Controlling Lawn Burweed: The Spring Lawn “Sticker”

Controlling Lawn Burweed: The Spring Lawn “Sticker”

Most lawn weeds are annoying, appearing in unwanted places and numbers, but few actually cause physical harm like the pest plant Lawn Burweed (Soliva sessilis)!  This infamous small, spreading winter weed’s seeds generally germinate when temperatures begin to cool in the fall (late October-November). Burweed then grows mostly unnoticed through the winter until spring, when it then produces the hard, spiny burs that contain the plant’s seeds and the plants finally die.  Once the burs have formed, Burweed’s presence makes walking on newly greened-up spring turf extremely painful for pets and people (barefoot of course, the burs aren’t large enough to puncture shoe soles).  At this point of the plant’s life, once it has made its unwanted presence known, control is not feasible as the Burweed plants have set seed, ensuring a new crop next year, and killing the remaining foliage doesn’t remove the burs.  What is a homeowner to do?

Newly germinated Lawn Burweed. Photo courtesy of the author.

Fortunately, Lawn Burweed is relatively easy to control chemically if one pays close attention to seasonal changes and uses herbicides (either pre-emergent or post-emergent herbicides) effectively.

Pre-emergent Herbicide Options:  The first chemical control option for Lawn Burweed is a timely application of the pre-emergent herbicide Isoxaben (sold under various brand names at most farm or garden stores) to prevent Burweed seeds from germinating, greatly reducing plant populations.  However, pre-emergent Isoxaben applications must be made before the plants sprout and begin to grow to be effective.  For Burweed, this generally means application in October, once nighttime temperatures dip into the 55-60 degrees F range for several nights in a row, as consistent temperatures in this range give Burweed seeds the signal to germinate.  Though we’re already past the point of pre-emergent herbicides being an option for control this year, homeowners should plan to include this method in their Lawn Burweed control plan for fall 2020!

Post-Emergent Herbicide Options:  If you haven’t already used a pre-emergent herbicide this fall for Burweed control, you must turn to post-emergent options.  Like pre-emergent herbicides, timing is critical if you want your post-emergent applications to work!  These herbicides are most effective when Burweed plants are young, small, vigorously growing, and haven’t set burs yet.  Successful post-emergent applications may be made from December-early February before burs harden.  Unlike pre-emergents, where there is only one strong option for Burweed control, many post-emergent herbicides exist that are extremely effective!  When shopping, look for products containing the following active ingredients:

Lawn Burweed around 10 days after emergence. Photo courtesy of author.

  • Atrazine – sold under many brand names and safe in Centipede, St. Augustine, & Bermudagrass. Do not use in Zoysia or Bahiagrass lawns.
  • Dicamba, Mecoprop, 2,4-D – commonly sold in three-way formulations through many brand names. Generally safe in Centipede, St. Augustine, Bermuda, Zoysia, & Bahiagrass lawns.
  • Metsulfuron – sold under several brand names and safe in Centipede, St. Augustine, Zoysia & Bermudagrass. Do not use in Bahiagrass. Be careful if used around ornamentals.
  • Thiencarbazone, iodosulfuron, dicamba – sold as Celsius WG from Bayer. Safe in Centipedegrass, Zoysiagrass, Bermudagrass, and St. Augustinegrass.  Do not use in Bahiagrass.

Lawn Burweed control with of all the above-listed herbicides will be most effective with a follow-up application 10-14 days later.

Note:  With the exception of the Thiencarbazone, iodosulfuron & dicamba mixture (Celsius), do not apply any of these post-emergent herbicides during spring turf green up.

As always, if you have questions about Lawn Burweed control or any other horticulture or agriculture related questions, please contact your local UF/IFAS County Extension office or consult any of the following related articles: https://nwdistrict.ifas.ufl.edu/hort/2015/10/06/lawn-burweed-prevention-is-easier-than-cure/ and http://blogs.ifas.ufl.edu/washingtonco/2017/10/11/prepare-now-to-avoid-lawn-burweed-infestation-later/

Happy gardening!

 

 

 

Beware Vaseygrass, an Aggressive Exotic Weed

Beware Vaseygrass, an Aggressive Exotic Weed

Vaseygrass produces prolific seed heads, and once introduced, can be spread easily by farming equipment. Photo by Herman Holley.

