Prepare to Evaluate Forage Stands for Winter Injury

Originally posted on the BEEF Newsletter

By:  Rory Lewandowski, OSU Extension Educator, Wayne County and Mark Sulc, OSU Extension Forage Specialist

Forage stands will begin spring greenup in the next few weeks, especially in southern Ohio. While winter injury in forages is very hard to predict, this winter has presented some very tough conditions for forage stands. This is especially true of legumes like alfalfa and red clover. Producers and crop consultants should be prepared to walk forage stands early this spring to assess their condition in time to make decisions and adjustments for the 2019 growing season.

Continue reading

Reducing soybean planting rates can increase income

source: Michael Staton, MSU Extension (edited), John Barker OSU Extension

Results from 40 on-farm replicated trials conducted in Michigan from 2015 to 2018 build a compelling case for reducing soybean planting rates.

Michigan soybean producers have consistently identified planting rates as the highest priority topic to evaluate in on-farm replicated trials. Furthermore, the producers wanted to evaluate the effect of low planting rates on soybean yield and income. The two factors driving the increased interest in reducing soybean planting rates are seed cost and white mold. To help Michigan soybean producers make planting rate decisions, the SMaRT (Soybean Management and Research Technologies) program conducted a total of 40 on-farm replicated trials from 2015 to 2018. Please see Figure 1 for the trial locations.

Eleven planting rate trials were conducted each year from 2015 to 2017 and seven trials were conducted in 2018. Four target planting rates (80,00, 100,000, 130,000, and 160,000 seeds per acre) were compared at all but one location where the lowest rate was not included. Stand counts were taken to determine actual final plant stands at each location in all years. To calculate the income (gross income – seed cost) generated by each planting rate, we used the USDA projected prices and average seed costs for treated seed for each year. None of the varieties planted in the trials were straight line or thin line plant type and a complete seed treatment was used at 33 of the locations.

Because we conducted the trials over four years, we learned how the planting rates performed over a range of growing conditions. Planting conditions were nearly ideal in 2015 but were much more challenging in 2016, 2017 and 2018 as evidenced by the average stand loss shown in Table 1. Statewide record yields were achieved in 2015 and again in 2016. However, yields declined significantly in 2017 due to excessive early rains and a lack of rain in August and September. Yields rebounded in 2018.

The effects of soybean planting rates on yield and income are shown in Fgure 2. The bars represent yield and the lines represent income. The figure clearly shows the year-to-year variability in yield and income. It also shows that the lowest two planting rates were the most profitable in 2015 and 2018 and the highest planting rate was the least profitable each year. Table 2 shows the average yield and income for all 40 locations.

When all 40 sites were combined, the yields from the highest two planting rates were identical and they beat the 100,000 seeds per acre planting rate by less than one bushel per acre and the 80,000 rate by only 2.2 bushels per acre. The 100,000 seeds per acre planting rate generated the most income.

These results are very similar to the 2018 Knox County Soybean Seeding Rate Trials shown below.

Click here to see the 2018 Knox County data from plot #1

Click here to see the 2018 Knox County data from plot # 2

Click here for the 2018 OSU eFields report

Click here for the MSU data mentioned above

What’s Legal to Apply to the LL-GT27 Soybean – The (maybe almost) Final Story

by: Dr. Mark Loux, OSU Extension

Having to issue a retraction to previous C.O.R.N. article where we thought we had it right is always fun.  About a month ago we ran an article that covered the legality of POST glyphosate and glufosinate applications to the LL-GT27 soybean, which is resistant to both herbicides.  The issue at that time was the legality of applying a mix of both herbicides, based on questions we had received.  Cutting to the quick, our conclusion was that because it was legal to apply the mixture since both herbicides could legally be applied and labels did not prohibit mixing.  We were naïve apparently, because that article caused the issue over whether it was actually legal to apply glyphosate to the LL-GT27 soybean to be raised.  Since then, ODA, USEPA, and the companies who are the involved registrants have been working to come to a solution that clarifies this issue and keeps us all moving forward toward a resolution.  The issue here seems to be this – wording on most glyphosate labels specifies application is allowed to “Roundup Ready” and “Roundup Ready 2 Yield” soybeans, and since the LL-GT27 soybean is not designated as such, those glyphosate products could not legally be applied.  After a month of deliberation, the USEPA issued some guidance which took the form of the following:

