• What is sugarcane mosaic virus? Where did it come from, and why does it have sugarcane in its name?
    Answer:

    Sugarcane mosaic virus (SCMV) in Florida was first identified in sugarcane in rural western Palm Beach County. It was also found in the early 1960’s in St. Augustinegrass, but did not pose a serious problem. Variety selection in sugarcane mostly eliminated the problem in that crop. Prior to 2013, fewer than five specimens of St. Augustinegrass with mild symptoms of the virus were noted by the University of Florida, Extension Plant Pathology Lab. Genetic (genome) testing now shows the virus that attacks sugarcane is distinctly different from the virus that attacks St. Augustinegrass lawns. Current research also suggests that a genetic variation of SCMV, and a new virus together cause the disease that kills Floratam variety of St. Augustinegrass. A third virus has also been found in testing, but it is not thought to add to the disease in Floratam.


  • Why is sugarcane mosaic virus a problem?
    Answer:

    Sugarcane mosaic virus usually kills the Floratam variety of St. Augustinegrass in three or less years.


  • How is sugarcane mosaic virus spread?
    Answer:

    The virus is spread in the moist plant sap from infected grasses. Exposed plant sap occurs mostly when lawns are freshly cut. Lawn mowers, trimmers, equipment wheels, and other similar equipment pick it up at that time. Once the sap and clippings dry out, they no longer transmit the virus to new grass. The virus does not survive for long outside plant tissue. Mowing when lawns are wet can extend the viability of the virus on equipment because it keeps the plant sap hydrated longer. It is also believed that aphids, which typically do not like St. Augustinegrass, transmit the virus by probing the grass with their mouthparts. They quick-ly probe other areas looking for suitable plants to feed on and thereby transmit the virus to other parts of the lawn.


  • Can wheels from vehicles or lawn equipment spread the disease?
    Answer:

    Yes, if wet plant sap from affected freshly cut lawns is carried to unaffected, but susceptible lawns.

     


  • Can the disease be spread by irrigation water, or reclaimed irrigation water? Can stress from excessive salts, nutrients or high pH in reclaimed affect disease severity?
    Answer:

    No, the virus does not survive in irrigation water. Nutrient containing reclaimed water should not affect the spread of the virus. Additionally, despite recommendations to follow Best Man-agement Practices on the Floratam St. Augustinegrass, stress from improper nutrition or pH does not impact virulence and therefore survivability of Floratam affected by sugarcane mosa-ic virus.


  • Does the virus survive in soil?
    Answer:

    ​No. Once the virus is out of the plant tissue, and the sap dries, the virus is destroyed.


  • Can non-symptomatic grass be a source of the virus?
    Answer:

    ​Yes, if the grass is a know host of the virus. Lawns may not be showing obvious symptoms, but may contain the virus. Symptoms may be especially difficult to see during the warmer and wetter months.


  • Do clippings need to be removed from freshly mowed lawns?
    Answer:

    ​No, clippings dry out very quickly and then are not a source of the virus. Additionally, clippings recycle some of the nutrients back into the lawn. Clippings should only be removed if other fungal leafspot diseases are seriously affecting the lawn.


  • How long will Floratam St. Augustinegrass live after infection?
    Answer:

    ​Sugarcane mosaic virus kills Floratam within three years. Sometimes death occurs more rapidly.


  • Why is Floratam variety St. Augustinegrass so widely planted?
    Answer:

    Floratam is the most commonly planted variety of St. Augustinegrass in Florida, with some es-timates above 95 percent. It was released in 1973 by the University of Florida and Texas A&M University as an improved variety resistant to another virus – St. Augustine Decline Virus. St. Augustinegrass Decline Virus is not currently thought to be in Florida. Floratam variety was probably also initially resistant to chinch bugs. Large chinch bugs populations can be destruc-tive to St. Augustinegrass if not treated with an effective insecticide.


  • Why do I have sugarcane mosaic virus on my lawn, but others do not?
    Answer:

    ​The virus currently is quite wide-spread in both Palm Beach and Pinellas Counties, Florida. It has also been found in several other Florida counties. It is likely that it is more wide-spread, but is not being noticed or diagnosed via laboratory testing yet. If it is confirmed on your property, it reflects an awareness of the problem by you or your landscape professional.


