State agriculture officials have completed ground spraying of the pesticide malathion in northern Santa Clara County and announced plans for an aerial spray to battle an infestation of Mediterranean fruit flies. Gov. George Deukmejian told agriculture officials that he will declare a state of emergency in Santa Clara County, agriculture department officials said. The emergency declaration allows authorities to spray malathion without issuing an environmental impact report that could take months to prepare, Curry said. The state will also release 30 million sterile Medflies a week until biologists decide that the infestation has been curtailed.