BEIJING -- The prospect of a bumper rice harvest this year has been dimmed by a surge in plant diseases and pests this year, the Ministry of Agriculture said Tuesday.

About 350 million mu (23 million hectares) of farmland have been stricken by pests this year, up 21 percent year-on-year, according to data published on a website that monitors plant pests nationwide.

Large areas of southern China, where most of the country's rice is grown, are suffering from pests, according to the website. Hunan, Guizhou and Sichuan provinces are having their worst problem with agricultural pests in two decades.

In addition, various crop diseases have affected thousands of mu of rice, a more serious problem than in recent years.

The Ministry of Agriculture has warned of further problems in the second half of the year, predicting that farmland invaded by pests and crop diseases may top 1 trillion mu, a surge of 40 percent over 2011.

In response, the MOA has ordered agricultural authorities to share knowledge with farmers on how to deal with the problem.