Willie Chance

Is it okay to apply herbicides to lawns during green up?

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Tim R. Murphy. Retired UGA Weed Scientist

Rank growth of winter annual weeds occurs at the same time that warm-season turfgrasses begin to green-up, or emerge from winter dormancy. These weeds compete with the turfgrass for soil moisture, nutrients, growing space, but most importantly for sunlight. Warm- season turfgrasses, with the exception of St. Augustinegrass, are not highly shade tolerant. Thick mats of winter weeds will shade the turfgrass at a time that root carbohydrates are being exhausted by the green-up process. Additionally, thick mats of winter weeds shade the turfgrass and decrease photosynthesis. The net result is a weakened, or less dense stand of turfgrass, that is readily infested by summer annuals such as crabgrass.

Purple Deadnettle, Robert Vidéki, Doronicum Kft. Bugwood.org
Purple Deadnettle, Robert Vidéki, Doronicum Kft. Bugwood.org

Preemergence herbicides

Research has shown that the preemergence herbicides, such as Balan, TeamPro, Surflan, XL, Ronstar and many others, that are used for summer annual grass control do not significantly affect the spring green-up of labeled warm-season turfgrasses. A possible exception is Pennant (metolachlor). There have been some significant delays in the green-up of hybrid bermudagrass with Pennant applications to dormant turf.

Postemergence herbicides

The situation with postemergence herbicides is dramatically different. Most postemergence herbicides will slightly delay the early spring growth of warm-season turfgrasses. These delays can range from a few days to a few weeks.

In the event of an overdose (an extremely high rate), delays in spring green-up can occur for a longer period of time. Usually, the turfgrass will completely recover within two to six weeks with proper cultural management.

With the exception of Image, most postemergence herbicides can safely be used during green-up. Some slight delay in green-up may be noted; however, this effect can be lessened by:

  1. Using the lowest recommended rate
  2. Insuring that the application equipment is properly calibrated
  3. Using spot treatments
  4. Following all recommended cultural practices, fertility, irrigation, etc. to promote rapid spring growth.

The use of postemergence herbicides should be avoided during the spring green-up of turfgrasses that have been poorly managed, or that are experiencing winter injury problems. Properly maintained, healthy, vigorous turfgrasses are more tolerant to postemergence herbicides than turfgrasses that have not been properly maintained or are suffering from winter injury.

Some postemergence herbicides state on the label “Do not apply during spring green-up.” Obviously, these products should not be used at this time of year. However, the use of other postemergence herbicides is warranted if there is a severe weed infestation on properly maintained turfgrasses. The slight delay in green-up from the use of these herbicides is more than compensated for by the removal of competition that dense mats of weeds exert on the turfgrass.

As always – read and follow all pesticide labeling directions!

Get updated on fire ant baiting

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Get updated on fire ant baiting

Article written by Mike Merchant, Texas A&M Agrilife Extension Entomologist, in his blog Insects in the City

Fire ants remain the most prevalent outdoor ant pest in most areas of the southern U.S.  Throughout the U.S. we estimate the annual cost of fire ant control at over $6 billion.  But the cost of this pest goes far beyond measurable dollars.  Fire ants reduce the recreational value of our parks and backyards, disrupt wildlife populations, and send thousands to emergency rooms each year from their painful stings.

So as we get ready to enter fire ant season, it may be a good time to bring yourself and your staff up to speed on fire ant control. Many people are surprised to learn that fire ants are not an especially difficult pest to manage, once the biology and control tools are understood.

One of the best places to learn about fire ant management is the eXtension fire ant website, a place where the best information about fire ant is assembled by Extension agencies throughout the South. This information was recently summarized and presented in an informative webinar by Dr. Fudd Graham, fire ant specialist with Auburn University.   Dr. Graham focuses on fire ant biology and use of baits for fire ant control.

It’s worth knowing something about how fire ant baits work because they are the most economical, ecologically friendly, and effective control methods for fire ants. The webinar will provide you or your technician with an hour of training that should pay for itself many times over.

