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28
Jun
2018
A Common Mistake: Waiting Too Long to Manage Kernel and False Smut with Fungicides
Author: Yeshi Wamishe, Extension Rice Plant Pathologist

By Yeshi Wamishe, Extension Rice Pathologist

For most consistent results in suppressing kernel and false smuts, we recommend fungicides that contain propiconazole with a Tilt equivalent rate minimum of about 6 fl oz per acre, applied during booting.  Applications after full swollen boot will be less likely to provide suppression of either disease.  Applications can also be timed to manage sheath blight in most cases. Fungicide applications to control neck blast are generally too late for best smut suppression.  Therefore, fungicide applications to protect rice from neck and panicle blast need to be carried out separately later at recommended timing. Recommended fungicides and rates for best suppression of kernel and false smut results include:  Tilt 6 fl oz per acre; Bumper 6 fl oz per acre; Propimax 6 fl oz per acre (alone or in combination with Quadris or GEM);  Stratego 19 fl oz;  Quilt Xcel 21 fl oz per acre or at least 17.5 fl oz per acre). Pre-mix fungicides or combining triazoles with strobilurin fungicides help to suppress both the smuts and sheath blight. To check on threshold for sheath blight go to scouting for sheath blight.

Timing for fungicide application to suppress kernel smut and false smut is between early (slightly swollen) to mid-boot (full swollen) in reference to primary tillers (Figure 1). Remember: Fields with history that received excessive nitrogen are more prone to these smuts. Also, if fungicides are applied too early, they may wear out and the desired disease suppression may not be obtained.

Fig. 1. Early to mid-boot is the optimum timing for kernel and false smut fungicide application.

Fig. 1. Early to mid-boot is the optimum timing for kernel and false smut fungicide application.

Fig. 2. Protective fungicide application to suppress kernel and false smut after late boot will be less effective since the fungicide will not have enough time for maximum effect.

Fig. 2. Protective fungicide application to suppress kernel and false smut after late boot will be less effective since the fungicide will not have enough time for maximum effect.


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