IPM

Field Observations Thru September 15

Corn

Growth & Development

Most of the corn that I have seen this week is in either the late R4 (Dough) or the R5 (Dent) growth stage.  A few fields are approaching the final growth stage R6.

R6 – Physiological Maturity

  • Occurs approximately 66‐70 days after silking.
  • R6 is reached  after the milk line disappears and the starch has reached the base of the kernel.
  • Kernels have reached maximum dry weight.
  • Kernel moisture is  about 35% at physiological maturity.
  • Black layer occurs after physiological maturity and  serves as a visual verification that the plant is mature. Black layer typically occurs at 30%  moisture but varies by hybrid and environment.
  • Husks and many of the leaves are no longer green, but the stalk may be green.
  • Only external stress can reduce yield now,  such as plant lodging or insect feeding.

Scouting

At this growth stage look for:

  • Ear rots.
  • Stalk rots.
  • Anthracnose top dieback.
  • Stalk lodging.
  • Abnormal ear fill which identifies periods of stress.
  • Weed escapes (especially Palmer and Waterhemp).

This is also a good time to get an accurate yield estimate.

Soybeans

Growth & Development

Soybeans are continuing to mature.  Last week I highlighted the R7 growth stage, the last growth stage is R8 full maturity.

R8 – Full Maturity

  • 95% of pods reached mature color
  • Mature pod color does not necessarily indicate that beans are ready to harvest
  • 35% grain moisture in freshly matured pod
  • 15% within another 5 to 10 days
  • Below-optimum plant stands cause more branching, low pod heights & can delay maturity
  • Above-optimum plant stands increase lodging.

Scouting

At this growth stage look for:

  • Green stem syndrome.
  • Lodging
  • Sprouting seeds
  • Pod shattering
  • Weed escapes (especially Palmer and Waterhemp).

This is also a good time to check soybean yield potential.

County Rainfall Update

Weed management practices: Fall scouting and equipment cleaning

 

Weed management encompasses more than controlling actively growing weeds. You can be proactive to help prevent the future spread of weeds. Two different management practices are discussed below: fall scouting for weed escapes and equipment cleaning.

Fall scouting can help plan for future control

Weeds that escape control by in-season management practices can cause several problems, including the possibility of reduced harvest efficiency and crop yield. Even if these factors do not justify an herbicide application, it is important to consider the future costs of seeds produced by those escapes – particularly if those escaped weeds produce a lot of seed and/or are herbicide resistant.

Just a few escapes of species such as waterhemp or Palmer amaranth can have a big impact. For example, research conducted in Georgia showed that one female plant in five acres added about two million seeds per acre to the soil. Those seeds can have impacts for many years. It took six years of total palmer amaranth control to deplete the seedbank by 98% in Texas. In some situations, scouting during the weeks leading up to harvest may provide an opportunity to remove these plants by hand to reduce the number of seeds in the soil.

Scouting for weeds at harvest, even if you simply make notes from the combine, is important for planning future weed management.

When scouting, make notes about

  • which weed species are present,
  • where weed escapes are present, and
  • any changes in the size or location of areas with weed escapes.

Some observations might be the result of soil or environmental conditions, while others might suggest problems with the herbicide selection or application equipment. However, some of these escapes might indicate the presence of herbicide-resistant weeds in your field – especially if the same herbicide program has been used for a number of years. Two examples of observations that might indicate herbicide resistance are 1) a growing patch of a particular species, or 2) herbicide failure on a few plants of a single species that is normally controlled.

Stop spreading weed seed during harvest activities

Weeds can spread in a variety of ways, including on farm equipment. As you move harvest equipment from field to field, be aware of the potential to spread weed seed – especially if uncontrolled weeds are known or suspected to be herbicide resistant. Some steps to prevent spreading weeds when moving harvest equipment from one field to another are listed below.

  • Clean new-to-you equipment so someone else’s weeds are not introduced to your farm.
  • If possible, harvest fields with excellent weed control first.
  • Harvest fields where weeds are or might be herbicide resistant last.
  • Harvest around areas with extremely dense weed populations.
  • Slow the combine to ‘self-clean’ between fields.
    • Run the unloading auger empty for a minute or two.
    • Open grain elevator doors, rock trap, and unloading auger sump then run the separator with maximum airflow and suction.
  • Use an air compressor to remove material remaining in the rock trap and grain auger and from the head, feeder house, straw spreader.
  • Take half a day to do a deeper clean when possible.
  • Check fall-tillage equipment between fields.

