AS EVERY newly accredited expert on Proposition You-Know-What started boldly predicting right after the vote in California, the "13 fever" - or spirit, if you prefer - is now spreading through the land in various strains. In fact, if you look right around you, you'll note that groups of would-be tax-whackers even now are scrambling about Montgomery and Prince George's counties with armloads of petitions calling for parsimony.

By zeroing in on shopping malls, the petitioners do especially well; after all, what better therapy is there at the end of a shopping trip through the supermarket than a sign a petition for tax relief? Still, voters should look before they leap at the chance, for the ultimate effects of these moves may not be nearly so pleasing.

For one thing, people here - unlike the voters of California - do not have the safety net of a multibillion-dollar surplus from income taxes. For another, most local elected officials already got a good whiff of the June 6 sentiment out West and have since begun rustling up their own proposals for easing property-tax burdens. Moreover, the leadership of other citizen-petition drives is not always falling into the best of hands: It's a natural of the old "taxpayer alliance" crowd, which in many localities up to now has been on the political fringes, taking potshots at any public spending proposal without regard to citizen need (or financial sense, for that matter, since bonds in certain instances may be more palatable than pay-as-you-go policies).

Anyway, a proposal can be placed on the November ballot in either of the two countries if its organizers can get 10,000 valid voter signatures on their petitions by Aug. 21. In Montgomery, the proposal of the County Taxpayers League would roll the property-tax rate back to $2.25 per $100 assessed value - down from the current $2.60 level; and it would permit tax rates to be raised only by a vote of six of the seven county council members. We're not sure what magic there is in that particular decrease figure, but the six-out-of-seven vote requirement strikes us as far too stringent.

In Prince George's, a drive begun by two county Democrats - veteran politician William Goodman and candidate-for-delegate David Bird - proposes an even worse set of restrictions. Their proposal would freeze county property-tax revenues at 1979 levels - a ceiling on the amount the government could collect. Not only is that a dangerous bind in which to put any local government; it doesn't even allow for the collection of additional revenues from new development in the county. Retired state senator Meyer Emanuel, a longtime student of county and state fiscal affairs, has rightly noted that a vote for this proposal would put "a straitjacket on the government."

Rather than lock themselves and their governments into misguided, rigid fiscal constraints, the wiser course for concerned citizens would be to concentrate on weighing the views of candidates for public office and to be wary of those office-seekers who jump too carelessly onto the referendum bandwagons. Most of the candidates are quite sensitive to the revolt now running against the automatic effects of severe inflation. How sensibly they speak to that issue is what matters.