Overseeding Perennial Peanut with Cool-Season Forages

Overseeding Perennial Peanut with Cool-Season Forages

Jose Dubeux, Erick Santos, David Jaramillo, Liza Garcia, Luana Dantas, UF/IFAS North Florida Research and Education Center, Marianna

Rhizoma perennial peanut (Arachis glabrata Benth.) is an important hay crop in Florida. Rhizoma peanut hay is locally produced within Florida, and it has important stakes in the horse and dairy industries. This warm-season perennial legume is also a valuable forage option for grazing systems (Dubeux et al., 2018). In addition to adding N via biological N2-fixation, rhizoma peanut has greater nutritive value than most warm-season perennial grasses. As a result, greater livestock performance is achieved when mixing this legume in grazing systems. Many producers using rhizoma peanut want to overseed their field with cool-season forages when the rhizoma peanut is dormant. Common questions that precede the decision to overseed rhizoma peanut fields are: 1) Will it hurt my rhizoma peanut regrowth in the following season? 2) Does it matter which cool-season forage I plant? How about annual ryegrass and clovers? Would they damage the rhizoma peanut because of their late growth in the season?

In order to address these questions, we set up a trial at the UF IFAS NFREC in Marianna, FL. We assessed different overseeding treatments on rhizoma peanut fields, including the control (no overseeding), Prine ryegrass, FL 401 rye, FL 401 rye/Prine ryegrass mix, Prine ryegrass/Crimson/Red/Ball clover mix, FL 401 rye/Crimson/Red/Ball clover mix, FL 401 rye/Prine ryegrass/Crimson/Red/Ball clover mix, and Crimson/Red/Ball clover mix. Seeding rates used are described in Table 1. These different overseeding treatments were applied on a dormant Florigraze sod using a no-till drill in 17 Nov 2015, after mowing the stand down to a 2-inches stubble height. We applied 150 lb/acre of 20-5-20 and 100 lb/acre of Kmag (22% K2O, 22% S, and 10.8% Mg) in all treatments. Plots were harvested three times: 11 Feb, 17 March, and 21 Apr 2016. After the third harvest, plots were fertilized with 300 lb/acre of Kmag. On 22 July 2016, we harvested the rhizoma peanut to assess whether or not the overseeding treatment affected the regrowth.

Overseeding treatments varied their biomass accumulation along the three harvests (Figure 1). Earlier forage types, such as FL 401 rye, produced more in the first harvest, as expected. Treatments with clovers and annual ryegrass produced more biomass later in the season, at the third harvest. The option of forage type or mixtures will depend on the objective of each operation. For hay producers, earlier forage production during the cool-season may free up the land earlier, allowing regrowth of rhizoma peanut without other forages being present. For grazing operations, mixtures would likely be a better option because they would help bridge the gap during the spring-summer transition.

Figure 1. Cool-season herbage accumulation of different overseeding treatments on Florigraze rhizoma peanut

Figure 1. Cool-season herbage accumulation of different overseeding treatments on Florigraze rhizoma peanut; UF IFAS NFREC Marianna; 2016.

In the summer harvest (July 2016), the rhizoma peanut from all treatments, including the control that was not overseeded, produced similar amounts of biomass across treatments (Figure 2). This result demonstrates the viability of overseeding rhizoma peanut fields with cool-season forages. The major aspect to highlight is the importance of timely harvest the cool-season forages during the springtime, allowing the rhizoma peanut to regrow.

Figure 2. Summer herbage accumulation of Florigraze rhizoma peanut after overseed during the cool-season with different forage options.

Figure 2. Summer herbage accumulation of Florigraze rhizoma peanut after overseed during the cool-season with different forage options. UF IFAS NFREC Marianna; 2016.

We have been overseeding cool-season forages on strip-planted rhizoma peanut in a grazing trial (Figure 3A). We have been doing this for the last three years, and the rhizoma peanut is vigorous and growing (Figure 3C). The critical phase is the springtime, when rhizoma peanut (and bahiagrass) is starting to regrow (Figure 3B). During this transition, it is important to pay closer attention to the grazing management, in order to reduce the canopy density and open spaces to allow the perennial forages (rhizoma peanut and bahiagrass) to regrow.

