Fungicide Spray Schedule for Tobacco Transplant Production

 

Fungicides are an important tool for managing diseases in tobacco float beds, and getting the best results from these inputs hinges on using each product at a time when it will have the most impact in preventing a particular problem.  The following is a suggested schedule for timing the applications of products labeled for diseases in tobacco float beds.  The emphasis is on preventive use, and the timings are based on an 8-week transplant cycle (seeding to useable plant).

 

Suggested Spray Schedule

2 to 4 Weeks after Seeding

When roots of plants emerge from trays and enter float water, apply Terramaster EC at 0.7 to 1 fl oz/100 gal of float water for control of Pythium root rot.  Make a follow-up application of Terramaster at 1 fl oz/100 gal of float water no earlier than 3 weeks later (see below).

3 to 4 Weeks after Seeding

When plants have reached the size of a dime, apply Manzate Pro-Stick for suppression of Rhizoctonia damping-off and target spot.  The rate is 0.5 lb/100 gal of water (equivalent to 1 tsp/gal).  Use 3 gal of spray solution per 1000 sq. ft of bed (~400 trays); apply as a fine mist to ensure good foliar coverage.

5 to 6 Weeks after Seeding

The first time plants are clipped:

  • If target spot is not present, continue with Manzate Pro-Stick; increase spray volume to 6 (or more if needed) gal/1,000 sq. ft.  Don’t exceed 12 gallons of spray volume per 1,000 sq. feet (even on the largest plants).
  • If target spot is active, substitute Quadris for Manzate at a rate of 0.14 fl oz/1000 sq. ft of bed.  This is the equivalent of 4 cc (~1 tsp), and should be diluted in 4 to 5 gallons of water before dispersing as a fine spray.
  • One application of Quadris is permitted on tobacco seedlings in float beds.

6 to 7 Weeks after Seeding

  • Make follow-up application of Terramaster EC at 0.7 to 1 fl oz/100 gal of float water.
  • If Quadris was not applied earlier, make one application of this fungicide at the second clipping.

7 Weeks after Seeding.

Continue with Manzate Pro-Stick, slightly increasing spray volume per 1,000 sq. ft as plant size increases, not to exceed 12 gallons of spray volume per 1,000 sq. feet (even on the largest plants).

8 Weeks after Seeding (and beyond)

Continue with Manzate Pro-Stick.  A final application of Terramaster EC can be made at 0.7 to 1 fl oz/100 gal of float water if needed; do not apply more than 5 days before transplanting.

 Additional Information

  • The amount of float water in a bed (in gallons) is calculated by the following formula: (the number of trays in the bed) X (the water depth in inches) X 1.64.
  •  5 cc = approximately one teaspoon (tsp).
  • 1,000 sq. ft = 400 trays.
  • For more information on float-bed fungicides, refer to the “2014 Fungicide Guide for Burley and Dark Tobacco” (UK Plant Pathology Fact Sheet No. PPFS-AG-T-08).
  • Manzate Pro-Stick is the only mancozeb fungicide currently labeled for tobacco float-beds.  Growers must have a copy of the 24(c) label for Manzate at the time of application.
  • Banrot, Rovral, Iprodione 50W or Ridomil Gold are not approved fungicides for use in tobacco greenhouses.

 

by Clint Hardy, Daviess County ANR Agent and Kenny Seebold, Extension Plant Pathologist

Posted in Tobacco