Taiwan threatened to take China to the World Trade Organization on Sunday after Beijing announced that it would stop importing sugar apples and wax apples from the island due to pest concerns. The relationship between Taipei and Beijing, which claims to have democratically ruled Taiwan as its territory, has been the worst in decades, and China is increasing political and military pressure to make the island accept sovereignty. Chinese customs officials said they had repeatedly detected pests called “planococcus minors” in sugar apples (also known as sweetsop or custard apples) and wax apples from Taiwan. We requested the Guangdong branch...