To Spray Or Not To Spray?

Head Scab Forecasting System Click here to enlarge

Most of our wheat is nearing a time when a decision must be made –

To spray or not to spray?!  

Fungicide costs can range from $12 to $18 per acre plus application cost.  Today’s new crop wheat is hovering around $6.20 per bushel.

All of the wheat fields that I have looked at are showing no signs of disease pressure.  The head scab forecast system is showing a very low chance of scab and the 6 – 10 day precipitation outlook is for below normal rainfall and mild temperatures.  These factors are not conducive to disease development.

Below are additional thoughts from Dr. Pierce Paul and Dr. Kelley Tillman from this week’s C.O.R.N. Newsletter.

Fungicide and Insecticide at Flowering: Is This Really Warranted?

The wheat crop is flowering or will soon begin to flower in southern and central Ohio. Flowering will continue in the northern half of the state over the next two weeks. This is the growth stage as which the crop is most susceptible to infection by Fusarium graminearum, the fungus that causes head scab. Consequently, questions are being asked about applying a fungicide at flowering to control head scab, and at the same time, mixing in an insecticide to control cereal leaf beetle. According to the scab forecasting system (https://www.wheatscab.psu.edu/), the risk for head scab development has been low across the state over the past week. This is likely due, at least in part, to the cool, relatively dry conditions we have experienced across most of the state. The extended forecast suggests that dry (rain-free) conditions will persist over the next week or so.

Warm and consistently wet or humid conditions are required for head scab to develop. In fact, humid/wet conditions are also necessary for the development of most of the other economically important diseases of wheat such as SeptoriaStagonospora, and rust. When conditions are as consistently dry as they have been over the last few weeks, fungicides are not warranted. However, do continue to monitor the weather, and if it begins to rain, use the scab forecasting system to determine if the risk for scab is increasing as the crop continues to flower in the northern half of the state.

We specifically do not recommend tank-mixing an insecticide with a fungicide application if the insect populations do not legitimately warrant it.  Not only will it kill pollinators, but it also can eliminate the beneficial parasitic insects that attack cereal leaf beetle.  Insecticide is warranted for cereal leaf beetle control if there are 3 larvae per stem up to the boot stage, followed by a threshold of 1 larva per stem or flag leaf at boot stage and thereafter.  As the wheat begins to mature and grain fill has progressed, the need for spraying diminishes as it will not provide a return on investment.

Field Observations Thru May 19

Throughout the growing season I will post information on different pests or issues I am seeing in our fields in Knox County.

We are making a lot of planting progress this week.  Maybe not the most ideal conditions, but, we are getting seeds in the ground!  Below are a some to observations to keep an eye on.

Alfalfa

Not many changes this week, continue to scout fields for Alfalfa Weevil.

Click here for Alfalfa Weevil Scouting Guide

 

 

Corn

Soil Crusting

When heavy rains occur after planting, soil crusting can become a concern, inducing a shallow hard layer on the soil surface that forms due to rapid drying (e.g., warm days and wind).  This can affect seedling emergence.  Click here for more information.

Planting Depth

Occasionally check and verify planting depth.  When we get in a hurry sometimes we let a few things slide.  Improper planting depth can haunt you later in the season.

Plant Stand

Most of our early planted corn has emerged.

Now is a good time to take a few stand counts to evaluate your plant stand.  For 30 inch rows, measure 17′ 5″ and count the number of plants.  Multiply the number of plants you count by 1,000 to determine your plant stand.  Click here for more information.  Plant Stand Table

Click here to read the following post from OSU Agronomists Osler Ortez, Laura Lindsey, Alexander Lindsey

Soybeans

Same story as corn.  Check for emergence issues, planting depth and stand counts for early planted beans.  Check back next week for more detailed information on these issues.

Wheat

Continue to scout wheat, especially if you are considering a fungicide application.  More information can be found in this post.

