Special Local Need Label For Use Of Quadris On Greenhouse-Grown Tobacco Approved

 LEXINGTON, KY.
    Kentucky’s burley tobacco producers have dealt with some pretty serious cases of target spot in greenhouses and outdoor float beds. Severe levels of target spot on seedlings can be costly in terms of delayed development, and can also lead to the introduction of the target spot pathogen in the field. Managing target spot effectively involves good management practices, such as ensuring that plants are well-ventilated, adequately fertilized, and treated with fungicides where appropriate. Mancozeb fungicides (Dithane DF or Manzate ProStick) can be used on a 5-7 day schedule, beginning around 2-3 weeks after seeding (when seedlings are dimesized or larger), to suppress target spot. Although mancozeb is not specifically labeled for target spot, it is reasonably suppressive when applied preventively.
   Good-to-excellent control of target spot can be achieved with Quadris fungicide. Effective now through December 31, 2012, growers can make ONE application of Quadris at a rate of 6 fl oz/A to tobacco seedlings in greenhouses or outdoor float beds. This is the equivalent of 0.14 fl oz (4 cc) of product per thousand square feet of float bed (roughly 400 trays), applied in a spray volume of 5 gallons – enough to get good coverage of foliage. For best control of target spot, we recommend making the Quadris application before symptoms are seen (or when they first appear at the very latest). In most years, target spot becomes active in Kentucky in late April or early May. To get ahead of the disease, a good strategy would be to apply Quadris after the 1st or 2nd clipping. After making the Quadris treatment, producers should switch back to mancozeb until plants are set in the field. This is critical to stay in compliance with the label, and to minimize the risk of resistance development. Quadris is most likely compatible with products like mancozeb or Orthene, but it would be advisable not to mix Quadris and agricultural streptomycin to avoid potential injury to seedlings. In terms of weathering, Quadris is rainfast within an hour or two of treatment.
   In cases where target spot is severe on float plants, treatment with Quadris may be needed at about 5- 6 weeks after setting to suppress the disease in the field. For more information on using Quadris on tobacco after transplanting, consult the 2011-2012 Kentucky-Tennessee Tobacco Production Guide (University of Kentucky Publication ID-160).
   It’s important that growers who use Quadris in the greenhouse or outdoor float bed have a copy of the 24(c) label in their possession. This label can be obtained from farm chemical suppliers or online at http://www.cdms.net/LDat/ld5QN006.pdf. It is equally important to remember that the greenhouse application counts toward the seasonal limit (4-5 applications) allowed on tobacco. Δ
 DR. KENNETH W. SEEBOLD, JR.: Extension Plant Pathologist, University of Kentucky