  • How can you identify sugarcane virus in your lawn versus nutritional deficiencies, fungal or other problems?
    Answer:

    ​Symptoms to the untrained eye can often be confused with other common St. Augustinegrass maladies including nutritional deficiencies, fungal problems and cold damage. The only way to be sure the Floratam St. Augustinegrass has sugarcane mosaic virus is through laboratory testing.


  • How do I collect, send and pay for lab testing??
    Answer:

    A sod plug at least 4 or 5 inches across and a couple of inches deep into the roots of sympto-matic (yellow mottling - not dead yet) Floratam St. Augustinegrass should be shipped over-night in a Ziploc type plastic bag to:

    University of Florida Plant Diagnostic Center
    2570 Hull Rd, Bldg 1291
    Gainesville, FL 32611-0830
    Telephone: 352.392.1795
    Email: pdc@ifas.ufl.edu

    Samples can have most of the soil gently shaken off to reduce shipping weight. Send samples early in the work week so they do not sit over the weekend waiting for analysis by the lab. The specimen submittal form is available at: http://plantpath.ifas.ufl.edu/media/plantpathifasufledu/plant-disease-clinic/PDC_Submission_form_CC-1.19.16.pdf

    The form indicates a cost of $40 for Florida residents and businesses for plant analysis, but virus testing costs are $60.


  • Why does my SCMV Floratam St. Augustinegrass look great in the summer, and bad in the fall and winter?
    Answer:

    ​Floratam St. Augustinegrass is a tropical grass and grows much more vigorously during the warmer and wetter months. Once growth begins to slow, usually around October or November, symptoms become more evident.


  • Are other lawn grasses susceptible to sugarcane mosaic virus?
    Answer:

    ​Yes, but it does not kill them. Grasses that are know hosts of sugarcane mosaic virus are other St. Augustinegrass varieties, Bermudagrass, Paspalum, Bahiagrass, and ornamental fountain grass (Pennisetum spp.). Other monocots including crabgrass, sorghum, corn and sugarcane can also be hosts to the virus. Zoysiagrass is not a host.


  • Are other landscape plants susceptible to, or carriers of the virus? How about broadleaf weeds, pets, birds, other wildlife or people walking on the lawns?
    Answer:

    No, broadleaf plants are not affected. Other grasses beyond those listed above are not known to be carriers of sugarcane mosaic virus. Pets, wildlife and people walking on other than freshly mowed affected lawns do not typically spread the disease because they are not picking up plant sap. Aphids feeding on the affected grass can spread the virus. No other insects have yet been identified as spreading the virus.


  • What are the suggested mowing and lawn maintenance practices for an affected Floratam St. Augustinegrass lawn?
    Answer:

    University of Florida Best Management Practices are recommended for maintenance of sugar-cane mosaic virus affected Floratam St. Augustinegrass. This includes mowing to 3.5 to 4 inches in height for this turfgrass variety. Shorter mowing may increase stress on the lawn. Proper or shorter mowing will not affect the ability of the virus to be transmitted to other lawns. Unfortunately however, Best Management Practices have not been successful in extending the longevity of sugarcane mosaic virus affected Floratam St. Augustinegrass.


  • Are there any chemicals, fungicides or pesticides that can be applied to lawns to cure the sugarcane mosaic virus?
    Answer:

    No. Interestingly, a relatively frequent fungal pathogen of St. Augustinegrass, take-all root rot is often found in virus affected areas. The likely connection is that the fungus is more likely to attack SCMV stressed turfgrass. Weeds also tend to be more of a problem in stressed SCMV affected St. Augustinegrass, just as they are in lawns mowed below recommended heights, or that receive inadequate or excessive irrigation, or inadequate nutrition.


