Edis weed seed shapes

Planting Pinellas [email protected] (Pinellas County Extension)

Gardening Tips and Information for Growing Great in Pinellas County. Presented by UF/IFAS Pinellas County Extension faculty and staff.

  • 23 AGO 2013

Fall Gardening 101

Theresa Badurek, Urban Horticulture Extension Agent Agapanthus(Photo-UF/IFAS)In the fall the weather will begin to cool and the rains will slow down. (Hard to imagine these days, isn’t it?) These conditions present several challenges for the home gardener, but there are some things you can do to prepare your garden (and yourself) for the cooler, drier weather. If you use annualsin your landscape it may be time to replace some of the summer annuals. In early fall (Sept.-Oct.) try plants like ageratum, coleus, celosia, zinnia, and wax begonia to give your landscape color into cooler weather. Then once temperatures start to cool (Oct.-Nov.) you can plat petunia, pansy, snapdragon, dianthus, and alyssum. When shopping for annuals choose compact plants with healthy leaves, good color, and lots of flower buds (they don’t have to be in bloom at the time of purchase). For more information about gardening with annuals in Florida: http://edis.ifas.ufl.edu/pdffiles/MG/MG31900.pdf. Since annuals are seasonal they should make up focal areas in the garden, but not too much space, as they require a lot of energy and resources for such a short life-span. Lots of bulbs like to get their start in these cooler months. Plant agapanthus, amaryllis, and lilies now for blooms next spring and summer. Divide and replant perennials and bulbs that have grown too large- be sure to do this by November so they can become established before the weather turns colder. Add organic matter to new planting areas and monitor water needs during establishment. For more information about dividing and propagating plants: http://edis.ifas.ufl.edu/mg108. Cilantro (Photo-Iowa State University Extension) Plant herbs that tolerate the warm temperatures of early fall, such as Mexican tarragon, mint, rosemary, and basil. Later in the fall when the weather is cooler try parsley, cilantro, garlic, and thyme. Since some herbs are annuals and some are perennials remember to group them accordingly so you won’t be disturbing the perennials when replanting the annuals. Many herbs are also suited to planting in containers- but you must remember that those plants in containers will dry out faster than those in the ground and will need more irrigation attention. For more information about growing herbs in your Florida garden: http://edis.ifas.ufl.edu/pdffiles/VH/VH02000.pdf. Cabbage (Photo-Purdue)In this cooler weather (Oct.-Nov.) you can plant cool-season vegetablecrops, such as celery, cabbage, lettuce, collards, and many others. For more information about vegetable gardening in Florida, including suggested crops and their planting dates: http://edis.ifas.ufl.edu/pdffiles/VH/VH02100.pdf. In September or October, fertilize your citrus with a balanced fertilizer. Many early season citrus varieties will be ready for harvest starting in October and November, such as ‘Navel’ and ‘Hamlin’ oranges, ‘Marsh’ grapefruit, ‘Orlando’ tangelos, ‘Meyer’ lemons, and more. If necessary, fertilize your St. Augustinegrass and bahiagrass lawns with a fertilizer containing at least 50% slow-release nitrogen and no phosphorous in early October. Do not use a “weed and feed” product. No lawn and landscape fertilizer containing nitrogen can be used in Pinellas County before October 1st. (For more info on the Pinellas County Fertilizer ordinance: http://www.pinellascounty.org/PDF/Fertilizer-Ordinance-Brochure.pdf.) As the weather gets cooler the turf will not need as many nutrients so this is best applied in early October. Enjoy planning for this cooler season soon to come!

