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Ohio State University Extension


C.O.R.N. Newsletter 2010-39

Dates Covered: 
November 23, 2010 - December 7, 2010
Greg LaBarge
Seed Treatment Rates and PhytophthoraSeed Treatment Rates and Phytophthora

Seed Treatment Rates and Phytophthora

In the greenhouse assay we took seed that was treated at the low, mid and high rates of the fungicides and then inoculated with P. sojae at 0, 3, 5, and 7 days after planting.  These seedlings were then harvested – at 14 days after planting.  We used a zoospore suspension, similar to what would occur in the field.  The fungicides all provided some level of protection, but the only rates where no disease developed were at the 0.64 fl oz/cwt and at the 1.5 fl oz/cwt.  Some root rot did occur in these studies across the lower rates, since we harvest the seedlings early – we did not allow time for plant death to occur.

Field studies.  One thing we have learned after years and years of seed treatment work, saturated soil conditions need to occur before seedling emergence in order for infections to occur. This was nicely demonstrated through a north central soybean research project funded program in which several states evaluated varieties with different combinations of resistance (susceptible to gene stacks plus high partial resistance) with and without seed treatments.  As you would expect in some locations, there was no benefit to the seed treatment.  Rain did not fall or the varieties had Rps genes that were effective towards that P. sojae population so no disease developed.  In Ohio and in Ontario, Canada the results were different.  Both of these locations had precipitation (rain &/or irrigation).  Also, at both of these  locations, the fields have a very highly diverse pathogen population-so the Rps genes would not have been 100% effective.  In these fields, seed treated with the high rate of Apron XL were significantly better than the non-treated in at least one of the two years of the study. 

We have evaluated the rates of seed treatment in the field for a number of years.  Realistically, this is very challenging in that for a soil borne disease, inoculum is not the same across the study, not every area of the field is saturated for the same amount of time.  We also have some variety interactions, and where if the flooding comes too late or is not enough, the effect of the seed treatment will be missed.  Despite these challenges we were able to demonstrate this effect at Northwest Branch.  Here is some data from 2004:

Seed Treatment              

Trifoliate Stand

Final Stand

Yield (Bu/A)









Maxim plus Apron XL (0.16 )




Maxim plus Apron XL (0.32)




Maxim plus Apron XL (0.64)








LSD (P<0.05)





In this study, the ApronXL at 0.16 and 0.32 were not always significantly different from the nontreated check, but the 0.64 fl oz rate was.

When these recommendations were developed they came with the background that no seed treatment equals, metalaxyl-in-furrow. 

Here in 1997, we had the following results:

Seed Treatment              

Low Partial Resistance

High Partial Resistance




Ridomil 2E (1.1 oz/1000’)



Apron 1.5 fl oz/cwt



Apron XL (0.16 fl oz/cwt)



Maxim + ApronXL (0.16 fl oz/cwt)



LSD (P<0.05)



P value




We are still digging through this old data – and this year’s data from 3 locations also supports using the high rate for the fields in Ohio with very high disease pressure from Phytophthora sojae.  Fields that are well drained, cultivated, and have a good rotation, will most likely NOT see the difference in the rates compared to fields which are prone to saturation, no-till and have soybeans in them at least every other year.  Another factor that can also mask the effect of seed treatments is how good the resistance genetics are in the variety and how diverse is the pathogen population in a particular field.  For locations which battle Phytophthora year in and year out – the high rate of seed treatment is the safe way to go.

Ohio Soybean Performance Trials

New Herbicides for 2011

Callisto Xtra (Syngenta) is a premix of Callisto and atrazine for postemergence use on field corn, seed corn, sweet corn, and yellow popcorn.  Can be applied from emergence until corn is 12 inches tall.

