By Yeshi Wamishe, Extension Rice Pathologist; and Jarrod Hardke, Extension Rice Agronomist
Field history information is critical to matching rice cultivars with the right fields. For instance, planting a blast-susceptible cultivar in historically blast-prone fields is not advisable. Usually hybrids, and varieties such as CL172 and CL153, have better packages for blast resistance. However, if you plan to raise a blast-susceptible cultivar in blast-prone fields, you need to plan ahead for the appropriate cultural management strategies together with the right fungicides at the right rates, timings, and frequencies. The same is true with diseases such as kernel smut and false smut. In general, the mantra for an adequate rice disease management plan is “choose the cultivar that is best suited to your field history”.
In disease management, weather is the greatest variable because we don’t control it. However, through research and experience, we know that diseases are more severe in late-planted rice. Disease situations can be worse if the cultivar of your choice is also late maturing. For instance, this year we have seen more severe false smut in RT Gemini 214 CL, RT XP760, Roy J, and Diamond that were planted late than those planted earlier. Please note that most cultivars, including hybrids, do not have good resistance package for false smut and kernel smut. The pathogen of false smut is more favored by humid and cooler temperatures whereas the kernel smut pathogen likes warmer and humid conditions. In general, fields planted as early as possible, using the recommended seeding rates and received balanced fertilization and adequate water, usually end up with encouraging grain yields.
The table on rice cultivar reactions below is based on historical and recent observations from test plots, grower fields across Arkansas, and other rice states in the southern U.S.A. In general, these ratings represent expected cultivar reactions to disease under conditions that most favor severe disease development. Lodging may be caused by diseases such as sheath blight. Hence, lodging data are included in the table for your additional information. Please see the acronym descriptions given below the table. This information will be updated as additional data becomes available.
View the pdf version of the table here: Commercial Rice Cultivar Responses to Major Rice Diseases in Arkansas