One hundred and fifty years after they helped forge their home nations' ideas of pride and patriotism, Wagner and Verdi have proved they can still provoke a bust-up between Germany and Italy.

As opera houses around the world gear up to celebrate the 200th birthdays of the composers – they were both born in 1813 – the decision by Milan's La Scala to seemingly overlook its local hero and instead open its season on Friday with Wagner's Lohengrin has sparked angry criticism.

The theatre's decision to opt for Wagner, whose pounding operas were the soundtrack for German unification, over Verdi, whose uplifting works inspired Italy's own Risorgimento, comes as Italians feel the bite of austerity policies they see as dictated by Berlin, a humiliation lightened only by Italy's beating of Germany in the European championships this summer.

"This choice is a smack for Italian art, a blow for national pride in a moment of crisis," Milan's daily newspaper, Corriere della Sera, declared, claiming there was disquiet in the orchestra at La Scala, where Verdi made his professional debut. "Would the Germans have inaugurated a Wagnerian year with a work by Verdi?" asked the paper.

Peter Conrad, the British author of Verdi and/or Wagner, a study of the lives of both men, agrees. "As La Scala's musical director and a Wagner specialist, [Daniel] Barenboim has put his tastes ahead of Italy's," he told the Guardian. "This reminds me of how a German banker paid for a bust of Wagner to go up in Venice at the start of the 20th century before the local town hall then shamefully put up one of Verdi next to it. Italy gets trampled on because it is not good at celebrating its own culture."

However, Stéphane Lissner, La Scala's general manager, pointed out that next year the theatre will stage five works by Wagner against eight by Verdi and open next season with Verdi's La Traviata, "which is chronologically exact, because Verdi was born in October, while Wagner was born in May," he said. "The rest is just stupidity and ignorance." Moreover, Barenboim – a Wagner expert – was only free this month, he added.

Barenboim has chimed in, saying: "What difference does it make inaugurating the season with one or the other when almost all the works of both will get performed?"

Unlike La Scala, Naples' San Carlo opera house – for which Verdi composed works including Luisa Miller – has had no doubts about opening its season this week with La Traviata.

"Verdi is in the DNA of Italians," said the San Carlo's artistic director Vincenzo de Vivo. "After Italy unified he believed in the country but felt betrayed by politics, and if we can convey his moral values today through music we can help the rebirth of Italy."

Conrad said the row reflected the intense rivalry between the composers and their supporters. "Verdi went incognito to the Italian premiere of Lohengrin in Bologna with a copy of the score and wrote 'mad' in the margins, while Wagner thought Verdi's work was hurdy gurdy," he said.

"When Wagner died, Verdi almost crowed and went on to have a second career in which he composed Otello and Falstaff, although he resented critics who saw Wagner's influence in them."

Anti-German sentiment flared at the first performance of Lohengrin at La Scala in 1873, with loud whistling and scuffles breaking out in the audience. A fearful Wagner, who had turned up to conduct, decided to get off the stage and let an Italian pick up the baton.

Since then, La Scala's hardcore music lovers have kept their feisty reputation alive, and were back in action at a concert on Monday, whistling singer Cecilia Bartoli for what they considered an under par performance, prompting Barenboim to tell the crowd: "We are at a concert, now shut up."

Come Friday, fighting in the audience may not be on the cards when Lohengrin returns to Milan, but Conrad said the night would be more than just about opera: "This row is about the continuing balance of power in Europe – there is always a nationalist edge when we talk about Verdi and Wagner."