  • 16 AGO 2013

You Could Have it Made in the Shade

During the summer when the heat is stifling, it’s important to take advantage of shade when you are outdoors. If your yard has no shade trees you may not have much respite from the heat. Shade on your home and air conditioner may also decrease your energy costs in the summer. With all of these benefits you may be considering planting shade trees on your property. Planting a tree is a (hopefully) long-term commitment so you want to choose the right tree from the start. If you choose an evergreen tree you will have shade year-round while deciduous trees will shade your house in summer but allow the sun to warm your house in winter when they lose their leaves. You can plant shade trees at any time of year; just be sure to follow UF recommendations for proper planting practices. To learn more about these practices visit Planting and Establishing Trees at http://edis.ifas.ufl.edu/pdffiles/EP/EP31400.pdf. Pinellas County is unique in several ways- most of us have smaller lots to work with, some have salt breezes from the water to contend with, and we all have wind storms. You may be wondering what shade trees can we plant here that will thrive in our unique environment? A favorite shade tree in our county is the Live Oak, Quercus virginiana (large tree, zones 8-11). Live oak is a great choice but grows very large- up to 40 to 60 feet in height with a 60 to 100 foot spread. It is drought and salt tolerant as well as wind resistant, which is why it’s a popular choice if you have the room. Sparkleberry, Vaccineum arboreumSweetgum, Liquidambar styraciflua If you have a moist but well-drained site and space you could consider Sweetgum, Liquidambar styraciflua (large tree, zones 5b-10a) or Sparkleberry, Vaccinium arboreum (small tree, zones 7-10). These two choices are deciduous, so they will lose their leaves in winter when you would probably prefer more sun anyway. Their leaves also turn beautiful colors before they fall bringing seasonal color to your landscape. Sparkleberry has high wind resistance and sweetgum is considered to have medium-high wind resistance. Sparkleberry also flowers profusely if grown in full sun. Silver variety of Buttonwood, Conocarpus erectus For smaller property with drier conditions you might consider the following small trees, all of which are salt and drought tolerant and have high wind resistance: Buttonwood, Conocarpus erectus (small tree, zones 10a-11), Simpson’s Stopper, Myrcianthes fragrans (small tree, zones 9-11), and Yaupon Holly, Ilex vomitoria (small tree, zones 7-10). These three choices are all evergreen and will provide year-round shade. All three of these choices can be grown as a large shrub or a small tree. Each of these have unique characteristics that take them beyond a simple shade tree: Buttonwood has a silver variety that has silvery leaves that shimmer in the sun and the wind, Simpson’s Stopper has reddish, flaking showy bark and Yaupon Holly produces beautiful red fruit in the fall and winter on the female plants (males must be present for fruit production). Yaupon Holly, Ilex Vomitoria Yaupon Holly fruitThe right shade tree for you may not be on this short list, but remember to consider size, evergreen vs. deciduous, color, seasonal interest, and match growing conditions to your site conditions for the greatest chance of success. For more guidance with this and other plant choices in your landscape please visit the interactive plant selector Florida-friendly Plant Database at http://floridayards.org/fyplants/. For information on the health and maintenance of shade trees please visit: http://hort.ifas.ufl.edu/woody/maintenance.shtml. *Northern Pinellas County is in zone 9b, central and southern Pinellas County is zone 10a.

  • 6 MAY 2013

Florida Summer Gardening 101

It’s May and the weather is still pleasant… for now. Soon we will be battling hot summer sun, bugs, humidity, and torrential rains every afternoon. These conditions present several challenges for the home gardener, but there are things you can do now to prepare your garden (and yourself) for the heat. Smart garden planning will give you more time to play here! Photo courtesy Pinellas County. If you use annuals in your landscape you probably know by now that many of them don’t tolerate the Florida heat very well. Just because a plant is being sold in local garden centers does not necessarily mean it’s the right time to plant them here in Florida. However, there are several annual plants that take our temps in stride. They include salvia, torenia, wax begonia, coleus, and ornamental peppers. When shopping for annuals choose compact plants with healthy leaves, good color, and lots of flower buds (they don’t have to be in bloom at the time of purchase). Click here for more information about gardening with annuals in Florida. Coleus, photo courtesy UF/IFAS Okeechobee County Since annuals are seasonal they should make up focal areas in the garden, but not too much space, as they require a lot of energy and resources for such a short life-span. Right now is also a great time to plan new perennial plantings, including trees, palms, shrubs, and groundcovers. If you have a plan at the ready you can be prepared to install once the rainy season starts- then you won’t need to water as often yourself. Just remember that if you plant something before you go on vacation you should ask a friend or neighbor to care for it while you are gone. Click here for more information on establishing new trees and shrubs. But that’s not all you can do this time of the year. You can also plant some herbs that like the heat such as basil, Mexican tarragon, and rosemary. Since some herbs are annuals and some are perennials remember to group them accordingly so you won’t be disturbing the perennials when replanting the annuals. Many herbs are also suited to planting in containers- but you must remember that those plants in containers will dry out faster than those in the ground and will need more irrigation attention. Click here for more information about growing herbs in your Florida garden. Southern peas, aka black-eye peas, courtesy UF/IFAS ExtensionIf you think your new herbs might get lonely out there, don’t hesitate to try your hand at vegetable gardening. But (and this is a biggie) you can’t plant the same veggies in the summer that you can up north. Our hot temps just won’t work with many of the usual veggies, but there are several crops you can grow here in the heat including okra, southern pea, and sweet potato. Click here for more information about vegetable gardening in Florida, including suggested crops and their planting dates. Summer (June, July and August are great) is also a good time to solarize your vegetable garden, so you can add this to your summer gardening plan. What does that mean? Well, this one prep can help reduce soil pests and even kill weed seeds, making your garden more successful throughout the fall gardening season. Solarizing involves harnessing the heat of the sun by covering the soil with clear plastic and is most effective in the summer months. To solarize, you want to prepare your soil with any amendments such as compost or manures before you begin. Make sure your garden is clear of rocks, twigs, weeds, and other debris. Till the soil to at least 6 inches to make sure the heat will penetrate deeply enough to be effective. The day after a good rain or irrigation is best for applying the clear plastic sheeting over the soil. Lay sheets of clear plastic over the soil and bury the edges to