 

Mike Merchant is an entomology specialist for Texas AgriLife Extension. He works with pest management professionals, school facilities managers, extension volunteers, researchers and other extension professionals. His areas of specialty center on research on insects affecting man including spiders, scorpions, fire ants, termites and others. His program also focuses on training school maintenance professionals in principles of integrated pest management (IPM). His goal is to make schools healthier, cleaner places to study and live.

Sidney B Meadows scholarship application now available

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Meadows Scholarship 1

For more info visit the Sidney B Meadows Scholarship website

We invite you to apply or advise a horticultural student of the benefits of this scholarship. Scholarships are awarded, through a competitive process, administered by a selection committee based on academics, character, determination, probability of a career in horticulture, and financial need.

In 2014, twelve $1,500 scholarships were awarded, totaling $18,000. The number and amount of scholarships awarded each year is determined by the board of directors based on the fund’s income (interest and dividends) from the previous year.

Scholarship applications for the 2015 year a now available. Deadline for application is May 29th. Selections will be made by July 1, and recipients will be notified soon thereafter. Awards will be made July 22 in Atlanta during SNA2015.

Please refer to the eligibility requirements, and download the 2015 Application below, or call the Fund office at 678.813.1880 to receive an application via email attachment, fax or regular USPS mail.

Visit the Sidney B Meadows Scholarship website

Severe weather chances increase as we move into spring

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Taken from the CASE website

Now that spring is here and warmer, more humid air is entering the US, severe weather and tornado chances are increasing across the country.  There is an excellent animation that shows how the region of severe weather occurrence moves around the country at the NOAA Storm Prediction Center.   The area of most likely severe weather moves north and south with the area of greatest temperature contrast and most active storm track as the sun’s angle changes over time.

The Weather Channel has also provided a series of bar graphs which show the monthly probability of tornadoes for over 40 cities around the country (link).  From the graphs you can see that the Southeast has a split severe weather season, with the major peak in spring and a secondary peak in late fall.

For answers to every question you can ask about tornadoes, check out the tornado FAQ from the Storm Prediction Center.

And make sure you have access to real-time severe weather warnings via smartphone app or NOAA weather radio, especially if you are working outside on high-risk days.

 

severe-prob-3-16-2015-from-spcATL-tornado-by-month-TWC 

When do we expect the last frost?

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Taken from the CASE website and written by Pam Knox, University of Georgia Agricultural Climatologist

Now that March is upon us and the atmospheric pattern has shifted into something that is bringing more spring-like weather to the Southeast, it’s time to think about planting.  And that means thinking about the last frost of the winter.

AgroClimate has a tool which shows the last frost date by county for the Southeast.  The 50 percent map shows the average date for the last frost, while the 10 percent map shows the date that one in ten years will see a frost, and the 90 percent map shows the date for which in just one out of ten years the last frost will come early (or in other words, in 9 out of 10 years the last frost will come later than this date).  The maps below show the dates for 32 F.  You can find the tool athttp://agroclimate.org/tools/Freeze-Risk-Probabilities/.



   

If you need the information for a different temperature threshold, then a good source of information is the Southeast Regional Climate Center.  You can go to their web page www.sercc.com and pick “Historical Climate Summaries” from the “Climate Data” menu at the top.  Pick your station and then look for “Spring Freeze Probabilities” on the left menu.  Here is the graphical output for Tifton, GA.

tifton-spring-freeze-probabilities-sercc

What this shows is that for Tifton, for a temperature of 32 F (orange line) at the 50th percentile (for the average date), the date is about March 10.  You can click on the link for tabular data to get a table of numbers instead of the graph shown here.  Keep in mind that this is for the period of record for the station, and that last dates for spring freeze have been trending earlier in the season in recent warm years.  If you have a different source of freeze information that you like to use, please let us know!

