Since varietal genetic resistance is not always available for all diseases, cultural management strategies are highly recommended. However, in some instances, use of fungicides to reduce disease pressure has become inevitable in our rice production system. To benefit the most from fungicide application the following pointers are suggested:
1. Know the history of your field and the varieties planted.
2. Keep on scouting, starting two weeks after planting and more frequently from green ring until after heading, scouting for sheath blight in particular. It can help determine fungicide rate and timing.
3. Manage your fields well to benefit the most from fungicide application. Avoid automatic fungicides application. Apply fungicides when and where needed.
4. Apply fungicides at recommended timing and rate.
5. Use adequate volume of water to mix the fungicides to provide better foliage coverage.
6. Check for the compatibility of chemistries if tank mixing is desired.
7. You may use combination fungicides (Triazole + Strobilurin) as protective if you wish to target more than one disease such as kernel smut, false smut, and neck blast. However, note that the best timing for fungicide application against the smuts is early boot and for blast is late boot stage of the main tillers.
8. Adjust the rates of individual fungicides if mixing compatible products with different modes of action when tank mixing.
9. Rotate chemistries with different modes of action to reduce the chance of creating resistance to fungicides.
10. Use higher recommended rates of the fungicides for better disease control. See minimum and maximum rates of fungicides on Table 1, 2, 3, 4.
- On assessment of the research from Dr. Rick Cartwright the following information has been extracted for sheath blight disease of rice:
- Stratego at 16 oz provided 14-17 days control, whereas the 19 oz for 21-24 days. Quadris at 6.4 oz provided 10-14 days control while 9 oz for about 21 days. But the full rate 12.5 oz provided 28 days of control. Moreover, his research had indicated Azoxystrobin (Quadris) to be somewhat more effective on sheath blight than Trifloxystrobin (GEM)–but the difference was just slight.
- To suppress minor leaf and sheath diseases fungicide application may not be warranted. These diseases may be controlled by broad spectrum fungicides, such as a strobilurin, if already applied for major diseases such as sheath blight and blast.
Please see the linked pdf below for additional information on products and rates.