Peak (Syngenta) is now labeled for postemergence use in field corn.  Peak contains prosulfuron, the component of Exceed that provided residual control of burcucumber, so a primary use of Peak in Ohio may be to mix with other postemergence herbicides to improve residual control of this weed.  Peak can be applied to corn up to 30 inches tall, but should be applied as a directed spray using drop nozzles when corn is past the 6-collar stage or more than 20 inches tall.  Crop rotation is restricted to corn where rates above 0.25 oz/A are used or when used north of I-70 and mixed with Spirit.  See label for other recrop guidelines.

TripleFlex (Monsanto) is the same herbicide as SureStart (Dow AgroSciences), just renamed and marketed by Monsanto.  Labels of the two products are also similar.

Authority XL (FMC) is a premix of chlorimuron and sulfentrazone for fall, preplant, or preemergence use in soybeans.  A previously available product, Canopy XL, contained these same ingredients, and was widely used in Ohio.  The ratio of sulfentrazone to chlorimuron is higher in Authority XL compared with Canopy XL, which can result in improved residual control of black nightshade and ALS-resistant waterhemp and marestail.  Can be applied to soils with pH up to 7.6, but recrop intervals are extended to at least 18 months for all crops except small grains where soil pH is 7.2 or higher.

Warrant (Monsanto) contains acetochlor, and is labeled for postemergence application to soybeans and corn, to provide residual control of later-emerging weeds, including annual grasses, pigweeds, waterhemp, black nightshade, and lambsquarters.  Warrant does not control emerged weeds, so it should be mixed with glyphosate in postemergence applications to Roundup Ready crops.  Optimum timing of application in soybeans (mixed with glyphosate) is when weeds are 2 to 4 inches tall and soybeans are at V2 to V3.

Kixor products BASF introduced three new products in 2010 based on a new active ingredient, saflufenacil, a broad-spectrum broadleaf weed herbicide.  Kixor is the overall name for saflufenacil-based herbicide technology.  The three new products included:  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 and Optill, a premix of saflufenacil and imazethapyr (Pursuit) for soybeans.  Changes for 2011 include:  a name change – “Integrity” has been renamed “Verdict”; and Verdict is now labeled for use in soybeans at 5 oz/A (which provides the same amount of saflufenacil as 1 oz/A of Sharpen).  Labels have been changed to recommend only MSO with saflufenacil in burndown situations (regardless of what else is in the mix), whereas the previous labels allowed COC or MSO.

Cleansweep D and Cleansweep M (Nufarm) are premixes of bromoxynil (Buctril), fluroxypyr (Starane), and 2,4-D or MCPA, respectively, for control of broadleaf weeds in wheat, oats, and barley.  Cleansweep D can be applied from the fully-tillered stage of crop growth until (but not including) the jointing stage.  Cleansweep M can be applied from the 2-leaf stage up to and including flag leaf emergence.  Labels do not specify whether these products can be applied in the fall, or applied using 28% as the spray carrier.  Allow 4 months between application and soybean planting.

Huskie (Bayer) controls many winter and summer annual broadleaf weeds in wheat, oats, and other small grains.  Huskie is a premix of bromoxynil and pyrasulfotole, which is an HPPD inhibitor (same site of action as Callisto).  Appy in fall or spring after crop reaches the 1-leaf stage, up to flag leaf emergence.  Apply with AMS (0.5 to 1 lb/A) or UAN (1 to 2 qts/A) for most effective control.  Can be applied using UAN as the spray carrier. The fertilizer solution should not exceed 50% nitrogen, and the nitrogen rate should not exceed 30 lbs/A.  Soybeans can be planted 4 months after herbicide application.