It is very difficult to completely remove weed seeds from harvest equipment. However, taking a few minutes to reduce the number of seeds on your harvest equipment may save time and money in the future.

FSR Weed ID Quiz

Test your weed identification skills at this year’s Farm Science Review.

  • The quiz is 40 multiple choice questions over 25 different weed specimens.
  • The highest score in each participant category will receive a prize at the conclusion of the 2023 FSR.
  • Categories: Adult, High School/FFA, Youth, Extension Educator.
  • Weed ID Quiz tables will be located at the Ag Crops Tent Plot Area Tuesday thru Thursday.

Field Observations Thru September 8

Corn

Growth & Development

Most of the corn that I have seen this week is in either the R4 (Dough) or the R5 growth stage.

R5 – Dent

  • The second to last stage of corn development.
  • R5 (dent) occurs approximately 31‐33 days after silking.
  • Kernels are dented in at the top with the “milk line” separating the liquid and
    solid (starch) portions.
  • Within R5, kernels are often staged according to the progression of the milk line; i.e. ¼, ½, and ¾.
  • At the beginning of R5, kernels have 60% moisture content.
  • Stresses will reduce kernel weight at this time.

Scouting

I have heard a wide range for projected corn yields this year.  The Yield Component Method is the most widely used procedure for estimating corn yield.  While  you are out checking potential corn yields, also keep an eye out for:

  • Ear rots.
  • Stalk rots.
  • Anthracnose top dieback.
  • Stalk lodging.
  • Abnormal ear fill which identifies periods of stress.
  • Weed escapes (especially palmer & waterhemp).

Soybeans

Growth & Development

Soybeans are continuing to mature.  Last week I highlighted the R6 growth stage  the next stage is R7 the last growth stage prior to maturity.

R7 – Begining Maturity

  • One mature-colored pod anywhere on the main stem.
  • Yellow pods are moving toward maturity.
  • Tan, brown or tawny pods (depending on variety) signal physiological maturity.
  • Seeds at the R7 growth stage are at approximately 60% moisture.

Scouting

  • Foliar diseases – Sudden Death Syndrome, White Mold, and Frogeye Leaf Spot.
  • Insect feeding – Grasshoppers.
  • Weed escapes (especially Palmer and Waterhemp).

Estimating soybean yields

It is much more difficult to accurately predict soybean yield.  The process to estimate soybean yields can be found here.

County Rainfall Update

Field Observations Thru September 1

They are here!  Palmer Amaranth and Waterhemp are prevalent in MANY Knox County fields.  One female plant can produce 1,000,000 seeds.  If you find Palmer Amaranth or Waterhemp you should do whatever you can to prevent these devastating weeds from going to seed, including removing the entire plant from the field.

Continue to remain vigilant!  

Click here for tips on identifying pigweed, palmer and waterhemp.

Corn

Growth & Development

Most of the corn that I have seen this week is in either the R3 (Milk) or the R4 (Dough) growth stage.  Some of our early maturing hybrids have reached the R5 dent stage.

Scouting

Disease pressure throughout the county continues to be very low. Continue to scout for:

  • Foliar diseases – Gray Leafspot, Tar Spot, Northern Corn Leaf Blight.
  • Weed escapes (especially Palmer and Waterhemp).

Soybeans

Growth & Development

Most of the corn that I have seen this week is in the R6 (Full Seed) growth stage.  Some of the early maturity beans are entering the R7 (Beginning Maturity) stage soon.

Scouting

Disease pressure throughout the county continues to be very low.  As you continue to scout your bean fields, look for:

  • Foliar diseases – Sudden Death Syndrome, White Mold, and Frogeye Leaf Spot.
  • Insect feeding – Grasshoppers.
  • Weed escapes (especially Palmer and Waterhemp).

County Rainfall Update

Field Observations Thru August 25

Corn

Growth & Development

Last week I highlighted the R3 (milk) growth stage.  R4 is the next stage, occurring approximately 26 days after silking.

R4 – Dough

  • This stage is about 26 days after silking.

 

  • The kernel has thickened to a pasty (doughy) consistency from the earlier milky state (starch has continued to accumulate and kernel moisture content has decreased).
  • The embryo of the seed is growing while the kernels are just beginning to dry at the top (dent).
  • Kernels have accumulated 50 percent of their dry weight and have about 70 percent moisture.
  • Unfavorable environmental conditions or nutrient deficiencies still can result in unfilled kernels and “chaffy” ears.

