Commercial navel and Valencia orange groves in the San Joaquin Valley were used in experimental applications of parathion for citricola scale control in field tests during the period from 1947 to 1950.

Parathion is extremely toxic to humans and the most serious hazard relating to its use is danger to personnel who may come in contact with the compound while making applications or working in newly treated groves. Precautions recommended by the manufacturer should be followed carefully.