C.O.R.N. Newsletter: 2014-07
Sharpen Label Changes – It’s Something AnywayAuthor(s): Mark Loux
A recent change to the Sharpen label results in more utility for this product in spring burndown programs for soybeans. Sharpen can now be applied in a mixture with other PPO-containing herbicides, as long as the following conditions are met: applied at least 14 days before soybean planting; soils are medium to fine-textured; or soils are coarse-textured soils but have 2% or higher organic matter. This pertains to any product containing flumioxazin (Valor, Valor XLT, Envive, etc), sulfentrazone (Authority products, Sonic), and fomesafen (Prefix, Vise). The Sharpen label previously allowed these mixtures only when applied at least 30 days before planting. Labels for most of the PPO-containing residual herbicides appear to also be changing to recommend mixtures with Sharpen at least 14 days before planting. These labels refer the user to the Sharpen label for specifics on timing, rate, soil type, etc.
So what’s the broader picture on Sharpen use in spring burndown programs? Or as one agronomist asked – if I have to wait 14 days to plant when I apply a mixture of Sharpen with a Valor or Authority product, what’s the advantage compared with using a mixture of a Valor or Authority product with 2,4-D and some additional metribuzin? Good question although it may miss the point somewhat. This is not necessarily an either/or situation. One of the common problems in marestail control programs is the variable effectiveness of the spring burndown in fields that were not treated with herbicide the previous fall. Variability in control generally increases as the spring progresses and marestail plants become larger and older, and environmental conditions play a role also. So there can be an advantage to mixing Sharpen with an already comprehensive herbicide program to try to minimize this variability. Even the lowest rate of Sharpen can provide some additional residual control, and there are certainly some fields where applicators try to avoid the use of 2,4-D due to neighboring gardens, vineyards, greenhouses, etc.
Our main problem with the new label is that it doesn’t go far enough, and allows only the 1-oz rate of Sharpen in mixtures with PPO herbicides. Increasing the Sharpen rate can substantially increase the help it provides with residual control of marestail, and this is still possible only when using a metribuzin-based program. When applied 14 days before planting, the 1.5-oz rate of Sharpen can be used in combinations with metribuzin, Canopy DF, Matador, Boundary, etc, following the same soil type restrictions listed in the first paragraph. The 2-oz rate can be used 30 days before planting. BASF is apparently still working out how to label the higher rates with PPO herbicides, but we have been told that we could possibly see this sometime in the future.
New Developments in the World of Soybean PathologyAuthor(s): Anne Dorrance
At the regional soybean disease workers meeting in Florida earlier this month, colleagues from Kentucky and Indiana both reported the presence of the fungus,Cercospora sojina, that are resistant to the strobilurin fungicides. This fungus causes frogeye leaf spot on soybean. There are lots of Cercospora species that cause disease on a number of different hosts (gray leaf spot on corn; Cercospora on beets etc.) To date we have not identified any Cercospore sojina isolates that are insensitive to these fungicides. More monitoring will take place in 2014.
Also at that meeting – there was quite a bit of discussion about kudzu. Much of it was killed back, but unfortunately it had been dry in some parts of the south, so the rust spores had survived in some areas. Predictions on soybean rust for 2015 will depend on how long it will take for the kudzu to leaf out – which will be delayed this year; and then how long it will take rust to begin to develop on the kudzu. Lots of discussion and as always lots of interest.
Two new videos are out on soybean rust. The videos include highlights from numerous research and Extension projects carried out by land-grant university researchers from around the country involved in soybean rust research and monitoring efforts. They were produced with support from the American Public Land Grant Universities Association, Cooperative Extension, the Experiment Station Committee on Organization and Policy (ESCOP), the U. S. Department of Agriculture’s National Institute of Food and Agriculture, and the United Soybean Board.
The first video (http://youtu.be/m07iu6HaQpc) provides an overview of soybean rust, its impacts, its spread in the U.S., and how responding to this disease has changed the way researchers, Extension educators and farmers now approach soybean diseases in general.
The second video (http://youtu.be/8NQW7YAmEBE) deals with efforts undertaken across the country to model, predict and forecast soybean rust through the use of “sentinel plots.”
Among its many accomplishments, the team has identified management strategies for soybean rust; made efforts to test and register fungicides for use in the U.S., giving soybean producers more options for controlling the disease; and established an extensive network initially of over 2,300 sentinel plots, helping farmers know more precisely where the disease is likely to occur and when and what types of fungicides to use.
A new fungicide which has activity towards Oomycetes was labeled this month. INTEGO Solo is the name of the product from Valent, but much of the initial field testing was done in Ohio. The active ingredient ethaboxam, provides similar or greater efficacy towards the diversity of watermolds that attacks soybean and corn seed and seedlings in Ohio. This will give an added benefit to many of the areas in the state that continue to struggle with replanting issues.
Nitrogen Recommendations for Wheat
Soon wheat will be greening-up across the state. Ohio State University recommends applying nitrogen between green-up and Feekes Growth Stage 6 (early stem elongation), which is generally the latter part of April. The potential for nitrogen loss will decrease by waiting to apply closer to Feekes 6. Greenup will be later this year and a common sense approach would recommend applying as soon as field conditions allow application equipment, particularly since days available for field activities may be limited between now and Feekes 6.