“Users of pesticide products containing glyphosate should refer to the pesticide product labels of herbicide products containing glyphosate for the specific registered uses on pesticide-resistant crops such as soybeans with glyphosate-resistant trait(s).  Regardless of the herbicide product name (brand name), if the label of the glyphosate product states it is for over-the-top (post-emergent) use on glyphosate-resistant soybeans, and it is not otherwise restricted by other label statements/directions for use, it can be used on any soybean that has a glyphosate-resistant trait.  However, if the label of the glyphosate product states it is for use on crops such as soybeans, with specific glyphosate-resistant traits by name, then the glyphosate product can only be used on those crop(s) with those traits specifically identified on the label.  Ultimately, growers and commercial applicators must comply with the entirety of the pesticide label.  Please let us know if you have any questions.”

Questions – yes – excuse us while we look for the head scratching emoji.  We can try to interpret in real-life speak.  Here’s what it comes down to:

– the important part of the glyphosate label here is the use-specific directions, or the section within the larger “Roundup Ready” part of the label that deals with soybeans.

If the soybean section of the glyphosate product label does not mention specific genetics by trade name, but just the wording “glyphosate-resistant” or “glyphosate-tolerant”, then it is legal to apply that product to the LL-GT27 soybean.

– if the soybean section of the label restricts use to certain genetics by trade name –  “Roundup Ready”, “Roundup Ready 2 Yield”, etc, then it would not be legal to apply to the LL-GT27 soybean.

– if the wording on the label is along the lines of “For Use on Soybeans with the Roundup Ready gene”, or similar wording with other specific genetics, it would not be legal to apply to the LL-GT27 soybean.

Our not exhaustive search through glyphosate product labels indicates that most if not all do not contain any wording about “glyphosate tolerance” in the soybean section, and indicate use is specifically on “Roundup Ready” or “Roundup Ready 2 Yield” or “Soybeans with the Roundup Ready gene”.   This includes Roundup PowerMAX, Durango DMA, Abundit Edge, Credit Extreme, and Cornerstone to name a few.  Manufacturer reps with a glyphosate product label that varies from this are free to contact us so we know.

The inability to use glyphosate on the LL-GT27 soybean affects primarily growers who bought it for the genetics or other traits and not the LibertyLink trait, who might have planned to use only glyphosate POST.  Most of the utility of this soybean on problem broadleaf weeds comes from the LibertyLink trait though (and it’s definitely legal to apply glufosinate POST).  There’s plenty of generic clethodim around to help out with grass.  We assume label language will adapt over time to take care of the glyphosate issue.  We’re not even sure this issue would have come up if we hadn’t tried to clarify the tank-mix legality and stepped right in it.  There appeared to be some confusion in the field about this though, with different stories being told, and better to just clear it all up way in advance of the season.  Stay tuned for the next chapter.  Offer void where not legal.  Legality may vary by state.  Your mileage may vary.  Side effects may include confusion, apathy, anger, and spontaneous profanity.

Nitrogen Application Timing for Weak Wheat Stands

Source: Ed Lentz, OSU Extension

Late-planted wheat fields had little opportunity for growth before cold and wet conditions moved into the area last November. Fall tiller production was limited because of early cold weather soon after planting. In addition, some wheat stands have been damaged this winter from lack of snow cover, standing water, saturated soils, ice sheets, and days of very cold temperatures.

In these situations, producers have asked whether they should apply nitrogen earlier to increase the number of spring tillers. Keep in mind, it is fall tillers that provide most of the yield in a wheat field. Heads developing from spring tillers generally are much smaller than heads from fall tillers.

In northern climates, the vegetative period of growth is much shorter than the other wheat regions of the country; thus, plants have a much shorter time to recover from winter damage. From my experience, producers will have limited success in improving yields of poor stands and stands with reduced-growth by applying nitrogen earlier. A producer may get a few more spring heads, but not enough to significantly change the yield situation. The earlier application will also significantly increase the risk of nitrogen loss. In fact, a producer may need to readjust their yield potential for these fields and reduce their total nitrogen rate accordingly.