Scouting

Disease pressure throughout the county continues to be very low. Continue to scout for:

Chaffy Ears

  • Foliar diseases
  • Weed escapes (especially Palmer and Waterhemp)
  • Head smut
  • European corn borer
  • Barren stalks, poor pollination
  • Nutrient deficiencies

 

Soybeans

Growth & Development

Soybeans are continuing to mature.  Recent rains will help with seed fill.  Last week I highlighted the R5 (Beginning Seed) growth stage.  R6 is the next stage, occurring approximately 10 days after R4.

R6 – Full Seed

R6 Full seed

Pod containing a green seed that fills the pod cavity at one of the four uppermost nodes on the main stem with a fully developed leaf

 

  • Beans of many sizes can be found on the plant
  • Total plant pod weight is maximized
  • Large amounts of nitrogen are still being accumulated from the soil and remobilized to the seed
  • Root growth is complete between R6 and R7.

Scouting

As you continue to scout your bean fields, look for

  • Foliar diseases – Sudden Death Syndrome, White Mold, and Frogeye Leaf Spot.
  • Insect feeding – Grasshoppers.
  • Weed escapes (especially Palmer and Waterhemp).

Click here for tips on identifying pigweed, palmer and waterhemp.

County Rainfall Update

Weed of the week – Cocklebur

Every year it seems as if we have one weed that that hasn’t really been a problem for a while suddenly pop up everywhere.  This year Cocklebur wins the 2023 award for Comeback Weed of the Year!

Family:  Asteraceae (Composite family)

Life cycle:  Annual

Description: Erect plant reaching heights of 6 to 7 ft.  Stems are rough with dark spots.  Leaves are rough, triangular in shape with wavy or toothed margins and long petioles.  Inconspicuous flowers produce egg-shaped burs with two beaks at end. Seedling has long, fleshy cotyledons.

Seedlings:  The stem below the cotyledons (hypocotyl) is purple at the base and often green in the upper portion. Cotyledons are linear to oblong in outline, waxy, smooth, fleshy, thick, approximately 3/4 to1 3/4 inches long and usually no more than 1/2 inch wide. The first true leaves are opposite, while all subsequent leaves are alternate.

Roots:  Taproot

Stem: Mature stems are green, 1-4 ft. tall, highly branched, hairy, and flecked with maroon to black spots.  Ridges are present on the stem.  Upright hairs cause leaves to feel abrasive and gritty.

Leaves:  The first true leaves are opposite, all subsequent leaves are alternate. Leaves are triangular to ovate in outline, have stiff hairs, and are approximately 2 to 6 inches long. Leave are irregularly lobed with leaf margins that have relatively inconspicuous teeth. Leaves occur on long petioles and also have three prominent veins on the upper surface of the leaf that arise from the same point.

Flower/Seedhead:  Inconspicuous, greenish in color, arising from the area between the leaf petioles and the stems (axillary flowers) and at the ends of the erect stems (terminal flowers).

Special Identifying Characteristics:  The relatively large, linear to oblong waxy cotyledons helps to distinguish this weed in the early stages of development.  Additionally, the long-petioled triangular leaves, stems with maroon to black stem lesions, and the distinctive prickly cocklebur fruit are all features that help in the identification of this weed.In the early stages of development, this weed might be confused with Giant Ragweed (Ambrosia trifida), however the cotyledons of common cocklebur are much longer and more linear than those of giant ragweed. Spiny Cocklebur (Xanthium spinosum) is a closely related and similar species, however, unlike common cocklebur, this weed has very distinctive 3-parted spines that arise at the base of each leaf.

If you have a dog, you will now if you have cocklebur! 

Red Crown Rot of Soybean

Figure 1. Foliar Symptoms

Red crown rot (RCR) is a soybean disease caused by the soilborne fungus Calonectria ilicicola that is spreading to parts of the Midwest. There have been no confirmed reports of RCR in Ohio, but it has been detected in Kentucky and Illinois.  RCR can be easily confused with other soybean diseases that cause similar foliar symptoms.

RCR can be misidentified as sudden death syndrome (SDS) or brown stem rot (BSR) as all three diseases can cause yellowing between the leaf veins or interveinal leaf chlorosis (Figure 1.)

Figure 2. Stem discoloration

Proper diagnosis will require digging up the plant, scraping the soil off, and inspecting for red discoloration on the outer stem (Figure 2). Also look for small, brick red perithecia (fungal sexual structure) on the lower stem or root crown area. These perithecia will be smaller than the tip of a pencil and more likely to be observed following wet weather.

