Scouting

Potato Leafhopper is Arriving in Alfalfa

This Spring has presented plenty of challenges, and another is coming in from the south. Potato leafhoppers (PLH) are being carried into Ohio fields on southern winds and can quickly become a concern. PLH arrives around the time of first cutting and can be a pest of alfalfa into September. PLH can reach maturity in three weeks, and multiple generations can be present at the same time, being very damaging.

PLH is relatively easy to identify; the adults are lime green, wedge-shaped, and are roughly 1/8 of an inch in length. The immature nymph stages look similar but are smaller and lack wings. PLH feeding damage, commonly called hopper burn, is seen as the yellowing of alfalfa leaf tips in a V-shaped orientation.

For a video on identifying PLH, follow this link: PLH Identification and Damage in Alfalfa

Just like every pest, scouting is critical to know when spraying is an economically sound decision. To scout PLH, a 16-inch diameter sweep net, and a yardstick are needed. Be sure that the sweep net is 16 inches in diameter; if not, the control thresholds will not be accurate. With the sweep net, take 10 pendulum swings, making solid contact with the field canopy. After 10 swings, count the adults and nymphs collected, and be sure to check the seams around the rim for PLH nymphs. Take multiple samples from around the field for more accurate estimates. It is best to sample in dry and calm conditions.

For a video demonstration of PLH scouting, follow this link: Scouting for PLH in Alfalfa

The threshold for when control should be considered is 1 PLH for 1 inch of stand height. For example, if the alfalfa is 16 inches in height, the threshold for control would be 16 PLH adults and nymphs per 10 swings.

If a field has reached the threshold where action is needed, there are some extra considerations to give thought to. If the alfalfa is close to harvest, be sure to account for the preharvest interval restrictions for insecticides; there may be instances where an early or timely harvest is the better choice. Be sure to monitor the following cuttings for continued PLH pressure. PLH is most damaging to young stands, fresh regrowth, and stressed stands, since feeding can remove a great percentage of leaf area compared to a healthy mature stand.

For more information on potato leafhopper, see this factsheet: Potato Leafhopper on Alfalfa

**SLUG ALERT**

As if the extremely wet and cool weather wasn’t enough to worry about, slugs are becoming active in many fields.  Again this year I am participating in the United Soybean Board Multi-State Slug Monitoring Project.  As part of this project, I have several fields throughout Knox County that I monitor for slug activity on a weekly basis.  Today was the first time I found any significant activity.  Several fields are now beginning to show significant slug feeding.  To make matters worse most of the slugs that I am finding are small juvenile slugs.  This would indicate that a slug hatch has recently occurred.  These juvenile slugs are like teenagers – As they grow, they will eat anything in site, and a lot of it!

Scout your fields now!!

Wheat Management for Spring 2025

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 and 10. Most of our wheat has progressed to the Feekes 9 growth stage,  some fields are or soon will be in 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.

 

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.

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.

 

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.

Sidewall compaction from planting into wet soils

Source: Agronomy eUpdates

Figure 1. Sidewall and seed zone compaction in heavy clay soil.

Conducting field work — including planting, tillage, or traffic in general — after wet weather can cause soil compaction, particularly sidewall compaction in the seed furrow. The worst cases of sidewall compaction are seen after a field has been planted when the soil was too wet, followed by a period of dry weather. If the soil stays moist, the roots can usually grow through the walls of the seed furrow. However, if the soil gets dry, the roots can have a harder time growing through that seed furrow wall, and instead grow along the furrow, resulting in what is referred to as sidewall compaction.

With corn, the plants might look fine for a while, but the symptoms of this problem will probably show up after the plants reach several inches tall. Symptoms can mimic drought stress, nutrient deficiency, or both.

Since there are not any good ways to fix sidewall compaction once it exists, the best practice would be to avoid creating the problem in the first place. This means waiting until soils are dry enough to plant. The way to test for this is to dig down to the desired planting depth and make a ball with the soil. Next, see if the ball will crumble or crack apart, or if it deforms like molding putty. If it crumbles, it is ready to plant. If it deforms, it would be best to wait before resuming field operations. Even waiting as little as half a day could make a big difference.

Other considerations

  • Planting too shallow: Planting shallow in wet soil may lead to wheel compaction below the seedling depth. This results in limited downward root growth and seeds growing horizontally.
  • Too much down pressure: If you must work in wet soil, then the down pressure of the row unit and press wheels needs to be reduced to limit compaction around the seed.
  • Soil structure: Tilled soils often lack proper soil structure, causing the standard closing wheel to pinch the sidewalls over the seed from additional pressure. This is frequently a concern in heavier-textured soils, i.e., higher clay content.

Wheat Management for Spring 2025

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 6.  Most of our wheat has progressed to the Feekes 6 growth stage, some fields are approaching Feekes 7 growth stage.

Feekes 6 – First Node Visible. 

Prior to Feekes 6.0, the nodes are all formed but sandwiched together so that they are not readily distinguishable. At 6.0, the first node is swollen and appears above the soil surface. This stage is commonly referred to as “jointing.” Above this node is the head or spike, which is being pushed upwards eventually from the boot. The spike at this stage is fully differentiated, containing future spikelets and florets.

Split wheat stem showing developing spike.

