There's a fly in Gov. Jerry Brown's soup

Gov. Edmund G. (Jerry) Brown Jr. of California is a youthful veteran of major political wars -- two successful gubernatorial campaigns, an impressive though abortive bid for the Democratic presidential nomination in 1976, and a capitulation in Proposition 13 which he made look like a victory.

He probably will run for the US Senate next year. But first he must brush aside a . . . fly.

The Mediterranean fruit fly, which state agricultural officials hoped they had eradicated last winter in the San Francisco Bay Area, has turned up again in parts of Santa Clara County.

Its reemergence is a very serious business in a state where the economy counts heavily on many of the 200 kinds of fruit the "Medfly" attacks.

If the fly spreads to other fruit-growing areas like the San Joaquin Valley, it could mean disaster for many farmers and for the state. Other fruit-producing states -- especially Florida and Texas -- are threatening to ban fresh California fruits and vegetables.

Last winter, fruit was stripped from trees in the infested areas, millions of sterile male Medflies were released to foil the reproductive cycle, and the pesticide called malathion was sprayed at ground level to kill flies as they emerged from the pupa stage.

Now the governor's Medfly Technical Review Committee wants him to authorize aerial spraying of malathion. Otherwise, they say, newly hatched Medfly larvae may not be destroyed, but survive to reinfest the area in about two weeks.

That's the political rub.

Some 500,000 people live in the affected area. Most have some fruit trees in their yards, but do not depend on them for their livelihood. Tens of thousands of those people do not want malathion sprayed over the area.

Farmers and state pesticide authorities say malathion sprayed in the diluted form needed to kill Medflies won't harm people. Research evidence is heavily weighted against risk to humans. But a respectable minority of scientists say long-term effects are unpredictable and may be harmful.

So an environmental decision becomes a political one.

Governor Brown delayed his decision while his Technical Review Committee held a hearing July 7 in Los Gatos. It was picketed by residents -- many mothers with their babies and young children -- opposed to malathion spraying.

Experts recommended aerial spraying, but when local officials threatened to go to court to stop such actions, they were cheered.

After a July 8 meeting with his committee, Governor Brown announced his decision: no aerial spraying -- at least not until other methods are given a chance. He called on residents of the 600- square-mile infested area to strip all fruit trees by July 13; called out a massive force of government workers to ground-spray, strip trees, and mind highway, airport, and bus station checkpoints.

He also asked President Reagan for emergency aid, funds, and equipment to help meet "what could be a national threat posed by the Medfly infestation and a potential economic crisis in this, the largest food-producing state in the nation."

If, on review in the next two days, it is found the program is not totally effective, the governor admits he may have to order spraying of malathion over the area.

The political risk for Brown besets him on two sides. Agricultural interests are angrily charging him with "political expediency" in not ordering aerial spraying.

If the alternative plan fails, he will have to order spraying. There is no guarantee that even aerial spraying will stop the spread of the infestation. If that's the case, the governor woul d be open to the charge that his delay was the cause.