By Yeshi Wamishe, Extension rice pathologist
Information on developmental stages related to timings for scouting (Figure 1) and management actions are extremely useful. Scouting is needed to determine the presence or absence of a disease, identify the pattern, and predict the potential damage to the crop. Diseases, including other field problems, need to be identified timely and accurately. Since each field is different, scouting needs to be conducted on field-by-field basis. Guessing wrong can be costly. For instance, applying a fungicide when the issue is related to herbicide, insects, or bacteria results in a cost with no benefit.
Most diseases require preventative measures with cultivar selection, best cultural practices, and ultimately fungicides applications. Therefore, pre and post planting preventative measures are cultivar resistance or tolerance and best cultural practices. Fungicides are supplemental and are applied if required. After all, rice benefits the most from fungicides if the field is managed well.
Scout for diseases to take timely management actions. Check fields to know the field and cultivar history, know seed quality, know the possible reasons for grain loss and be proactive for the next season.
Check for sheath blight after heading. However, post-harvest interval (PHI) need to come into consideration for fungicide application. Moreover, fungicides containing Propiconazole are not recommended after heading for any of rice diseases.
For blast suppression, once the necks are completely out of boots, it is already too late for fungicide application.
Fungicide timing for selected rice diseases
Please visit the table in Rice Info Page1 for fungicide timing for selected rice diseases and on Page 2of the same PDF for fungicides and active ingredients for rice disease management in rice.