Late Season Annual Bluegrass Control in Residential Turfgrass

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Clint Waltz and Patrick McCullough, Turfgrass Specialist and Weed Specialist, University of Georgia

Annual bluegrass - Robert Vidéki, Doronicum Kft., Bugwood.org
Annual bluegrass – Robert Vidéki, Doronicum Kft., Bugwood.org

Annual bluegrass (Poa annua L.) is a troublesome winter annual weed in residential turf. Compared to most turfgrasses, annual bluegrass has a lighter green color, coarser leaf texture, and produces unsightly seedheads.

Annual bluegrass seed germinates throughout the late-summer and early-fall once soil temperatures drop below 70° F. Seedlings grow and mature in fall, overwinter in a vegetative state, and produce seed in spring. A second germination can occur in late-winter as soil temperatures rise and the days become longer.

Annual bluegrass is a prolific seed producer and individual plants may produce hundreds of viable seed, even when closely mowed. Annual bluegrass flowers over several months in spring and produces seed that may remain dormant in soil for years before germinating. Annual bluegrass often dies from summer stresses but may survive in protected sites that receive irrigation. Controlling annual bluegrass in mid- to late-spring in residential lawns can be difficult.

Annual bluegrass can produce seeds even when closely mowed. Image - John Kaminiski
Annual bluegrass can produce seeds even when closely mowed. Image – John Kaminiski

Control in bermudagrass and zoysiagrass

Up until mid-February (when the bermudagrass was fully dormant) applying a glyphosate containing product (e.g. Roundup) was an option for postemergence annual bluegrass control. Even then, care must be taken not to “overdose” the weed and harm the bermudagrass. Applicators commonly over-spray the weed with glyphosate and some herbicide moves deep into the bermudagrass canopy where it contacts green bermudagrass stolons near the ground. Any green part of the plant in the bermudagrass can absorb the glyphosate which can damage the plant.

It is now too late and risky to consider spraying glyphosate to control annual bluegrass in dormant bermudagrass. While bermudagrass may still look “completely” dormant it is starting to greenup and the application of glyphosate during greenup can damage the turf. Do not apply glyphosate to dormant grass of any type other than bermudagrass since other grasses never really go completely dormant and may be damaged by the herbicide.

There are a few selective herbicidal options to control annual bluegrass at this point in the season. In bermudagrass and zoysiagrass, if the annual bluegrass population is bad enough the best option is treating with either Revolver (foramsulfuron) or Monument (trifloxysulfuron).

Control in centipedegrass and St. Augustinegrass

Neither of these herbicides is labeled for use on centipedegrass or St. Augustinegrass. In centipedegrass and St. Augustinegrass, atrazine containing products are an option but large annual bluegrass grass plants are difficult to control with a single application.

The weed is an annual cool-season grassy weed that will die-out in a couple months as temperatures warm. For now, having patience and tolerance maybe the best option. Plan for next winter and spring. Begin with good turfgrass cultivation this summer. For example:

  • Deep and infrequent irrigation encourages turfgrass root development which improves the ability of the lawngrass to compete with weeds.
    • Identify and alleviate soil compaction since annual bluegrass prefers compacted soils. For rapid recovery and improved vigor, core aerifications should be performed during the active growth period of warm-season turfgrasses.
    • Mow the lawn at the appropriate height for the grass species. Lower mowing heights may stress turf and reduce its ability to compete with annual bluegrass. For proper mowing height recommendations, visit www.GeorgiaTurf.com
    • Lastly, begin a preemergence herbicide program in late-summer to help control the seed that were deposited this season.

Landscapers can help homeowners with controlling annual bluegrass now and planning a healthier lawn to prevent annual bluegrass next year.

Ambrosia Beetles begin flying in Jan and Feb!

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Will Hudson, UGA Extension Entomologist

 Asian or granulate ambrosia beetles are tiny (<1/8″) wood-boring insects that attack the trunks of young and weakened trees and shrubs. Ambrosia beetles tunnel into stems and construct galleries where they raise their young. Beetles carry on their bodies a fungus that grows in these galleries producing ambrosia which feeds both adults and larvae. Ambrosia beetles can also carry the spores of disease pathogens that infect the tree. The growth of these fungi can lead to weakening or death of the tree.

Ambrosia beetle sawdust 'toothpicks' - Byron Rhodes, UGA, Bugwood.org
Ambrosia beetle sawdust ‘toothpicks’ – Byron Rhodes, UGA, Bugwood.org

As ambrosia beetles tunnel, they push sawdust out through their entry hole. This sawdust can cling together forming short ‘toothpicks’ sticking from the infested stem. These toothpicks make it easy to identify ambrosia beetle attacks.

Wind or rain may destroy these toothpicks leaving just the small holes and scattered sawdust from the beetle. Since the entry holes are only about the size of a #2 pencil lead, close inspection is necessary to detect these attacks in time to treat. Ambrosia beetles attack many types of trees and shrubs including crape myrtles, cherries, oaks, sweet gums, pecans, peaches and others.

The ambrosia beetle’s first flight occurs with mild weather typically in February but possibly as early as January. Cold weather will put them off for a while, but we usually see a big emergence of the granulate ambrosia beetle ranging from February in south Georgia to early March in north Georgia.

Young trees in nurseries and trees that have been in landscapes for less than three years old are vulnerable to attack even if they are not obviously stressed. This is especially true during the green-up period. Prompt action can save these trees if the number of attacks (“toothpicks”) is less than 4 – 5 per tree.

Growers of nursery trees and shrubs, as well as landscapers with new trees, can apply a spray to protect vulnerable trees. The spray should be repeated every 10 – 14 days until the plants are completely leafed out.

If applied in time, pyrethroid insecticides can repel the beetles even after plants are attacked. Pyrethroids like permethrin (Pounce, Astro), Talstar, Decathlon, or others will work. Once the trees have leafed out completely, they are less attractive to the beetles unless the trees are under stress. Prevent stress to shrubs and trees to lower chance of ambrosia beetle injury.

Spray affected trees, being careful to cover the trunk completely. Monitor the trees for signs of wilting of the new leaves, a sign that a pathogen has been introduced. Once the wilting starts, the tree will probably die. Do not assume the attack will be fatal, since trees may recover. Also watch treated trees to see if new toothpicks develop – a sign that the ambrosia beetles are still active.

Nursery trees that are attacked should be sprayed and separated from the rest of the block (if possible), and watched closely for signs of wilting. Nursery trees that are attacked but don’t wilt may not need to be destroyed. If they leaf out and seem healthy and no further toothpick formation is noted, then the small holes will heal quickly and leave no permanent damage.

If you see toothpicks on larger trees, the tree is probably severely stressed. If attacks are confined to one limb, pruning is an option. If the attacks are on the main stem, prepare to remove the tree if it dies.

Considering the history of this pest in Georgia, there is a good chance that any given nursery or landscape will suffer little or no damage and spraying will not be necessary. Watch susceptible trees or shrubs closely for beetle attacks.

Traps can be used to monitor the activity of this pest. For more information on constructing Ambrosia beetle traps see Activity Monitoring in this publication.

Prune liriope and pampus grass in late winter

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liriope MSWTwo ornamental plants in the landscape that are commonly sheared are liriope and ornamental grasses such as pampas grass. Shearing in late winter removes old growth and makes way for new shoots.

Liriope

Annual removal of liriope foliage is not a necessity; however, cutting back is desirable if severe winter injury to the foliage has occurred. Running a lawn mower over the plants is a practical means of removal. Hedge shears may be a more practical means for large individual clumps.

In Georgia, new growth often begins to emerge in February and March; therefore, prune earlier or plan to cut back high to prevent injury to the new shoots.

Severely pruning mondo grass (Ophiopogon japonicus) is not recommended.
Severely pruning mondo grass (Ophiopogon japonicus) is not recommended.

Mondo grass (also called monkeygrass or Ophiopogon) redevelops slowly after severe pruning. Do not shear these plants.

Homeowners and maintenance personnel often neglect fertilizing lilyturf and thus do not obtain maximum vigor. A broadcast application of a general lawn or shrub fertilizer in early spring and again in mid-summer should be adequate to maintain the desired vigor.

