Remember those publicity pictures of a pretty girl in a bathing suit posing provocatively against the trunk of a graceful, curving coconut palm tree here?

Save them. They may become collectors' items.

Coconut palm trees-the kind that made Miami Beach famous-are dying away, victims of lethal yellowing, a virus-like disease which scientists have been unable to control.

Of course, the West Indian coconut isn't the only palm that grows here, but it is the tallest and most graceful-and the one tied indelibly to the image of Miami Beach. Most of those still standing here are on Miami Beach, where the city until recently had undertaken an inoculation program that stayed the progress of the disease. But this has now been abandoned because of its expense.

Whether the 11,000 palms which thus had been preserved on the beaches and main thoroughfares of Miami Beach now will die is not yet known. The incubation period of the disease is six months, so the first signs of failing trees will not come until sometime this month or in May, at the earliest.

As replacements for the West Indian palms, the county, municipalities and private homeowners here have turned to the blight-resistant dwarf Malay coconut palm. It is similar to the West Indian, but does not grow as rapidly or as tall. Its nuts and fronds are yellow in color rather than green.

As a result, visitors see fewer of the familiar tall palms that used to grace many of this city's avenues, dooryards and beachfront, and those they do see are not quite the same in appearance. Then, too, only 250,000 of the Malay variety have been planted in Greater Miami, whereas at least 400,000 have died.

So far, Florida is the only area in the United States hit by the blight, which also affects 24 other varieties of palms, including the date palm and the popular Christmas palm. More than 500 varieties of palms are known.

Coconut palms also are found in Texas, California and Hawaii, but none of these states has been affected by the blight. California and Hawaii have put embargoes on the importation of coconut seeds, leaves or other material from Florida.

Lethal yellowing first made its appearance in Florida in the 1930s, when it killed about half the West Indian coconut palms in the Florida Keys.Again, in the 1950s it was found in Key West, where it destroyed three quarters of that island's palms.

In late 1971, it moved onto the Florida mainland for the first time, appearing in Coral Gables, a suburb of Miami, and began to spread rapidly. Today, 95 percent of the coconut palms in Dade County (the Miami area) have been destroyed, according to Dr. Henry Donselman, a member of the University of Florida research team based in disease. About 65 percent of the palms in Broward County (Fort Lauderdale) and 20 percent of those in Palm Beach County are gone.

Massive regular doses of tetracycline antibiotic seem to arrest the disease, researchers have found, but do not cure it. The expense of such a program has prompted all municipalities in the Miami area to abandon it in favor of a replanting program.

Currently the city of Palm Beach is injecting 42,000 coconut palms with tetracyline every four months, and so far has lost less than 2 percent of its palms. And the inoculation program on Florida's west coast apparently has arrested the disease there. The injections leave ugly black drip stains and plug marks on the trunks of the trees.

Most of the Malay variety seeds come from Jamaica, which had lethal yellowing as far back as 1891 and has been hard hit by the disease, but availability is limited because Jamaica keeps most of the nuts to replace its own extensive coconut plantations.

New hybrid varieties, like Maypan, a cross between the Malay and Panama Tall palms, show promise because they have more vigor than the Malay. But these are years from producing any significant quantity of trees.

Meanwhile, the tourist who strays from this city may have a difficult time finding a suitable coconut tree to photograph. Little Malays, not fully grown, are visible here and there, as are other non-coconut palms. But on some avenues, other tropical trees have been used to replace the coconuts.

This bothers Donselman. "I think out tropical atmosphere is very important," he said, adding that he regards the coconut palm as imparting more of that atmosphere than other trees. "We did a survey on what kind of postcards people buy here, studying the 50 bestselling cards produced by one of the top postcard companies here. It turned out that all of the top five showed coconuts, and that coconuts or coconut palms were depicted in all 50.

"This, to me, shows how important this tree is to us."

Donselman says his research team believes the blight is caused by a mycoplasma, a simple form of life which is neither plant nor animal and occupies an evolutionary niche between viruses and bacteria. Much current research is aimed at striking at the suspected carrier of the mycoplasma, an insect called the plant hopper.

If a solution is not found soon, the remainder of Florida's tall, curving coconut palms may vanish-and then where would th epublicists pose those smiling girls in bikinis?

Somehow, a pine tree just isn't as romantic. CAPTION: Picture 1, The vanishing West Indian palms; photo by Chris Hansen, Miami Beach Tourist Development Authority.; Picture 2, North Shore Park, Miami Beach, where Dwarf Malay palms replace the dying palms; photo by Tom Gura, Miami Beach Tourist Development Authority.