Figure 3. Overseeding of cool-season forages on strip-planted rhizoma peanut in Marianna, FL. A. Cool-season mixture of FL401 rye-RAM oat-Dixie Crimson-Southern Belle red clover-Ball clover; B. transition period during the Spring; C. strip-planted rhizoma peanut growing during the summer.

Figure 3. Overseeding of cool-season forages on strip-planted rhizoma peanut in Marianna, FL. A. Cool-season mixture of FL401 rye-RAM oat-Dixie Crimson-Southern Belle red clover-Ball clover; B. transition period during the Spring; C. strip-planted rhizoma peanut growing during the summer. Photo Credit: Jose Dubeux, UF/IFAS

Take-Home Message

Rhizoma peanut can be overseeded during the cool-season with different forage options without reducing the warm-season regrowth. However, if the cool-season forages form a dense stand during the spring, it is important to graze it off or remove the excess forage with hay equipment. Harvest management during the spring is critical to allow regrowth of the rhizoma peanut.

Dubeux, J., L.E. Sollenberger, J. Vendramini, M. Wallau, A. Blount, L. Garcia-Jimenez, E. Santos, and D. Jaramillo. 2018. Strip-planting rhizoma peanut into grazing systems. EDIS SS-AGR-421. Printer friendly pdf version: https://edis.ifas.ufl.edu/pdffiles/AG/AG42100.pdf


Fall Weed Control in Pastures

Fall Weed Control in Pastures

Fall is not generally the right time to control many pasture weeds.  However, some perennial weeds are effectively controlled by fall herbicide applications.  Fall is a good time to treat for weeds such as cogongrass, blackberries, dewberries, biennial thistles, and Chinese Tallow trees.


cogongrass flowering

Cogongrass flowering

Cogongrass is an invasive warm season perennial grass.  It spreads by rhizomes and seed in north Florida.  It can quickly spread from roadsides or forest areas into pastures.  Established areas of cogongrass can have massive root systems making them difficult to control.  Eradication of cogongrass infestations often take 3 or more years of twice a year treatments.  Currently, only products with the active ingredients glyphosate and imazapyr are effective against cogongrass.  Spring and fall treatments of either glyphosate, imazapyr or a combination of the two should be applied until the infestation is eradicated. Both of these herbicides are non-selective and will likely result in bare ground in treated areas.  These areas are not going to produce adequate forage for animals so owners should consider this in their grazing management plan.  For more information on cogongrass and treatment plans, please read the following UF/IFAS publication: Cogongrass (Imperata cylindrica) Biology, Ecology, and Management in Florida Grazing Lands

Blackberries and Dewberries

blackberry plants

Blackberries grow upright and have hard, tough thorns.

Blackberry and dewberry control in pastures is difficult to achieve.  The first step is identification of the plant.  Blackberries grow upright while dewberries have a low vine-like growth habit.  Dewberries have slender thorns and red hairs on the stem while blackberries have hard, tough thorns and no hairs.  Blackberries grow up to 3-6 feet tall, however, dewberries rarely reach over 2 feet in height.  Also, the seeds of dewberries are harder and much larger than that of blackberries.

dewberry plants

Dewberries have slender thorns and red hairs on the stem and are low growing and somewhat vine-like.

For blackberries, effective broad spectrum herbicides include:  Pasturegard HL (triclopyr + fluroxypyr), or Remedy Ultra (triclopyr ester).  You can either apply these herbicides in the spring when the plants are blooming, or in the fall.  Fall applications are more effective.

For dewberries, use Pasturegard HL (2pt/acre) but only expect 60-70% control.

Remember to wait at least 6 weeks after applying the herbicide before mowing.  For more information on blackberries and dewberries in pastures, please read the following UF/IFAS publication:  Blackberry and Dewberry: Biology and Control

Biennial Thistles

first year thistle plant

First year thistles, in the rosette stage, are easiest to control.

