Proper Use and Handling of Glyphosate in Plant Nurseries
http://edis.ifas.ufl.edu/ ( Publisher's URL )
Full Citation
Permanent Link: http://ufdc.ufl.edu/IR00000960/00001
 Material Information
Title: Proper Use and Handling of Glyphosate in Plant Nurseries
Physical Description: Fact Sheet
Creator: Steed, Shawn Thomas
Stamps, Robert H.
Publisher: University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication: Gainesville, Fla.
Publication Date: 2012
Subjects / Keywords: Glyphosate
Plants -- Effect of glyphosate on
Abstract: "Glyphosate is the most used herbicide in the nursery industry in the United States. Used for postemergent control of vegetation, it controls annual and perennial grasses, broadleaves, and sedges. But it is easy to cause unintended damage to desirable vegetation if this product is used incorrectly. This 4-page fact sheet outlines the proper use of glyphosate for plant producers and their employees."
Acquisition: Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Diana Hagan.
Publication Status: Published
General Note: "ENH1198."
General Note: "Original publication date May 2012."
 Record Information
Source Institution: University of Florida Institutional Repository
Holding Location: University of Florida
Rights Management: All rights reserved by the submitter.
System ID: IR00000960:00001


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ENH1198 Proper Use and Handling of Glyphosate in Plant Nurseries1Shawn T. Steed and Robert H. Stamps2 1. This document is ENH1198, one of a series of the Environmental Horticulture Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date May 2012. Visit the EDIS website at http://edis.ifas.u.edu 2. Sha wn T. Steed, Extension agent II, Hillsborough County Cooperative Extension Service, and Robert H. Stamps, professor, Mid-Florida Research and Education Center-Apopka; Environmental Horticulture Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, 32611. The use of trade names in this publication is solely for the purpose of providing specic information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication do not signify our approval to the exclusion of other products of suitable composition. All chemicals should be used in accordance with directions on the manufacturers label. The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or aliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A&M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim DeanGlyphosate is the largest-selling single crop protection chemical worldwide (Woodburn 2000) and the most used herbicide in the nursery industry in the United States (Norcini et al. 1996). It is used for postemergent control of vegetation. Glyphosate is an extremely eective chemical that controls a broad spectrum of annual and perennial grasses, broadleaves, and sedges. is herbicide acts as an inhibitor of an enzyme that leads to the formation of several essential amino acids required for normal protein synthesis. Glyphosate has the ability to spread throughout the plant and concentrate in the growing regions where these amino acids are most needed for new growth. As a nonselective, translocating herbicide, it is easy to cause unintended damage to desirable vegetation if this product is used incorrectly. is publication outlines the proper use of glyphosate for plant producers and their employees. As with any herbicide, glyphosate should not be overused and should be one of several components of an integrated weed management program. In addition to chemical control, growers should employ biological, mechanical, and cultural weed control techniques. In the case of glyphosate, its general overuse and the common practice of using it alone (hence only a single mechanism of weed control action) have resulted in the selection for an increasing number of glyphosate-resistant weed populations (Owen and Zelaya 2005). In addition, the improper use of glyphosate has resulted in weed population shis where glyphosate-tolerant weeds predominate. An increasing number of glyphosate-tolerant and resistant weeds are emerging (Beckie 2011), some of which are showing up in plant nurseries. (See Identication, Impacts, and Control of Ragweed Parthenium [Parthenium hysterophorus L.] [http://edis.ifas.u.edu/ep448] and Prevention, Early Detection, and Eradication of Benghal Dayower in Field Nurseries [http://edis.ifas.u.edu/ep350] for more information.) erefore, it is recommended that, whenever possible and appropriate, glyphosate be used along with residual herbicides with overlapping ecacy of control of the target weeds. is will result in better, longer-term control and lengthen the time before additional herbicide applications might be needed. Before using any herbicide (or other pesticide), the entire label should be read and understood. Remember: e label is the law!