  • 7 DIC 2012
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Insect, Plant & Disease ID

Lara MillerNatural Resource Agent Identification Resources:Insects, Plants, & DiseasesMany Florida residents find unknown plants growing in their yard, unknown bugs in their houses or gardens, and apparent diseases on what were previously healthy plants. So what resources are out there to help you turn the unknown into known? Extension OfficesYour local Extension office should be your first point of contact for helping you identify any mysterious problems or species in your home or yard. You can call, e-mail, or visit the office in person. Lawn and Garden HelpWe offer walk-in Lawn and Garden Help Desk services at the following locations:· Pinellas County Extension Office 12520 Ulmerton Rd., Largo, FL 33774 Walk-In Hours: Mon-Fri 8am-5pm (excluding holidays)· Pinellas County Master Gardener Plant Clinic Palm Harbor Library 2330 Nebraska Ave., Palm Harbor, FL 34683 Wednesdays from 10am-2pm, January through mid-November Lawn and Garden Help LineLawn & Garden assistance is also available by phone at (727)582-2100 and then Press 1. Hours of Operation: Monday, Tuesday, and Thursday 9am-12pm and 1pm-4pm When you do, have or send the following:· Photographs (digital or snapshot) or a physical sample if you are making an in-person visit.· As detailed a description of the organism or disease symptom as possible (e.g., where and when you saw it, behavior, any others present, how long it has been occurring, the type of damage). Even if your county Extension office cannot make the identification or disease diagnosis, the agents will be able to help you with forms and samples to send to UF/IFAS’s diagnostic laboratories. InsectsThere are thousands of insects in Florida, and knowing whether the one you found is harmless, beneficial, or damaging is key for deciding on control measures. The Insect ID Lab can analyze insect samples sent by Florida residents. The Help Desk can provide answers or information on preparing a sample to send to the Insect ID Lab. The lab will charge $8 per sample sent.Send samples in a crush-proof container with the accompanying submission form (205KB pdf). Sending samples in flat or padded envelopes is discouraged.Collecting a Sample1) The more specimens included in a sample, the better. 2) In most cases, you should kill and preserve the insects before sending them. a. Do this by placing them in the freezer or in a vial with rubbing alcohol. i. Caterpillars will not preserve well in an alcohol solution. Moths and butterflies should be kept dry.b. Take special care if you believe the insect could be a new or exotic species. Contact your Extension office or read the submission guide for more details. PlantsYou can either bring in a physical specimen of the plant (or blossom, leaf, etc.) or a photograph to the Help Desk. Multiple photographs are best, with pictures of leaves, bark or stem, blossoms, seed pods, as well as the whole plant itself.In addition to the pictures or sample, pass along as much additional information as possible:· Size and shape of plant, leaves, blossoms, seeds.· Growth habit and location.· Conditions in location (e.g., sun, soil type and moisture, cultivated or forested area).· Colors of plant and blossoms.If the Extension agent or Master Garden

  • 30 NOV 2012

by Theresa Badurek, Urban Horticulture Extension Agent, UF/IFAS Pinellas County Extension Dahoon Holly, Ilex cassineWe all know that there are many beautiful holiday plants to enjoy this time of year. This year I would like to focus on a group of plants that not only bring us pleasure, but also provide something for our wildlife- hollies. There are several native hollies that we can grow here that provide food and habitat for our wildlife while also providing decoration both outside and in. Holly fruits are a favorite winter food for many birds and mammals, providing seasonal nutrition for our feathered and furry friends. In addition to providing a food source, holly shrubs and trees also provide habitat for many birds. While the most important benefit of these plants is enjoying them outdoors in their natural state, they can also be used as cut greens in holiday decorations (the evergreen varieties). Keep in mind that hollies are dioecious plants: the male and female flowers are on separate plants and female plants produce berries. If you are looking for berries for holiday décor you will want to make sure you have some female plants. Also, many of the dwarf varieties do not produce berries. If you don’t already have hollies in your landscape you may consider planting them now for next year. Hollies prefer part shade but most will tolerate full sun, they prefer acidic soils, and they all require a well-drained soil. Here are a few suggested native hollies: American Holly, Ilex opaca. This is the holly most traditionally associated with the holiday season. It has spiny leaves and red or yellow fruit. Click here for more info.  Fruit of Ilex opaca Foliage of Ilex opaca Dahoon Holly, Ilex cassine. This holly makes a great specimen or street tree. It even has another seasonally appropriate common name- Christmas Berry. Click here for more info. Fruit and foliage of Ilex cassineIlex cassine Yaupon Holly, Ilex vomitoria. Depending on the variety you choose this can be a small shrub or a small tree. Click here for more info.    Fruit and foliage of Ilex vomitoria Ilex vomitoria ’Dodds Cranberry’  These hollies, and others, would make great additions to the landscape-and great gifts for those on your holiday shopping list too. You will enjoy them and the wildlife will thank you. Happy holly-days everyone!

Managing Weeds in Florida Lawns

A weed is a plant in the wrong place or one that you do not want in your turfgrass. The first step in considering any type of weed control is to appropriately identify the weed. Control without weed identification may well create more issues, including turfgrass damage or death.

There are several types of turfgrass weeds based on growth habit and life cycle. Growth habit weeds include the following:

  • Broadleaves—Two seed leaves at germination, true leaves with net-like veins, and generally showy flowers; clover, beggarweed, matchweed, etc.
  • Grasses—One seed leaf, hollow rounded stems with joints and parallel veins in their true leaves; crabgrass, annual bluegrass, torpedograss, etc.
  • Sedges/Rushes—Sedges have triangular-shaped solid stems. Rush stems are round and solid. Both prefer moist habitats; yellow and purple nutsedge, etc.

Life cycle weeds include the following:

  • Annuals—life cycle is completed in one growing season.
  • Biennials—life cycle is completed in two growing seasons; vegetative growth in the first growing season and flowering in the second.
  • Perennials—life cycle is completed in three or more years.

The most successful weed control is based on proper turfgrass management practices that are used to create a dense and healthy yard. Consider the first of nine Florida-Friendly Landscaping TM principles: right plant, right place. Match the turfgrass variety with the site conditions of sun and shade. All turfgrasses, even those that are shade tolerant, require a minimum of five to six hours of sun each day. Bermudagrass and bahiagrass do not thrive in any shade conditions, which makes them more susceptible to weeds.

Proper cultural practices are required for dense turf to be capable of preventing weed infestations. Cultural practices include fertilization, watering, mowing, and pest control. Over and underperforming any of these practices increase the likelihood of weed invasion.

Both foot and vehicle traffic can damage turfgrass, which, again, is an invitation for weeds. Soil compaction and excessive water saturation should be corrected. Pests that disrupt/create holes in the soil surface, such as mole crickets and armadillos, create open areas, which encourage weed populations.

Lynn Barber, Agent

University of Florida/IFAS Extension, Hillsborough County

Lynn Barber, Agent, University of Florida/IFAS Extension, Hillsborough County, is responsible for educating residents on the nine principles of the Florida Friendly LandscapingTM program. These principles include right plant right place, water efficiently, fertilize appropriately, mulch, attract wildlife, manage yard pests responsibly, recycle, reduce stormwater runoff, and protect the waterfront. Barber is past president of the Florida Association of Natural Resource Extension Professionals and has received numerous awards for programming, publications, and television and radio segments. As a Master Gardener, she has given back thousands of hours in environmental horticulture education to the community.

Prevention is easier than control. Consider a groundcover instead of turfgrass in heavily-shaded areas. Scout your turfgrass regularly to identify potential weed and pest issues. Avoid parking, driving, and excessive walking on your yard. Water appropriately, ½–¾ inch per event, which includes rainfall. Fertilize appropriately, two to three times per year, and if you leave your grass clippings on your turfgrass, you can decrease fertilizations to one to two times per year.

Weeds can be controlled using the following methods:

  • Mowing—at the proper height and frequency for your turfgrass variety, remove no more than 1/3 of the leaf blade and mow when turfgrass is dry.
  • Hand pulling—if few weeds are present, this can be less time-consuming and easier than some options; remove roots, may need a trowel or shovel.
  • Herbicides—any chemical that damages or kills a plant, must follow the label instructions, the label is the law. Herbicides can be selective (control specific weeds without damaging other plants), nonselective (control/kill all plants), contact (affect only the portion of the plant tissue contacted by the herbicide), and systemic (kill plant over several days). Herbicides can be pre-emergence or postemergence. Pre-emergence are mainly used to control annual grasses (crabgrass, annual bluegrass) and some annual broadleaf weeds. This product is used before weed seed germination. Post-emergence herbicides are used on weeds that have emerged. It is easier to control younger versus older weeds.
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For additional information on controlling weeds in your lawn, weed control prior to turf establishment and in established turfgrass areas, application procedures and general pesticide information, please see the University of Florida publication, Weed Management Guide for Florida Lawns, by J. Bryan Unruh, Ramon G. Leon, Barry J. Brecke, and Laurie E. Trenholm at: edis.ifas.ufl.edu/ep141, from which this article was adapted.

As always, follow the landscape or architectural control procedures in your deed restrictions before making changes. For more information about the nine principles of the Florida-Friendly Landscaping™ Program, or for assistance with gardening-related questions, contact your local Extension office and/or visit the University of Florida website: solutionsforyourlife.com or edis.ifas.ufl.edu.

Alternatives to Synthetic Herbicides for Weed Management in Container Nurseries

Weed management is one of the most critical and costly aspects for container nursery production. High irrigation and fertilization rates create a favorable environment for weed growth in addition to crop growth. Weeds can quickly out-compete the crop for light and other resources, reducing the rate and amount of crop growth as well as salability (Berchielli-Robertson et al., 1990; Norcini and Stamps, 1992). Weed management in nursery production is most effectively achieved by preventative practices, primarily with the use of pre-emergent herbicides (Gilliam et al., 1990; Gallitano and Skroch, 1993).

However, there are valid reasons for managing weeds using alternatives to synthetic herbicides (Sidebar 1). Ornamental crops encompass a wide array of species, and herbicide products must be tested on each for effective, safe and legal use. Even when a product is labeled for a crop, it may not be sufficiently effective for the weeds present or may induce crop damage under certain circumstances. Finally, use of synthetic herbicides in greenhouses and other enclosed structures is often prohibited on product labels.

Reasons for not using synthetic herbicides:

  • Crop or site is not labeled for use with synthetic herbicides
  • Crop is damaged by synthetic herbicides
  • Synthetic herbicides are not effective on the target weeds (due to tolerance or resistance)
  • Grower desires to employ sustainable alternatives to synthetic chemical herbicides
  • Concerns about synthetic herbicide leaching and run-off

Increased emphasis on sustainability also results in growers choosing alternatives to synthetic herbicides. The Floriculture Sustainability Research Coalition (http://sustainablegreenhouse.wordpress.com/) defines sustainable production as a practice that aims to reduce environmental degradation, maintain agricultural productivity, promote economic viability, conserve resources and energy and maintain stable communities and quality of life (Dennis et al., 2010; Hall et al., 2010). Social, economic and regulatory issues might influence nursery producers to adopt sustainable production methods. With the adoption of more sustainable practices, producers should also have the ability to reduce input costs related to fertilizers and chemicals as well as reduce potential point source nutrient and chemical pollution. In addition, sustainable production of nursery plants could foster the development of new specialty nurseries, thus creating a market niche for “locally grown using sustainable methods.”

Weed management alternatives to synthetic herbicides include sanitation, exclusion, prevention, hand weeding, mulching and use of cover crops, heat and non-synthetic herbicides. Only some of these alternative methods can be used to control weeds in containers, but all can be used to manage weeds around containers and in non-crop areas. Also, most alternatives are not used alone because they cannot individually achieve weed control comparable to synthetic herbicides. Two or more alternatives are usually used simultaneously in order to achieve acceptable levels of weed control.

Sanitation ? Exclusion ? Prevention

One of the most effective and economical means of avoiding weed problems is preventing their presence through exclusion and sanitation (Chappell et al., 2012; Diver et al., 2008; Wilen 2010; Sidebar 2). These practices prevent or reduce the number of weed seeds and propagules (bulbs, corms, rhizomes and stolons) that can grow and reproduce, compounding weed management efforts. The first critical step in reducing weed infestations is to follow adequate sanitation measures during propagation and liner production. Liners are often the initial source for new weed species into production areas (Chappell et al., 2012; Wilen 2010). Few, if any, herbicides may be used in this phase of production, necessitating reliance on sanitation and hand weeding. When receiving liners from an outside source, it is critical to monitor containers for weed emergence and to remove weeds before they reproduce and spread. If possible, visit liner and seed vendors to check out their sanitation practices before doing business with them. Additionally, equipment, containers, substrates and fertilizers used in production should not contain weed seeds or propagules (Case et al., 2005; Wilen 2010; Chappell et al., 2012). Simply washing equipment and containers and covering substrate storage areas can significantly reduce weed pressure.

Effective methods for weed exclusion,
sanitation and prevention:

  • Use containers, potting substrates and
    fertilizers that do not contain weed seeds
  • Use weed-free plant/seed sources
  • Use clean equipment
  • Manage a weed-free zone around and
    under containers
  • Manage weeds growing along the perimeter
    of the nursery and around a surface
    irrigation source

Seeds are the primary source of weeds in production environments (Wilen, 2010). Considering the immediate nursery environment is the source of most weeds (Cross and Skroch, 1992), the elimination of seed-bearing weeds within and adjacent to production areas can greatly reduce weed incidence and severity. This may entail working with neighboring property owners to be effective. Surface irrigation water also may be a source of weed seed if not sufficiently filtered before application (Kelley and Bruns, 1975). To reduce weed introduction via irrigation water, weeds from the periphery of surface water supplies should be controlled prior to seed set. Irrigation intake pipes should be placed below the water surface yet high enough to avoid suction of sediment from the bottom of the water source. This is often accomplished using a floating dock system to suspend the intake pipe in the water column.

Hand Weeding

Regardless of prevention efforts, wind, equipment, birds and other animals (including humans) will eventually introduce weeds (Wilen, 2010). Non-chemical control of weeds is done on a very limited basis in the nursery industry; however, it is critical to scout regularly for invading weeds and deal with them before they mature and spread. Hand weeding is extremely labor intensive and thus an expensive control option (Mathers, 2003; Neal, 2003). In addition, it may be difficult to find laborers willing to work for wages typical of the geographic area where the nursery is located, particularly near urban areas.

Nonetheless, hand weeding is an integral part of any successful weed control program since even pre-emergent herbicides are not 100 percent effective in eliminating weeds. In field nurseries, mechanical cultivation is practiced, but typically as a supplement to an herbicide regime. Therefore, weed management should include regular scouting and hand weeding or mechanical control to prevent emerging weeds from maturing and dispersing seed. Nurseries should strive to create a culture where “no weeds” is everyone’s mantra.


Figure 1. Permeable disk-type mulches composed of coconut fiber (upper left and lower right) and hair (upper right and lower left).

Mulch is applied to the substrate surface to create a physical barrier that inhibits weed seed germination and suppresses weed growth (Ferguson et al., 2008). Mulch is a traditional means of weed management in field nurseries and landscapes and may be adapted to container production (Case et al., 2005; Billeaud and Zajicek, 1989).