Most thistles in Florida are biennial, meaning they live for two years.  Thistles begin as a rosette and remain in this stage for the first year.  In year two, the thistle sends up a stalk and flowers, produces seeds and dies.  Thistles bolt (send up the stalk) January through July and flower from April through August.  Each plant can produce up to 4,000 seeds. The key to controlling thistles is to keep the plant from flowering and producing seeds.

Thistles in the rosette stage are the most susceptible to herbicides but are hardest to see in the field since they lay flat on the ground.  Once the thistles bolt, they are harder to kill with herbicides.  Effective herbicides for thistles during the rosette stage include 2,4-D, triclopyr, GrazonNext HL, PastureGard HL and Weedmaster.  For more information on thistle control in pastures, please read the following UF/IFAS publication:  Thistle Control in Pastures

Chinese Tallow Trees (Popcorn Trees)

chinese tallow seedling

Chinese Tallow seedlings can be treated by foliar applications of triclopyr ester.

Chinese Tallow, also known as the Popcorn Tree, was introduced in the US over 200 years ago.  They are prolific invaders of natural areas, pastures, wetlands, and yards.  Mature trees can be cut down with a chain saw and the stump promptly treated with an herbicide with the active ingredient, triclopyr amine.  You should try to make the final cut as low to the ground as possible.  You can use a paint brush to apply the herbicide to the stump.  A basal bark application of triclopyr ester plus a penetrant oil can be used on smaller trees.  Treat the trunk to a height of 12 to 15 inches from the ground, thoroughly wetting it on all sides with the herbicide mixture.  Basal bark treatments are only effective on saplings and seedlings less than 6 inches in stem diameter.  Sometimes suckers may sprout from remaining roots.  A foliar application can be used on these sprouts from July to October, before onset of fall color. For more information on Chinese Tallow, please read the following UF/IFAS publication:  Natural Area Weeds: Chinese Tallow

For more information on pasture weed control, use the following publication link:  Weed Management in Pastures and Rangeland

Pest Identification is Essential and Sometimes Surprising

Pest Identification is Essential and Sometimes Surprising

Throughout my 22 year history as an Extension Agent, I have been the first responder for all sorts of strange things farmers, ranchers, and landowners encounter.  This is one of the critical roles county agents play all over the country.  If you see something odd or unusual, whether it is a new weed, insect or disease, your county agent should be one of the first people you contact to get information.  It is very possible that if you find something you have never seen before, others may not have not seen it either.  County agents are connected to a vast network of experts and identification labs that can help figure out what those strange new things are. Because of the ports, huge numbers of visitors, and tropical storms, new pests and diseases show up in Florida on a regular basis.  It is very important to have new pests identified, before they have the opportunity to spread.

Most of the time the plants, bugs, and diseases agents have identified by experts are harmful in some way to the crops we grow.  Whether it is toxic weeds in pastures, insects feeding on plants, or diseases in crops, the first thing you need to know is, “What is it?” Once the issue is identified, most of the time there are some type of control options available.  Sometimes, however, things are not at all what you expect.  Such was the case this summer as four types of plant pests were identified that turned out to be harmless, and in some cases were actually beneficial.

Specimen #1

Aschersonia aleyrodis on Satsuma is a fungus that feeds on whitefly nymphs. Photo credit: Doug Mayo, UF/IFAS

A citrus grower thought that his satsuma trees were under serious attack.  White flies were already an issue as noted by the sooty mold growing on the leaves, and then this terrible scale that he had never seen was all over the undersides of the leaves of the trees.  While from a distance this looks much like a harmful scale insect, it turned out to be a beneficial fungus that destroys whitefly nymphs!

Dr. Xavier Martini, UF/IFAS Entomologist in Quincy shared the following information:

What you have is not scale, it is citrus whitefly nymphs that have been attacked by an entomopathogenic fungi called Aschersonia aleyrodis. It is very good to have this fungus, because it helps control the whitefly population.

You can read about this in the Featured Creature article entitled: Citrus WhiteflyScroll down to the section called: Parasitic fungi for more details.