Vaseygrass produces prolific seed heads, and once introduced, can be spread easily by farming equipment. Photo by Herman Holley.

Beware Vaseygrass, an Aggressive Exotic Weed

A couple months ago I got a concerning call from a local small farmer. Rich Pouncey, of Bumpy Road Farm in northern Leon County, was very troubled by an unwelcome visitor he found growing on his farm.

Rich, who grows multiple crops, including heirloom corn varieties to create his delicious cornmeal and grits, noticed something amok in a portion of his rows. With closer inspection – and a visit from Extension Agent Les Harrison – it was identified as vaseygrass (Paspalum urvillei). Vaseygrass, an aggressive exotic species from South America, was starting to take complete control of a large section of Rich’s small growing space he had reserved for upcoming collard production.

With its abundant seed heads and our consistent summer rainstorms, vaseygrass quickly took over a section of Rich's field. Photo by Molly Jameson.

With its abundant seed heads and our consistent summer rainstorms, vaseygrass quickly took over a section of Rich’s field. Photo by Molly Jameson.

Rich, who prides himself on supporting biological diversity, soil health, and native pollinators, uses strictly organic growing methods in raising his crops. Therefore, the presence of such an aggressive exotic was truly of grave concern.

Rich is not sure exactly how this weed was introduced to his fields. He suspects it may have been hidden in a soil amendment he purchased, but he cannot be certain of the source. It is certainly a reminder to be careful when bringing in outside equipment, mulch, and any new agricultural products.

When mature, vaseygrass can grow to six-feet tall with plentiful seed heads, and it flourishes in warm, wet conditions. It spreads by seeds and has very high rates of germination during times of abundant rainfall. The grass is low in nutrition – making it a poor choice for grazing cattle – but in a hay field, it will spread like wildfire if not controlled.

Vaseygrass is a true perennial bunch grass, with a small root system and, fortunately, few rhizomes. Rich began pulling and black bagging as much of the grass as he could each day, but struggled to keep up, and it quickly spread through more than a tenth of an acre of his field.

When hand pulling wasn't enough, Rich switched to solarization, hoping to kill emerged vaseygrass seedlings and seeds with heat. Photo by Herman Holley.

When hand pulling wasn’t enough, Rich switched to solarization, hoping to kill emerged vaseygrass seedlings and seeds with heat. Photo by Herman Holley.

About six weeks ago, Rich changed strategies and began solarizing the area with clear plastic sheeting. Tightly covering soil with clear plastic sheeting in the warmest summer months can trap heat and increase temperatures, potentially killing weeds, pests, and diseases within the top foot of the soil surface. He will find out soon if this control strategy has been successful, as he’ll be pulling up the plastic in September. He knows that if the solarization is not successful, he may have no choice but to use chemical control methods, which will mean he will have to wait years to grow any crops in this area he wishes to market as organically grown.

If hand pulling isn’t enough, small infestations of vaseygrass can be controlled by spot spraying a one percent glyphosate solution at 1.2 ounces/gallon. Be aware, mowing and tilling can make the problem worse, as the scattering and burying of seeds can exacerbate the infestation.

For more details about identifying and controlling vaseygrass, read the UF/IFAS EDIS publication, Identification and Control of Johnsongrass, Vaseygrass, and Guinea Grass in Pastures (https://edis.ifas.ufl.edu/ag372).

If you suspect vaseygrass is growing on your property, contact your local county extension agent to get the grass properly identified and help spread the word about its presence.

Backflow Preventers: An Important Link Between Gardeners and the Potable Water Supply

Backflow Preventers: An Important Link Between Gardeners and the Potable Water Supply

Horticulture Extension Agents are asked a wide variety of questions, from plant identification to erosion control, from herbicide selection to water regulation. We’re usually expected to know the answer on the spot, too. We’re also expected to write a lot and share information with the public. Well, oftentimes, those factors come together to give us writing inspiration. A challenging question leads to research and gathering of information, which leads to an answer that should be shared so others can learn from it. A recent question regarding the use and regulation of backflow preventers from a longtime gardener inspired my latest knowledge quest and what I found seemed important enough to share with other gardeners.

I would guess that backflow preventers probably aren’t a common item on people’s minds, unless you’re a plumber or in the water supply business. However, backflow prevention devices help ensure that when we turn on the tap to drink, cook, clean, flush, bathe, and yes, garden, that the water isn’t contaminated.

These larger backflow preventers are required to be installed and regularly inspected for certain plumbing systems. They usually hide under utility boxes or fake rocks. Credit: UF/IFAS.

Backflow preventers do just what their name implies, they prevent backflow. Backflow in a plumbing system happens when pressure in another part of the system drops, causing water from other locations to move in to equalize the pressure difference. This can be a problem in a potable water system when the main line loses pressure and water from a contaminated line is pulled in to the main line, potentially contaminating many users water. This can happen when a pipe breaks or during fire-fighting activities, for example. Contaminants of concern include chemical and biological agents, such as heavy metals, industrial compounds, bacteria, and pesticides.

Many of our indoor fixtures have built-in backflow preventers, such as toilets and bathtubs. Exterior backflow preventers, usually found under boxes or fake rocks near the water connection, are required for plumbing systems considered to be more of a hazard risk or where higher pressures could more easily flow back into the line. Examples of such plumbing systems include those with fire-fighting systems, hospitals, several-storied buildings, those associated with certain industrial processes, and, finally back to gardening, irrigation systems. In 1990, the Florida Building Code required that all residential irrigation systems include a backflow preventer. While the Florida Building Code also requires backflow preventers on all hose connections, i.e. spigots, many residential homeowners do not have these in place nor do water suppliers have the budgets to inspect each home’s spigots. A survey of 200 homes in the Midwest during 2002 found that 91% of homeowners did not have a backflow preventer attached to their spigots. I’m not sure north Florida would fare much better.

Gardeners should be aware of this responsibility and go ahead and install a backflow preventer on their outdoor spigots. This is especially true for those that use hose-end fertilizer or pesticide applicators, mix pesticides, or leave a pressurized hose connected to a sprinkler or other device. In addition to chemicals, all sorts of bacteria, algae, and other contaminants can grow in or enter a hose and get sucked back into the house’s line or, worse, the public supply line.

Backflow preventers are cheap and easy to install. A simple brass backflow preventer that connects between the spigot and the hose runs from $3 to $10 and will typically last for several years. You know it’s still working when water leaks out of the backflow preventer as you turn the spigot off. That’s a pretty easy and inexpensive fix to make sure the potable water source stays clean.

A simple and inexpensive hose bibb/spigot backflow preventer can help gardeners protect their potable water supply. Credit: Univ. S. Cal.

For more information on backflow prevention devices, and to keep writing ideas coming in, please contact your local UF/IFAS Extension Office.

April is Safe Digging Month

April is Safe Digging Month

Call 811 before you dig. No one wants a weekend project to be the cause of Internet, phone and cable outages. Worse yet, what if someone gets hurt from contact with natural gas or electrical lines? That’s why it is so important to have buried utilities in the yard located and marked before digging. Sunshine 811 coordinates each individual company to clearly mark where the service lines are located. Homeowners are required by law to contact 811 three days before any soil removal is done. The service is free.

Have information prepared before making the request. Describe the work to be performed (e.g. fence install, landscaping, irrigation install), including the type of equipment that will be used. Specify the exact location on the property and how long the work will continue. Finally, provide all the contact information (e.g. name, phone number, e-mail), should there be any additional questions.

Call 811 or request a single address ticket online. Receive a ticket number and wait two full business days, not counting weekends or holidays. Then contact 811 again. Make sure that all the utilities have responded in the Positive Response System (PRS). Sometimes that may mean that the company doesn’t have anything to make in the area.

If there are utility lines running through the yard, they will be marked with specifically colored paints or flags. Red is used for electrical lines, orange indicates communication lines, yellow means gas, blue is used for potable water, purple is reclaimed water, and green indicates sewer lines. White lines may be used to outline digging areas and pink are temporary survey marks. This is the APWA Uniform Color Code.

Every effort is made to locate the lines as accurately as possible. But, the safest thing to do is hand dig to expose the utility line before using any mechanized equipment. Lines can vary up to 24” from the marked line and depths can be less than 5”. Remember there may be access lines running through the property even if that service isn’t utilized at that address.

Keep safe this spring. Call 811 before digging.

