The geographical distribution of sunflower diseases in China

In various areas of China, the fourth largest sunflower-producing country in the world, 25 sunflower diseases have been reported: 19 caused by fungi, one virus disease and five caused by different species of broomrape. Their geographical distribution and economic significance are discussed. Fungi are the most prevalent disease causing agents in every region. More species of broomrape have been recorded in China than in any other country in the world. Orobanche coerulescens has not previously been reported to attack sunflower but is an important cause of disease in China. The number of diseases recorded differs among the regions, with 14 in North-east China, 11 each in North, North-west and South-west China, 10 in East China and six in Central and South China. This distribution broadly corresponds to the intensity of sunflower production. Only Puccinia helianthi and Septoria helianthi are reported in all the regions; 64% of the diseases are restricted to one or two regions. Alternaria helianthi, Septoria helianthi, Sclerotinia sclerotiorum and Orobanche coerulescens are considered to be the most important, causing 10-50% losses in yield, and even crop failure in some areas in some years. Much work remains to be done on disease control to promote the development of sunflower production in China.