By Yeshi Wamishe, Extension Rice Pathologist
Following adequate cultural practices is an important disease management strategy along with planting resistant cultivars. In addition, seed treatment fungicides are cheaper and easier than spray fungicides. Balancing N, P, and K also promotes good growth and plant health. Planting as early as possible is also recommended for disease escape.
Below a few tips are suggested for your consideration before the 2018 rice planting to minimize common rice diseases.
To reduce seedling diseases: Use clean, plump and “healthy” or healthy-looking seeds for planting. Use fungicide- and insecticide-treated seeds particularly in fields with a history of seedling diseases or low and weak plant stand.
To reduce damage from straighthead: For a field with a history of straighthead, plant resistant or moderately resistant varieties to straighthead. Moreover, manage your field size for timely “drain and dry” strategy based on the University of Arkansas DD50. Big field sizes get difficult to drain and re-flood in a timely manner.
To reduce the effect of hydrogen sulfide toxicity: In a field with a history, manage your field size for timely “drain and dry” strategy. The timing and the strategy is similar to that for straighthead. If your field slope allows, such a field can be a possible candidate for row rice or alternate wetting and drying (AWD) rice production systems. Contrary to continuous flood, these systems can allow oxygen into the soil and lower the toxicity effect.
To lower blast epidemics: In a rice field with a history of blast or a field in “blast prone” category as described in the best defense is a good offense, match your field with the variety of your choice. Plant resistant varieties in blast prone fields. Although seed treatment does not warranty neck blast protection, it is recommended for early season leaf blast (see the comment on seed treatment for blast in MP154 Page 112. Note: Blast-susceptible varieties are not recommended for row or AWD rice production system.
To lower the incidence of sheath blight: Manage your seeding and nitrogen fertilizer rates. Rice grown lush with dense canopy or rice with short or medium height and varieties rated susceptible or very susceptible, often show more sheath blight under favorable weather conditions.
To lower kernel smut and false smut: In a field with a history of one or both of these smuts, manage the nitrogen fertilizer rate. Excessive N rates are often the culprit.
To lower the chance for bacterial panicle blight (BPB): Use clean and plump seeds for planting. Early planting, adequate seeding, and nitrogen fertilizer rates have been proven to lessen the disease incidence. BPB is highly weather dependent. The bacteria can be carried within healthy-looking seeds. However, more than one weather factor is involved for disease epidemics.
To see the reactions of commercial rice cultivars to common diseases: go to Cultivar Reactions.