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 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
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.
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
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 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
Dr. Clive Bock, USDA-ARS talked to attendees about pecan scab management at the 2018 Pecan Field Day
This year’s UF/IFAS Florida Pecan Field Day took place on Thursday, September 13, 2018 at the Jefferson County Extension Office in Monticello, Florida. Extension specialists from Florida and Georgia provided growers from across the state with information about current pecan production practices and management tips. Pesticide continuing education units (CEUs) were provided for Florida and Georgia pesticide applicators, as well as for Certified Crop Advisors. Simpson Nurseries of Monticello sponsored a barbecue lunch for the attendees.
The focus of the Pecan Field Day was primarily on production practices. Speaker topics included Best Management Practices (BMPs) and cost-share opportunities for growers, weed management, fertility, pecan scab management, insect pest management and information regarding new pecan varieties. The following provides a short summary of topics discussed by each speaker, followed by links to download PDF (printable) versions of the presentations given at the Pecan Field Day.
BMAPs, BMPs and Cost-Share Opportunities
Dr. Andrea Albertin, UF/IFAS Water Resources Agent provided information on the implications of the 2016 Florida Water Bill. According to this bill, farmers in a Basin Management Action Plan (BMAP) can choose to either: (1) enroll in the Florida Department of Agriculture and Consumer Sciences (FDACS) (BMP) program and implement BMPs or (2) monitor water quality on their farm. Currently, in the Florida Panhandle there are several BMAP areas: Wakulla Springs, Wacissa Springs, Jackson Blue Springs and the Suwannee River Basin. There is financial assistance available from FDACS, NRCS, water management districts, and the Mobile Irrigation Lab for farmers enrolled in the BMP program.
Herbicides for Pecan Orchards
Dr. Peter Dittmar, UF/IFAS Weed Specialist shared information on the current herbicides labeled for use in Florida pecan production. It’s important to know which weed you are targeting and selecting the proper herbicide for its control. He also discussed the benefits of using a pre-emergent herbicide to reduce the use of post-emergent herbicides and to decrease the likelihood of building herbicide resistant weed populations.
Dr. Lenny Wells, UGA Pecan Specialist discussed the importance of proper fertilization for young and mature pecan trees. Leaf sampling between July 7th and August 7th are the most effective means of determining nutrient requirements, and soil sampling should be done in the fall/winter to determine pH and toxicities.
Pecan Scab Management
Dr. Clive Bock, USDA-ARS-SEFTNRL Plant Pathologist spoke on the proper fungicide spray distribution and coverage for effectively managing pecan scab. He stressed the importance of rotating fungicide modes of action as resistance is an issue. Phosphite fungicides are effective for controlling pecan scab on the fruit and the foliage. There are organic options available for managing pecan scab.
Management of Common and Occasional Pests of Pecan
Dr. Ted Cottrell, USDA-ARS-SEFTNRL Entomologist discussed managing the black peach aphid using gibberellic acid, a plant growth regulator. He also talked about mating disruption as a possible control for the pecan nut casebearer and the hickory shuckworm. Mating disruption prevents the male insect from finding the female, thus the mating process is disrupted. There are several types of scale insects that occur on pecan, and timing insecticide applications to the crawler stage are effective.
New Pecan Variety Releases
Dr. Patrick Conner, UGA Pecan breeder provided variety data from trials in Georgia demonstrating trends in pecan performance. The pest resistance, yield, nut quality and tree attributes for several varieties were discussed. He also discussed tree availability for different varieties.
Sponsors of the 2018 Florida Pecan Field Day included Farm Credit of Northwest Florida, Savage Equipment of Georgia and Simpson Nurseries.
Florida Pecan Growers Association
Following the Pecan Field Day, the Florida Pecan Growers Association met for their annual meeting. The Florida Pecan Growers Association is looking to grow their organization and connect with pecan producers across the state. If you are a current or prospective pecan grower in Florida and are interested in becoming a member of the Florida Pecan Growers Association, please contact me. The Florida Pecan Growers Association will hold their next meeting at 9:30 EDT on March 1, 2019 at the Jefferson County Extension Office (2729 W. Washington Hwy. Monticello, FL 32344).
For more information on pecan production or about upcoming educational events, contact your local extension office.
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During summer and fall, a lot of us spend hours trekking through forested areas and pasture lands, either for work, if we are lucky, or by simply enjoying the great outdoors. Unfortunately, there are not-so-nice life forms that also enjoy this time of year, like poisonous plants. There is a long, long list of enemies when discussing poisonous plants. However, there are a few more common, native plants, like poison ivy, poison oak, poison sumac and poisonwood that we should be fully aware of in our surroundings, along with their friendly mistaken counterparts. This article will help to distinguish poison ivy from Virginia creeper.
Figure 1: Poison Ivy on Left / Virginia Creeper on Right in Fall Colors. Credit: Sydney Park Brown, UF/IFAS.
Poison Ivy (Toxicodendron radicans) grows in just about any location imaginable. Poison Ivy is probably the most common and most irritating (mentally & physically) poisonous plant one will come in contact with. This is a woody shrub that can reach 6 feet in height or grows like a vine up to 150 feet tall on trees. As a vine, it is often found on fences and trees. The leaf forms three leaflets, which can be 2-6 inches in length and may have smooth edges or can be toothed. Leaves are shiny with a tint of red most of the year. Leaves will turn purple before dropping in the fall. Remember the old saying when it comes to identifying poison ivy, “leaflets three, let it be.”
Virginia Creeper (Parthenocissus quinquefolia) is commonly mistaken for poison ivy. It is a climbing vine as well with similar growth patterns. However, there are some distinguishing traits, as Virginia Creeper has five leaflets, instead of three. Virginia Creeper also has blue-black berries along with tiny, sticky segments that are used to attach to surfaces. During the fall, Virginia Creeper leaves turn red before dropping.
There are some important precautions about poison ivy that we should remember when out and about. Warmer months correspond with the increased sapping stage of poisons plants, which means the allergic reaction from contact is both more likely, and possibly more severe. The four native poisonous plants mentioned earlier all contain urushiol. This is a plant oil that causes a severe skin rash when contact is made. People have different sensitivity levels to exposure. Symptoms appear within a couple of days and the itching and burning of the skin can last weeks. Over the counter products with the active ingredient dient bentoquatam can help prevent or reduce the reaction. This product must be applied before contact is made. If exposed, as soon as possible clean area with warm, soapy water and rinse with cool water. Contaminated clothing should be washed separately from other laundry. Severe reactions may need professional medical treatment.
Poison ivy, poison oak, poison sumac, and poisonwood. Credit: Cook (2012); Larry Korhnak, UF/IFAS
Contact your local county extension office for more information on poisonous plants in your area. Supporting information for this article can be found in the UF/IFAS EDIS publications: “Identification of Poison Ivy, Poison Oak, Poison Sumac and Posionwood,” by Sydney Park Brown.
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.
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.
Photo Credit: Tennessee Vascular Plants Eugene Wofford
Perilla Mint is a toxic ornamental that has escaped from landscapes in the Southern U.S. and is now an established pasture weed. As a summer annual it grows in shaded areas up to a height of 2 feet tall. It is often identified by its purple shading on the undersides of the leaves. All parts of the plant are toxic to livestock, with symptoms including labored breathing and death. Late April to early June is the ideal time to scout your pastures for Perilla Mint.
For help identifying weeds or developing a control plan for your operation, please contact your county extension agent.
For more information on this topic please use the links for the following publications: