Corn of Many Colors

Source: Alexander Lindsey, Steve Culman, Peter Thomison, OSU Extension

As corn is emerging and beginning to grow, we are again seeing many colors present. In any given field, corn can appear dark green in sections, while other sections are yellow and occasionally purple. Yellowing (due to low nitrogen or sulfur uptake and/or limited chlorophyll synthesis) or purpling (reduced root development and/or increased anthocyanin production) of corn plants at this stage of development generally has little or no effect on later crop performance or yield potential. If it’s induced by environmental conditions, the yellow or purple appearance should change to a healthy green after a few sunny days with temperatures above 70 degrees F (and as soils dry). If plants remain yellow then closer inspection and assessment is needed to determine if the yellowing is caused by nutrient deficiency or some other factor. Cooler wet conditions often increase the appearance of these different colors. Some hybrids are more likely to increase anthocyanin (purple pigment) content when plants are cool.

 

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Ponding and Saturated Soils: Results of Recent Ohio Corn Research

Source: Alexander Lindsey, Peter Thomison

Persistent rains during May and early June have resulted in ponding and saturated soils in many Ohio corn fields and led to questions concerning what impact these conditions will have on corn performance.

The extent to which ponding injures corn is determined by several factors including (1) plant stage of development when ponding occurs, (2) duration of ponding and (3) air/soil temperatures. Corn is affected most by flooding at the early stages of growth (see https://agcrops.osu.edu/newsletter/corn-newsletter/2018-15/young-corn-wet-feet-what-can-we-expect). Under certain conditions, saturated soils can result in yield losses. Saturated soil conditions can result in losses of nitrogen through denitrification and leaching. Additionally, root uptake of nutrients may be seriously reduced even if plants are not killed outright by the oxygen deficiency and the carbon dioxide toxicity that result from saturated soil conditions. Root growth and plant respiration slow down while root permeability to water and nutrient uptake decreases. Impaired nutrient uptake may result in deficiencies of nitrogen and other nutrients during the grain filling stage. Once the corn has reached the late vegetative stages, saturated soil conditions will usually not cause significant damage. Moreover, moderate temperatures should help minimize the level of stress.

Although standing water is evident in fields with compacted areas, ponding has usually been of limited duration (i.e. the water has drained off quickly within a few hours). In Ohio in 2017-2018, we observed a 10% yield loss when corn was flooded at V4 for 2 days and received 120 lbs N pre-plant + 60 lbs N sidedress (applied post-flood). When flooded for 4 or 6 days, yield loss increased to 15 and 33%, respectively, when receiving the same N regime. If the additional 60 lbs N was not side-dressed post-flood, yield losses increased to 30, 50, or 57% for 2, 4, or 6 days of flooding, respectively. According to Dr. Emerson Nafziger at the University of Illinois (http://bulletin.ipm.illinois.edu/?p=1240) “…At the time the crop reaches stage V13 (about head-high), it still has to take up 110 to 120 lb of N, and in years when June is wet, a common question is whether or not the crop might run out of nitrogen, leaving the crop short. While the need for 20 or more lb of N per week would seem to raise the possibility of a shortage, the production of plant-available N from soil organic matter through the process of mineralization is also at its maximum rate in mid-season. For a crop with a good root system growing in a soil with 3 percent organic matter, mineralization at mid-season likely provides at least half the N needed by the crop on a daily basis. This means that normal amounts of fertilizer N, even if there has been some loss, should be adequate to supply the crop.”

If the rain has been paired with strong winds, root lodging may occur. Yield losses of 4, 10, and 15-25% have been reported for 100% root lodging at V10, V13-15, and V17-R1, respectively in Wisconsin. Results from Ohio in 2018 suggest these values may be greater than previously reported (8, 37, and 58% yield loss when root-lodged at V10, V13-14, and VT-R1, respectively).  This trial will be repeated in 2019 in Ohio.

Disease problems that become greater risks due to ponding and cool temperatures include Pythium, corn smut, and crazy top. Fungicide seed treatments will help reduce stand loss, but the duration of protection is limited to about two weeks. The fungus that causes crazy top depends on saturated soil conditions to infect corn seedlings. There is limited hybrid resistance to these diseases and predicting damage from corn smut and crazy top is difficult until later in the growing season. However, the economic impact of these latter two diseases is usually negligible.

Spring Herbicide Applications on Winter Wheat – Part 2 Labeled Herbicides

Source: Purdue University (Edited)

If weed infestations are severe enough to require a herbicide application, the use of liquid nitrogen fertilizer solution as a carrier is a popular option for applying herbicides and topdressing the wheat crop in a single pass over the field.  Caution should be taken when using a liquid fertilizer as a herbicide carrier as moderate to severe crop injury can result, especially in saturated conditions.  Many post applied wheat herbicide labels allow for liquid nitrogen carriers, but require different rates and types of surfactants than if the herbicide was applied with water as the carrier.  Table 1 includes precautions to be taken when applying wheat herbicides using liquid fertilizer as a carrier; further details and directions can be acquired from the herbicide label.

Another consideration growers should take into account when planning early spring herbicide applications is the plant back restrictions to double crop soybeans.  A large percentage of the herbicides listed in Table 1, especially those with activity on Ryegrass and Brome, have soybean plant back restrictions greater than the typical three month time period between spring applications and double crop soybean planting.  The soybean plant back restrictions greatly reduce the number of options available to wheat producers who double crop soybeans after wheat.  Refer to Table 1 for more specific plant back timing restrictions.Click Here For Complete Table

Evaluation of Adapt-N and FieldView Corn N Fertilizer Tools in Ohio

Source:  Dr. Steve Culman, OSU Extension

NutrientStar, an independent evaluator of nutrient management tools, has just released results testing the performance of two web-based tools that provide customized corn nitrogen fertilizer rates: Adapt-N and Climate FieldView. Both tools are available for farmers in Ohio to use for a fee.

NutrientStar conducted 61 trials over 3 years evaluating Adapt-N and 21 trials over 2 years evaluating FieldView in Ohio. A summary of findings is presented below.

Compared to ‘farmer normal practice’ using the tools produced a range of yield differences across trials and years in Ohio. Some trials yielded more grain using the tools (positive values) and some yielded less grain (negative values). When all trials within a year were averaged, both tools resulted in lower yields compared to farmer normal practices (8 – 41 bushels/acre less). Depending on the year, farmers lost on average between $6 – $131/ acre on their return to N fertilizer.

The results varied by state, with some states benefiting from the tools and other states not benefiting from the use of the tools. Unfortunately, these tools have not performed well in Ohio to date.

An alternative approach to deciding corn N fertilizer rates is to use the economic model that Ohio State University Extension endorses. This simple calculator is based on maximizing farmer profitability. It uses 3 inputs to determine at what point will additional N fertilizer not pay for itself with more yield. This free, publicly-available tool was recently updated with extensive on-farm trials in Ohio and can be found here: http://go.osu.edu/corn-n-rate

More information on Adapt-N evaluation: http://nutrientstar.org/tool-finder/adapt-n/

More information on FieldView evaluation: http://nutrientstar.org/tool-finder/climate-fieldview/