Wheat does not need large amounts of nitrogen until jointing (Feekes GS 6), generally the latter part of April. Soil organic matter and/or nitrogen applied at planting generally provide sufficient nitrogen for early spring growth. Ohio research has shown no yield advantage for nitrogen applied before jointing. The longer the time between nitrogen application and jointing, the greater the risk for nitrogen loss. Nitrogen source will also affect the potential for loss. Urea-ammonium nitrate (28%) has the greatest potential for loss, ammonium sulfate the least, and urea would be somewhere between the two other sources.

Ohio research has also shown that yield losses may occur from nitrogen applied prior to green-up regardless of the nitrogen source. The level of loss depends on the year (losses would be smaller if the ground is not frozen or snow/ice covered). This same research did not observe a yield increase from applications made prior to green-up any year compared to green-up or Feekes GS 6 applications.  Keep in mind that green-up is a descriptive term and not a definable growth stage. My definition of green-up is when the new growth of spring has covered the dead tissue from winter giving the field a solid green color – thus, growing plants.

There is a legitimate concern that wet weather may prevent application of nitrogen at early stem elongation. Ohio research has shown a yield decrease may occur when nitrogen application is delayed until Feekes Growth Stage 9 (flag leaf fully emerged). Thus a practical compromise is to topdress nitrogen any time fields are suitable for application after initial green-up to Feekes GS 6. There is still a potential for loss even at green-up applications. To lessen this risk a producer may want to use a nitrogen source that has a lower potential for loss such as urea or ammonium sulfate. ESN (polymer-coated urea) would be another option but it needs to be blended with urea or ammonium sulfate to insure enough nitrogen will be available for the crop between Feekes GS 6 – 9. The source of nitrogen becomes less important as the application date approaches Feekes GS 6 (jointing). The percentage of urea and/or ammonium sulfate would need to be increased with ESN for application times closer to Feekes GS 6. A producer may want to consider the use of a urease inhibitor with urea if conditions are favorable for volatilization losses: warming temperatures, drying winds and no rain in the forecast for 48 hours.

A split application of nitrogen may also be used to spread the risk of nitrogen loss and to improve nitrogen efficiency; however, Ohio State University research has not shown a yield increase from this practice compared to a single application after green-up. In a split system, the first application should be applied no sooner than green-up. A smaller rate should be applied with the first application since little is needed by the crop at that time and the larger rate applied closer to Feekes GS 6.

In summary, some wheat fields look rough coming out of the winter. Applying nitrogen earlier may slightly increase the number of spring heads but probably not enough for a significant yield increase. The earlier application will increase the potential for nitrogen loss. University recommendation would be to topdress nitrogen when fields are suitable for application after initial green-up to early stem elongation.

Wetter Pattern than Normal will Continue into March…and Possibly April

By: Jim Noel

Not a lot of great news in the short-term. The wet pattern so far this year is likely to persist into March as an active weather pattern from the Pacific Ocean moves across the U.S.

In addition, the temperature gradient is amplified more than normal this late winter into early spring meaning colder north and warmer south. This will help fuel the storms and keep things active.

The outlook for March calls for temperatures near or slightly below normal with precipitation above normal.

The outlook through May calls for near normal temperatures and near to above normal rainfall.

The two week rainfall graphic from the NOAA/NWS/Ohio River Forecast Center calls for 1.5 to 3.0 inches of rain across the state of Ohio. Normal is about 1.5 inches so expect above normal precipitation the next several weeks. The greatest totals the next 2 weeks will be in the southern and western sections of the state. Precipitation will begin to increase starting later this week.

All indications are the last freeze this freeze will be normal or a little later than normal. Hence, expect 2 and 4 inch soil temperatures to lag behind normal at least through April.

On another topic, if you think overall it has been wet, it has. The last 10 years is the wettest on record since 1895 in Ohio. The attached graphic shows the 24-month running average precipitation index for Ohio, provided by the NOAA Midwest Regional Climate Center.  It shows even the drought in 2012 was not enough to turn the index negative for a 24-month period. You have to go back to the 2008/2009 period to see the last time the index was negative. No other time since 1895 has the index been positive for so long. Looking deeper at the data it does show northwest Ohio has seen the index drop briefly negative a few times over the last 10 years while southern areas have been all positive. Bottom line, it has been wet overall for quite a long time now.