Dwarf pampas grass Image - Jeff Webb
Dwarf pampas grass Image – Jeff Webb

Pampus grass

Prune pampas grass annually to remove the previous year’s foliage and make way for new growth.  Pruning is best done in late winter, prior to the new growing season. Use hedge shears, lopping shears or power pruners to cut the plant back close to ground level. Be sure to wear a long-sleeve shirt and gloves when pruning to protect yourself from the sharp leaf blades.

After pruning pampas grass, apply a light, broadcast application of a complete fertilizer, like 8-8-8 or 10-10-10, to help stimulate new growth.

This is edited from these publications – where you can find more information.

Liriope Culture in Georgia 

Pampas Grass

Care of Ornamental Plants in the Landscape

Cold February gives way to warm March weather

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Written by Pam Knox, UGA Agricultural Climatologist, and taken from the CASE website

February 2015 was the second coldest February since 1978, based on preliminary data from National Weather Service stations, rivaling the chilly February of 2010.  Precipitation was variable across the state, although most stations were close to normal.  Two major storms caused significant impacts across northern Georgia in mid- and late February.

Temperatures across the state were well below normal in February.  In Atlanta, the monthly average temperature was 40.4 degrees F (6.8 degrees below normal), in Athens 40.3 degrees (6.9 degrees below normal), Columbus 44.7 (6.4 degrees below normal), Macon 43.7 (6.3 below normal), Savannah 47.3 (5.7 below normal), Brunswick 49.2 (5.3 below normal), Alma 47.7 (6.5 below normal), Augusta 42.8 (6.3 below normal), Albany 47.7 (4.7 below normal) and Valdosta 49.5 (4.7 below normal).

A number of daily low temperatures were broken this month, most during a cold outbreak February 19-21.  On February 20, Athens set a record low of 14 F, smashing the old record of 18 F set in 1958.  Columbus recorded 21 F and Macon 18 F, beating the old records of 22 F and 21 F, both also set in 1958.  Savannah set both a record low minimum and maximum temperature on that date, reporting a high of 41 F, which broke the record of 44 F, and a low of 21, breaking the old record of 22 F set in 1958.  Alma and Brunswick set record low maximum temperatures on both the 19thand 20th and Augusta set a record low maximum temperature on the 19th.

The thermograph below (produced using cli-MATE from the Midwestern Regional Climate Center) shows the daily temperature observations for Athens for the last three months to show how much below average this cold outbreak was.

athens-thermograph-winter-2015

 

The highest monthly total precipitation from National Weather Service reporting stations was 4.70 inches in Augusta (0.28 inches above normal) and the lowest was in Brunswick at 2.69 inches (0.78 inches below normal).  Atlanta received 4.15 inches (0.52 inches below normal), Athens received 3.99 inches (0.49 below normal), Macon received 4.36 inches (0.0 below normal), Columbus 4.22 inches (0.22 below normal), Savannah 3.44 inches (0.65 above normal), Alma 3.62 inches (0.18 below normal), Valdosta 4.60 inches (0.44 above normal), and Albany 4.03 inches (0.13 below normal).

 

Atlanta and Athens reported daily precipitation records for traces of snow on days which had never experienced snow before: Atlanta reported snow on the 21st, and Athens on the 19th and 20th.

The highest single-day rainfall from CoCoRaHS stations was 3.20 inches in Eastman in Dodge County on February 26, followed by 2.95 inches received southeast of Sylvania in Screven County on the same date. The highest monthly total rainfall was 6.52 inches, observed south of Americus in Sumter County, followed by 6.31 inches south of Senoia in Coweta County.  The highest daily snowfall value was 8.2 inches reported near Rabun Gap on the 26th, and they also had the highest monthly snowfall total of 12.1 inches.

Two winter storms caused problems in northern Georgia this month.  On February 16-17 a storm brought freezing rain, sleet and snow to areas of the northeast, dropping many tree limbs and cutting power to many.  At the height of the storm almost 100,000 people in Georgia were without power.  Many schools closed due to hazardous weather as well as lack of power.