Wheat Growth and Development – Feekes 10.2 – 10.5

Today managing your wheat crop requires knowledge of the different growth stages of the plant.  Growth stage identification is critical for scouting and proper timing of fertilizer and pesticide applications.  Each week throughout the rest of the growing season I will discuss the various wheat growth stages I am seeing in our wheat fields and management issues at each stage.  Today I will focus on the heading stages Feekes 10.2 through Feekes 10.5 .

FEEKES 10.1-10.5 – HEADING 

Figure 1. Wheat flag leaf, ligule, awns and head at Feekes 10.5.

 

Heading marks the emergence of the wheat head from the leaf sheath of the flag leaf, and is subdivided into stages based on how much of the head has emerged.

Stage 10.5 is shown in Figure 1.

 

 

 

  • 10.1    Awns visible, head beginning to emerge through slit of flag leaf sheath.
  • 10.2    Heading one-quarter complete.
  • 10.3    Heading one-half complete.
  • 10.4    Heading three-quarters complete.
  • 10.5    Heading complete.

If you need a reminder on how to determine the different heading growth stages, watch this video.

Management.

Scout for insects, weeds, and diseases. A fungicide application may be considered to protect heads from scab.

Check fungicide label for pre harvest interval restrictions and proper growth stage for application.

Click here to go to an earlier post containing the 2023 Wheat Fungicide Ratings. 

Wheat Growth and Development – Feekes 10.1

Today managing your wheat crop requires knowledge of the different growth stages of the plant.  Growth stage identification is critical for scouting and proper timing of fertilizer and pesticide applications.  Each week throughout the rest of the growing season I will discuss the various wheat growth stages I am seeing in our wheat fields and management issues at each stage.  Today I will focus on Feekes 10.1.  While growth stage does vary throughout the County, most of our field have passed through Feekes 10 and are at (or approcahing) Feekes 10.1 growth stage.

Feekes 10.1 – The start of heading

Heading marks the emergence of the wheat head, and is subdivided into stages based on how much of the head has emerged.  The first heads escape through a split in the flag leaf sheath at Feekes 10.1. All heads are out of the sheath at Feekes 10.5. It usually takes 3 to 5 days for the head to fully extend above the flag leaf. Temperatures below 30 degrees Fahrenheit may damage the developing head. Crop water demand can exceed 0.3 inch per day during heading through the soft dough stage.

Management

Scout for insects, weeds, and diseases. A fungicide application may be considered to protect heads from scab. Check fungicide label for pre harvest interval restrictions and proper growth stage for application. Click here to go to an earlier post containing the 2023 Wheat Fungicide Ratings. 

Field Observations Thru May 12

Throughout the growing season I will post information on different pests or issues I am seeing in our fields in Knox County.  This week Mother Nature is finally cooperating, a little, and we are starting to make some planting progress.  Below are a some to observations to keep an eye on.

Alfalfa

Continue to scout fields for Alfalfa Weevil.

Click here for Alfalfa Weevil Scouting Guide

 

 

Corn

Finally, we are planting!  While conditions are not perfect, we are able to get some seeds in the ground!

Most of our early planted corn has sprouted, some has finally begun to emerge.  As you evaluate your plant stand, do not be too concerned, yet – it is still early!

Click here to read the following post from OSU Agronomists Osler Ortez, Laura Lindsey, Alexander Lindsey

Soybeans

Same story as corn.  Early planted soybeans are beginning to emerge. As you evaluate your plant stand, do not be too concerned, yet – it is still early!

Click here to read the following post from OSU Agronomists Osler Ortez, Laura Lindsey, Alexander Lindsey

Wheat

Trapped heads in Wheat.  While rare, I have seen this before. It looks like the heads are trapped in the boot.  This is usually a weather related issue.

Under warm conditions, the heads are pushed out of the leaf sheath quickly, but when it’s cold/cool, the process is slower, causing the heads to get trapped.  This is particularly problematic on awned varieties.  This issue could cause some constriction and affect grain full at the tips of the head, but usually not a major cause for concern.  

