CFS Growing Insights 6.12.2019

Weather Update

A long stretch of warm temperatures and low rainfall has allowed for a lot of field operations to progress over the week. 6” soil temperatures have steadily increased above 65o F, helping soil phosphorus become more available, but increasing the speed of nitrification.

Below is table outlining the different planting dates based on a field south of Mankato, and the estimated corn growth stage. The last week’s heat has helped push the crop along, and V5 corn (5-leaf collars present) will be here soon!


 

Comparisons of the 2019 growing season to 2013 seem to be made every day. Several agronomists have shared their experiences from 2013, and offered their thoughts on the year after the 2013 harvest:

  • “The consensus was that most people wished they would have planted their corn late into the spring if they could have gotten it in.”
  • “Modern hybrid genetics provided tremendous ability to adapt and perform at higher yield levels than we anticipated in 2013.”
  • “We are getting better and better at managing in-season for maximum yields. Even though we may struggle in reaching full genetic potential because of a later planting date, we can still reach high yield levels that should be profitable.”

Corn Growth and Development

As corn continues to rapidly grow through vegetative stages, it’s starting to uncover some variability in crop growth. Whether it’s differences in color or growth stage, the above-ground portion of the plant might not tell the whole story of what the corn plant is experiencing, especially with some of the compaction from planting that roots are encountering.



The picture (ABOVE) shows a common trend in many local fields, with 2 plants in close proximity both at the same growth stage, but major differences in height and root growth. As V5 approaches and corn starts the determination process of kernel rows per ear, it’s critical to understand what may be limiting crop growth. Tissue sampling offers insight into a crop’s potential “hidden hunger.”  Plant tissue samples help to understand how well your crop is taking up nutrients given the conditions we’ve had this year.

History shows that a known limiting factor, zinc, could also be a key yield factor this year. The table below outlines the number of tissue samples taken in the CFS territory that have shown responsiveness or deficiency to zinc between V4-V8. The 5-year average shows that 88% of tissue samples show zinc as a potential limiting factor, and 2013 results increased to 91%.  

Zinc plays a critical role in maximizing leaf and vascular growth and root development. A larger, more robust root system allows for increased nutrient uptake and more efficient water use. Zinc is also immobile in the soil and requires the roots to find concentrations of zinc in the soil to be taken up. Historical data shows that zinc deficiencies start around the V4-V5 growth stage.

Prior to V4-V5, the tissue samples often show zinc at adequate levels as the first 4 true leaves are already formed in the seed embryo, so applying zinc in starter fertilizer or using Croplan seed with a zinc seed treat often fulfills the early zinc needs. Contact your CFS representative if you’d like to take tissue samples on your fields.

Early Season Corn Management Decisions

If you are deficient in zinc, you can consider applying a foliar micronutrient. At CFS, we rely on two different products, Max-In Ultra ZMB, and Max-In Zinc. Both of these products contain CornSorb® technology to greatly increase the movement of micronutrients through the leaf cuticle and less zinc subject to loss through evaporation and other environmental forces. Max-In Ultra ZMB is a foliar micronutrient and combines zinc, manganese, and boron into one product. Max-In Zinc is a zinc-only foliar product option.

  • WinField United AnswerPlot data shows that 1 quart/acre of Max-In Zinc applied at V5 is responsive 55.6% of the time, and equivalent to 6 bpa increase in yield.
It’s critical to maintain zinc sufficiency, as tissue sample results confirm its role in nutrient uptake efficiency and leads to increased levels of key nutrients. The table below outlines data from MN that shows when zinc is sufficient in the plant, more often nutrients like N, P, K, and S have adequate/excessive levels. However, when zinc is deficient, the data tells us it’s much harder to keep those nutrients at required levels.

Another foliar application consideration to enhance root growth is a plant growth regulator. PGRs are hormones that regulate the growth and development of plants. There are five basic classes of plant growth regulators. Each of these has a different effect on plants, ranging from stimulating plant growth to dictating seed germination. Plant responses may vary depending on PGR type, rate and application timing. Ascend® SL plant growth regulator by WinField United contains three EPA-registered active ingredients to promote cell division, leaf expansion, and stimulate root formation.

Two other biostimulants CFS is using on a trial basis are focused on triggering reactions in a plant ranging from stress alleviation to yield enhancement.

  • Voyagro™ biostimulant fertilizer works well on highly managed corn acres where there is moisture stress prior to application or where moisture stress is anticipated. A foliar application from V4 to V8 in corn is recommended when fertility is adequate and available moisture is low. Answer Plot® research indicates that in areas that had less than 2 inches of rain immediately following a Voyagro application, there was a positive return on investment 93 percent of the time. The average yield response of a Voyagro application under these conditions was 3.8 bushels per acre.       
  • Toggle® is another biostimulant fertilizer that is derived from seaweed and enhances root growth, promotes the synthesis of antioxidants and improves photosynthesis by increasing chlorophyll production in plants. Toggle works best on acres where stress is known to occur, such as areas where drought and high temperatures. A foliar application around V5 and again at flowering can offer stress protection in corn.
A V5 application of fungicide may also be an important agronomic consideration this year. Normally at tassel, we would use the individual hybrid response to fungicide scores to understand the likelihood of a positive response to fungicide, but V5 application should be made based on plant observations. If you notice brown discoloration starting on the corn’s mesocotyl or crown region, a V5 fungicide application can be used to manage potential seedling diseases.

 
 

Dicamba Soybean Decisions

With the dicamba application deadline approaching, several questions are being raised on DRA’s and what needs to be in the tank with Xtend-type products. In general, DRAs help reduce off-target applications by making spray droplets larger. Larger droplets also means fewer droplets, so follow guidelines for spray volume to ensure good coverage. Most dicamba tank mixes should be applied at 15 gallons per acre, but be sure to check the label and consult your agronomist with any questions before making an application.

  • Not All DRA's Are The Same: Even among approved DRAs, you will find performance differences. While all DRAs start out doing the job of increasing spray droplet size, some DRAs may not maintain that performance over time as they are subjected to recirculation within the spray tank. This is because shear forces are imposed on a spray solution moving through a spray system can cause DRAs to act differently. Some DRAs are more susceptible to shear forces. The label often dictates what tank-mix partners you’ll need to use, especially in the case of low-volatility dicamba.
  • Not All Approved Products Are Effective: Just because a product is approved for application doesn’t mean it’s the most effective and economical choice.
CFS Dicamba Recommendation:
  • CFS’ relies on OnTarget™ as a drift and deposition aid for new dicamba herbicide technologies, as it was specifically designed for ultra and extra coarse nozzles, for use with the new dicamba herbicide chemistries.
  • CFS also recommends adding InterLock® adjuvant to the dicamba tank mix with glyphosate and OnTarget® adjuvant, as data shows that there is a 60 percent reduction in the number of fine spray particles. This adjuvant system has been formulated to reduce driftable fines with dicamba and improves the efficacy of dicamba herbicides by enhancing droplet spreading and canopy penetration.