Fungicides

Field Observations Thru July 21

Corn

Corn growth varies greatly throughout the county, but, more fields are beginning to tassel.  As corn begins to tassel, nutrient (K > N > P) and water (0.30 inch per day) demands for the crop are close to maximum. Heat and drought will affect potential number of kernels.  Scout for insects (e.g., corn leaf aphid, western bean cutworm, corn earworm, fall armyworm) and diseases (e.g., gray leaf spot, southern rust, northern leaf
blight). Total leaf defoliation severely affects final yields.

VT (Tasseling) – Stage VT occurs two to three days before silking, when the last branch of the tassel is completely visible but silks have not emerged yet from the ear shoot. The plant has reached full height and the pollen shed begins. The time between VT and R1 can vary with different hybrids and due to environmental conditions.
Pollen shed (pollen drop) normally occurs during the late morning or early evening. Hail damage is more serious at this time than for any other growth period. All leaves have emerged and the complete loss of a pollen source would result in no grain formation.

We are nearing a point in the growing season where it is time to scout your corn fields and make a decision regarding fungicide applications. Click here to view the 2023 corn fungicide ratings.

Soybeans

Postemergence herbicide applications – Don’t forget the preharvest intervals (PHI) for grazing or harvest. Read more here.

 

Soybean Postemergence Weed Control – Grasses

Soybean Postemergence Weed Control – Broadleaves

Soybean Growth & Development – R2: Full Bloom

  • Open flower at one of two uppermost main-stem nodes
  • About 50% of the total mature node number has been established.
  • Very rapid nitrogen (N), phosphorus (P), potassium (K) and dry-matter accumulation is occurring and will continue through R6.
  • Defoliation of the plant of 50% at this stage will reduce yield by 6%.
  • Approximately 60 days away from beginning of physiological maturity (R7).

County Rainfall Update

Mount Vernon, OH

Corn Water Requirements

Soybean Water Requirements

Field Observations Thru May 26

Alfalfa

Most of our first cutting is complete.  If you have not mowed yet continue to monitor for alfalfa weevil.  As regrowth starts begin to monitor for potato leafhopper.

Corn

What a difference a week makes.  Most of our corn is now planted and about 50% has emerged.

 

Soil Crusting

Soil crusting is still an issue.  Continue to scout for emergence problems.  A few fields saw a return of the rotary hoe to help break the crust and aid in crop emergence.

Beans

Like corn, bean planting is coming to an end.  Soil crusting is also an issue in many of our bean fields. Continue to scout these fields for emergence problems.  Read more here.

Slugs

Slug damage was a problem early in a few fields.  The forecasted warm and dry weather should help to eliminate this problem.

 

Wheat

Scout for disease and insects:

Cereal Leaf Beetle Scouting Information

Powdery Mildew Scouting information

Head Scab Scouting Information

Most of our wheat is nearing a time when a decision must be made.  All of the wheat fields that I have looked at are showing no signs of disease pressure.  Here are some factors to consider

  1. No existing disease pressure
  2. The head scab forecast system is showing a very low chance of scab
  3. Fungicide cost can range from $12 – $18/acre plus application charges
  4. New crop wheat price is hovering around $6.20/bushel
  5. The 6 – 10 day precipitation outlook is for below normal rainfall and mild temperatures.

READ MORE HERE

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 Septoria, Stagonospora, 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. 

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.