A second major winter storm caused problems across northern Georgia in late February.  The storm was part of a large weather system which brought mixed winter precipitation to areas from Texas to Washington DC. You can read a detailed write-up of the storm from the Peachtree City National Weather Service office athttp://www.srh.noaa.gov/ffc/?n=20150225_heavy_snow.

soil-moisture-feb-28-2015

Because of the cold weather this month, no severe weather was reported anywhere in the state in February.

The above normal precipitation in south Georgia increased soil moisture, helping to eliminate abnormally dry conditions in some areas.  The driest part of the state is now in the far north.

soil-moisture-feb-28-2015

The cold temperatures caused frost damage to early blueberries in south Georgia.  Estimates of losses ranged for 10-15 percent in areas where frost protection was used to 30-40 percent in areas where it was not.  This is expected to delay the delivery of early Georgia blueberries to markets for one to two weeks.  Small grains have also continued to suffer from the cold conditions.

The outlook for March shows wet and cold conditions may continue into the first half of March.  By mid-month, a major pattern shift is expected to bring much warmer air into the Southeast.

When should we prune azaleas & crape myrtles (and other plants!)

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Prune spring blooming azaleas after they bloom and crape myrtles in late winter before growth begins.

Info edited from Pruning ornamental plants in the landscape

Because flowering ornamentals form their flower buds at different times of year, pruning times must be adjusted accordingly. Many spring-flowering plants such as azalea, dogwood, forsythia, redbud and rhododendron set flower buds in the fall, so pruning during the fall or winter months eliminates or decreases their spring flower display. Plants that typically flower during the summer form flower buds on new growth and can be pruned during the winter with no effect on their flowering. Examples of this type of plant are crape myrtle and abelia.

As a general rule, plants that flower before May should be pruned after they bloom, while those that flower after May are considered summer-flowering and can be pruned just prior to spring growth. One exception to this rule is the oakleaf hydrangea, a summer-flowering shrub that forms flower buds the previous season. Another exception is late-flowering azalea cultivars, which bloom during May, June or even July. Prune both the oakleaf hydrangea and the azalea cultivars after they bloom. Table 1 provides suggested pruning times for other plants.

Table 1. Suggested Pruning Time for Common Flowering Trees, Shrubs and Vines

Prune after Flowering
Azalea Japanese Pieris
Beautybush Lilac
Bigleaf hydrangea Mockorange
Bradford Pear Oakleaf hydrangea
Bridalwreath Spirea Pearlbush
Clematis Pyracantha
Climbing roses Redbud
Crabapple Saucer Magnolia
Deutzia Star Magnolia
Dogwood Shrub Honeysuckle
Doublefile Vibernum Thunberg Spirea
Flowering Almond Vanhoutte Spirea
Flowering Cherry Weigelia
Flowering Quince Winter Daphne
Forsythia Wisteria
Japanese Kerria Witchhazel

Prune before Spring Growth Begins
Beautyberry Goldenrain Tree
Camellia Japanese Barberry
Chaste Tree (Vitex) Japanese Spirea
Cranberrybush Viburnum Mimosa
Crape myrtle Nandina
Floribunda roses Rose-of-Sharon (Althea)
Frangrant Tea Olive Sourwood
Grandiflora roses Anthony Waterer Spirea
Glossy Abelia Sweetshrub
Hedges

Ornamental plants that are not grown for their showy flowers can be pruned during the late winter, spring or summer months. Avoid pruning during the fall or early winter because it may encourage tender new growth that is not sufficiently hardened to resist the winter cold.

Some shade and flowering trees tend to bleed or excrete large amounts of sap from pruning wounds. Among these trees are maple, birch, dogwood, beech, elm, willow, flowering plum and flowering cherry. Sap excreted from the tree is not harmful, but it is unsightly. To minimize bleeding, prune these trees after the leaves have matured. Leaves use plant sap when they expand, and the tree excretes less sap from the wound.

For more information, see the publication Pruning ornamental plants in the landscape.

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