Timing Critical When Controlling Annual Lawn Weeds

Timing Critical When Controlling Annual Lawn Weeds

Mature Florida pusley weed blooming in lawn

Florida pusley is common summer annual weed. Photo credit: Larry Williams

If weeds were a problem in your lawn last summer, the coming weeks are the time to apply a pre-emergence herbicide to prevent their emergence again this spring and summer.

 

Timing of a pre-emergence herbicide application for summer annual weeds such as crabgrass should be during February when day temperatures reach 65° to 70°F for four to five consecutive days. This generally coincides with when azaleas and dogwoods first begin to bloom. This in not when these plants are in full bloom but when the first flowers begin to open along the lower branches, particularly on azaleas. Note: This timing is not true for chamberbitter. Chamberbitter requires warmer soil temperatures to germinate. Apply a pre-emergence herbicide during April when battling chamberbitter.

 

 

Most pre-emergent type herbicides won’t work when applied after weeds are visible. The product must be applied just before seedlings emerge.

 

The weeds growing now in local lawns are not summer annuals. Summer annual weed seeds are still dormant awaiting warmer spring temperatures to germinate and emerge.

 

Most of the weeds in yards now are winter annuals. A few include annual bluegrass, chickweed, henbit, hop clover, lawn burweed and wild geranium.

Mature winter annual weeds in lawn

Winter annual weeds in lawn. Photo credit: Larry Williams

A pre-emergence herbicide should have been applied during October to help prevent these weeds.

 

A few common summer annual weeds include crabgrass, Florida pusley, chamberbitter, sandspur, spotted spurge and doveweed.

 

If your lawn has a history of summer annual weeds, one control option is to apply a pre-emergence herbicide. Timing is critical in order for pre-emergence herbicides to work.

 

Look for lawn pre-emergence products that contain the active ingredients oryzalin, benefin, pendimethalin, DCPA or bensulide.

 

For season-long weed control, a second application may be needed about six to nine weeks after the initial application. To activate some products, irrigation or rain may be necessary following application. Because pre-emergence products may interfere with lawn grass seed germination, delay re-seeding six to sixteen weeks after application.

 

Overuse of some types of pre-emergence herbicides can cause a lawn to produce short stubby weak roots. So only apply the product if there is a pest to control – in this case, if you have had a history of summer annual weeds. Otherwise, save your money and time. Use pre-emergence herbicides only on lawns that have been established for at least a year. These products can severely injure newly planted lawns.

 

It is the user’s responsibility to read and follow all label directions and precautions when using any pesticide, including herbicides.

Late Spring Signals Leaf Gall for Some Camellias

Camellias are a Panhandle favorite, as the flowers can highlight a landscape with bright, vibrant colors in fall and winter. However, spring time can bring about these colors in a negative way, in the form of leaf gall.

The camellia is native to Asia and brought to America in the late 1700’s. These plants have proven to be a dependable addition to the southern landscape with minimal care. When camellias are correctly planted and cared for, minimal disease problems arise. However, camellias can contract leaf spot, dieback, root rot and bud and leaf gall.

Camellia Gall Credit: Patty Dunlap, Gulf County Master Gardener.

 

Leaf and bud galls are caused by the fungus Exobasidium vaccinia. The gall appears as thickened, waxy and enlarged leaves or buds during the cool spring months. One or several leaves on a single shoot may be affected. Once you’ve found infected leaves, no chemical control will be effective. Actually, no fungicide has been found very effective in combatting this condition. However, control can be accomplished in the home garden by simply pinching off and destroying infected leaves. Disease activity usually stops with warmer weather. A best management practice to curb infection is to reduce overhead watering during cool, wet weather periods of spring. Great news, this condition does not cause any long-term issues with the plant.

For more information regarding fungal issues in landscape plants, contact your local county extension office.

Fun camellia fact: The young leaves of the species, Camellia sinensis, are processed for tea, one of the world’s most popular drinks. Please see UF/IFAS EDIS publication, “Tea Growing in the Florida Landscape” by Jonathan H. Crane and Carlos F. Balerdi: http://edis.ifas.ufl.edu/pdffiles/HS/HS30800.pdf

Supporting information for this article can be found in the UF/IFAS EDIS publication, “Camellias at a Glance” by Sydney Park Brown: http://edis.ifas.ufl.edu/pdffiles/EP/EP00200.pdf

UF/IFAS Extension is an Equal Opportunity Institution.