Aschersonia aleyrodis fungus on the underside of a satsuma leaf looks terrible, but it was actually making a bad situation better by reducing the whitefly population on young satsuma trees. Photo credit: Doug Mayo, UF/IFAS.

Specimen #2

The beneficial fungus Beauveria bassiana is a natural enemy of kudzu bugs on soybeans. Photo credit: Doug Mayo, UF/IFAS.

A soybean grower saw something he had never noticed before.  A white mold was growing in spots all over the stems of soybean plants in a field.  This is where you have to be careful.  Soybeans can get white mold, which is caused by the fungus Sclerotinia sclerotiorum.  If you do a google search for Soybean white mold, you will find pictures that look somewhat similar.  Upon closer inspection, at the NFREC Plant Pathology Lab, in Quincy,  the fungus was actually Beauveria bassiana which is a biological control of kudzu bugs.  The white spots in the photos are actually dead or dying kudzu bugs, and the fungus was growing on the insects, not the soybean stalks.  You can read more about this beneficial fungus at: Kudzu bugs’ decline is attributed to two factors.

The white spots are beneficial fungus Beauveria bassiana that are attacking kudzu bugs not the soybean stalks. Photo credit: Doug Mayo, UF/IFAS

Specimen #3

Slime mold found growing on a centipede lawn. Photo credit: Doug Mayo, UF/IFAS

A landowner noticed this really strange growth on her centipede lawn.  It looks hideous and destructive.  In truth, it was a relatively harmless plasmodial slime mold, named Fuligo septica.

Larry Williams, UF/IFAS Okaloosa Horticulture Agent shared the following information:

Slime molds mostly function as saprophytes, feeding on and breaking down organic matter. It should not cause any permanent problems or major damage to the lawn. One such slime mold is commonly referred to as “dog vomit” slime mold.

Here is a link to an article on slime molds that pop up on lawns, in mulch, and damp areas under trees with high organic matter: Those Mysterious Molds

Slime mold growing on the moist organic matter in a Jackson County Lawn. Photo credit: Doug Mayo, UF/IFAS.

Oklahoma State University’s diagnostic labs had gotten so may calls from concerned homeowners that they developed a YouTube video on slime molds:

Specimen 4

Harmless slime mold growing on centipede lawn after multiple rainy days. Photo credit: Doug Mayo

A similar scenario was seen on a centipede lawn at a county building in Jackson County.  This slime mold is commonly found on lawns and pasture grasses during extended rainy periods in Florida. While it looks like a serious disease, it is really just another plasmodium species that feeds on decaying organic matter.  As with the large slime mold in specimen 3, what you are seeing is actually the spore masses that will generate more slime molds when conditions are favorable again for growth.  You can knock these off with a garden hose, if you want to, but they disappear almost as fast as they form.  No real harm is done to the grass that is just serving as a platform for slime mold reproduction.

Read more about it in this article written by Matt Orwatt, UF/IFAS Washington Horticulture Agent: Frequent Rains Induce Slime Mold in Panhandle Lawns


Most of the time, when you see something that does not look normal it is a bad thing, such as weeds, fungal diseases, or damaging insects. But before you spend money on a control, it is really important to have a positive identification of the pest.  Not everything unusual is harmful.  Modern pesticides have become very target specific, so it is vital to first find out what this new thing is before you spend money trying to control it.  So the next time you see something alarming or strange in your crop, pasture, or landscape, contact your local county agent, so you can find out for certain what you are dealing with, and get some science-based advice on a plan of action, if one is needed.

Managing Carbohydrates from Grazed Pastures for Horses with Metabolic Disorders

Managing Carbohydrates from Grazed Pastures for Horses with Metabolic Disorders

Florida pasture grasses contain lower sugar content than in other parts of the country.  Even so, pasture access might need to be limited to help control calorie intake. Limiting grazing time may cause some horses to overeat when they are turned out, so consider using a grazing muzzle or feeding horses some hay before turnout to slow intake. Photo Credit: Amy Parker

Marcelo Wallau, Lori Warren, Carissa Wickens, Jose Dubeux and Doug Mayo, UF/IFAS Extension

As extension specialists, we are often asked about nonstructural carbohydrates (NSC) in forages and the potential risks grazing poses to insulin-resistant horses. Numerous blog posts and reports have been written on the topic, alarming horse owners everywhere. However, for horses managed on pastures in Florida, is over-consumption of NSC actually a problem?

