Tar Spot Update

Summary

Last week Dr. Damon Smith, with the University of Wisconsin, gave an update on Tar Spot and I thought his findings were extremely valuable and the most relevant information I have seen to date.

Tiny black spots against a brown lesion are a symptom of the tar spot complex in corn.

Keynotes

- Tar Spot can overwinter and has been in WI for 3 years. It is also in Eastern IA. The first two years Tar Spot was in Wisconsin, it did not infect plants until late August. This year it arrived Mid-June.

- There hasn’t been a single plant found with the Monographella version (the really bad type only found in Mexico so far)

- Tar spot is causing yield loss in the absence of any another disease, such as grey leaf spot.

- Hybrid tolerance incredibly variable. Some can handle it, some take a huge yield hit with this disease.

- Early hybrids take less of a hit. Research is showing that at 10% of the leaf area covered with Tar Spot yields are reduced by 8 bu/ac. Longer maturity (103-113 day) hybrids lost 15 bu/ac when 10% of the leaf area was infected.

- University plant pathologist are creating a phone app (the TarCaster) that will hopefully be able to predict the arrival of the disease based on the weather. They already have a similar program for predicting white mold. They expect that to be out for testing this upcoming year.

- Yield losses appear to be dependent on when the plants become infected with Tar Spot. For example, this year infection started between V8 and VT is some regions but in previous years infection did not start until after milk stage.  There is barely a hit on yield if it arrives during the Milk stage.

-Fungicide does help if timed properly, and at least Headline Amp and Delaro are labeled for Tar Spot.

-University plant pathologist plan on releasing a fungicide update around the end of December to show when the optimum time will be for applying fungicides to control/suppress Tar Spot.

Registration of Dicamba for Use on Dicamba-Tolerant Crops

In 2018, EPA extended the registration for two years for over-the-top use (i.e. use on growing plants) of Dicamba to control weeds in fields for cotton and soybean plants genetically engineered to resist Dicamba. This decision was informed by extensive collaboration between EPA, the pesticide manufacturers, farmers, state regulators, and other stakeholders. The registration includes label updates that add protective measures to further minimize the potential for off-site damage.  The registration will automatically expire on December 20, 2020, unless EPA further extends the registration. States affected include Iowa, Illinois, Minnesota, and Wisconsin.

Read the full article at epa.gov.

What are Liquid Suspension Fertilizers

And Should I Consider Using Them On My Farm?

Summary

  • Liquid fertilizers offer some unique advantages compared to dry granular fertilizers:
    • Accurate nutrient application distribution
    • Can be tank mixed with many pesticides
    • Macro and micro nutrients can be evenly blended
    • Can be easily surface or subsurface banded
  • Liquid suspension fertilizers offer the same unique advantages and are cost competitive with dry granular fertilizers.
  • A recent summary of 39 science-based studies showed that banding fertilizer reduced phosphorus fertilizer fixation in the soil, caused roots to concentrate in nutrient rich fertilizer bands, and resulted in increased nutrient uptake and 4.5% higher corn yields.
  • Local on-farm research shows that surface banding liquid suspension fertilizers on 15" centers increases corn yields by 4.2 bu/ac and profitability by 16.7 $/ac compared to broadcasting equivalent rates of dry granular fertilizer.

Liquid Fertilizers – Some Unique Advantages

Liquid fertilizers offer unique advantages over dry granular fertilizers. Liquid fertilizers can be applied extremely accurately, can be tank-mixed with many different pesticides, and micro nutrients can be evenly blended in liquid solutions. These factors result in uniform nutrient application for both macro and micro nutrients, and increased profitability due to higher crop yields and fewer trips across a field when compared to dry granular fertilizers.

Liquid fertilizers offer unique advantages over dry granular fertilizers.

Graphic of two corn kernels.

Liquid Suspension Fertilizers – Unique Advantages at Affordable Costs

Liquid suspension fertilizers provide the same agronomic and economic advantages as clear liquids (starter fertilizer, foliar sprays, those used in drip tape or over the top irrigation systems), but are more reasonably priced than clear liquids.