Two general types of mulch have been adapted to container production: disk barriers and loose-fill products. Disk barriers are permeable or impermeable products in the shape of a disk with a slit for placing the disk around a stem and on the substrate surface. Disk barriers include impermeable, disk-shaped solid plastic or cardboard lids, and permeable barriers composed of woven or particlebased products held together by resins or other binders (Chong, 2003; Mathers, 2003; Frangi et al., 2010; Figure 1; Sidebar 3).

Disk-type Mulches:

Figure 2. Gaps between the disk edge and container rim, along the installation slit and around the plant stem allow weeds to grow.

Disks can be useful for weed control, may reduce water loss from container plants and have been shown to neither positively nor negatively affect plant growth (Ruter, 1997; 1999). However, disks have issues of cost, handling, irrigation, fertilization and problems with fitting containers adequately to prevent weeds, especially with multi-stem plants (Chong, 2003; Mathers, 2003; Ruter, 1999). If utilizing impermeable disks, plants must be irrigated below the disk via drip irrigation to maintain adequate soil moisture. Additionally, fertilizer must be placed under the disk to maximize plant growth (Ruter, 1999).

Disks must be installed by hand, increasing labor costs. Disks must fit the container exactly or there will be gaps between the disk edge and container rim where weeds can grow (Figure 2). Even with exact container fit, there will be gaps along the disk installation slit and around the plant stem where weeds can grow. In addition, the disk system is limited to plants with a central leader because disks are not designed to fit around multiple stems. Finally, some disk products may be blown away or displaced by wind, resulting in exposed substrate where weeds can grow. Disks are usually removed before sale and often may be reused several times; however, both practices involve additional labor.

Loose-fill mulches are applied as a top-dressing to the container substrate (Smith et al., 1997; Mervosh and Abbey, 1999; Chong, 2003; Mathers, 2003; Case et al., 2005; Ferguson et al., 2008; Cochran et al., 2009). Many loose-fill mulches are agricultural byproducts that are locally available and inexpensive (Sidebar 4). The ideal loose-fill mulch provides little or no nutrients, dries quickly after irrigation, resists decomposition, applies easily, is cost effective, non-toxic to humans and crops, readily available and will be accepted by customers. Few products have many of these characteristics.

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Weed control efficacy of loose-fill mulches generally increases with increasing depth of application (Smith et al., 1997; Penny and Neal, 2003; Cochran et al., 2009). Application of loose-fill mulches may be mechanized (e.g., during potting; Chong, 2003). However, there are challenges associated with this option. Some mulches may contain weed seeds or phytotoxic components. Organic mulches often facilitate weed seedling development and may reduce available nitrogen near the substrate surface if not composted (Billeaud and Zajicek, 1989). Spillage during handling and production is an issue. Most loose-fill mulching systems are considered more costly than an effective pre-emergence herbicide program, but an economic comparison of such systems has not been reported.

Loose-fill Mulches:

  • Hulls and shells (almond, cocoa,
    hazelnut, pecan, peanut, rice, etc.)
  • Starch/straw combination product
  • Sawdust
  • Wood chips
  • Bark
  • Chipped yard waste
  • Shredded tires
  • Shredded, crumbled or pelletized recycled
    newspaper (Figures 3 and 4)

Figure 4. Examples of pelletized and processed and colored recycled newspaper that can be used as a mulch.

Living Mulch

Figure 5. Ryegrass seeded around a deciduous plant acts as a living mulch in winter, dying in spring and serving as a mulch.

Living mulches are used with success by many field nursery crop producers (Diver et al., 2008) and can be adapted to container production, particularly with deciduous crops in winter (Figure 5). These living mulches or cover crops may be used as a seasonal ground cover that suppresses weeds without competing with crop production. Such systems must be customized to local conditions to find the right combination of crop, living mulch species and other compatible weed management practices.

Other Alternative Methods

Most other non-traditional alternatives to synthetic herbicides are not adapted to managing weeds in containers but may be applied around containers and in non-crop areas. For example, heat can be used to manage weeds in non-crop areas (Mathers, 2011). Heat acts to kill weeds by denaturing proteins in cell membranes and breaking down the cellular structure of the weed. Alternatively, heat can induce water within cells to boil, thereby exploding cells and desiccating the plant. Application equipment has been developed to apply heat via propane-generated flame, infrared emitters and direct application of boiling water or steam. Solarization, in which sunlight warms soil in a plastic-enclosed area, results in high temperatures that kill weeds, seeds and disease and pest organisms (Stapleton et al., 2008).