Nonstructural carbohydrates are a form of energy reserve in plants, and include simple sugars, fructan and starch. The major source of NSC in a horse’s diet is usually from grains, which range from 60 to 85% starch, and commercial concentrate feeds, frequently containing molasses and other ingredients to increase palatability. In forages, the concentration of NSC depends on plant type, management, and season of the year, typically highest in the spring and fall when growth is slow and seedheads are present. Temperate climate forages (e.g. orchard, timothy, or our cool-season species here in Florida, such as oats, ryegrass and clovers) tend to have more NSC (around 16%) than our warm summer grasses (around 8%), such as bahiagrass and bermudagrass.

Several factors are known to contribute to the development of metabolic disorders in horses, including genetics (Morgans, Arabians, ponies, and Spanish breeds are most affected), overfeeding (of anything, not just grain), overweight/obese animals (those prone to being “easy keepers”), and lack of exercise. The most common metabolic disorders are Cushing’s Disease (pituitary pars intermedia dysfunction) usually associated with aging, and equine metabolic syndrome (resulting from the genetic and management factors described above). What they share in common is insulin resistance (similar to, but not exactly like Type 2 diabetes in humans), making them susceptible to secondary diseases such as laminitis or founder. These horses tend to be more sensitive to sugar, starch, and fructan in the diet. Not all horses have these problems. In fact, the frequency of laminitis in horses is low, ranging from 2 to 5% (Kane et al., 2000) and normally is related to horses which have a predisposition, either genetic or acquired from sub-optimal management practices.

For horses with metabolic disease or a history of laminitis, feeding diets with less than 10% NSC is recommended. Reducing NSC in the diet can be accomplished by cutting back on grain consumption and any other sort of treat containing high sugar levels. For lush pastures containing cool-season forages, there may be a need for limiting pasture access and timing turnout to occur in the period from late night to early morning when sugar and fructan levels in the grass will be at their lowest. For pastures containing Florida’s warm-season forages, NSC is less of a problem, but pasture access might need to be limited to help control calorie intake. Note that limiting grazing time may cause some horses to overeat when they are turned out, so consider using a grazing muzzle or feeding horses some hay before turnout to slow intake. These approaches combined with monitoring horses’ body condition and weight will allow owners and farm managers to safely utilize forages in feeding horses diagnosed with metabolic disorders.

Although the incidence of insulin-resistance is relatively low, many people worry about the health of their horses housed on pasture. What is important, however, is to provide a balanced diet which is in accordance with the category and use of the animal: growing, lactating and active horses (working or athlete) need a more nutrient dense diet to meet their requirements, while most leisure horses’ nutrient requirements can be met primarily by forages and a vitamin-mineral supplement. Nevertheless, the low NSC content of most forages in Florida represent a low risk, even for horses with pre-disposition for metabolic disorders


The following are some additional references and suggestions for further reading on this topic:

  • Kronfeld DS, Harris PA. 2003. Equine grain-associated disorders (EGAD). Compendium on continuing education for the practising veterinarian. 25:974–83.
  • Lameness and laminitis in U.S. horses. 2000. USDA: APHIS: VA, CEAH, National Animal Health Monitoring System. Fort Collins,CO. Contract No.:N318.0400.
  • Kane AJ, Traub-Dargatz J, Losinger WC, Garber LP. 2000. The occurrence and causes of lameness and laminitis in the U.S. horse population. San Antonio TX: Proceedings of the 46th AAEP; Nov 26–29; p.277–280.
  • Longland, A.C., and B.M. Byrd. 2006. Pasture Nonstructural Carbohydrates and Equine Laminitis. J. Nutr. 136(7): 2099S–2102S
  • Wickens, C. 2016. Monitoring Body Condition in Horses: Helpful Smart Phone Apps for Horse Owners.