Ohio State recommends the Tri-State guide for N rates in wheat. This system relies on yield potential of a field. As a producer, you can greatly increase or reduce your N rate by changing the value for yield potential. Thus, a realistic yield potential is needed to determine the optimum nitrogen rate. To select a realistic yield potential, look at wheat yield from the past five years. Throw out the highest and lowest wheat yield, and average the remaining three wheat yields. This three-year average should reflect the realistic yield potential.
Table 10 in the Tri State guide recommends 110 lb N for yield goals of 90+; 70 lb for 75 bu; and 40 lb N for 50 bushel yield goal (these recommendations are for total N and include any fall N). If you prefer to be more specific the following equation may be used for mineral soils, which have both 1 to 5% organic matter and adequate drainage:
N rate = 40 + [1.75 x (yield potential – 50)]
We do not give any credit for the previous soybean or cover crop, since we do not know if that organic N source will be released soon enough for the wheat crop. The Tri-state recommends that you subtract from the total (spring N) any fall applied N up to 20 lb/A. Whether you deduct fall N depends how much risk you are willing to take and your anticipated return of investment from additional N. Based on the equation above and deducting 20 lb from a fall application, a spring application of 110 lb N per acre would be recommended for a yield potential of 100 bu, 90 for 90 bu potential; 70 for a 80 bu potential and 40 lb N per acre for a 60 bu potential. Nitrogen rate studies at the Northwest Agricultural Research Station have shown the optimum rate varies depending on the year. However, averaged over years, yield data from these studies correspond well with the recommendation equation given above. These studies have also shown that regardless of the year, yields did not increase above a spring rate of 120 lb N per acre. Nitrogen rate work in 2013 at the OARDC Northwest Agriculture Research Station once again showed no response above a spring rate of 120 lb N per acre.
Pelletized Lime in Production SystemsAuthor(s): Ed Lentz, CCA
Pelletized lime has been on the market for over ten years in Ohio. It consists of finely ground limestone held together by some form of binding agent to make a pellet. Since it requires more processing than traditional ag lime it often costs considerably more than bulk ag lime. However, since it is in a pellet form it can easily be blended with other fertilizers and applied with regular dry fertilizer equipment.
University research has shown that pelletized lime does not raise soil pH faster than high quality ag lime. This should not be a surprise since high quality ag lime includes a large portion of material this has been finely ground.
Pelletized lime is one of the many sources of lime available to producers in Ohio. When evaluating a pelletized-lime source ask for the analysis sheet to obtain the Effective Neutralizing Power (ENP) value. Ohio lime regulations require liming materials sold in Ohio to have the ENP listed on the analysis sheet. This value should be given as pounds of ENP. The ENP for pelletized lime would be determined on the lime source prior to the pelletizing process.
Effective neutralizing power takes into account all the components that determine the quality of the lime, i.e., neutralizing ability, particle or grind size, and water content. This value will allow a producer to determine the actual price per pound of neutralizing ability for a lime source and also to calculate how much of a source will be needed to equal a ton of recommended lime. For example, if the lime recommendation was for two tons (one ton = 2000 pounds), a lime source with an ENP of 1000 pounds would require an application of four tons to satisfy the two ton lime requirement since for every ton of this lime source it only provides an effective neutralizing ability of 1000 pounds. If the lime source had an ENP of 1500 pounds, it would require an application of 2.7 tons to fulfill the requirement of two ton recommendation of lime. These calculations would also be true for pelletized lime source.
Once a producer knows how much lime needs to be applied for a source they can compare price based on ENP. In other words, a producer can determine how much effective neutralizing material they are actually buying in a source. Also remember if adding lime this spring, consider the following management practices:
1) 2 ton applications may be made anytime during the cropping season
2) Applications > 2 tons should be split applied
3) Do not apply more than 8 tons in one season
4) Urea forms of N fertilizer should not be surface applied where lime has recently been surface applied to prevent volatilization losses.
In summary pelletized lime is one of many sources available to Ohio producers. Its ENP value will allow comparisons to other lime sources. Additional information on lime may be found in Soil Acidity and Liming for Agronomic Production Bulletin AGF 505, (https://agcrops.osu.edu/specialists/fertility/fertility-fact-sheets-and-bulletins/AGF505.pdf) the Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat and Alfalfa (http://ohioline.osu.edu/e2567/). Possible effects of lime on spring applied herbicide performance can be found at (http://corn.osu.edu/newsletters/2010/2010-02).
For the remainder of March temperatures may range 5-10 degrees below normal with about normal rainfall. The outlook for the first week of April calls for temperatures a few degrees above normal and normal rainfall. The outlook for the remainder of April then switches back to slightly colder than normal temperatures (-1F to -3F) and slightly wetter than normal weather. Normal April highs are mainly in the 50 degree range and lows in the 30-35 degree range. Normal rainfall is about 0.75 to 1.00 inches per week now.
It still looks like based on historical data that the last freeze could be 1-2 weeks late this spring. Years like this one would include the 1963, 1979 and 1994 spring seasons. Also, looking at those years, hail activity was increased with cold air aloft.
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.
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