Japan’s Shine Muscat Grapes Dealing with Flowering Issues

Agriculture, Forestry and Fisheries Ministry website
Problems with flowering led to this deformed bunch of Shine Muscat grapes.

The Shine Muscat grape at times is afflicted by a problem with flowering, an issue reported in 30 of Japan’s 46 prefectures that cultivate the popular variety.

Yamanashi Prefecture, which boasts the nation’s largest grape production, has already reported having the problem this year. In 2021, about 200 cases of where flowering was abnormal or nonexistent were confirmed.

The problem was first reported to the Agriculture, Forestry and Fisheries Ministry around 2017. This flowering issue has been occurring usually from late May through June, affecting the Shine Muscat’s quality and harvest volume.

Shine Muscat grapes were found to have developed the flowering issue in prefectures from the Tohoku region to Kyushu over the years, according to a survey conducted by the ministry in April. In 19 of the 30 prefectures, the Shine Muscat’s quality and harvest had declined.

There was no consistent trend, however, in the years or regions when or where the issue occurs, according to the survey. Among the possible causes suggested so far include weather conditions and the amount of fertilizer used.

As this might affect production and export of the sought-after grape, the ministry has commissioned the National Agriculture and Food Research Organization (NARO) and agricultural experiment stations of Yamanashi and four other prefectures to ascertain the actual situation and to elucidate the primary cause of the phenomenon.