October 23, 1985

MUSHROOM mania is the current epidemic sweeping through American produce markets. Indeed, the abundance in specialty-food shops of what were once called toadstools - chanterelles, boletes, oyster mushrooms, morels, cauliflower mushrooms, shiitakes, meadow mushrooms and many other varieties - makes it hard to believe that there was a time when even commonplace fat, white, fresh cultivated mushrooms were unknown in our supermarkets. ''Americans went from not knowing anything to going wild about the stuff,'' said Giorgio DeLuca of Dean & DeLuca in SoHo. ''I don't know why - maybe it's part of the health thing.'' His food shop at 121 Prince Street (Greene Street) has, for a number of years, stocked fresh wild mushrooms, imported and domestic.

The United States said today that the Soviet Union had begun deploying a new intercontinental nuclear missile in violation of the 1979 treaty limiting offensive strategic weapons. Secretary of Defense Caspar W. Weinberger said in a speech that he could ''confirm officially'' that deployment of the single-warhead missile, known as the SS-25, had begun. The State Department spokesman, Bernard Kalb, said the Soviet Government had informed the United States that SS-25's had been deployed. [In Sofia, Bulgaria, according to CBS News, a Soviet spokesman, Vladimir B. Lomeiko, denied that the deployment was a treaty violation. Mr. Lomeiko, in Sofia for a Warsaw Pact meeting, affirmed the Soviet position that the SS-25 was a modification of an existing weapon, the SS-13, and that the modification was permitted by treaty.] Reagan Looks to Gorbachev Talks Meanwhile, President Reagan, on the eve of his visit to the United Nations, said that he was ''determined to build a more constructive relationship'' with the Soviet Union and to seek reductions in the nuclear arsenals of the two countries. [Page A3.] Mr. Weinberger's remarks on the SS-25 missile seemed intended to portray the Soviet Union as a violator of international agreements when there is debate about a new United States interpretation of the 1972 treaty limiting antiballistic missile defenses.

Colleges in the New York area, faced with mounting student and parental concern over AIDS, have started programs to teach students and staff members about the disease. Some college officials began the programs after students or teachers contracted the disease, but most say they are acting because they are sure there will be cases. The colleges report they are also working to set policies on such issues as whether AIDS victims will be allowed to remain in dormitories and whether other students in the dorm will be told of the victim's illness, problems that are now handled on a case-by-case basis. The officials said educational programs could slow the spread of the disease, acquired immune deficiency syndrome. They also said the programs might allay what they see as irrational fears of AIDS that have led on some campuses to incidents of harassment of homosexuals, the group most likely to contract the usually fatal disease.

Serenity usually returns when the couture houses take over the runways during the week of ready-to-wear openings. In these collections, couture designers are more concerned with making wearable clothes than with carving new design paths. Their presentations are consequently more soothing. This season is no exception. Valentino, who shows his couture collection in Rome but chooses to introduce his ready-to-wear here, and Hubert de Givenchy both showed calm, attractive collections for spring and summer.

Schools Chancellor Nathan Quinones said yesterday that he would seek the immediate dismissal of nearly half the community school board members in New York City for failing to file financial-disclosure statements, as required by state law. At a news conference at Board of Education headquarters in downtown Brooklyn with James F. Regan, president of the board, Mr. Quinones said the city would ask the State Education Commissioner today to dismiss 126 of the board members. The action would affect 28 of the 32 boards, each of which has nine members elected for three-year terms. 'Example of Lawlessness' ''This drastic action is necessary,'' the Board of Education said in a resolution passed last night, ''because to permit public officers to violate the law with impunity will set an example of lawlessness for schoolchildren under their care, will undermine the public's confidence in such officers and will impede the board's and the Chancellor's efforts to insure that corruption and conflicts of interest do not interfere with the proper functioning of the New York City school system.''