Time to Order Winter Forage Seed and Ryegrass Seed Comparison

Time to Order Winter Forage Seed and Ryegrass Seed Comparison

Dennis Hancock, UGA Extension Forage Specialist

Book Your Seed Soon

I don’t mean to be an alarmist, but… you may want to buy your winter grazing seed soon. Annual ryegrass seed supplies are tight, and the prices look to be as high or higher than last year. Small grain seed supplies are rumored to be lower, and the seed quality challenged because of poor weather during the harvest season.

Calibrate Your Drill for Different Ryegrass Varieties

Seed sizes can vary considerably from one seed lot to another. But, the difference between diploid and tetraploid ryegrass varieties is HUGE!

There are several varieties of annual ryegrass on the market that are tetraploids, meaning their plant cells contain 4 sets of chromosomes (4n) rather than the 2 sets of chromosomes found in the more common diploid (2n) varieties. Consequently, tetraploid varieties have seed that may be up to 150 to 200% the size of diploid varieties (see figure below). Even though the seeding rate is the same (i.e., same lbs/acre), one will likely need to adjust the seed metering unit opening depending upon whether they are planting a diploid or tetraploid variety to ensure the appropriate seeding rate is being used. So BE SURE to calibrate, check, and adjust the drill frequently to account for differences in seed size between diploid and tetraploid varieties.

Each of these beakers contains 20,000 seed of their respective varieties. Note that the seed of tetraploid varieties takes up approximately 140-150% of the same volume as the diploid varieties. Photo credit: Henry Jordan, UGA Statewide Variety Testing Program.


Get the Most Out of Your Pasture Herbicide Applications

Get the Most Out of Your Pasture Herbicide Applications

If you have pastures or hay fields, weeds will always be an issue. Good fertility and grazing management will go a long way towards keeping weeds in check and these factors should be evaluated and addressed as a means of weed prevention. However, chances are that from time to time it will become necessary to use herbicides to control problem weeds. There are many excellent herbicides available for use in pastures and hay fields. Thankfully, when selected and used correctly, these products are an economically sound way to control most of our problem weeds.

Caution: the general effectiveness of these herbicide products can cause producers to become somewhat nonchalant when it comes to management decisions surrounding their use.  As an Extension Agent, I often get the call or text, “What’s best for killing (insert problem weed here)?” There needs to be much more to the conversation than the desired one or two-word answer. Herbicides are a management tool, and their usage should be based on their ability to add value to your operation.

Selecting the wrong herbicide for the job or applying a product in a manner that limits its efficacy virtually guarantees a negative economic impact. Some recent conversations I’ve had with experienced pasture managers have reminded me that we can all stand a reminder on how to maximize the efficacy and overall value associated with our usage of pasture/hay field herbicides. The following are a few key principles to help you maximize the value realized out of your herbicide program.

  • Know your enemy – weeds

    If you don’t know exactly what weed(s) you are trying to control, planning and delivering an effective herbicide program is nearly impossible. No single herbicide controls all weeds. To even begin selecting the best herbicide option for your situation you must know what weeds you are trying to control. Even if weed identification doesn’t excite you, don’t skip this step in the process. Your County Extension Agent is available to help you through the entire process, including weed identification.

  • Always consider forage tolerance when selecting a herbicide

After you have identified your problem weeds you can begin to determine what products will provide effective control. Be careful, not all pasture herbicides are safe for all types of pasture grass. This consideration requires that you understand what your forage base is composed of. Bahiagrass, bermudagrass, and crabgrass are all common warm season forages in NW Florida and they each tolerate various herbicides differently. To further complicate matters it is not unheard of for all three of these species to be growing intermixed in the same field. If you are controlling weeds in broadleaved forages (perennial peanut, clover, etc.) forage tolerance is a huge concern – very few pasture herbicides can be used safely on broadleaf plants. Failing to consider forage tolerance to herbicides can be a very costly mistake. Herbicide injury can cause substantial production loss or even complete stand loss.

