot over had 750 eggs/cup of soil.

3) In addition the varieties yielded quite differently. When SCN populations were high – the two varieties with resistance from PI88788 – had significantly different yields. We’ve heard about this, where the varieties that were developed from PI88788 don’t always act the same. The resistance in PI88788 for SCN comes from five to six different genes. In each new variety they all have the main gene, but they also have a different set of the additional genes. This is why we can sometimes see that one variety with PI88788 may give better control to SCN in one field but not in another. It is key then to rotate varieties with SCN resistance -- to keep SCN guessing.

4) When SCN populations are high – greater than 500 eggs/cup of soil, varieties with Peking did very well. Before this becomes a recommendation, we need to get the fall SCN counts and see if the SCN populations declined when Peking was planted.

More data to analyze and soil samples to count, but initially we are gaining a much better understanding of SCN in Ohio – and it is taking yield. There was a 21% loss in yield at the Sandusky location when the susceptible variety was compared to the best resistance line. The only symptom was uneven maturity.

Upcoming Agronomy Programs

The calendar of upcoming statewide and regional agronomy meetings and seminars is being updated regularly with new offerings can be found at https://agcrops.osu.edu/calendar/. Be sure to check this for your area of the state.

Upcoming meetings in December include the following:

December 8
Ohio No-Till Field Day 8:00 a.m.
Der Dutchman Restaurant, Plain City
Cost:$20 prior December 2 / $25 at the door

December 17
2009 Ohio Grain Farmers Symposium 7:30 a.m.
Veterans’ Memorial Civic and Convention Center of Lima/Allen County
Cost:$30 members / $40 non-members

December 18
Central Ohio Agronomy Day 9:00 a.m.
OSU/COTC Newark Campus – Founders Hall, Newark
Cost: $20.00

January 7
Crop Production Conference 8:00 am
Fawcett Center, Columbus
Cost: $75

January 8
Advanced Agronomy School 8:00 am
Fawcett Center, Columbus
Cost: $100

Online Lessons For To Prepare for New Pesticide Applicator Testing

Lessons to help individuals study for their new applicator test in the CORE category are now available online. The lessons can be purchased as a complete package or individually. When purchasing the lessons, you will have access for 30 days. More information is available at http://pested.osu.edu/online.html

Ohio Crop Budgets and Input Outlook

Crop products budgets for the 2010 corn, soybeans and wheat are no available in both a Excel spreadsheet and Adobe pdf file formats. They can be found at http://www-agecon.ag.ohio-state.edu/programs/FarmManagement/Budgets/index.htm.

Materials presented at the recent OSU Department of Agricultural, Environmental, and Development Economics Outlook Kickoff Meeting held October 26, 2009 covering input outlook, land values and cash rents is available online at: http://aede.osu.edu/Programs/FarmManagement/Programs/Input%20Outlook%202010.pdf

For more economic related information check out the Ohio Ag Manager Newsletter at http://ohioagmanager.osu.edu/~ohioagmanager/news/index.php

Thoughts on Compaction From The Fall Harvest

Many Ohio corn and soybean growers are harvesting record crops. However, they may be facing compaction issues because of saturated soils at harvest.

"Many farmers will be unable to get back in their fields after harvest," said Randall Reeder, an Ohio State University Extension agricultural engineer. "Many fields have ruts and severe compaction issues."

So what can farmers do to break up that soil and smooth out rough fields? According to Reeder, options are limited.

"Farmers may be facing two types of compacted fields. One type is where there is an isolated compacted area. I suggest they do whatever is necessary to get that area ready for planting and leave the rest of the field alone," said Reeder. "The other type is compaction across the entire field, and whatever is done in terms of tillage operations is applied to 100 percent of the field."

Reeder offers the following options to aid growers in preparing for spring planting:

•Do nothing about deep compaction, especially if it turns out to be a wet spring. "You don't want to make a bad situation worse by performing deep tillage on wet soils because it destroys the soil structure," said Reeder. "If a farmer can get a no-till planter or drill across rutted ground reasonably well it may be better to take a slight yield hit in 2010 and then try to correct the deep compaction problem after harvest."

•Perform light shallow tillage, but only if the soil is dry. "If ruts or tracks are more than 2 or 3 inches deep, a light tillage pass can smooth out the soil and create a surface ideal for planting," said Reeder. "Fill in ruts enough to eliminate standing water."

•Use this fall as a valuable learning opportunity. “Consider the benefits of continuous no-till, especially with controlled traffic. Strip-till, either fall or spring, may be best for corn planting.”

Research has shown that compaction affects crop yields. Years of Ohio State research on Hoytville silty clay loam showed that through compaction, 10 percent to 15 percent of the potential crop yield was being left in the field. Recent research shows that continuous no-till soil resists compaction from heavy loads better than soil that is subsoiled every three years, resulting in higher yields.

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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.