Fungicides Timings for Selected Rice Diseases
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Green Ring |
PD+7 |
Early Boot |
Mid-Boot |
Late Boot |
Up to 10% Head out |
50-75% Head out |
After Heading |
Availability of Products |
|---|---|---|---|---|---|---|---|---|---|
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H2S Toxicity |
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No |
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Straighthead |
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No |
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BPB |
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No |
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Blast |
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Yes |
Yes |
Yes |
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Yes |
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Sheath Blight |
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Maybe |
Maybe |
Yes |
Yes |
Maybe |
Maybe |
Check PHI |
Yes |
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Kernel Smut |
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Yes |
Yes |
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Yes |
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False Smut |
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Yes |
Yes |
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Yes |
Blast: For neck and panicle blast, two applications may be required for maximum suppression with the first at late boot to 10% head out and the second at 50-75% head out. (Head out refers to what proportion of individual heads are out of their boot in about 50% of tillers). If the necks of the main and secondary tillers are out of the boots, fungicide application is too late. Increase flood depth for early season leaf blast. In cases of leaf burn due to leaf blast, treat hot spots.
Sheath blight: Boot application and later at heading may be required if a cultivar is S or VS and weather favors disease. If earlier application is done due to severe sheath blight, PD to boot application may be needed depending on how fast the disease progresses. However, more than one application for sheath blight alone is not profitable. It may be wise to pair timing with fungicides to suppress other rice diseases.
Kernel and False smut: Timing is narrow and critical. > 6 Oz/Acre rate of Propiconazole equivalent is critical to maximize protection/suppression. Difenoconazole containing fungicides such as Amistar Top may also be used alternative to Propiconazole.
Hydrogen Sulfide (H2S) toxicity and Straighthead: follow the "drain and dry” strategies.
Bacterial Panicle Blight (BPB): Nothing to be done and hard to predict its presence. Planting seeds from BPB harvest is the best approach to manage this disease.
PHI= Pre Harvest Index.