On the Source of Rumex obtusifolius Invading Tame Pasture

Abstract

Rumex obtusifolius is noxious weed in tame pasture. In order to obtain the information for controlling the weed, the research was undertaken on its seed productivity and the invading source into tame pasture. Rumex came into flower from 3 to 14, June in Nishinasuno, Tochigi Pref. and the seeds came to mature about four weeks after the flowering time. The number of the Rumex seeds produced was very large-about 10, 000 per plant. It is apparent, compared with other references, that the flowering and maturing time depends on the climatic conditions, especially on temperarure. Previously, it was said that Rumex would invade tame pasture by means of the mixture with ladino clover seeds. So the mixture ratio of Rumex seeds in the commercial pasture plant seeds sold in Japan was examined. The pasture plant seeds, except for white clover, slightly contained other plant seeds and inert matter. Especially in ladino clover seed, there was no contamination of Rumex seed, whereas red clover and orchardgrass contained a few Rumex seed per 50g of the commercial seeds. These results indicate that the seed contamination could not be a dominant source of Rumex in tame pasture. Therefore, Rumex in tame pasture originates in the seeds produced by wild Rumex around the pasture.