  • How can spread of the virus be controlled?
    Answer:

    Grass clippings and plant sap should be blown off mowing equipment on sugarcane mosaic virus affected sites. Equipment should then be sprayed until wet with recommended sanitizers, and allowed to dry to destroy any virus that may remain on the equipment. A good man-agement technique for commercial lawn maintenance companies is to mow sugarcane mosaic affected lawns as the last lawns of the day, and then sanitize. Theoretically, newly planted sugarcane mosaic virus infected sod could be a source, but currently none of the sod farms tested so far by the University of Florida Extension Plant Pathology Lab has been positive for the virus.

     


  • What are the current recommended mower and trimmer sanitizing materials?
    Answer:

    Spray sanitize mower/line trimmer equipment after working on affected properties until wet (and allowed to dry) with one of the following based upon effectiveness research trials:

    - Potassium peroxymonosulfate & Sodium Chloride (Virkon S) mixed at a 2 percent solution

    - Household Bleach (9 parts water mixed with 1 part bleach) Caution: bleach rusts steel


  • Can the disinfectant materials be applied to sugarcane mosaic virus affected lawns for control?
    Answer:

    No. The materials are surface disinfectants, and would not destroy the virus inside the living plant tissue. In addition, they are not legally labeled for disease management on lawns, and many are toxic to lawn grasses.


  • What are other management options?
    Answer:

    Replace dying Floratam St. Augustinegrass with Bitterblue or Palmetto varieties of St. Au-gustinegrass. Both are currently shown to be resistant to the virus. Palmetto variety St. Au-gustinegrass is somewhat finer textured than Floratam, and both will require slightly different management than Floratam, especially regarding fungal problems. Lawn areas can be com-pletely resodded with recommended varieties, or they can be "plugged" with smaller pieces into existing affected Floratam St. Augustinegrass lawns. Plugging allows the resistant varie-ties to fill in as the Floratam declines and dies. Neither Bitterblue nor Palmetto can be planted from seed. Do not replant Floratam on the same site. Bitterblue is an older variety that has been used since the 1930s. It also may be difficult to find a source of. Contact the Palm Beach County Extension office at 561.233.1750 for sources in Florida.

    Overseeding the virus affected Floratam with a cool season grass like ryegrass can be a tem-porary aesthetic measure for the winter snowbird season. This provides a green lawn during the mid-fall to early spring in southern Florida. Turf dyes are another temporary option.

    Florida.


  • What are the long-term solutions for sugarcane mosaic virus on Floratam St. Augusti-negrass lawns?
    Answer:

    Use measures described in this document to minimize spread and replace affected Floratam St. Augustinegrass with resistant grass varieties. Ongoing University of Florida research may provide additional information including other possible Floratam replacement St. Au-gustinegrass varieties. Mower virus transmission studies are also being conducted to see if sanitizing recommendations can be improved. Studies to confirm the viruses causing SCMV in Floratam St. Augustinegrass are also underway.


  • What research is underway to help solve the problem?
    Answer:

    The University of Florida Plant Pathology Department is currently testing additional St. Au-gustinegrass varieties for resistance to sugarcane mosaic virus. They are also testing for the effectiveness of virus sanitizers. Results should be available during the next two years.


  • How can I track the spread of the virus in Florida?
    Answer:
    The University of Florida Plant Pathology Department provides a link to a tracking map of counties that currently have identified the virus via their laboratory analysis. The map can be found at:
    http://maps.bugwood.org/eddmapscounty.cfm?sub=56472&notitle&states=fl&limitstate
     

    For further information, contact the University of Florida/Palm Beach County Extension Master Gardener Hotline at telephone: 561.233.1750 or email: mgardenfwd@pbcgov.org

    Date: Revised March 13, 2017

    Author: William L. Schall, Palm Beach County Extension

    Thanks also to Dr. Phil Harmon, University of Florida for much of the technical information in this publication, and to Laurie Albrecht, Palm Beach County Extension for identifying many of the included questions.


For further information, contact the University of Florida/Palm Beach County Extension Master Gardener Hotline at telephone: 561.233.1750 or email: mgardenfwd@pbcgov.org

Date: November 2015
Author: William L. Schall, Palm Beach County Extension

Thanks also to Dr. Phil Harmon, University of Florida for much of the technical information in this publication, and to Laurie Albrecht, Palm Beach County Extension for identifying many of the included questions.