varietal resistance造句

• Varietal resistance is the primary management tool, and eliminating weeds and infected perennial ornamentals that may harbor the virus is critical.
• More cost effective, organic control measures such as dry fallow and rotation have proven effective, but farmers cannot afford taking the land out of production for the necessary length of time to abate the destructive levels of RRN . Weed control and natural resistances of rice are possible control measures that may prove more effective in the future, but the lack of extensive research efforts for varietal resistance renders the latter unsuccessful.