NO PRESIDENT is ever short of places to put on his itinerary when he travels abroad, and no president or presidential staff can be faulted for wanting to keep the list at a manageable length. Is it not possible, however, that President Reagan might want to reconsider the decision not to include Dachau, the World War II German death camp, in the plans for his trip to the Bonn economic summit in May? A stop at this camp was at one time under consideration. It was scratched, it has been reported, on grounds that present-day Germans were not involved in the Nazi Holocaust and that a visit to Dachau could be misconstrued.

But a decision not to visit Dachau might more likely be misconstrued. Dachau is one of the places where millions of Jews and others were slaughtered. It represents the fullest horror of the World War whose 40th anniversary is being observed this spring -- perhaps the last big anniversary that will be marked by large numbers of people who were of age at the time.

The triumph of arms is certainly the most splendid event to be memorialized in this anniversary season, but the tragedy of human loss is the moral core. To pass by the occasion to bear witness at Dachau is to remove a whole vital dimension of American participation in the war -- and to give unintended but unavoidable support to the vile campaign to pretend there was no Holocaust at all.

What is odd about the decision to leave out Dachau is that the president has himself shown a deep personal awareness of the Holocaust. In a White House ceremony in 1981 he recalled in compelling detail his wartime work editing the first film that came in about the death camps. The film, he said, "remains with me as confirmation of our right to rekindle these memories, because we need always to guard against that kind of tyranny and inhumaniy."

Nor need there be any serious apprehension that our German allies will take umbrage. West German citizens have long since confronted the darkness of the Hitler period; their leaders have made the difficult and necessary symbolic pilgrimages to the scenes where the Nazis strew death. There is reason to believe that Germans would be gratified to present a common face, with an American president, to the evils of their country's past. A president with Ronald Reagan's compassion for the victims of tyranny need have no political hesitation to remember them and, in remembering them, to raise the moral barrier against any repetition of the great Nazi crimes.