Tar Spot – A “New” Corn Disease

Adopted from: CPN-2012 Corn – Tar Spot, Crop Protection Network

Initial symptoms of tar spot are brownish lesions on the leaves. Black, spore-producing spots appear later, making the leaf feel rough or bumpy. (Purdue Botany and Plant Pathology photo/Kiersten Wise)

Tar spot is a foliar disease of corn that commonly occurs throughout Mexico, Central America, South America, and the Caribbean. The disease was identified in the United States for the first time in 2015 in northern Illinois and Indiana. As of 2018, it has been confirmed in Iowa, Michigan, Wisconsin, Ohio, and Florida.  During the 2018 growing season, the prevalence and severity of the disease increased dramatically, and in some areas tar spot caused substantial yield losses.

In the United States, tar spot of corn is caused by the fungus Phyllachora maydis. The fungus produces small (0.2-0.8 inch), round to semi-circular, raised black structures called stromata.  In severe cases, stromata may also be observed on leaf sheaths and husks.  Tar spot severity on ear leaves at growth stage R5 (dent stage) can exceed 50 percent in susceptible hybrids when conditions are favorable for the disease.

Corn at any developmental stage is susceptible to infec­tion by the tar spot fungus when conditions are favor­able. Disease symptoms have been observed as early as the third-leaf (V3) growth stage in the United States. P. maydis overwinters on infested corn residue on the soil surface, which serves as a source of inoculum for the subsequent growing season. It is not known if P. maydis overwinters on or infects any other plant hosts in the United States.

Conditions that Favor Disease   In Latin America, cool temperatures (60-70°F) and high relative humidity (greater than 75 percent) favor tar spot development. In addition, disease incidence increases when there is at least seven hours of free moisture on the leaves due to rain, fog, or high relative humidity. However, it is not currently known what conditions favor the disease in the United States. In both 2015 and 2018, warm weather and periods of persistent rain and high humidity during the growing season likely favored the development and spread of the disease.

Continuous corn cultivation with minimum tillage practices, and high application rates of nitrogen fertilizer are also positively correlated with increased disease in Latin America. Although corn lines have been identi­fied in Latin America that have resistance to tar spot complex, U.S. observations indicate that most hybrids grown in the North Central region are susceptible to P. maydis (although they differ in susceptibility).

Yield Losses and Impact   Preliminary data from the Midwest indicate that severe tar spot outbreaks can reduce yield by more than 30 bushels per acre. Yield losses are a function of reduced ear weight, poor kernel fill, loose kernels, and vivipary (a condition in which the seed germinates while still on the cob). Observations also suggest that stalk rot and lodging are increased when tar spot severity is high. Severe tar spot also reduces forage quality.

Diagnosis  You can diagnose corn tar spot in the field by examining corn leaves for the presence of black, tar-like spots. To date, tar spot has been observed most often during mid-to late grain fill (growth stages R3-R6) and usually on leaves below or near the ear leaf. You can observe stromata in green and senesced tissues. Occasionally, you may also observe necrotic brown tissue surrounding the black structures, which produces a fisheye appear­ance.

Management  Most of what we know about tar spot has originated from Mexico and Central America. However, differences in the environments, fungal populations, hybrid genetics, and cropping systems may influence disease development in different areas. Our understanding of this disease in the United States is limited because of its very recent history.

However, several management practices may help reduce tar spot development and severity.

  1. Manage residue. Tilling fields buries infected residue and encourages it to decompose, which may help reduce the amount of overwintering tar spot inoculum.
  2. Rotate to other crops. This will allow residue to decompose and reduce the primary It is not yet known how many years it may take to sufficiently reduce inoculum.
  3. Avoid highly susceptible hybrids.
  4. Investigate fungicides. Some fungicides may reduce tar spot, however, we have little data about application timing that will provide an effective and economical response.  Efforts are underway to understand the biology and epidemiology of this disease, which may help formulate fungicide application decisions in the future.