How can this be?

FIRST: the phosphoric acid used to make the phosphorus fertilizer source in liquid suspensions takes fewer manufacturing/processing steps than the phosphoric acid used to make starter fertilizer-grade clear liquids.

SECOND: in liquid suspensions, a small amount of clay is used to keep fertilizers suspended in a liquid solution. This is particularly important for the potassium source used to make liquid suspension fertilizers.

For example, without the added clay, only about 1 lb of potassium chloride could be dissolved in 1 gallon of water, but with the addition of a small amount of clay, that same 1 gallon of water can hold about 3 lbs of potassium chloride. Liquid suspensions are higher analysis fertilizers (higher % plant nutrients per/gallon material), which reduces transportation costs. When lower transportation cost are paired with more cost-effective raw materials, liquid suspensions can be priced lower than clear liquids, and are cost-competitive with dry granular phosphorus and potassium fertilizers.

Three-panel graphic of corn plant spreading roots into fertilized areas of the soil
Figure 1
Fertilizer Source N-P-K-S-ZN-B Rate lb/ac Yield bu/ac Fertilizer Cost $/ac Net Return $/ac
Liquid Dribble Band 21-50-75-15-0.5-0.2 231.2 47.1 +16.7 $/ac Liquic
Dry Broadcast 227 44.8 Dribble Band

Table 1

Banding Liquid Suspensions for Increased Fertilizer Nutrient Uptake and Crop Yields

Bar graph showing 3% increase in soybeans and 12% more in corn.
Figure 2. Nutrient uptake changes from banding vs broadcasting equivalent rates of ammoniated phosphorus fertilizers. Adapted from Nkebiwe, et al., 2016.

Besides being cost-effective, liquid suspensions are extremely easy to surface or subsurface band.

Banding nutrients achieves two goals: reduced phosphorus fertilizer fixation with Ca2+, Al3+, and Fe3+, and roots become highly concentrated in nutrient-rich fertilizer bands (figure 1). As a result of reduced phosphorous fertilizer fixation (tied up in non-plant-available forms) and increased root activity in nutrient-rich fertilizer bands, the amount of applied fertilizer that is taken up by both corn and soybean crops is increased. In fact, a group of crop scientist recently organized 39 science-based studies with the objective of comparing the effects of banding vs broadcasting fertilizer phosphorus on nutrient uptake and crop yields (Nkebiwe et al. 2016). Averaged over 112 comparisons of banded vs broadcasted phosphorus fertilizer sources, they found that banding phosphorus fertilizer increased nutrient uptake by 12% (figure 2) and corn yields by 4.5% (9 bu/ac or $31/ac at 200 bu/ac yield level) compared to broadcasting the phosphorus fertilizer sources.

Fertilizer Applications—Advantages and Disadvantages

Graphic of a corn plant subjected to broadcast fertilizer

Dry Broadcasting

Advantages

  • Many acres can be covered rapidly
  • Low application costs

Disadvantages

  • Application uniformity is poor and can result in reduced crop yields
  • Broadcasting results in fertilizer fixation in the soil and lower crop nutrient uptake when compared to banding fertilizer
  • Blended dry fertilizers sift or segregate during transportation and handling which can lead to lower or higher fertilizer applications rates than intended
Graphic of a corn plant subjected to subsoild band-applied fertilizer

Subsurface Banding

Advantages

  • Application uniformity is very consistent
  • Replenishes subsoil plant nutrients
  • Banding reduces fertilizer fixation in the soil, increases root activity in nutrient rich bands, and leads to higher nutrient uptake and often higher grain yields
  • During dry weather, subsurface placed nutrients remain more plant-available than fertilizer nutrients placed on the soil surface
  • Eliminates the chance for fertilizer runoff during high intensity rainfall events

Disadvantages

  • 3 to 5 times slower than broadcasting or dribble banding fertilizer nutrients
  • Slower application increases labor costs
  • Initial investment in high horsepower tractors and subsurface placement implements can be high
  • Yield increases when compared to broadcasting or dribble banding fertilizer may not always be high enough to cover added labor and equipment costs
Graphic of a corn plant subjected to dribble band-applied fertilizer