  • Always consider the residual effects of herbicides

Many of the most effective pasture herbicides have a residual component. This means that the product will continue to provide herbicidal activity for an extended period (this varies product to product and with environmental conditions) after its initial application. Generally, this characteristic serves to enhance weed control, but it can cause significant issues when not properly accounted for. Commonly, these potential issues are addressed on herbicide labels as “plant back restrictions” or the amount of time after the application of an herbicide until it is safe to plant various crops in the treated area.

Crop rotations have made row-crop producers accustomed to paying close attention to plant back restrictions. Livestock and hay producers more commonly operate with a perennial forage base. However, residual herbicide issues can arise when warm-season pastures are over-seeded with cool-season annual forages. Many common, summer applied, pasture herbicides can potentially damage fall planted winter annuals.

This field, being harvested for baleage, is comprised of a fairly even mix of bahia, bermuda, and crabgrass. Their is also a mixture of annual and perennial weeds in this field. This mixture of species makes product selection and application timing fairly complex.  Photo Credit: Mark Mauldin

After consideration of the three points above, it is possible to determine what product(s) are suitable for your situation. Once the suitable options have been identified, product price becomes a key point to consider. Product price should be evaluated in terms of cost per acre, considering application rate. With a known herbicide cost per acre, be sure that forage quantity and/or quality improvement associated with the herbicide application financially justifies the application. Be sure to remember that benefits provided by effective herbicide use can and should last many years.

A perfectly selected product applied incorrectly will likely not achieve the desired weed control or financial return. The following are a few considerations to help ensure/improve the efficacy of pasture herbicides. This is by no means an exhaustive list, simply some points that I have commonly and/or recently seen producers fail to consider.

  • Use the correct rate

    More is not always better and less only saves money if the weeds are still controlled. Use the labeled rate. In the event a range of rates appears on the label, see comments below on spray timing. To know you are using the correct rate, your application equipment must be correctly calibrated. Your county Agricultural Extension Agent can help with this process.

  • Use surfactant

    Always follow label recommendations. That said, generally speaking, herbicide efficacy will be improved by adding 0.25-0.50% (by volume, of the total spray mixture) Non-Ionic Surfactant. This translates to 0.64-0.32 oz/gal of spray mixture or 1qt/50gal – 1qt/100gal of spray mixture. In the big scheme of things, surfactant is inexpensive and is generally always a good investment.

  • Spray timing is crucial

    Determining the most effective timing for herbicide applications is very closely related to knowing the specific weeds you are facing. It is generally more cost effective to control annual and new (first year) perennials earlier in their growing season. Waiting later into the growing season allows weeds to become stronger and make seed. Weeds may be controlled after seed set (often requiring higher herbicide rates), but in most cases there will be subsequent generations to deal with. Spraying earlier in the growing season also allows for weeds to be controlled before they have a chance to negatively impact that season’s forage production. Timing is even more crucial when it comes to controlling established perennial weeds. The ideal timing varies by species and situation and should be confirmed before spraying. In general, these weeds are most effectively controlled with late-summer/early-fall herbicide applications.

Regardless of species, herbicide efficacy is reduced when weeds are stressed at the time of application. Post emergence herbicides (the vast majority of pasture products are in this category) are most effective when applied to “happy,” actively growing weeds.

Herbicides can be very effective, especially when their application is timed well. The hayfield pictured here was sprayed one time early this summer. Note the unsprayed area to the left, the entire field looked like that last summer. Photo Credit: Mark Mauldin

Again, this was not an exhaustive list of the considerations that need to be made prior to an herbicide application; only an attempt to address some of the points I have seen producers overlook this summer. Always read and follow herbicide labels – the label is the law.

Herbicides are effective tools that when used properly can have a positive economic impact on your operation. Please take the time to carefully evaluate your situation and make well informed decisions to ensure that your weed control efforts are as successful as possible.

For a more in-depth explanation of any of the topics addressed in this article or other questions relating to pasture/hayfield weed control please contact your county’s Agricultural Extension Agent.

Weed Management in Pastures and Rangeland 2018 – is also an excellent publication on pasture weed management.