Arkansas Rice: Properly Managing Kernel and False Smut

    Both kernel and false smut are severe in late planted susceptible rice. Under favorable conditions most of rice cultivars are susceptible including hybrid rice. Fields with history and excessive nitrogen are more prone to smuts.

    Triazole fungicides containing Propiconazole (Tilt equivalents) are still preventative options. Kernel smut is more sensitive to the fungicides with up to 90% to 95% suppression provided the rate, timing and coverage are done right. False smut can be suppressed only from 50% t0 70%. Rate for tilt equivalent has been increased from 4fl oz to a minimum of 6 fl oz per acre in recent years.

    Fungicide application timing after late boot is too late. Early or late boot split is also too late (Picture 1). The correct timing is from early boot to mid boot (Picture 2). Fungicide applicationbefore early boot is too early for the fungicides to stay effective until heading. Tilt (Bumper or Propimax) can be included in the list below for suppression of kernel and false smut.

    For good coverage a minimum of 10 gallons of water per acre is encouraged to mix the fungicides.

    Table 1. Strobin and triazole contents of commonly used fungicides for kernel and false smut suppression

    Fungicide Rate oz/acre Strobin Triazole Strobin rate oz/acre Triazole rate oz/acre
    Quilt 21 – 34.5 azoxystrobin propiconazole 6.3 -10.3 6.1- 10
    Quilt Xcel 21 – 27 azoxystrobin propiconazole 11.9 -15.3 5.9 -7.6
    Stratego 16 – 19 trifloxystrobin propiconazole 4.0 – 4.7 4.6 -5.5

     

    Figure 1. Protective fungicide application to suppress kernel and false smut after late boot is not beneficial. It is already too late. Early or late boot split is also too late.

    Figure 1. Protective fungicide application to suppress kernel and false smut after late boot is not beneficial. It is already too late. Early or late boot split is also too late.

    Figure 2.  Early to mid-boot is the correct timing for kernel and false smut fungicide application.

    Figure 2. Early to mid-boot is the correct timing for kernel and false smut fungicide application.




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