Dribble Banding

Advantages

  • Many acres can be covered rapidly
  • Application uniformity is consistent for each plant
  • Banding reduces fertilizer fixation in the soil, increases root activity in nutrient rich bands, and leads to higher nutrient uptake and often higher grain yields
  • Low application costs

Disadvantages

  • Floaters equipped with high capacity pumps and oversized hoses are needed to apply liquid suspension fertilizers

Liqui-Grow's Local On-farm Research – 2016 & 2017 Results

For the last two crop seasons (2016 & 2017), we have partnered locally with growers to compare what effects broadcasting dry granular fertilizers vs surface dribble banding liquid suspensions fertilizers has had on corn yields. These studies were on-farm strip trials set up as valid experiments with randomized treatments and multiple replications. The dry fertilizers and liquid suspension fertilizers were applied at the same plant nutrient rates per acre. These trials were located in Traer Iowa, Morning Sun Iowa, Washington Iowa, and Roseville Illinois.

In 74% of the side-by-side comparisons, surface-banded liquid suspension fertilizers produced more corn grain than equivalent rates of dry broadcasted granular fertilizers.

We applied the fertilizer, and the farmer cooperator harvested the plots with their commercial combines.

In 74% of the side-by-side comparisons, surface-banded liquid suspension fertilizers produced more corn grain than equivalent rates of dry broadcasted granular fertilizers (figure 3). Moreover, in 68% of those side-by-side comparisons, net returns were higher for the liquid suspension fertilizers (figure 4). Overall we found that yields were increased by 2% (4.2 (bu/ac) and profit per acre was increased by $16.7/ac from banding vs broadcasting fertilizer nutrients (table 1). Our findings are similar to those recently summarized by Nkebiwe et al. 2016, and are yet another example of what effects banding has on fertilizer nutrient availability, crop nutrient uptake, and grain yields.

Banded liquid suspension yield increased graph
Figure 3. Yield increase from using banded liquid suspension fertlizers vs brodcasted dry granular fertlizers in 16 side-by-side comparisons.
Banded liquid suspension net return graph
Figure 4. Net return from using banded liquid suspension fertlizers vs brodcasted dry granular fertlizers in 16 side-by-side comparisons.

Summary

Liquid suspension fertilizers offer unique agronomic and financial advantages. These advantages include accurate fertilizer placement and distribution, macro and micro nutrients that stay blended in solution, and a product that is exceptionally easy to surface or subsurface band apply. These factors together result in reduced fertilizer fixation, increased nutrient availability, and often statistically higher crop yields and net returns than broadcasted granular fertilizers.

References

Nkebiwe, P.M., M. Weinmann, A. Bar-Tal, and T. Müller. 2016. Fertilizer placement to improve crop nutrient acquisition and yield: A review and meta-analysis.
Field Crops Res. 196:389–401.

Doctor in the Field

There’s a new doctor in the field. And by “field” we mean the corn field.

For the last two and a half years, Liqui-Grow’s Lead Agronomist, Jake Vossenkemper, has been working on his dissertation in Crop Sciences at the University of Illinois. Jake has been a PhD student since the spring of 2012.

On Monday, March 27, 2017, Jake gave his final defense for his dissertation on crop management factors that interact with soybean planting dates. Through his research, he found that soybean-planting date, seed treatments, and cultivar maturity selection are all-important management decision to consider for producing maximum soybean yields. He also found that warm fall temperatures can increase soybean yields by 3 to 6 bu/ac compared to normal fall temperatures. In addition, he found that when temperatures remain warm in the fall, full-maturity soybean varieties often out yield mid-maturity soybean varieties. These finding add to our understanding of what factors are important to maximizing soybean yields, and may help soybean breeders breed for resistance to cold late-season air temperatures.

We are all very proud and excited for Jake’s most recent accomplishment! He will graduate on May 13, 2017.​