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Soybean Nutrient Profile: Magnesium

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Click on the link below to see this week’s featured nutrient, magnesium.  This nutrient profile is a part of a weekly series dedicated to the function of the 16 essential nutrients in soybean.  After excluding carbon, hydrogen, and oxygen, we are left with a thirteen part series in which we will explore how nutrients are used throughout the plant as well as how to identify deficiency symptoms and develop nutrient management decisions. 

Soybean Nutrient Profile: Magnesium

Check back weekly to find the newest soybean nutrient profile.  Contact your local extension agent with any questions you may have.

Bt Cotton Situation

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Over the past two weeks Louisiana has experienced a slow but steady corn earworm moth flight in cotton, which  has lead to a slow but steady egg lay.  Fortunately, this type of worm activity has not put the selection pressure on our  Bt technology we experienced last year.  This has also drastically reduced our insecticide oversprays as well. As of this week, Louisiana has more cotton that has not been sprayed for bollworms than cotton that has been sprayed.

Based on small plot research and Bt sentinel plot work from the Louisiana cotton growing areas, all of the technologies are performing better this year than last year. Results from our Bt technology tests indicate Bollgard 2 varieties are experiencing an average of 2.5% fruit injury, Bollgard 3 varieties are experiencing an average 3.0% fruit injury, both Widestrike and Widestrike 3 varieties are experiencing 4.0% fruit injury. TwinLink and TwinLink Plus are experiencing 5.0% and 3.0% fruit injury respectively.  These numbers are also reflected in reports I am receiving from the field with only a few instances of rescue sprays needed for bollworm escapes in Bt cotton.  Remember, the fruit injury threshold for Louisiana cotton is 6% with the presence of live worms.

Overall, this is good news for Louisiana cotton producers and signals that our Bt technology may still have some life left in it. Beware, this situation can change quickly and bollworm escapes can and will happen in all technologies. Scouting is key and under light pressure our Bt technology is appearing to hold but if pressure intensifies a rescue spray may be warranted.   Keep in mind that bollworms are cryptic feeders, and worms that have established in squares and bolls may not be controlled by insecticides including the diamides. If you have any questions or comments, please feel free to contact your county agent or me.

Top leaf death in irrigated corn at the Dean Leaf Research and Extension Center, Alexandria, Louisiana, three quarter milk stage. July 17, 2018. Primarily due to high temperatures.

Top Leaf Death or Dieback in Corn

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Please see this post on top death in field corn by Dr. Dan Fromme: LSU AgCenter Corn, Cotton and Grain Sorghum Specialist.

We all know that as a corn crop progresses toward physiological maturity, the leaves naturally begin to senesce (die).  The timing and pattern of leaf senescence are genetically regulated but are also influenced by environmental triggers, including sever photosynthetic stress.  This year, where much of the grain fill period has experienced severe drought and/or heat stress, the onset of leaf senescence can occur earlier than expected prior to kernel black layer.  This means leaves begin to die sooner than expected, and the leaf pattern of leaf senescence sometimes changes.

Top leaf death in irrigated corn at the Dean Leaf Research and Extension Center, Alexandria, Louisiana, three quarter milk stage. July 17, 2018.  Primarily due to high temperatures.
Top leaf death in irrigated corn at the Dean Leaf Research and Extension Center, Alexandria, Louisiana, three quarter milk stage. July 17, 2018. Primarily due to high temperatures.

Most often the leaf pattern of senescence that we see in most years is one where leaf death begins at the bottom of the plant and slowly moves up toward the upper leaves.  However this year, due the late season stress, leaf senescence is progressing from both the bottom and the top of the plant with green leaves remaining in the middle of the plant for some time until complete leaf senescence occurs.  Also, these fields appear to cause an unusual golden glow in the upper canopy against the morning or evening sun.  The impact or effect on grain yield will depend on how early in the grain filling period the death of the upper leaves occurs.  This year, we might see some test weights on the low side.

Citations:  Nielson, R.L., Top leaf death or dieback in corn .2011.  Purdue University Department of Agronomy.

Soybean Nutrient Profile: Calcium

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Click on the link below to see this week’s featured nutrient, calcium.  This nutrient profile is a part of a weekly series dedicated to the function of the 16 essential nutrients in soybean.  After excluding carbon, hydrogen, and oxygen, we are left with a thirteen part series in which we will explore how nutrients are used throughout the plant as well as how to identify deficiency symptoms and develop nutrient management decisions. 

Soybean Nutrient Profile: Calcium

Check back weekly to find the newest soybean nutrient profile.  Contact your local extension agent with any questions you may have.

Soybean Nutrient Profile: Sulfur

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Click on the link below to see this week’s featured nutrient, sulfur.  This nutrient profile is a part of a weekly series dedicated to the function of the 16 essential nutrients in soybean.  After excluding carbon, hydrogen, and oxygen, we are left with a thirteen part series in which we will explore how nutrients are used throughout the plant as well as how to identify deficiency symptoms and develop nutrient management decisions.  

Soybean Nutrient Profile: Sulfur

Check back weekly to find the newest soybean nutrient profile.  Contact your local extension agent with any questions you may have. 

Soybean Nutrient Profile: Nitrogen

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Click on the link below to see this week’s featured nutrient, nitrogen.  This nutrient profile is a part of a weekly series dedicated to the function of the 16 essential nutrients in soybean.  After excluding carbon, hydrogen, and oxygen, we are left with a thirteen part series in which we will explore how nutrients are used throughout the plant as well as how to identify deficiency symptoms and develop nutrient management decisions.  

Soybean Nutrient Profile: Nitrogen

Check back weekly to find the newest soybean nutrient profile.  Contact your local extension agent with any questions you may have. 

Soybean Nutrient Profile: Phosphorus

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We are already on our third installation of the soybean nutrient profile series.  Click on the link below to see this week’s featured nutrient, phosphorus.  This nutrient profile is a part of a weekly series dedicated to the function of the 16 essential nutrients in soybean.  After excluding carbon, hydrogen, and oxygen, we are left with a thirteen part series in which we will explore how nutrients are used throughout the plant as well as how to identify deficiency symptoms and develop nutrient management decisions.   

Soybean Nutrient Profile: Phosphorus

Check back weekly to find the newest soybean nutrient profile.  You can also find the links to the two previous nutrient profiles below.  Contact your local extension agent with any questions you may have. 

Soybean Nutrient Profile: Potassium Soybean Nutrient Profile: Manganese

Soybean Nutrient Profile: Potassium

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Click the link below to find the second installation of the soybean nutrient profile series featuring potassium.  This nutrient profile is a part of a weekly series dedicated to the function of the 16 essential nutrients in soybean.  After excluding carbon, hydrogen, and oxygen, we are left with a thirteen part series in which we will explore how nutrients are used throughout the plant as well as how to identify deficiency symptoms and develop nutrient management decisions.   

Soybean Nutrient Profile: Potassium

Check back weekly to find the newest soybean nutrient profile.  Contact your local extension agent with any questions you may have.

Soybean Nutrient Profile: Manganese

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Click the link below to find the first soybean nutrient profile on manganese.  This nutrient profile is the first in what will be a weekly series dedicated to the function of the 16 essential nutrients in soybean.  After excluding carbon, hydrogen, and oxygen, we are left with a 13 part series in which we will explore how nutrients are used throughout the plant as well as how to identify deficiency symptoms and develop nutrient management decisions.   

Soybean Nutrient Profile: Manganese

Check back weekly to find the newest soybean nutrient profile.  Contact your local extension agent with any questions you may have.

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