Onion downy mildew and blight, as well as thrips and leafminer. Downy mildew can be controlled with sprays of dimethomorph, manganese zinc, moldocin, pyraclostrobin, pyraclostrobin, manganese, dimethomorph and cyanazole spray. Thrips: When onion thrips cause damage, spray control with spinosad, spirotetramat, pymetrozine, nitenpyram, and thiamethoxam. The spotted leafminer is also called the ghost painting talisman. Use cyromazine, or abamectin plus silicone spray to control.