Alternatives to synthetic herbicides include natural chemicals, such as acids, soaps, oils and salts that can act as contact herbicides (Diver et al., 2008). These non-synthetic herbicides are best used as a targeted spray or in noncrop areas because contact can lead to damage of plants in production. It is important to note these products do not kill roots and repeated applications will be necessary for weeds that have the ability to regenerate from their roots.

For example, solutions of vinegar can be sprayed to damage weeds (Diver et al., 2008; Fausey, 2003). Vinegar is a product of fermentation containing about 5 percent acetic acid. It is more effective as a non-synthetic herbicide when concentrated to levels of 15 percent and 30 percent acetic acid by distillation and freeze evaporation, respectively. Acid solutions are believed to cause changes in plant cell pH that result in loss of cell membrane integrity and eventual death.

Similarly, salts of fatty acids (soaps) act by penetrating cells and disrupting cell membranes, ultimately causing desiccation and death (Diver et al., 2008). Soaps include pelargonic acid, ammonium nonanoate and potassium salts of fatty acids.

Plant-based oils such as cinnamaldehyde (the primary component of cinnamon) have been used as contact herbicides (Diver et al., 2008; Fausey, 2003). Oils are believed to cause disruption of cell membranes. Plant-based oils include clove, eugenol, lemongrass, citrus, thyme and oregano.

Salts such as sodium chloride (table salt; Mathers, 2011) or ammonium chloride (Fausey, 2003) can be used to kill plants. They cause dehydration of plant tissue via osmosis. Some combination products mix acetic acid, salt, citrus oil, eugenol, etc.

Other alternative products include hydrogen dioxide (Fausey, 2003) and plant byproducts. Corn gluten meal, derived from processing corn, has not proven effective in containers (Mervosh and Abbey, 1999; Wilen et al., 1999), particularly in high rainfall/irrigation areas. Mustard seed meal has shown promise for use with crops grown in the ground (Boydston et al., 2011; Handiseni et al., 2011) but has not been evaluated for use in containers. Finally, although there have been advances in biological control of arthropod pests and plant pathogens in nursery crops, no such strategies are currently available for weed control in nurseries.


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Diver, S., L. Greer and K.L. Adam. 2008. Sustainable small-scale nursery production. ATTRA. 28 pp. www.attra.ncat.org/attra-pub/nursery.html

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Handiseni, M., J. Brown, R. Zemetra, and M. Mazzola. 2011. Herbicidal activity of Brassicaceae seed meal on wild oat (Avena fatua), Italian ryegrass (Lolium multiflorum), redroot pigweed (Amaranthus retroflexus), and prickly lettuce (Lactuca serriola). Weed Tech. 25(1):127?134.

Kelley, A.D. and V.F. Bruns. 1975. Dissemination of weed seeds by irrigation water. Weed Sci. 23(6):486-493.

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Mathers, H. 2011. Green vs. Greener: Alternative Ornamental Weed Control. Groundwork 2011 (May): 7-8, 10- 13. May 2011. http://www.lcamddcva.org/GW/d_gw_0511.pdf

Mervosh, T.L. and T.M. Abbey. 1999. Evaluation of fabric discs, mulches and herbicides for preventing weeds in containers. Proc. Northeastern Weed Sci. Soc. 1999:122.

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Norcini, J.G. and R.H. Stamps. 1992. Container nursery weed control, Circular 678. Revised August 1994. Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL. 11 pp.

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1 This document is ENH, 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 September 2012. Visit the EDIS Web site at http://edis.ifas.ufl.edu.

2 Assistant Professor and Extension Horticulturist – Nursery Production, Department of Horticulture, University of Georgia, 211 Hoke Smith Building, Athens, GA 30630.

3 Extension Specialist and Professor, Environmental Horticulture Department, University of Florida/IFAS, North Florida Research and Education Center, 155 Research Road, Quincy, FL 32351.

4 Professor and Extension Cut Foliage Specialist, Environmental Horticulture Department, University of Florida/ IFAS, Mid-Florida Research and Education Center, 2725 South Binion Road, Apopka, FL 32703.

Status and Revision History
Published on Sep 13, 2012
Published with Full Review on Mar 28, 2017

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