In general, concentrate scouting efforts for RCR in low-lying, saturated areas of the field between the R3 (beginning pod) and R5 (beginning seed) growth stages. Keep an eye out for scattered patches of plants dying off early.

If you have questionable areas in your beans and suspect RCR or sudden death let me know.  I can collect plant samples and send them to our lab for diagnosis.

Field Observations Thru August 18

Corn

Growth & Development

Corn development continues to vary throughout the county.  Last week I highlighted the R2 (Blister) growth stage.  R3 is the next stage, occurring approximately 20 days after silking.

R3 – Milk Stage

  • Occurs approximately 18‐20 days after silking.

  • The  kernel is colored yellow with the inside containing ‘milky’ white fluid.
  • Kernel moisture  content is approximately 80%
  • Starch is beginning to accumulate in the kernel.
  • Stress is not as severe at R3 as at R1; however, yield reduction can occur due to a reduction in the number of kernels that ultimately develop and to the final size and weight of the kernels.
  • Very little root growth occurs after R3.

Scouting

Disease pressure throughout the county continues to be very low.  At this stage of growth, with little to no disease pressure, and new crop corn under $5 can we justify at least $25 per acre for a fungicide application?

Read more on disease scouting here.

Soybeans

Growth & Development

Like corn, soybean development continues to vary throughout the county.  Beans are looking much better than they were a few weeks ago. Last week I highlighted the R4 (Full Pod) growth stage.  R5 (Beginning Seed) is the next stage, occurring approximately 10 days after R4.

  • Seed is 1/8 inches long in the pod at one of the four uppermost nodes on the main stem with a fully developed leaf .

  • Rapid seed filling begins, while root growth slows.
  • Dry weight and nutrients begin redistributing through the plant to the developing seed.
  • 50% defoliation can decrease yield by 15-17%.
  • Symptoms of many diseases, including white mold and SDS begin to show up at this growth stage.
  • This is a good growth stage to determine the severity of disease.
  • Treating most diseases with fungicides is not recommended at this time.

Scouting

All of the bean fields that I have seen this week look very similar to this one.  I am seeing very little (if any) disease pressure.  Current and projected weather conditions may change  this.  As you continue to scout your bean fields, look for Sudden Death Syndrome, White Mold, and Frogeye Leaf Spot.

Weeds

It’s that time of year when weeds are beginning to show their ugly heads above the soybean canopy in many fields.  During your scouting, if you find Palmer Amaranth or Waterhemp you should do whatever you can to prevent these devastating weeds from going to seed, including removing the entire plant from the field.

Click here for tips on identifying pigweed, palmer and waterhemp.

County Rainfall Update

Is it Pigweed or Palmer? – Hope it’s not Waterhemp!

It’s that time of year when weeds are beginning to show their ugly heads above the soybean canopy in many fields.  During your scouting, if you find Palmer Amaranth or Waterhemp you should do whatever you can to prevent these devastating weeds from going to seed, including removing the entire plant from the field.

Each of the last 3 weeks I have included a post highlighting the different characteristics of Pigweed, Palmer Amaranth and Waterhemp.  These posts also included a step by step video to help with the identification process for these weeds.

Depending upon the growth stage, identifying these weeds in the field can be challenging. If a seedhead is present, most weeds are easier to identify, including pigweed, palmer and waterhemp. If you have seen a mature palmer seadhaed you will never forget it!  (see pictures above)

When trying to differentiate between these weeds I look for the following 3 plant characteristics:

1.Hair

Pigweed has hair the others do not.  Rub the stem and leaves checking for a “rough” texture.  Palmer and waterhemp will be smooth.

 

2. Leaves

Long Lanceolate Leaves

Waterhemp has long, slender leaves (lanceolate). While pigweed and palmer are more oval in shape.  Pigweed is wider in the middle and palmer is wider near the base of the leaf (this is usually hard do differentiate in the field).

 

 

3. Petiole

The petiole is the part of the plant that connects the leaf to the stem.  The petiole on palmer plant is as long or longer than the leaf.  Pigweed and waterhemp have much shorter petioles (often less than 1/2 the length of the leaf).

These weeds are here, they best way to prevent the spread is by preventing them from developing a seedhead.  One mature female plant  can produce up to 1,000,000 seeds.

 

Weed Identification Videos

 

If you  are still not sure about the identification, do not hesitate to call 740-397-0401) or send (barker.41@osu.edu) me a picture!!!