2Step One: Identify the Weed Speciese rst step toward proper application is to identify the weed species that must be controlled. Identication may be accomplished using guides, such as Weeds of Southern Turfgrass by T. R. Murphy et al., available from the UF/IFAS Extension Bookstore (http://ifasbooks.ifas.u.edu), or weed samples may be taken to your local Extension oce for help with identication. Weed samples should include as many parts of the plants as possible, especially reproductive structures like owers or seeds.Step Two: Read and Follow Label InstructionsCorrectly identifying the weed species allows the applicator to determine the amount of glyphosate product to be mixed in a spray tank to obtain the recommended concentration for the target weeds. Follow the label closely and adhere to the warnings that are mentioned, especially those regarding proper application listed under General Information on the label. ese can be summarized in the following list: 1. N ever mix glyphosate in galvanized steel or unlined steel container spray tanks. Doing so can cause a highly combustible hydrogen gas to form and may result in metal corrosion if le in contact for a period of time. 2. G lyphosate can be washed o with either rain or irrigation water for a period of time aer application. Check the label of the glyphosate formulation for that critical time period. 3. G lyphosate is rapidly inactivated once in the soil. Weed seeds that germinate aer application will not be controlled. 4. A nnual weeds are harder to control the larger they grow and when they are stressed. ey should be treated before they start to develop reproductive organs (cones, owers, etc.). 5. G lyphosate may not translocate well when weeds are not growing, and reduced control may result when the weeds have been recently cut or if there are drought conditions. 6. V isible symptoms of the herbicides eects may take days to develop, especially in cold or cloudy conditions. 7. D o not let glyphosate-containing spray contact the foliage or green bark of desirable plants. Glyphosate should also not be allowed to come in contact with thin-barked plants. Applicators and handlers must wear long-sleeved shirts, long pants, shoes, and socks. Although not mandatory on the label, it is a good practice to wear chemical-resistant (e.g., butyl rubber, polyvinyl chloride) gloves when mixing and spraying glyphosate (Monsanto 2006) because a sprayer may clog, a leak may develop, or the applicators hands may come in contact with the herbicide. Hands and forearms are the most common place of contact for mixers and handlers. Always remember that anyone who is applying or handling glyphosate is considered a handler under the Worker Protection Standard Act. (For more information on the Worker Protection Standard, visit http://edis.ifas. u.edu/topic_wps.) Even a person who merely picks up a jug of herbicide to move it around on the farm is considered a handler and must have been trained as a handler. Also, waterproof gloves are required for early entry into glyphosate-treated areas if contact is anticipated with anything that has been sprayed.Step Three: Properly Calibrate Spray Equipmente next step is to properly calibrate spray equipment before making an application. e applicator must know what type of sprayer will be used and how much liquid is being applied over a certain amount of area. For help on this topic, please refer to Herbicide Calibration and Application (http://edis.ifas.u.edu/ topic_herbicide_calibration_and_application). Glyphosate sprays can be applied over a range of concentrations depending on the weed growth stage and species and the ability to obtain coverage with the spray. Check the product label for specic recommendations. For most of the weeds typically found around nurseries, 1%% solutions (volume glyphosate product/volume of water) are usually eective. However, if hard water (containing the cations calcium and magnesium) is used to make up the spray solution, some of the glyphosate may be bound up, thereby decreasing the sprays ecacy. is antagonism can be overcome by dissolving ammonium sulfate (AMS) in the water before adding the glyphosate (Peterson and ompson 2009). e recommended rate of dry AMS is 1%% (weight of AMS/weight of solution). An equivalent rate of a liquid formulation of AMS may also be used. Other adjuvants (inert ingredients), such as urea (Li et al. 2012) and commercially formulated products, can also be used to counter the eects of hard water. Further, be aware