Click here for more information

Wheat Growth and Development – Feekes 10

Today managing your wheat crop requires knowledge of the different growth stages of the plant.  Growth stage identification is critical for scouting and proper timing of fertilizer and pesticide applications.  Each week throughout the rest of the growing season I will discuss the various wheat growth stages I am seeing in our wheat fields and management issues at each stage.  Today I will focus on Feekes 10.  While growth stage does vary throughout the County, most of our field have passed through Feekes 9 and are at (or approcahing) Feekes 10 growth stage.

Feekes 10 – Boot

The head is inside the leaf sheath giving it a swollen appearance.  The flag leaf sheath and peduncle elongate and the developing head is pushed through the flag leaf sheath.  Temperatures below 28 degrees Fahrenheit may cause damage to the developing head.

If you need a reminder on how to determine if wheat is at Feekes GS 10, watch this video.

Management

Scout for insects, weeds, and diseases. Application of 2,4-D after wheat reaches the boot stage of growth can result in trapped heads, missing florets, or twisted awns.

Wheat Growth and Development – Feekes 9

Today managing your wheat crop requires knowledge of the different growth stages of the plant.  Growth stage identification is critical for scouting and proper timing of fertilizer and pesticide applications.  Each week throughout the rest of the growing season I will discuss the various wheat growth stages I am seeing in our wheat fields and management issues at each stage.  This week I will focus on Feekes 9.  While growth stage does vary throughout the County, most of our field have passed through Feekes 9 and are at (or approcahing) Feekes 10 growth stage.

Feekes 9 – Ligule of flag leaf visible.

The flag leaf is completely emerged from the whorl. Flag leaf and the next-to-last leaf (penultimate leaf ) combined account for 70 to 90 percent of the photosynthates used for grain fill and must be protected for the plant to develop to its full potential.

If you need a reminder on how to determine if wheat is at Feekes GS 9, watch this video.

Management Scout for insects and diseases. Consider a fungicide application to protect the flag leaf if foliar diseases are present on the lower canopy. Nitrogen application can increase grain protein levels.

Wheat Growth and Development – Feekes 8

Today managing your wheat crop requires knowledge of the different growth stages of the plant.  Growth stage identification is critical for scouting and proper timing of fertilizer and pesticide applications.  Each week throughout the rest of the growing season I will discuss the various wheat growth stages I am seeing in our wheat fields and management issues at each stage.  This week I will focus on Feekes 8.  While growth stage does vary throughout the County, most of our field are at or beyond Feekes 8 growth stage.

Feekes 8 – Last leaf just visible.

The flag leaf starts to emerge from the whorl above the third or fourth node. Strong partitioning of photosynthates to the developing head.    The flag leaf will contribute 75% of the energy needs of the developing grain.  Crop water demand increases to about 0.3 inch per day.  Approximately 45 percent of the total dry matter is accumulated by this stage.

Management

To maintain optimal leaf area, scout for diseases and pests.

Field Observations Thru May 5

Throughout the growing season I will post information on different pests or issues I am seeing in our fields in Knox County.  This week, not much happening in our fields due to the cold, wet weather. Below are a some to observations to keep an eye on.

Alfalfa Weevil

 Even with the chilly weather we have experienced the last 2 weeks,  we have accumulated enough growing degree days for alfalfa weevils to be active. These cold temperatures may have slowed feeding but the temperatures haven’t been cold enough to kill the weevil larvae.  We are concerned that as soon as it warms they will speed up their feeding again with a vengeance.  Scout your fields now, not when excessive feeding grabs your attention.  Keep in mind that at a certain point, early harvest is preferable to treatment.

Click here for Alfalfa Weevil Scouting Guide

Here is a video about scouting weevils in alfalfa:  https://forages.osu.edu/video

Alfalfa Weevil Update  – C.O.R.N. Newsletter

Wheat 

Even with chilly temps wheat is growing at a good pace.  Most of our week is passing through Feekes 7 and is in (or soon will be ) in Feekes 8.  As our wheat approaches Feekes 9 it is time to scout your fields and evaluate your stand/yield potential and determine if fungicide applications are warranted.  2023 Wheat Fungicide Ratings can be found in this post from earlier this week.