PowerFlex (Dow AgroSciences) is labeled for control of annual grass and broadleaf weeds in wheat.  The active ingredient is pyroxsulam, an ALS inhibitor (group 2).  PowerFlex can be applied in the fall or spring when wheat is in the 3-leaf to jointing stage.  Most effective control results from treatment of grasses at the 2-leaf to 2-tiller stage of growth, and when broadleaf weeds are no more than 2 inches tall or in diameter.  Apply with nonionic surfactant or crop oil concentrate.  PowerFlex can be applied in spray solutions containing nitrogen fertilizer solution (UAN), but the spray solution should not be composed of more than 50% UAN and should not exceed 30 pounds of actual nitrogen per acre. When PowerFlex is applied in spray solutions containing UAN, use a non-ionic surfactant at a maximum of 0.25% v/v, instead of crop oil concentrate or methylated seed oil.  Temporary crop injury may result when liquid nitrogen is used as the spray carrier.  Grass control can be reduced if PowerFlex is mixed with dicamba or amine formulations of 2,4-D or MCPA.  Allow 5 months between application and soybean planting.

Pulsar (Syngenta) is a premix of fluroxypyr (Starane) and dicamba for control of broadleaf weeds in wheat and barley.  Pulsar applied alone has a fairly narrow spectrum of control, and should generally be mixed with MCPA ester or another broadleaf herbicide.  Apply before the jointing stage of wheat (label does not specify whether fall application is allowed).  Pulsar can be applied with nonionic surfactant to improve control under less than optimum environmental conditions, and can be applied in a spray solution containing up to 50% nitrogen fertilizer solution.  Allow 9 months between application and soybean planting.

Transgenic Products Evaluated in the 2010 Ohio Corn Performance Test

According to the USDA-Economic Research Service ( ) in 2010, 71% of Ohio’s corn acreage was planted to transgenic corn hybrids (36% of total acreage planted to stacked trait hybrids, 22% to herbicide tolerant hybrids, and 13% to some type of Bt hybrid). The acreage of corn planted to non-GMO hybrids (29%) was greater in Ohio than any other major corn producing state in the US in 2010. There were 37 non-transgenic (non-GMO) hybrid entries in 2010 OCPT.

2010 Ohio Corn Performance Test results are now available online at:  

Hybrids can be sorted by yield, brand, and transgenic traits online.

Table 1. Transgenic products evaluated in the 2010 Ohio Corn Performance Test



Major Insect Targets1

Herbicide Tolerance2

# of


Non-GMO (non-transgenic, Clearfield)




YieldGard Corn Borer




Roundup Ready




Agrisure GT




Agrisure CB/LL




YieldGard VT Rootworm




Herculex Xtra




YieldGard VT Triple (VT3)




Genuity VT Triple Pro (VT3P)




YieldGard Plus with Roundup Ready




Agrisure GT/CB/LL




Agrisure CB/LL/RW




Herculex 1 Roundup Ready




Herculex Xtra Roundup Ready




Agrisure 3000GT








Total Hybrid Entries




1 ECB – European corn borer; RW – rootworm

2 RR – Roundup Ready; GT – glyphosate tolerant; LL – glusofinate tolerant

For more details on transgenic seed technologies, including events associated with transgenic traits,  insects controlled or suppressed by various Bt toxins, refuge requirements, etc. consult the following:

Chris DiFonzo and Cullen,Eileen. 2010. Handy Bt Trait Table. Wisconsin Crop Manager University of Wisconsin. Available at URL:

R.L. Nielsen. 2010. A compendium of Biotech Corn Traits. Corny News Network, Purdue Univ. [On-Line]. Available at URL: (URL accessed Nov. 22 2010)

Weather Outlook

Outlook: Not many changes from what we discussed in September or October. The pattern is beginning to shift toward a La Nina pattern which will turn us wetter into winter and early spring.

Short term: Expect a 1-2 inch rain event this week followed by the coldest air of the season for this holiday weekend. A few places will be more or less than the 1-2 inches but that should be fairly representative for Ohio. Some snow showers near the Great Lakes after the storm.

Expect the trend of returning to normal rainfall and still a little warmer than average into years end then we will trend wet from January-March. Temperatures will trend from warmer to colder than normal from January-March.

For next corn/soybean season, La Nina's usually bring cool and moisture early springs then turn warmer and drier for summer.


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Crop Observation and Recommendation Network

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.