3that dierent commercial glyphosate formulations contain dierent adjuvants and can vary in ecacy (Chikoye, Lum, and Udensi 2010).Step Four: Apply SolutionWhen the appropriate application concentration is determined and thoroughly mixed, the solution can then be applied. For the best results, apply to dry weed foliage. Spray coverage should be uniform, complete, and made on a spray-to-wet basis, meaning the leaf surface should have a misted, wet appearance (Fig. 1). It is very important to remember that glyphosate translocates. Overapplication is one of the most common errors found with the application of glyphosate. ere is no need to spray weeds to the point of runo or until they are dripping wet (Fig. 2). Further, if the glyphosate solution enters the soil or is sprayed around nursery containers, it could injure soil organisms by direct contact and non-target plants through root uptake before inactivation can occur. In addition, overapplying glyphosate is a signicant waste of time and money. Using a temporary dye in the spray solution can help applicators check spray uniformity and keep track of what weeds have been treated (Figs. 1 and 2). e dye also helps to avoid skips and oversprays. Apply glyphosate solution to the target weeds only. Never spray in high wind conditions or at times when there might be temperature inversions. Temperature inversions are when temperatures are warmer at higher altitudes than on the ground. ey are associated with limited cloud cover and wind. ey also may be characterized by the presence of ground fog or smoke that moves horizontally rather than vertically. Avoid overspray or dri particles that may contact any desirable plants in the nursery. If the herbicide dris and contacts green leaves, shoots, or surface roots of desirable plants, they will be negatively aected by the herbicide. e potential for dri can be reduced by using spray nozzles designed to reduce the production of ne spray droplets and by avoiding the use of high sprayer pressures. Sprayer shields and hoods (Fig. 3) can work well in nursery production settings to minimize the potential of dri onto saleable inventory. Figure 1. The glyphosate spray should be applied to thoroughly coat the foliage without runo. The inclusion of a temporary dye can aid in the accurate and uniform application of the spray. Credits: S. Steed Figure 2. Too much glyphosate spray has been applied to this plant, and the runo represents wasted money and time and could negatively aect non-target plants and animals. Credits: S. Steed Figure 3. Shields can help to reduce spray drift to non-target plants. Credits: S. Steed


4Be aware that glyphosate can wash o of inorganic materials like gravel and plastic weed control fabrics (Grey et al. 2009). If that wash-o water comes in contact with the roots of plants, damage may occur. Likewise, it is reported that glyphosate can bind to bark used in potting mixes and be released when the containers are irrigated. erefore, use means other than herbicides to keep stored growing media weed free. Sprayers used to apply glyphosate and/or other herbicides should be dedicated for applying herbicides only and not used to spray crops with other materials, such as fungicides or insecticides. If the sprayer must be used to apply materials to desirable plants, it must be cleaned out immediately aer being used to apply glyphosate. Spray as much of the glyphosate solution out of the spray tank as possible, then rinse the tank with clean water. Rell the tank and spray clean water through the hose and nozzle. Running a cleaning solution of 1%% (volume/volume) ammonia in water through the system followed by a second clean water rinse nishes the cleaning process. Be careful not to dispose of the water used in cleaning anywhere where it could damage plants or cause environmental harm.Summarye eectiveness of glyphosate can be ensured by following the herbicide label and applying the product in the proper manner and quantities. Following proper application procedures reduces the amount of non-target damage caused by dri occurrences and saves time, labor, and money incurred by unproductive, wasteful applications.Literature CitedBeckie, H. J. 2011. Herbicide-Resistant Weed Management: Focus on Glyphosate. Pest Management Science 67 (9):1037. Chikoye, D., A. F. Lum, and U. E. Udensi. 2010. Ecacy of a New Glyphosate Formulation for Weed Control in Maize in Southwest Nigeria. Crop Protection 29 (9):947. Grey, T. L., W. K. Vencill, T. M. Webster, and A. S. Culpepper. 2009. Herbicide Dissipation from Low Density Polyethylene Mulch. Weed Science 57 (3):351. Li, P. L., S. He, T. Tang, K. Qian, H. W. Ni, and Y. S. Cao. 2012. Evaluation of the Ecacy of Glyphosate Plus Urea Phosphate in the Greenhouse and the Field. Pest Manage ment Science 68 (2):170. Monsanto. 2006. Roundup Original MAX Herbicide Material Safety Data Sheet. Monsanto Company. Norcini, J., M. Garber, W. Hudson, R. Jones, A. Chase, and K. Bondari. 1996. Pest Management in the United States Greenhouse and Nursery Industry: IV. Weed Control. HortTechnology 6 (3):211. Owen, M. D. K., and I. A. Zelaya. 2005. HerbicideResistant Crops and Weed Resistance to Herbicides. Pest Management Science 61(3):301. Peterson, D., and C. ompson. 2009. Glyphosate Weed Control Enhancement with Ammonium Sulfate and Commercial Water Conditioning Agents. Journal of ASTM International (JAI) 6 (5):JAI102147. Woodburn, A. T. 2000. Glyphosate: Production, Pricing and Use Worldwide. Pest Management Science 56 (4):309.