You can remove and carefully examine plants for the first node. It can usually be seen and felt by removing the lower leaves and leaf sheaths from large wheat tillers.  A sharp knife or razor blade is useful to split stems to determine the location of the developing head. The stem is hollow in most wheat varieties behind this node.

 

 

Management.

By Feekes 6.0, essentially all weed-control applications have been made. Do not apply phenoxy herbicides such as 2,4-D, Banvel or MCPA after Feekes 6.0, as these materials can be translocated into the developing head, causing sterility or distortion. Sufonyl-urea herbicides are safe at this growth stage, but for practical reasons, weed control should have been completed by now. Small grains can still show good response to N topdressing at this time.

Corn Growing Degree Days

Mother Nature is finally cooperating, and planting is off to a great start.  A common question is, “After planting how long before I can see corn?”  Once corn is in the ground, you can expect to see emergence around 100 growing degree days after planting. The Table below lists the approximate growing degree days for various corn growth stages.

New this year!  I will have a weather station set up by some of our research plots near Centerburg.  Click here to access our local weather data. This weather data should be able provide information to assist with many of your daily activities such as: spraying records, crop growth & development, insect scouting, anticipated disease pressure, and many more.

Wheat Management for Spring 2025

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 5.  Most of our wheat has progressed to the Feekes 5 growth stage, some fields are in Feekes 6 growth stage.

Feekes 5 – Leaf sheaths strongly erect. 

 

The beginning of the stem elongation phase.  The pseudo-stem is strongly erect and leaf sheaths are elongated. The developing head reaches the terminal spikelet stage and is pushed up into the pseudo-stem.

Terminal spikelet occurs at Feekes 5. This stage marks the completion of the spikelet initiation phase. At this stage, the number of spikelets per head has been determined.   Stress during this stage can reduce total number of kernels per head.

The first hollow stem stage occurs when there is approximately 0.6 inch of hollow stem below the developing head.  Crop water use is about 0.1 inch per day.

Management.

This is an ideal stage for spring topdress nitrogen application. Weed control efforts should be made prior to or during Feekes 5.0 with 2,4-D and other labeled herbicides. This is also a good stage to begin scouting for foliar diseases.  Tillers developing after this time are not expected to contribute to yield.

Controlling the Spread

Palmer Amaranth, Waterhemp, Marestail, Giant Ragweed, Lambsquarters, Pigweed, Burcucumber, Foxtail, Pokeweed, and Velvetleaf are some of the problem weeds we face annually in Knox County.  The first six weeds have documented herbicide resistance in Ohio.  The weeds in bold print are on the noxious weed list which requires control.

Arguably the single most daunting task facing some of us this year may be stopping the spread of weeds such as Waterhemp and Palmer Amaranth.  Waterhemp and Palmer Amaranth are two devastating, invasive weeds now found throughout Knox County.  These weeds, like no other weeds we have ever experienced, can and will change the way we manage our farms today.  These weeds can impact both your herbicide program and your trait-based seed selection.

Populations of these species can explode in just a few years if not controlled.  Consider each female plant of these two species can produce 1 million seeds.  If only one plant survives this year, how many of these seeds will germinate next year?  It’s not impossible to see a scenario where one surviving plant can turn into a million or more new plants within a few years.

Table 1. shows the seed production capabilities and the expected seed survival rate of different weed species prevalent in Knox County.

Controlling the spread

A monumental undertaking facing some this year will be to stop the spread of these weeds.  The most common avenues for weed seeds to spread are:

  • Machinery – Seeds are easily spread by many types of farm machinery, especially combines and mowing equipment.
  • Manure – Animals consume weed seed via various feed additives (cottonseed hulls) and hay.  Seeds are then spread in the manure.
  • Humans – Humans can spread weed seed through recreational activities and by moving items from field to field (power company moving big wood pallets).
  • Birds and wildlife – often transport weed seeds through their manure or by seeds in their coat.
  • Water – Heavy rains resulting in flooding can move weed seed to downstream fields.

Over the last three years I have personally seen evidence of weed seed movement throughout Knox County by each of these methods.

Invasive weeds pose significant risks to our farms.  Effective weed control programs and preventing the spread of these weeds is critically important.  These plants can have wide-ranging impacts on our farms for years to come.  Preventing these weeds from producing seed and/or removing or killing these plants before they produce seed is best way to control the spread.

 

Purple Fields Everywhere

While driving through Knox County looking at wheat fields last week, I noticed many, many “purple fields”.  The purple plants are a combination of purple deadnettle and henbit.  This time of year these plants (weeds) can be found in fields, roadsides, gardens, flowerbeds and landscaped areas.

These winter annuals begin to develop in fall, form a small rosette of leaves that overwinter, and complete their development in spring, forming flowers and seeds. They die in late spring and early summer after setting seed.

Purple Deadnettle vs. Henbit

Purple Deadnettle

Purple deadnettle and henbit belong to the mint family and thus have a square stem.  Both have two-lipped tubular flowers, opposite leaves. The leaves of purple deadnettle at the apex of the stems are tinted purple and fade to green as they mature. The leaves have a short petiole (stem) and are heart- or triangular-shaped with rounded teeth on the leaf margin.

 

Henbit

The leaves of henbit are more rounded and scalloped and clasp the stem directly – they do not have a leaf petiole.  Henbit flowers are pink to purple with darker purple spots than those of purple deadnettle. The flowers of henbit are longer and more slender than those of purple deadnettle.